MEAT PRODUCT
Meat, an excellent source of protein, iron and B vitamins, was processed as early as prehistoric times, probably by drying in the sun and later by smoking and drying over wood fires. Homer, in 850 B.C., recorded procedures for smoking and salting of meat. The purpose of meat processing was to prepare products that could be stored for considerable time periods at ambient temperatures. The high salt concentration that was essential for meat preservation before the widespread use of refrigeration is no longer needed or desired. Today, meat is processed with salt, colour-fixing ingredients, and seasonings in order to impart desired palatability traits to intact and comminuted meat products. Intact meat products include bacon, corned beef, ham, smoked butt and pork hocks. Comminuted meat products include all types of sausage items. Products intermediate to these categories are sectioned, or chunked and formed meats.
CURING
Meat-curing agents include Sodium Chloride, Nitrite, Ascorbate or Erythorbate and possibly Sodium Phosphate, Sucrose, Dextrose, or Corn Syrup and seasonings. The salt content of processed meats varies 1-12%, according to the type of product. Salt is used for flavour, preservation and extraction of my myofibrillar protein, whereas nitrite promotes colour development, flavour and preservation by inhibiting the growth of microorganisms and fat oxidation. Erythorbate acts as a colour stabilizer, reduces fat oxidation and inhibits undesirable nitrite reactions. Phosphates facilitate myofibrillar protein extraction, inhibit fat oxidation and improve colour development sugars and seasonings are used principally for flavour.
COLOUR CHANGES
The most obvious characteristic of cured meats is the development of the characteristic pink colour on heat processing compared to the brown colour of uncured cooked meat. The colour result from a reaction between the heme protein myoglobin and nitrite. Other heme protein, such as hemoglobin and cytochromes, react similarly but are present in much smaller amounts.
Only 20-30 ppm of nitrite are required for colour development but higher concentration are needed to maintain colour.
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Current regulations permit the use of Sodium and Potassium Nitrates and Nitrites in meat and poultry products. However, the status of these chemicals as food additives is in doubt because of tests indicating the possibility of carcinogenic properties. Nitrates are generally no longer used except in some dry cured products and are not permitted in pumped bacon. Nitrites are limited to 120 ppm ingoing in pumped bacon and must be accompanied by Sodium Ascorbate or Erythorbate at no less than 550 ppm. Neither Nitrites nor Nitrates are permitted in baby foods.
PICKLE CURING
Pickle-cured hams are generally pumped before being placed in the curing vat, that is, pickling solution (pickle) is injected in to the ham in order to hasten diffusion of the curing ingredients throughout the ham. For short cures, hams and pork shoulders are generally artery-or stitch-pumped. In artery pumping, a special needle is inserted into the end of the exposed artery and pickling solution (about 15 wt% of the ham depending on product and process) is pumped into the vascular system. Pump pressures are 340-380 kpa (3.4-3.8 atm.)
In stitch or spray pumping, the brine enters the meat through numerous perforations in the walls of hollow needles. Most hams and bacon cured in the United States are injected with automatic, multineedle injectors through a number of fine hollow-stemmed needles arranged in a bank which automatically moves the needles into the product as it moves on conveyor belts. The amount of water added to cured meat products is determined by government regulations. Cured and smoked hams and bacon shall not contain more than uncured hams. Canned cured pork products may not contain more than 8% added water, whereas noncanned cured products may contain added water up 10% of the uncured product. To accelerate the distribution of the pickling solution within the product and improve cure uniformity, boneless hams may be tumbled or massaged after injection.
DRY CURING
This is an older method in which curing agents are rubbed in dry form over the surface of the cut of meat. The cuts are then stored and allowed to cure. For large cuts, the cure must be applied several times. Dry curing is now used only on specialty items such as country-cured hams and bacons.
COMMINUTION
Comminuted meat may be cured or a fresh product. The degree of comminution varies considerably from one product to another. Sectioned or chunked and formed products may be composed of particles that weigh more than 450g each, whereas finely comminuted meats are chopped to a paste like texture of very small particles. Comminution equipment includes grinders, silent cutters, emulsion mills and flaking machines. In addition to comminution the meat is blended with other ingredients. Blenders, mixers, tumblers and massagers are used to subject the meat protein to mechanical action in the presence of salt. This causes the salt to extract the principal myofibrillar protein, myosin, from the muscle. The extracted myosin gels when the comminuted meat is heated to form a matrix, which entraps water and fat and binds the meat particles to each other.
Comminution reduces the raw meat material to small meat pieces, chunks, chips or slices. Sausages are comminuted, seasoned meat products that may also be cured, smoked, molded heat-processed. They are classified according to the processing methods used for their manufacture.
Large particles or chunks of meat can be massaged or tumbled in the presence of salt and phosphate (usually Sodium tripolyphosphate or hexametaphosphate) to extract salt-soluble proteins that form a tacky exudates which acts as a heat-set glue to bind the chunks of meat together after cooking. This method is used to prepare chunked and formed hams, roasts, and steaks. This is a growing area of production because it permits the manufacture of products that have the composition, shape and size preferred by the consumer.
SMOKING
Many intact and comminuted, cured meat products are smoked to impart a desirable smoked flavour and colour. The smoking process many also include a drying or cooking cycle, depending on the product.
The smoking process imparts a characteristic flavour to product. In addition, some phenolic compounds present in smoke provide protection from fat oxidation. Further protection is provided by the bacteriostatic effect of smoke components along with the drying effect that inhibits bacterial growth on the dried surface.
Modern processes use forced-air smoking chambers with close control of time, temperature and humidity. The processing cycle many include predrying, smoking, cooking, drying and cooling. Smoke is generated by electrical smoke-heated generators, which offer close control over temperatures and hence smoke composition or liquid smoke may be used as an atomized spray or regenerated smoke. Smoking chambers are designed for batch or continuous processes.
Oil or water-based liquid smoke can be added directly to the products as a flavouring in lieu of the smoking process. Oil-based liquid smokes are used when the product is sensitive to the low PH of water-based liquid smokes and to ensure penetration of the smoke components into the fat phase.
CANNING
Canned meats may be processed to be commercially sterile or semipreserved. The objective of commercial sterilization is to destroy all harmful bacteria or bacteria that may cause spoilage of the product under normal unrefrigerated storage. However, the process does not kill the spores of all heat-resistant bacteria.
Therefore, it is essential to cool the cans rapidly after processing and avoid storage above 35°C. The most persistent type of bacteria are sporeforming organisms. The common vegetative and nonsporeforming pathogenic bacteria are killed with adequate processing and are of little or no importance in spoilage.
The amount of heat, time and temperature required for a given degree of sterility depends upon the nature of the product, the PH curing salts, shape and size of the can and the type of heat processing retort used. Some products are packed into the can hot and others cold. Hot filling eliminates the need to apply a vacuum during can closure. The vacuum is necessary to avoid excessive strain on the can and its seams during processing and to minimize oxidative spoilage of the product.
Semipreserved or pasteurized products depend on curing and chilled storage for their preservation.
FREEZING
Frozen meat can be kept at low temperatures for many months. Freezing and subsequent thawing produce changes in the structure of meat that affect its physical properties. If meat is frozen very rapidly at low temperatures, the ice crystals are small and form within the fibers. The drip loss upon thawing is generally greater in slow-frozen than in quick-frozen meat. The rate of freezing is determined largely by temperature, freezing system and shape of the cut. Holding a quick-frozen product at high and fluctuating temperatures encourages the growth of ice crystals and protein denaturation and the advantage of low drip loss from rapid freezing is lost. The amount of drip in meat is further affected by temperature and length of storage, meat surface, thawing rate and the physiological condition of the muscle at slaughter and
Packaged frozen meat cuts are sold in the retail markets to a limited extent and stored both consumer in home freezers. Beef retains good quality for a year or more and pork for six months if properly packaged and stored at- 18 to-23°C. Freezer burn or dehydration and discolouration can be prevented with packaging systems that cling closely to the product surface and restrict movement of moisture from the product surface and the diffusion of oxygen into the product.
DEHYDRATION
Freeze-Drying
Freezing drying of meat results in a product with a sponge like appearance, practically devoid of moisture but resembling the original product. The composition and type of meat influence the acceptability and stability of freeze-dried meat.
Freeze-drying meat extends shelf life and reduces weight. The meat is readily defrosted by immersing in water before cooking. Under optimum processing and storage conditions, reconstituted meats have acceptable flavour, colour, texture and nutrient retention.
