Indian Meat Industry
Livestock Resource
India has the largest livestock population in the world. There are 192.9 million cattle, 78.8 million buffaloes, 44.8 million sheep, 118.3 million goats and 117.8 million pigs and 467 million chickens in the country (FAO, 1994). However, Indian Livestock Census (1992) shows slight variation in the livestock population (Tables 1 and 2)
Our country shares about 50% of the buffaloes and nearly 15% each of cattle and goat population of the world. India ranks first in the world in buffalo and goat population and sixth in the sheep population. The contribution of livestock to the national economy is estimated to be over 11%. Livestock output as a percentage of agricultural output comes to around 26%. National sample survey has reported that in India, livestock activities are carried out by over 90% of small cultivators and low wage earners to supplement their income. This is in contrast to the concept of large sized livestock farms in the developed countries. It is also noteworthy that 75% of our livestock population does not conform to the specific breed characteristics and has significantly reduced their production potential.
For a long time, meat industry has remained confined to a very small section of people in our country. These people had little knowledge of clean meat production and effective utilization of valued slaughterhouse by products. The scene is now changing. However, industry is still largely based on spent animals except for pig and farm poultry. Most animals are utilized for meat production after loosing their economic viability in the primary field. Cow (not bullock) slaughter is banned in India except in West Bengal and Kerala. The concept of meat type animals is yet to take roots in our country, although an awakening in this regard is discernible. Of late, particularly due to export potential, buffalo is emerging as a prospective meat animal.
Meat Production
Meat is an important livestock product, which in its widest sense includes all those parts of the animals that are used as a food by man. Though meat has a very high biological value, its production and processing has always been the subject of social prejudice. This factor has adversely affected the growth of meat industry. In many cases, social resistance and ignorance have resulted in inordinate delay and deferment of abattoir modernization schemes. An important milestone in this area was the establishment of a modern abattoir at Mumbai in 1973. Further, in the Fourth Five Year Plan, eight bacon factories were established with the foreign assistance. A few meat corporations were also formed to take up the development of slaughterhouses.
Table 3 shows the population, slaughter rate and meat production figures of our traditional meat animals. At present, other than poultry, almost 91 million animals are slaughtered annually yielding 3.98 million tonnes of meat (Table 4). It may be noted that nearly 60.6% is contributed by the cattle and buffaloes and 15.6% by sheep and goats. Nearly, 99% pig population is slaughtered annually contributing 9.9% of the total meat production. Poultry with a population of 467 million contribute 0.44 million tonnes of meat (10.7% of total meat production). There has been an impressive rise in the share of poultry and pig meat over the years and the same trend is likely to continue in future also.
The traditional form of meat industry is characterized by unorganized sector in the hands of butcher workers with very little knowledge of personnel hygiene. At present, there are 3600 licensed slaughter houses in the country. A large number of them are outdated and of substandard according to the present production and processing technology specifications. These slaughterhouses operate as service abattoirs where butchers slaughter the animals for a fee and both edible and non edible parts of the carcasses are delivered to the butchers. Most of them need modernization with facilities for lairage, slaughter hall, chilling room, rendering plant etc. While it is imperative to have all these facilities in big cities, a semi modern approach with mechanical hoist facility is the workable proposition for medium and small sized towns.
Table 3
During the last decade, ten modern abattoir complexes have come up in public sector. An equal number have become functional in private sector also. Eight new projects on modern mechanized abattoirs were initiated in 1990 91. In the Eighth Plan, five private sector export abattoirs are nearing completion. These developmental activities are necessary to improve the image of the Indian meat sector.
World Scene
Meat industry, although in a very developing stage in India, is the top food industry in the world. An analysis of world meat scenario reveals that Europe leads in production followed by Asia. Developed continents (N. America, Europe and Oceania) contribute about 60% to total meat production but they have a monopoly in meat exports as their share was as high as 84%. Nearly 55% of all world meat exports are being shared by European countries alone. The share of Asia in world meat export is very low (6.5%) but it is on the rise.
It is disheartening to note that India with a vast raw material base, contributes less than 1% to the world meat production. Our share in the export of meat is also of the same magnitude. The export of meat from India mainly comprises of fresh chilled meat, frozen meat and frozen meat products (Tables 5 and 6). A major chunk of meat exports amounting to Rs. 400 crores is contributed by buffalo meat (1994 95). Malaysia and UAE are the principal importers of buffalo meat from India (Table 7). However, Indian exports of meat constitute barely 0.8% of global export of this commodity. A great potential exists for exporting buffalo meat, beef and poultry in view of increased demand in gulf countries and higher cost of meat from developed countries. India has additional advantage of geographic proximity to gulf countries. There is an urgent need to tap the world meat export market by establishing modern and hygienic slaughterhouses with chilling facilities solely for export purposes.
Structure, Composition and Nutritive Value of Meat Tissues
Meat is predominantly composed of muscle tissue along with various types of connective tissue. The skeletal muscle is the principal muscle tissue in meat, although very little of smooth tissue is also present. The main connective tissue types are adipose tissue (fat), bone and connective tissue proper.
Structure of Muscle Tissue
Animal musculature is mostly of mesodermal origin. There are more than 300 muscles in the animal body. These muscles constitute about 30 45% of the live weight or 35 60% of the carcass weight of meat animals. In addition to the skeletal muscle, which forms the bulk of meat, a little of smooth and cardiac muscles are also present in blood vessels and heart respectively. Smooth and cardiac muscles are involuntary in nature. Skeletal and cardiac muscles are sometimes referred as striated muscles due to their specific microscopic appearance.
Skeletal Muscle and Associated Connective Tissue
In general, skeletal muscles are directly attached to the bones, although some attach indirectly via ligament, cartilage, fascia and skin. Each muscle is surrounded by a sheath of connective tissue known as epimysium (Fig.1). From the inner surface of epimysium, a septum of connective tissue penetrates into muscle and surrounds the bundles of muscle fibres or fasciculi. This connective tissue is called perimysium. It contains major blood vessels and nerves. Muscle fibres or specialised muscle cells are the structural units of the skeletal muscle tissue. Each muscle fibre (Fig. 2) is surrounded by a connective tissue layer called endomysium, beneath which is delicate sarcolemma or muscle cell membrane. It transmits nervous signals along the surface of muscle fibre.
Skeletal muscle fibres are long, narrow, almost tubular multinucleated cells, which may extend from one end to the other end of the muscle (Fig. 3). The nuclei are distributed peripherally close to the sarcolemma. Muscle fibres are usually 10 100m. in diameter with conical or tapering ends and their length ranges from 1 40 mm. The individual fibre may also be classified as red, intermediate and white. Most animal muscles contain a mixture of these three types. Red muscle fibres have smaller diameter, lower glycolytic metabolism and ATPase activity but higher oxidative metabolism as compared to white muscle fibres.
Myofibrils have a number of elongated unbranched contractile muscle fibre that