Freeze-drying does not entirely eliminate changes in meat products during processing and storage. Enzymic changes are reduced but not completely eliminated. Deteriorative changes include some loss of vitamins, protein denaturation, browning and fat rancidity. To avoid deterioration it is essential that the product is packaged under an inert gas, in moisture, gas and light impermeable.
AIR-DRYING
Precooked comminuted lean meat is dried in a forced-air rotary or tunnel dryer to less than 10% moisture for use as an ingredient in dried soups and stews. The dried product is often compressed to reduce its volume to about one third of the fresh meat volume for shipment.
BY-PRODUCTS
By-products in the meat-packing industry represent a substantial part of the sales value of the production derived from the slaughter of animals. By-products include variety meats, edible and inedible fats and hides and other inedibles. The value of meat or by-products depends upon the species and age of the animal, degree of finish and price.
Approved portions of the carcasses of clean, sound meat animals yield edible fats including lard (from swine), edible tallow (from cattle and sheep) and related products such as oleo stock. These may be consumed in the form of shortening for baking and similar food applications, or as frying fats.
Inedible fats are used widely in animal feeds and for other industrial uses. The principal products of this type are inedible tallow and grease.
Among the important nonfat by products are hides, skins, hair, wool, dried blood, bone, glue, gelatin, casings, sutures, tennis racket strings, pharmaceuticals, enzymes and hormones.
The efficient utilization of by-product is essential for the economic operation of a packing plant.
FAT EXTRACTION
Wet Or Steam Rendering
In this procedure, the raw materials are cooked in a closed vertical tank under pressure by direct steam injection, typically at 380-500 kPa (3.8-4.9 atm) for 3.6h. The tallow is drawn off from the top of the vessel after it has been allowed to settle for several hours. The process was used mostly for hard raw materials such as bones but is being replaced by modern methods.
Dry rendering
Both batch and continuous processes are available for dry rendering. The material is heated in a horizontal steam-jacketed cooking vessel equipped with rotating arms to agitate the material. The moisture driven off is usually vented through a condenser to recover heat and control atmospheric pollution. At the completion of the rendering operation the fat is separated from the cooked material (tankage) by basket centrifuges or expellers in batch processes and by continuous centrifugation in continuous processes. Bones are coarsely crushed before rendering. Viscera should be washed of their contents and should be rendered with minimum delay to maximize tallow quality in terms of colour and free fatty acid content.
Low Temperature Rendering
High-quality fats are produced by semibatch or continuous processes and the defatted residues may be used in some processed meat products. The raw material is first comminuted and then heated to about 45-50°C. The fat is then separated by centrifugation.
Fat Processing
After rendering, the fat is usually further processed outside the meat-processing plant. Depending on the desired product fat, the fats may be hydrogenated, bleached, deodorized, plasticized, interesterified or fractionated.
Unsaturation in the fatty acids is eliminated by hydrogenation in the presence of a catalyst under carefully controlled temperature, pressure and mixing conditions. Hydrogenation raises the melting point of the fat and modifies the plastic rang.
Bleaching can be achieved by liquid extraction, hydrogenation or treatment with absorbents.
Odiferous substances are removed by steam-stripping at 150-250°C under high vacuum. Free fatty acids also are removed by this process which yield a bland fat with a high smoke point.
Plasticizing imparts desirable textural properties to fats. The process often involves chilling the fat through its melting range to promote the formation of crystal nuclei, followed by mechanical working to inhibit the growth of large fat crystals. The fat is then tempered by holding it for a certain time at and appropriate temperature. Tempering inhibits subsequent crystal growth because of fluctuating temperatures below the fatâ€TMs melting point.
Interesterification rearranges the distribution of fatty acids on the glycerol moiety of the fat molecule. It is used particularly in shorting manufacture where it imparts desirable baking properties to the fat.
Fractionation involves separating animal fat by fractional crystallization into oils and fats which have specific applications.
CHAPTER 3
FLAVOUR AND TENDRENES
Typical ripe flavour overtones are missing in unaged meat. True beef flavour, for example, is fully developed after at least one week of aging. At the same time, as the bouquet develops the meat becomes more ana more tender. Ripe flavour develops during the normal aging process at low temperatures, which, as described in the previous chapter, is a slow and wasteful process.
As the methods in this chapter describe, natural flavour development and tenderization can be accelerated considerably by fungal and bacterial proteolytic enzymes, the process being complete in only a few days. About by a combined action of various flavouring and tenderizing agents.
SINULTANEOUS FLAVOURING AND TENDERZING ACTION OF MOLDS AND BACTERIA
A mold species, Thammidium elegans, seems to be quite useful for flavour development and tenderizing of meats, it imparts a black walnut taste to the meat which is characteristic of carefully and properly aged meat having rich, mellow flavour. The bacteria Pseudomonas and Achromobacter may similarly be applied. Aspergillus nigar, on the other hand, is said to enhance the flvour of meats without tenderizing; tenderizing is accomplished by prerigor mortis water injection with the mold.
Action Of Thammidium Elegans
Williams; has found that beef can be properly ripened and tendered, with improved colour, in approximately 48 hr if, after rigor mortis, the beef is introduced at a temperature of approximately 35°F into the meat-ripening space having airborne Thamnidium where the temperature of the meat is raised to approximately 60° to 75° F in less than 8 hr; then held at temperatures of approximately 65° to 75° F for 32 hr or more; and then reduced to approximately 32° to 35° F in less than 8 hr.
During the meat-ripening cycle the relative humidity is maintained above 90% and up to 100% saturation including supersaturation for all or part of the time cycle. During the cooling portion of the cycle the air in the meat-ripening space is sterilized to kill or inhibit the growth of undesirable mold and bacteria in the atmosphere.
During the cycling of temperature described on the previous page, the air in the space where the chilled meat is being ripened increases in temperature to approximately 70° to 75° F in 4 hr or more and during the cooling cycle decreases in temperature from approximately 70° to 75° F to approximately 33° to 35° F in approximately 4 hr, more or less, depending upon the meat load or volume of meat to volume of air space.
Thamnidium may be introduced both during the heating cycle of approximately 8 hr and during the holding cycle of approximately 36 hr. The presence of Thamnidium controls bacterial action even at the relatively high temperatures. Thamnidium is introduced into the meat aging space as by spraying in a glycerol suspension from an aerosol-type bomb. The same timing mechanism that times the heading, holding and cooling cycle in the meat-ripening space may also be employed to periodically actuate the atomizer for Thamnidium. Other means for introducing Thamnidium into the meat-aging space can be employed.
In view of the relative shortness of time during which Thamnidium is active in the processes, approximately 44 hr, practically no mold appears on the surface of the meat since about 4 days are required for the hyphae or whiskers of the mold to appear. However, the mycelia of the mold grow into the meat during the entire cycle enhancing the flavour of the meat. Thamnidium, by inhibiting bacterial activity which causes darkening of meat, actually contributes to the brightening of the colour of the meat.
As noted above, during the cooling cycle of approximately 4 to 8 hr, the atmosphere within the meat-ripening space is sterilized to destroy bacteria in the atmosphere which are deleterious to the meat. This sterilizing action is preferably continued until the end of the meat-ripening cycle, until removal of the meat from the ripening space, and until the ripening space is again filled with meat to be ripened. Thus, at the beginning of the ripening cycle, the air in the ripening space is substantially sterile. Both mechanical means and /or chemical sprays may be employed to sterilize the air in the ripening space during the cooling cycle.
For example, electrostatic precipitation may be employed, and/or propylene glycol or tributyltin oxide may be sprayed periodically in to the ripening space. Here again, the timing mechanism employed to regulate the meat-ripening cycle may be employed to periodically spray the chemical sprays into the meat-ripening space during sterilization of the atmosphere, or may be employed to actuate the electrostatic precipitator, or actuate combinations thereof.
Pre-Rigor Mortis Injection Of Aspergillus Niger Mycelium
Research and Development Company has discovered that the favour of meats can be greatly enhanced with improvement in tenderness by the use of the mycelium of the Aspergillus mold, particularly the Aspergillus niger used in citric acid production process. The bland or green flavour of meat is converted to an aged flavour without in any way detracting from other desirable qualities of the meat.
The appropriate time to inject the mycelium of Aspergillus niger into the carcass is immediately after slaughter while the tissues are still fluid and flaccid and before incipient rigor mortis. The amount of fluid containing the mycelium injected into the carcass is preferably proportional to the normal moisture loss during chilling of the meat being treated. It is known that carcass beef loses approximately 1% of its natural moisture during the first 24 hr in the cooler and another 1% during the next 5 to 7 days.
The quantity of fluid containing the mycelium should be equal to and not less than the amount of moisture lost by the beef during ordinary commercial practices. The fluid containing the mycelium serves to replace the moisture lost by the beef during chilling and cold storage and the beef is not softened or unduly moistened by addition of an amount of fluid equivalent to the amount of moisture lost by the beef.
It is preferred to introduce the mycelium in its fluid or aqueous carrier into the meat to be treated by injection. The fluid containing the mycelium is introduced into the carcass through a hollow needle which is introduced into the portions of the carcass to be treated at rather closely spaced intervals.
A representative eviscerated carcass of beef may weigh approximately 600 Ib and when divided into halves, each side will weigh approximately 300 Ib. such a carcass will lose approximately 6 Ib of moisture initially or 3 Ib of moisture for each side. Therefore a minimum of 3 Ib of the tendering fluid containing the mycelium is used for each side and a maximum of up to 6 Ib of the fluid may be employed. An average for such a side of beef is 4 Ib of the fluid containing the mycelium.
The fluid is introduced by stitch pumping. The 4 Ib are distributed into the half carcass by injecting approximately a pound of the fluid into the round; another pound is pumped into the muscle of the loin; another pound is pumped into the rib; and the remaining pound is pumped into the chuck and distributed through the neck and front shank. This provides adequate distribution throughout the entire carcass and results in uniform flavour enhancement of the beef.
After the meat has been treated in accordance with the process described above it is chilled in the normal way and handled by conventional practice. When the mycelium containing fluid is pumped into the meat there will be no trace of the fluid since the warm, fluid, flaccid muscles before rigor mortis absorb and distribute the fluid without trace. The mycelium of Aspergillus is sterilized to kill any living organisms and is then dried and powdered before introduction into solution and so does not require freezing or cooking to prevent overflavoring of the meat. Meat exhibits enhanced aged flavour within a short time after treatment of the carcass.
The fluid containing the mycelium of Aspergillus is introduced into the warm carcass on the killing floor at a temperature approximating 118 F. Carcasses of beef, lamb, veal, pork and other animals when first killed and dressed have a normal body temperature of approximately or above 98.6° F. If the fluid containing the mycelium is introduced into the meat at a temperature above 98.6° F or normal animal body temperature, and below a temperature which would cause searing or cooking of the meat, 120° to 125° F, the fluid will elevate the body temperature of the normally dressed meat and will improve the colour and appearance of the meat and will improve the colour and appearance of the meat as well as activate the natural enzymes thus causing an improved and accelerated aging and flavouring action.
The additional heat introduced by the fluid containing the mycelium and heated to approximately 118°F has beneficial effect of keeping the carcass warm for an hour or more of treating time, providing better distribution throughout the carcass of the flavouring fluid.
Improvement of tenderness is probably mainly due to the action of water injected under pressure. However, it probably can be partially attributed to the action of mycelium of Aspergillus.
The mycelium of Aspergillus is readily obtainable. A number of processes have been developed whereby a solution of sugars of various kinds is inoculated with Aspergillus niger for the purpose of producing citric acid. A mat consisting primarily of the mycelium of the fungus grows on top of the solution and through reactions which are not thoroughly understood the sugars are converted, to a greater or less extent, to citric acid. The efficacy of the fungus falls off rapidly when it starts to sporulate.
When this occurs the mat is removed, placed in a filter press, and the moisture, including the acid and remaining sugars, is expressed from it insofar as possible. The mycelium mat is a waste product which is available in large quantities. The mycelium mat may or may not be washed prior to the filtering in order to remove as much as possible of the sugar and citric acid solution, but whether it has been treated in this manner or not appears to make no difference in the flavour of the resultant meat product.
The resultant mycelium mat or filter cake, which may be obtained in this fashion, it then thoroughly dried and ground to the desired particle size. The degree of grinding is largely a matter of choice. Fairly coarse particles may be used or the mat may be completely pulverized. The preferred size of particle is approximately the same as that of ordinary table salt, or such as facilitate suspension and solution in the injection medium.
The ground, dried mycelium may be mixed with a substantially equal amount, by weight, of table salt (or other suitable taste or flavour additives), the two ingredients being thoroughly mixed. The proportions are not at all critical, but the average taste seems to be best met by equal proportions; enough of salt to taste the meat with sufficient Aspergillus flavour to give the meat the required zest.
It is no necessary to include salt with the mycelium, except that it might be helpful in preserving it while dry and is also not unbeneficial to the meat. Salt has some tenderizing effect upon meat. The meat seems somewhat more tender and juicy because of the hydroscopic properties of the salt in drawing and holding moisture.
The amount of mycelium which produces best flavouring results in the range of 0.05 to 0.2% of the weight of the carcass. Using 0.2 (600Ib beef), 19.2 oz or 540 g would be used per carcass. This is dissolved in an amount of solution equal to about 1% of the carcass weight or about 6 pints of fluid per carcass. Six pints of fluid equals 2,839 g containing 540 g of mycelium product, or 18.10%. The amount of salt added to this is discretionary, but within the limits, perhaps somewhat lower than is normally used on meat, so as to permit additional salting during cooking or at the table, without making the meat too salty.
Acid Activation of Thamnidium Elegans
Research and Development Company describes the discovery that the mold Thamnidium may be used in the home to age and impart flavour to meat within a period of 12 to 48 hr. the elegans strain is one of the four better known strains and is paiticularly efficacious for this process because of its activity at room or home refrigerator temperatures, its hardiness and its stability.
The mold Thamnidium, when in contact with meat, readily propagates and secretes a proteolytic enzyme. This mold, or more likely, the enzyme, functions to age the meat and to improve the flavour, imparting to the meat the highly desirable black walnut flavour and the accompanying rich, full flavour so well known to connoisseurs. This action of the mold can be activated or accelerated under room or home refrigeration conditions by the addition of an edible organic acid such as citric acid or tartaric acid thereto. The elegans strain is particularly desirable because it is psychrophilic or cold-loving and is particularly active at room or home refrigerator temperatures (32° to 50° F). It is rendered dormant at freezing temperatures and fails to grow at temperatures around 75° F. It is killed at temperatures approaching 100°F or above.
Referring to figure 1, the process is practiced by placing a cut of meat, such as the steak 10, on a rack 11 supported on a tray 12 having a removable cover 12, contained within the tray is the Thamnidium, which may be contained in a generally rectangular pillow 13 consisting of a previous mildewproof fabric cover 14, preferably of a material such as nylon or ramie netting, encasing an absorbent base material 15. The base material, which is preferably sawdust, shavings or, as shown, a cellulose sponge in particuiate form, is impregnated with the mold Thamnidium, preferably organic acid.
The amount of acid is not especially critical but should be maintained within the range of 1 to 10% based on the weight of mold used. The allow is preferably provided at one end with a pair or strings 16 for conventence in maintaining the pillow in the rolled from the storage, as shown in figre 1c and 1d.
In certain aspects the Thamnidium with edible acid may be absorbed in sawdust alone. Thamnidium may be cultured on a clear plastic base, provided with a suitable potato dextrose agar for growth of the mold and this assembly provide in the pillow under the absorbent base material. Alternatively and preferably, the mold is prepared in a suspension which is absorbed by the absorbent base material. Preferably, the citric or other organic acid in the form of a powder is sprinkled on the base.
The Thamnidium-impregnated base is most conveniently marked by wrapping it in a suitable moisture proof, relight covering, soon as ellophane (not shown), upon which is imprinted complete directions for use by the boutendor. Upon removal of the wrapping, exposing the base to the air, the base is hundred with one teaspoon of water in order to dissolve the citrisied and thus …mold.
The base is then put into the try, as shown and the entire assembly covered and left at room temperature or placed in the refrigerator. Thamnidium, being airborne, will rise and contact the surface of the uncovered meat. Saing protostele, the mold will have no affability for anything in the refrigerator except the meat. The mycelia will grow into the meat thus imparting the aged flavour and to some extant, tending to improve the tenderness and palarability of the meat. Preferably the meet is turned over once during me treatment period, which should perform 12 to 48 hr. Depending upon how much aged flavour is desired for the particular cut of must.
After use of the impregnated base it is best to store it in the moisture proof sirtignt wrapping at room temperature. The effectiveness of the base may last for many months and through many reuses. It stored in the freezer it will gradually lose its effectiveness. Six months storage at 0°F killed off 80% of the Thamnidium spores.
Example: Two identical unaged steaks, I thick were cut from a strictly fresh beef loin, A base as generally described before was prepared by thoroughly dampening the base, white ping sawduer, with a suspension of Thamnidium containing % by weight of citric acid. The culture had been grown on slants of pomtodextrose-agar and spores and bits of the hyphae were used to produce a heavy luxuriant growth. A suspension, in 25% solution of glycerol in sterile distilled water to which was added the % of citric acid, was made.
One of the steaks was placed on the rack several inches above the mold-containing base and the assemble was covered and placed in the refrigerator in an area maintained at about 40° F. The other or second steak was placed in a different refrigerator so as to avoid any contact by Thamnidium. The first steak was turned once during the treatment period of about 48 hours, so as to expose both sides to the direct airborne action of the moid.
Following this treatment, both steaks were cooked and sampled. Before cooking, it was observed that the second (untreated) steak had the normal poor appearance of meat held for two days in the refrigerator, i.e. it had large areas of gray rixed with the red, indicating the usual bacterial contamination. This steak has a rather old odor. The first (treated) steak was of a deep, rich, red, uniform colour with no noticeable bacterial contamination are with a well-aged odor i.e., the characteristic black walnut odor noticed when a well-aged loins e.g., hung for 21 to 35 days at 34°F is first opened up.
In comparing the cooked steaks, it was observed that the untreated steak, although good, was somewhat bland, whereas the treated steak seemed more tender, tasted like a much better piece of meat and had a rich, full- bodied flavour, all the characteristics of four or five weeks of aging.
Anta-Mortem Injection or Thamnidium and Aspergillus
If controlled amounts of Thamnidium and Aspergillus are injected into a living livestock animal in a physiological saline colution, thase live, active, viable organisms are distributed throughout the meat by the vascular system of the animal. After injection the livestock animal may be held alive for up to about 41 hour and then slaughtered. The carcass is then chilled and neld in a cooler for aging, that is, to permit the development of the mold spores within one tissues of one meat.
Hodges Research and Development Company has discovered that the retail cuts of meat from the carcass will show uniform improvement both in tenderness and in flavour. The Thamnidium injected into the living animal. Producers a delectable aged flavour in re meat the Aspergillus injected into the living animal, working synergistically with the Thamnidium, produces greatly improved tenderness in the meat.
The mold species belonging to the Thamnidium alegans and Aspergillus oryzae groups are preferred in this process because these organisms are nonpathogenic and will grow and elaborate the desired proteases in standard media and transplants will grow and flourish under ordinary laboratory procedures. Furthermore, Thamnidium and Aspergillus spores are both psychrophilic or cold-loving and are therefore able to carry out their functions of flavouring and tenderizing the cold meat at the temperature range in the usual cooler of 34° to 40°F.
The amount of Thamnidium and Aspergilus to be injected into the livestock animal may vary from 500 to 1,000 spores total of these molds per milliliter of the animalâ€TMs blood. Assuming that an average beef cattle has 10 liters of blood, the physiological aline injected coluion should contain from 5,000,000 to 10,000,000 spores total of these molds. These molds are usually used in equal amounts in the solution but variations from this ratio may be used.
It should be kept in mind that the Thamnidium mold contributes more to flavour than to tenderness while the Aspergillus mold contributes more to the tenderness of the meat than to its flavour. The satine solution is preferably of sterile distilled water having an isotonic salinity of approximately 0.8% NacI. Approximately 50 ml of the saline solution containing these molds is vascularly injected into the average beef cattle at 5 ml for each liter of blood.
Example: A. U.S. Good grade beef steer weighing approximately 1,050 1b and producing a 600 1b beef carcass consisting of two split, dressed sides of 300 1b each was injected with an isotonic blood-level temperature sline solution containing approximately 5 million.
Viable spores each of the molds Thanmidium elegans and Aspergillus oryzae. The live animal was restrained and an incision made in the jugular vein to permit the bloodstream to accept the alien solutions. Without difficulty, over a period of about 5 min, the entire 50 milliliters of solution was injected and gravity drained into the jugular vein and thereafter circulated throughout the vascular system to the venules, capillaries and arterioles of the flesh of the animal. Approximately 30 min after the injection, the animal was slaughtered and dressed in the usual manner and the two sides of beef were placed in a regular cooler for conventional chilling.
As a control for the process, a similar steer of like age and weight from the same feederâ€TMs lot was selected, held and slaughtered immediately following the treated steer. The two cattle were held in the same cooler under identical conditions for 10 days. Comparable steaks and roasts were cut from comparable sides of each beef at 2,5 and 10 day periods, rated for appearance, colour and other visual characteristics, then cooked similarly and compared organoleptically by a panel of meat experts. In all cases, the panel preferred the treated meat and rated it higher on their score cards both for tenderness and flavour. The improvement in flavour was more significant than the improvement in tenderness although tests made on a Warner-Bratzler shear machine of cylinders of meat cooked to 155°F indicated less resistance and therefore more tenderness for the treated meat.
CHAPTER 7
PRESERVATION : MOISTURE RETENTION AND SURFACE PROTECTION
A serious concern of the meat industry is the control of surface deterioration and shrinkage which results in large monetary loss. In the aging of beef, for example, excessive surface dehydration of the carcass or primal cuts makes it necessary to trim away the deteriorated outer portions in order to place the meat in a salable form.
Frozen meats are subject to a condition known as “freezer burnâ€. Frozen meat, when unprotected by a suitable packaging material, develop an objectionable surface texture and off-colour due to surface dehydration. There are methods of meat processing which limit the amount of moisture lost from the meat and protect the surface of fresh meats.
LONG CHAIN HYDROCARBON COATING
The preservation of the surface properties and the reduction of shrinkage of fresh meat involves several problems. Obviously, moisture evaporation must be prevented. Furthermore, the material used in this connection should permit the passage of atmospheric oxygen in order to maintain the meat surface pigments in oxygenated form. Hence, the material should be moisture-impermeable and, at the same time, sufficiently airpermeable. Long chain hydrocarbons seem to form a suitable coating which provides a barrier for reducing moisture loss.
Fatty Alcohol or Fatty Acid Protective Film
This process relates to an improved manner of handling meats, including carcass meat, primal cuts and other fresh meats, to reduce shrinkage attributable to the loss of moisture and to lessen freezer burn in frozen meats.
Swift & Company discovered that the holding of meat coated with a thin film of a fatty compound having the formula R-OH or R-COOH, where R is selected from the group consisting of an aliphatic radical or an acyl radical having from 11 to 12 carbon atoms or with a thin film of ethyl stearate will reduce the moisture loss normally experienced in the handling of the meat. The film of the long chain fatty compound is believed to be monomolecular in thickness and may be conveniently formed by the application of an aqueous dispersion of the compound to the meat surface preferably by spraying.
The aqueous dispersion is preferably an emulsion of the fatty material in water although the aqueous dispersion may be prepared by dissolving the fatty material in the water with the aid of a common solvent, such as ethyl alcohol. The use of the aqueous dispersion is important to the successful application of the material to form an air-permeable moisture-retarding barrier. The suitable materials are waxy, crystalline flakes or needles of high melting points which cannot be satisfactorily applied to the meat, except through an aqueous dispersion, to form the necessary monomolecular film.
The fatty alcohols and fatty acids of the foregoing formula vary considerably in their effectiveness in this process. Among the preferred materials are the fatty acids and alcohols having from to 16 to 20 carbon atoms inclusive and mixtures of those materials. The C10 to C20 materials will generally be found to provide the greatest resistance to water evaporation. Particularly suitable compounds include octadecanol, hexadecanol (commonly known as cetyl alcohol), stearic acid (octadecanoic acid), and arachidic acid (eicosanoic acid) as well as the ester ethyl stearate. The saturated alcohols and acids are usually more effective than the unsaturated materials of like carbon number; for instance, stearic acid is preferred to oleic acid.
Other fatty acids that may be employed include lauric, tridecylic, myristic, palmitic, margaric acids and the higher fatty acids such as the C20 and C22 fatty acids. The corresponding alcohols for example, dodecanol tridecanol etc. may be used but generally the fatty acids and alcohols, below the C16 to C20 carbon range are less effective than those of that preferred range. Dodecanol for example offers a relatively low resistance to moisture evaporation, being less than about one-sixth as effective as cetyl alcohol. Hexadecanol and octadecanol are particularly desirable materials and may be expected to reduce shrinkage from 30 to 70% of that experienced in their absence. Arachidic acid is also a particularly effective material.
The fatty material forms a thin invisible film on the surface of the meat which is permeable to air thus permitting the maintenance of the bloom on red meat. The material does not adversely affect the protein or fat of the meat nor does it impart an objectionable surface texture. The fatty compounds are readily applied with little labor and their use lessens the need for expensive humidity adjusting equipment. However, the process may be used in comunction with the maintenance of a high humidity, thereby still further reducing shrinkage loss. The fatty material in the amount needed is inexpensive and is generally effective at the temperatures at which meat is commonly held.
The aqueous emulsion may be prepared in the following manner. Equal weights of cetyl alcohol (hexadecanol) for example, and any of certain edible emulsifying agents are mixed together, after first heating both the emulsifying agents and the cetyl alcohol to a temperature in excess of 49°C. The warm mixture is then agitated with water in a mechanical shaker or a blender until the cetyl alcohol is placed in aqueous emulsion. In an alternative, the emulsifier may be added to the warm water and then heated cetyl alcohol introduced and the mixture shaken to form the emulsion. There are many emulsifiers suitable for use, among these are the edible partial fatty esters of polyhydric alcohols, including propylene glycol and glycerol.
The suitable emulsifiers include monoglycerides, diglycerides and mixtures thereof. A preferred emulsifier contains approximately 40% monoglyceride, 40% diglyceride and 20% triglyceride. An esterified mixture of lactic acid and glycerol may also be employed.
It is possible to prepare an aqueous emulsion without the aid of an emulsifier. In this instance, the cetyl alcohol or other material is added to water at an elevated temperature of about 90°C, and the mixture violently shaken or stirred. This will yield an emulsion, which will be suitable until the temperature reaches approximately 50°C; hence the emulsion should be sprayed immediately or the meat dipped before the temperature has dropped. It is recommended, when using such an emulsion, that a fine orifice spray not be employed. A colloidal mill may be advantageously used for the preparation of the stable emulsion.
The fatty acid alcohol, or ethyl stearate may be applied in water dispersions of remarkably low concentrations. These materials when applied to the meat surface in a dispersed water phase have the ability of forming an apparently continuous monomolecular film. Concentrations of 50 to 1,000 parts of the fatty material per million (ppm) of water have been profitably employed. However, emulsions of greater and less concentrations may be used with varying degrees of effectiveness.
Example, 1: Fatty mg of cetyl alcohol (hexadecanol) was dissolved in 1 ml of ethyl alcohol and the solution stirred into 1 liter of water having a temperature of approximately 70°C. Two pieces of beef from the same primal cut were obtained and one was dipped into the aqueous solution. The other piece was used as a control. The results of this experiment with the weights at 0, 24 and 48 hours. The treated sample had a fully acceptable colour and texture. No effort was made to adjust the humidity of the refrigerated room.
Example 2: A ewe carcass was split in half and one-half was sprayed with 75 ml of 50 ppm of an aqeous cetyl alcohol emulsion. Much excess liquid drained off of the carcass. The emulsifier used was a 40-40-20 mixture of mono-,di-, and triglycerides. The refrigerated space has a low humidity.
There was no difference in colour between the two sides of the split carcass and the meat in all respects presented an acceptable appearance. Aqueous octadecanol or arachidic acid emulsion as well as ethyl stearate emulsions will provide comparable protection. In each instance the emulsion can be prepared as described in either example 1 or example 2.
Example 3: The work of this example demonstrates the advantage to be had in the use of cetyl alcohol in connection with frozen meat. Frozen meats frequently exhibit an objectionable off-colour and texture described as freezer burn. Two pieces of beef, unfrozen, were selected and one piece was dipped in a 40-ppm aqueous emulsion of cetyl alcohol. The two samples were placed in an open display retail type freezer and held at 0° F for 72 hours and at the end of that period the control sample had a freezer burn of a degree that would have made it unsalable. The cetyl alcohol treated meat had an acceptable appearance and evidenced a pronounced improvement in colour and texture of the meat surface over the control sample. It is recommended that the aqueous emulsions be applied to the meat before freezing.
Preliminary Ice Coating
T.R. Anderson; has found that the usefulness of the fatty film on frozen meat may be improved by first coating the meat with ice and then forming the moisture retarding fatty film on that ice. It is believed that the fatty film, when used on frozen meat, to be effective, or at least to be most efficient, requires the continued existence of an ice layer intermediately disposed of the meat and the fatty film itself.
An ice layer is seemingly necessary for the proper alignment or orientation of the fatty molecules making up the monomolecular film. By first coating the meat with ice and then forming the fatty film, there is provided a considerable reserve of water needed for prolonging the effectiveness of the film. Where the fatty film has been formed by the simple application of an aqueous dispersion of the fatty material to the meat (without first forming an ice coating) the underlying ice is apparently made up of the water of the originally applied aqueous dispersion and the monomolecular film then becomes much less effective in retarding sublimation of moisture from the meat.
The ice glaze or coating may be formed by either spraying or dipping of the meat in water. In the instance where the ice coating is a lamination of ice layers, the lamination is built up through the multiple applications of water with each application followed by a freezing before the meat is again dipped or sprayed. In some instances, it may be profitable to freeze a block of ice around the meat.
Moisture loss from frozen meat may adversely affect its quality. Freezer burn caused by intense local drying in cold storage results in an objectionable whitened and wrinkled condition. With prolonged storage the drying may extend to the interior so that the flesh becomes loose and inelastic. The process will greatly reduce shrinkage and freezer burn.
The moisture-retarding film is formed of a saturated aliphatic compounds having the formula R-OH, R-COOH, where R is an aliphatic radical having at least 11 carbon atoms. Ethyl stearate may also be used. The fatty compound may be applied in the form of an aqueous dispersion, for example, an emulsion of the fatty material in water. The aqueous dispersion may be prepared by dissolving the fatty material in the water with the aid of a readily volatile solvent, such as ethyl alcohol. The suitable materials are, for the most part, waxy, crystalline flakes or needles of high melting points which cannot be satisfactorily applied to the meat, except through a dispersion, to form the necessary thin film.
The fatty acid, alcohol or ethyl stearate may be applied in water dispersion of remarkably low concentrations. Concentrations of 30 to 1,000 parts of the fatty material per million (ppm) of water have profitably been employed. However, dispersions of greater and less concentrations may be employed depending on the particular material used. The coating procedure with a fatty film is fully described by Anderson in U.S. Patent 2,948,623 previously discussed.
Intermediate Glycerol Layer
Film-forming fatty materials such as cetyl alcohol (hexadecanol), arachidic acid and octa-decanol form a thin film, believed to be monomolecular in thickness, on meat which significantly slows the loss of moisture from the meat. The film forming material is applied to the meat through an aqueous dispersion.
T.R. Anderson; has found that the fatty film may be formed through the application of a glycerol dispersion of the fatty material to the meat surface. Preferably, the application is achieved with the use of a glycerol-water dispersion (25 to 50% volume glycerol concentration) of the film-forming material. The dispersion may be prepared through the use of an emulsifier or of a readily volatile solvent, such as ethyl alcohol.
The presence of the glycerol on the surface of the meat is also thought to serve a useful purpose in maintaining the molecules of the fatty film in the proper orientation necessary to the continued effective existence of the film. The film formed by the fatty material on meat is believed to be monomolecular in thickness and to depend upon the presence of an intermediate layer (between the meat and fatty film) of polar material, e.g., water for its existence.
The various fatty materials, suitable for use in the formation of the moisture-retarding film, each possess a polar group in their configuration of atoms; for example, hexadecanol has an OH (hydroxyl) group at the end of a 16-carbon atom chain. The polar group is hydrophilic. The carbon chain being hydrophobic is repelled by water. The results is an alignment of the fatty film molecules, with the polar groups of the fatty molecules being attracted to the water (of the intermediate layer) and with the long carbon chains standing on end more or less perpendicular to the water surface and closely packed. The closely packed, erect fatty molecules retard the escape of water vapor from the water surface (and hence from the meat) so long as the molecules are aligned and compressed together.
The following is offered as a possible explanation of the process. Glycerol is suitable for use as the material of the intermediate layer (disposed between the meat and fatty film) because of its three hydroxyl groups and low vapor pressure. Glycerol has solubility characteristics similar to water and may be substituted in whole or in part for the water in the intermediate layer. The presence of the several hydroxyl groups in glycerol attract the polar groups of the various film-forming fatty materials and repel the long carbon chains of those compounds.
In shorts, the film-farming materials act towards glycerol as they do towards water, forming a moisture-retarding film. The low vapor pressure of glycerol assures the continued existence of the intermediate layer to support the fatty film in turn is thought to reduce still further glycerolâ€TMs low vapor pressure. The glycerol or glycerol-water oriented fatty film will suppress moisture evaporation from a meat carcass as does the water oriented film.
Glycerol has been commonly employed in a great variety of uses in connection with food. In fact, physiologically, it is a food, nontoxic and easily digested. It has a sweet taste and possesses little or no odor. In one embodiment of the process the meat is first coated with glycerol or preferably a glycerol water solution. An aqueous dispersion of the hexadecanol or other suitable fatty material is then applied to the glycerol coated meat to form the thin moisture-retarding film.
The moisture-retarding film is formed of a saturated aliphatic aliphatic radical having the formula R-OH or R-COOH, where R is an aliphatic radical having at least 11 carbon atoms. Ethyl stearate may also be used. The fatty compound may be applied in the form of a glycerol dispersion, for example, an emulsion of the fatty material in glycerol or glycerol and water. The glycerol dispersion may be prepared by dissolving the fatty material in the glycerol (or glycerol and water) with the aid of a readily volatile solvent, such as ethyl alcohol.
The fatty acid, alcohol or ethyl stearate may be applied in dispersion of remarkably low concentrations. Concentrations of 30 to 1,000 parts of the fatty material per million (ppm) of water and glycerol (or glycerol alone) may be profitably used. However, dispersions of greater and less concentrations may be employed, depending on the particular material used. The glycerol because of its high viscosity is preferably used in water solution. Water-glycerol solutions of varying concentrations may be employed. The detailed coating procedure with a fatty film has been previously described.
Example: Small chunks of stew beef were used in this experiment. The several chunks after treatment were refrigerated at 36°F. Sample No. 1 had no treatment at all. Sample No. 2 was dipped in water and Sample No. 3 was immersed in a 50 to 50% glycerol-water solution and drained. Sample No. 4 was treated with an aqueous dispersion of cetyl alcohol (500 ppm). Sample No. 5 was dipped in a cetyl alcohol (500 ppm) dispersion of water and glycerol (50 to 50% solution).
It will be seen from the following table that the glycerol and water treatment (no cetyl alcohol) Sample No. 3 was ineffective in reducing shrinkage, providing no more protection than the water dip of Sample No. 2. However, when used with a small amount of cetyl alcohol (Sample No. 5) the treatment reduced shrinkage significantly.
Intermediate Water Layer
Film-forming fatty materials such as cetyl alcohol (hexadecanol) arachidic acid, and octa-decanol form a thin film on meat, which significantly slows the loss of moisture from the treated meat. It appears that in time this moisture retarding film becomes less efficient, if not ineffective, when applied to chilled meat normally held in a dry state.
T.R. Anderson, has discovered that the effectiveness of the film toward moisture evaporation may be improved by supplying water to the treated meat in a mist, for example, through a heavy fog containing discrete particles of water or in a fine spray. Fortuitously, water introduced in this fashion to the treated meat does not permanently damage the monomolecular film. The film parts to permit the passage of the water particles there through and after wards, reforms. The fatty film, so to speak, is self-healing.
The following is offered as a possible explanation of the improved process. It is thought that the effectiveness of the hexadecanol or other fatty film depends upon the continued presence of an intermediate water layer between the monomolecular fatty film and the meat. The water of this intermediately disposed film is believed to be initially made up of water from the originally applied aqueous dispersion. Early in the refrigeration of the treated meat the moisture lost from the underlying water layer through the fatty film to the air is replaced by the free water of the meat; however, after a period of time the free water does not transfer to the water layer at the required rate and as a result in time the molecules of the fatty material making up the monomolecular film become randomly distributed with the result that the film loses its effectiveness.
The supply of the sprayed water to the intermediately disposed water layer is thought to continue the existence of the molecules of the overlying fatty film in the proper orientation necessary to the life of an effective film.
First a fatty film is applied to the meat (as previously described in U.S. Patent 2,948,623). The sprayed water is preferably supplied intermittently to the treated meat during its refrigeration. The frequency of application is regulated to supply that amount of water needed to assure the existence of the properly oriented fatty film. A particularly suitable apparatus for developing the water laden mist is the fogger described. For a large scale operation, a large number of the Kofford foggers will be required and they may be conveniently provided with a time control for intermittent operation if desired.
The greatest rate of moisture loss occurs during the cooling of the recently killed carcass from its body temperature to that of the refrigerator. The intermittent application of the mist during the early hours of refrigeration supplies the needed water to replenish that lost by evaporation from the water layer underlying the fatty film itself. Without the water furnished by the mist, the moisture required to continue the existence of the underlying water lying layer (and of the fatty film itself) would have to be supplied by the free water of the carcass.
Example: Twelve recently slaughtered carcass were divided into four lots of three each. Lots A and B were dipped in an aqueous dispersion of hexadecanol (concentration of 60 ppm). Lots C and D were dipped in water containing no film forming material. Lots A and C were hung in a first compartment of a refrigerated space maintained at 3° C. This compartment was provided with a fogger (mist forming apparatus). The other two lots (lots B and D) were hung in a second compartment (isolated from the first) of the same refrigerated space. No mist was supplied to the second compartment. Lots A and C were subjected to five minutes of mist every hour interval throughout a test period of eight hours.
The results demonstrate clearly the advantage to be had in supplying the sprayed water to the treated meat.
Lactic Acid-Fatty Acid Triglycerides
Freeze-dried meats under normal storage conditions are subject to nonenzymatic deterioration, resulting in loss of colour and the development of bitter flavour and off-odors. The products also have an affinity for moisture under these conditions. The development of new packaging materials and methods have been found to be helpful in delaying the rapid loss in quality of dehydrated foods under storage but are by no means 3 complete answer to the problem. For example, freeze-dried beef packaged in aluminium foil-paper-polyethylene pouches, and placed in storage at 70° F has a satisfactory quality life of only 3 to 5 days.
In order to protect the quality of freeze-dried meats, Armour and Company propose the use of a coating composition. Although this coating composition consists predominately of meat fat, and although it is applied to the exterior surfaces of the freeze-dried meat, the coated meat can be rehydrated without difficulty, using water at room temperature or below.
The coating composition employed is composed principally of lard and beef tallow in admixture with a minor proportion of a mixed lactic acid-fatty acid triglyceride. It is preferred to employ triglycerides which are formed from lactic acid and at least predominately from fatty acids containing from 14 to 18 carbon atoms. The triglycerides may contain from 1 to 2 mols of fatty acid, and from 1 to 2 mols of lactic acid. Mixtures of such triglycerides can also be used. A typical triglyceride is glycerol lacto palmitate. Glycerol lacto stearate can also be used, or mixture of the palmitate and stearate.
In one typical embodiment, the coating composition contains from 20 to 40% by weight of lard, from 50 to 70% of beef tallow, and from 5 to 20% of the mixed triglycerides. Somewhat improved results can be obtained by also incorporating in the composition from 1 to 10% by weight of a vegetable oil, such as soybean oil, cottonseed oil, or other normally liquid vegetable oil.
The coating is applied to the dehydrated meat, which may be beef, pork, lamb, etc. after the meat has been subjected to a freeze-drying procedure, and preferably as soon after freeze-drying procedure is not critical.
It is preferred to apply the coating by spraying. Coatings will liquefy within the temperature range from 75° to 100°F. In other words, at temperatures below 75°F, the composition will be substantially solid, while at temperatures of 100°F or above, the coating will be in the form of a flowable liquid. Consequently, to facilitate the application, the coating will be applied at a temperature within the range from 125° to 175° F would usually prove acceptable.
The principal requirements are that the coating composition be liquefied sufficiently to permit it to be sprayed and applied as a thin even coating, while at the same time not being at such a high temperature that it denatures or otherwise changes the character of the surface of the meat. For precooked freeze-dried meats, somewhat higher temperatures can be used without disadvantage than with freeze-dried fresh meats. However, the process is applicable to both fresh and cooked freeze-dried meats.
The configuration of freeze-dried meats is usually that of relatively thin slices so that the external surface area of the meat is relatively large compared to the volume. It is usually not necessary, however, to employ more than 1 part of the coating composition per 10 parts by weight of meat. In most applications, the desirable proportion will range from 4 to 8 parts by weight of the coating composition per 100 parts of the meat. Any large excesses of the coating composition should be avoided.
Example: One-fourth inch slices were cut from U.S. Canner Cutter bottom rounds and freeze-dried. After drying, the slices were cubed (1/2â€x ½†x ¼â€), sifted, and placed into polyethylene bags under nitrogen.
Treated cubes were sprayed with an emulsion mixture of 1 part of oleo oil (90% lard-10% soybean oil), 2 parts of deodorized beef tallow and 3/10 part of GLP (glycerol lacto palmitate) at the rate of 5 to 7% by weight of the meat product and at spray temperature of 160°F. the temperature of the meat product was approximately that of room temperature. The spray application was made as evenly as possible to all surfaces by constant mild agitation of the cubes during spraying. The mixture solidified immediately upon contact with the meat product. Samples of freeze-dried beef, not subjected to the treatment, served as the control.
After this preparation, two ounces of control and treated cubes were placed into laminated cans and sealed with 0,15â€, or 28†vacuum. These were stored at 40°, 70°, and 100°F for 0, 15, 30, and 60 days. At each sampling period, objective analyses were conducted. The results of this experiment indicated that the increase in moisture content during storage of the freeze-dried beef treated with the coating mixture was substantially reduced irrespective of vacuum or storage temperature. Moreover, the degree of moisture increase from 0 to 60 days storage was less for the treated samples.
CHAPTER 10
OTHER METHODS OF PRESERVATION
DEHYDRATION METHODS
Solvent Dehydration
The process developed by J.E. Thompson; wherein the solvent dehydration is effected without heating and within the range of ordinary room temperature, can be carried out with substantially unspecialized apparatus. Losses of solvent in the process, due to evaporation, are held to a minimum. Further the products obtained are readily rehydratable, and when reconstituted not only retain the desirable characteristic original flavour to a marked degree, but also exhibit satisfactory texture and consistency, or mouth feel. Fresh meats can be treated successfully by the process.
A solvent is employed which has the capacity to absorb water from the meat tissues, and which readily may be separated from the processed meat material after treatment. This solvent is nontoxic or sufficiently nontoxic that any minute residues that may be retained in the dehydrated meat can have no toxic effect when ingested into the human system, and further, exerts a specific antiseptic action on the meat during processing.
When ethanol is used as the solvent it not only fulfills the foregoing condition but has the advantage of being selective with respect to the fat content of the meat material, in that it is not only a good dehydrating agent, but also, in sufficient concentrations has the capacity to dissolve fatty material. According, if it is desired to defeat the meat, as well as dehydrate it, the water content of the ethanol should be a minimum, whereas if it is desired to dehydrate only, a higher water content could be present. The dissolved fat may be readily separated from the alcohol by addition of water. Likewise the degree of dehydration can be regulated by adjustment of the proportion of water in the ethanol, a concentrated solution acting as a strong dehydrating agent, and a weak aqueous solution of ethanol having a minimum dehydrating action.
Additionally, ethanol is an efficient bactericide and when used in the process has the beneficial effect of destroying microorganisms that are present in meat. Moreover, ethyl alcohol leaves no toxic residue in the final product. Ordinarily it is found satisfactory to use a standard denatured ethyl and alcohol 95.2%.
The separation of the spent solvent from the treated material may be effected by settling and decantation, filtration, and centrifugal separation. Thereafter the dehydrated residual meat product may be dried at atmospheric temperatures to remove remaining solvent. The separated solvent which will have taken up water from the meat material may be recovered for reuse by simple distillation or if desired, by azeotropic distillation. Fat, separated from the meat material, may be recovered in the supernatent layer of the spent solution. Where ethyl alcohol is used, separation of fat is induced by the presence of the dissolved water. If necessary the separation of the fat from the solvent may be brought about by further dilution with water.
The solvent extraction apparatus is illustrated in figure 1. A, 1b and C represent vessels wherein the solvent actions are effected. Each of these vessels is provided with closures a, b and c, respectively, to prevent evaporation of the liquid contents. M1, M2 and M3 indicate a batch of meat material during each of the 3 stages of processing. S1 S2 and S3 indicate the solvent which is used successively in vessels in vessels A, B and C. spent solvent is trans ferred from vessel C to distillation, the overhead being returned to supply source11 and thence to vessel A wherein the meat material M3 undergoes its final extraction. The watery liquids from the comparatively small losses of solvent during the course of the process, fresh solvent may be introduced as needed into the supply source.
In operation as illustrated, meat in a suitable state of subdivision is first introduced into vessel C wherein it is subjected to a relatively mild extraction with partially spent solvent S3. Thereafter the meat is separated from the liquid in vessel C by decantation and filtering, and transferred into vessel B wherein it is subjected to a stronger treatment with extracting solvent S2. Following this the partially dehydrated meat is transferred into vessel A where it is exposed to the action of the solvent in its most concentrated form. The processed meat is now ready after draining to be dried at room temperature. During the 3 stages of treatment, the meat is subjected in all to an amount of solvent equal to approximately 9 times the volume of the meat. The meat undergoes a marked shrinkage in volume. The total weight loss is about two-thirds of the initial weight as moisture and some fat.
Example: Fresh pork tissue was cut into pieces approximately 1†sq and ½†thick, placed in a vessel with special denatured ethyl alcohol (formula SDA-3A), and permitted to stand for a period of time sufficient to dissolve substantially as much water as the solvent would take up. The liquid was then drained off and the extracted material treated successively with fresh alcohol. It was found by this treatment that the lean tissue was very considerably reduced in volume, whereas the effect on the fat was comparatively small. By cutting away from the material initially the majority of its visible fat, a pork product was obtained which was suitable for use in preparing various cooked dishes.
With regard to the time for treating the samples in a 3-stage extraction process, equilibrium is reached in 4 to 24 hours, satisfactory results having been obtained at the end of 4 hours. The dehydrated samples absorbed water so as to be reconstituted taking up approximately 90% of the water removed and hold this water so as to give a product that is edible and may be used in the place of fresh meat. For example 1 lb of dehydrated products from which 3 lb of water had been removed could be soaked in water to restore the original approximate 4 lb weight. It was found that a final moisture content of 6 to 12% of the protein content of the final product kept quite well without refrigeration for several weeks. For indefinite longer storage the moisture content should be reduced to approximately 2%.
Drying Without Case Hardening
Case hardening is a problem confronting the manufacturer of dried foods and is especially acute in the field of meat drying. For example, when fresh meat is dried directly in hot air the surface dries first, thereby interfering with subsequent evaporation of moisture from the interior of the meat. This surface drying or case hardening produces a meat product which is often gummy in texture and which has very poor rehydration properties. For example, the appearance, texture and palatability of a rehydrated, case-hardened product are less than desirable and the rehydrated products is often not equal in weight to the initial fresh product due to its inability to readily absorb moisture through the hardened surface.
J.L. Shank; has provided a method for drying fresh meat without developing case hardening and with improved rehydration properties. By impregnating fresh meat with a minor amount of an edible colloid prior to drying, the meat may thereafter be dried directly in hot air without developing case hardening. Moreover, the product formed has excellent flavour and texture characteristics and, in some instances, almost doubles its weight or reconstitution with liquid. The meat may be impregnated with colloid by cooking it in a dilute solution of the colloid for a time sufficient to impregnate it with the desired amount of colloid.
The minor amount of colloid which is impregnated in the meat is sufficient to coat each surface film or fiber area with a film of the colloid through which moisture diffuses during the hot air drying. This colloidal film prevents excessive desiccation of the meat surface itself thereby preventing case hardening and insuring easy reconstitution when the meat is rehydrated. The colloidal film also facilitates the departure of moisture from the meat so as to produce a desiccated product having a substantially uniform moisture content throughout. Preferably the meat to be dried is sliced to develop thin sheets or strips; for example, sheets 1/8†to ¼†thick are especially suitable. Thicker sheets or slices are operable, particularly up to about ½†to ¾†thick, but of course length of time in the drier is correspondingly increased.
A convenient method of preparing the slices of meat is to first soft-freeze the meat to give it body and minimize juice loss during slicing and then cut sheets of the desired size and â€"shape. Thinner slices of meat, e.g., down to about 1/16â€, may be prepared but the resulting dried product will be quite fragile, and of course the thinner the slice the less acute the problem of case hardening. The sheets, strips or chunks are then cooked in a dilute solution of edible colloid. We have found that a cooked in solution containing about 1% colloid will completely prevent case completely prevent case hardening and can be advantageously employed to substantially always give a definite decrease in case hardening and an increased rehydration ratio.
Greater amounts of colloid up to about 6% or more, for example, can be used and will prevent case hardening and have excellent rehydration properties. However, when the concentration of colloid increases above about 2% the colloid content of the dried product rises above about 10% (weight basis), which of course cuts down the protein content of the dried meat. Thus, the upper level of colloid may be governed by the upper level of colloid tolerable in the final product. It has been found that about 2% colloid is the optimum level for good rehydration characteristics.
The cook solution may also contain flavouring ingredients, for example, salt. If, for example, salt is added in the cook solution, loss of natural salt from the fresh meat is substantially prevented. It will, therefore, be apparent that by controlling the salt content a low-salt dried meat can be produced. Low-salt content products are in demand for dietary purposes. The major amount of the cook solution is water, although several batches of meat may be cooked in the same solution so that some meat juices, solids, etc. may be present in addition to the colloid and any added flvouring ingredients. The amount of solution per unit weight of meat is not particularly important, it being necessary only that the resultant broth not be too thick or too watery.
Generally, about twice as much water as meat (weight basis) produces a very suitable solution. The colloids that are useful are the edible film formers. Examples include, but are not limited to, gelatin, starch and gum such as agar, locust gum, Arabic pectins, gum Irish moss, gum tragacanth, etc. the cooking time and temperature may be varied depending on the colloid used. For example if gelatin is used, the cooking temperature is preferably reduced to about 120° to 125°F.
After the cooking operation which may involve about 1 to 2 hours cooking at 200° to 212°F (or lower temperatures, especially if gelatin is used), the meat pieces are removed from the cook solution and deposited on a surface for drying. Drying screens are especially suitable. It will be noted that as the colloid solidifies the meat pieces tend to adhere to the surface. The screen can be placed in a hot air drier. Generally, time and temperature vary inversely in the drying operation, temperatures above 160° F hasten drying and temperatures of 190° to 220°F being optimum for meat drying. Humidity control in the ovens is not required.
The meat pieces are removed from the ovens when dry and may be packaged, if desired. Generally, the oven drying will be complete in 45 minutes to 3 hours. The time will be dependent on the desired moisture content. In this process the meat is considered dry when its moisture content falls between about 1 and about 7%. The dried meat thus prepared will be substantially free from case hardening and will have a rehydration ratio greater than one and in many cases (particularly if the optimum amount of colloid is employed) about 1.8 or 1.9%.
Initial peroxide ME/K 3-6
Rehydration ratio 1.8-1.9
pH 5.7-6.1
Example: 1:A quantity of beef was soft-frozen, sliced in sheets about %†thick and aliquot portions were cooked for 1.5 hours at about 200°F in water containing varying amounts of agar from 0.5 to 5.9%. A control cook was also run. The meat pieces were removed from the cooking solutions placed on screens and dried in a hot forced-air drier maintained at 190° to 200°F. After about 2 hours when the moisture content was reduced to less than 5%, the meat was removed from the drier. The following comparative table gives the analysis of the products.
The dried meat containing 1% or more agar in the cook solution showed no case hardening. The meat made with 0.5% agar was not completely free form case hardening, but was not unsatisfactory from an organoleptic standpoint and had better rehydration properties than the control. The control meat exhibited case hardening sufficient to be an undersirable product.
Example2: Beef pieces were cooked for 2 hours in an aqueous solution containing 1% salt and 5% gelatin. The cook temperature was maintained at 120° to 125°F. The meat was separated from the broth and dried at 160° F. The product was dry in 2 to 3 hours and exhibited no case hardening.
Example 3: Strips of thin beef were cooked for about 2 hours in an aqueous solution containing 0.5%, weight basis, gum Irish moss. The cook temperature was 212°F. After cooking the beef was separated from the broth and dried at 160° to 200°F. The product was dry in 45 minutes to 1 hour. No case hardening was exhibited.
Example 4: A batch of dried beef was prepared by the method of example 3 except that 0.5% gum tragacanth was substituted for the gum Irish moss. The product was free from case hardening and exhibited good rehydration properties.
PRESERVATION OF FLAVOUR
Antioxidant Application To Freeze-Dried Meats
Freeze-dried fat-containing meats become excessively rancid on exposure to atmospheric conditions within about 24 hours. Freeze-dried meats should therefore be protected from such exposure in order to protect them from spoilage. Borden, inc. provide a method for treating freeze-dried fat-containing meats with an antioxidant which effectively prevents the oxidation reaction from proceeding when such meats are exposed to atmospheric conditions. Treatment with the antioxidants extends its storage life considerably.
The method comprises fat-containing freeze-dried meat sprayed with at least 250 parts of an edible antioxidant for 1 million parts of fat which is meant to result in a freeze-dried meat product containing about 200 parts of antioxidant for 1 million parts of fat. This amount of antioxidant will prevent the meat at room temperature under atmospheric conditions from spoiling for at least 30 days.
The antioxidants used are of the hydroxy phenyl derivative class. Examples include butylated hydroxyanisole, and propyl gallate. The antioxidants may be used separately or in combination and in further combination with chelating agents such as citric acid and salts of ethylenediaminetetraacetic acid. The preferred combination is butylated hydroxyanisole and citric acid. The process is carried out by spraying the antioxidant composition onto freeze-dried meat in an inert atmosphere.
Freeze-dried meat, containing about 2% of moisture, is placed in a rotating and tumbling inducing apparatus such as for example what is conventionally called a pill coaler. The atmosphere prior to addition of the freeze-dried meat may be purged with an invert gas such as nitrogen or carbon dioxide. An antioxidant composition is then added as by spraying in the form of a fine mist onto the surface of the rotating and tumbling freeze-dried meat. The propellant generally used in the spraying operation is an invert gas, for example nitrogen or carbon dioxide. After treatment with the antioxidant the freeze-dried meat may be packaged in an inert gas (e.g., nitrogen) for use in commerce.
By spraying the antioxidant composition via an inert atmosphere onto a freeze-dried product which is continually tumbling and rotating the product is uniformly treated with the desired amount of antioxidant. As applied it does not absorb excessive liquid in local areas which would result in a soggy product. It is preferred to introduce the antioxidant composition (liquid) into the tumbling and rotating freeze-dried product at a rat not to exceed about 2 fl oz/hr/Ib of freeze-dried product. Generally the composition is sprayed at the rate of between about 0.5 and 1.5 fl oz/hr/Ib. The amount of inert gas carrier is not critical other than the economic limitation on excessive quantities and ineffective spray techniques with less than minimum amounts.
In general, about 150 to 500 parts by weight of antioxidant added, per million parts by weight of fat content, results in a usable product. Generally about 300 ppm will give storage life period in excess of 34 days. The preferred range is 200 to 300 ppm. A chelating agent may be admixed with the antioxidant in proportion in the range of up to 55 parts for 100 parts by weight of antioxidant composition consists essentially of an admixture of 100 parts by weight of butylated bydroxyanisole, 15 to 25 parts by weight of citric acid and propylene glycol in an invert carrier atmosphere of nitrogen or carbon dioxide. Where the storage temperature is in excess of room temperature storage life is decreased for a given amount of active antioxidant agent.
Deodorization of Raw meat
R. McCarthy, the former assigned to EEFP Corporation has provided a method for the removal of the undesirable flavour and spoilage-influencing substances from animal meat prior to final preservation (e.g., by canning, freezing, radiation treatment, etc.).
Raw animal meat, cut into pieces, is placed into open-top containers. Each container is then moved from the filling station to a high pressure and subcook heating station where the temperature of the meat and the pressure in the container are both raised, preferably by injecting steam from a steam source through the open top of the container directly into the meat while at the same time confining at least some of the steam and the vapors and gases from the meat, evolved as a result of the heating, in the container. After a suitable amount of time, the heating is discontinued and the pressure on the meat is reduced to atmospheric pressure by releasing the steam and evolved vapors and gases from the container.
The heat, pressure and sudden reduction of pressure all act to break down meat tissues and remove the barriers which they offer to the escape of flavour and spoilage influencing substances which are sealed in the meat cells and tissues. Next, the meat is moved to a low-pressure and extraction station and while still hot, is subjected to a vacuum. The pressure in the container is lowered to a value substantially below atmospheric pressure. This creates a pressure differential across the tissues of the meat since the liquids in the meat are still at or slightly above atmospheric pressure. As a result, these liquids, which are still hot, boil and the vapors and gases evolve from the meat tissues.
The container is at least partially inverted when connected to the vacuum source so the substantially all of the loose liquids and free vapors and gases are removed or extracted from the meat and removed from the container. Finally the container and its contents are moved for preservation, as by canning, freezing, radiation treatment, etc. The preserved meat product is then ready for future use as a source of food.
In figure 2 an open-top metal can C containing raw meat is shown supported on a pad 30 below the outlet end of a steam injection head 32. The steam injection head comprises concentrically arranged inner and outer frustoconical walls 34, 36 respectively, forming a central steam chamber 38 and an annular exhaust chamber 40 surrounding the steam chamber. The inlet end of the steam chamber is communicated through a three-way valve 42 with either conduit means 18 leading from the steam source 16 or vent passageway 20 leading to the atmosphere, by automatic movement of the valve plug 44.
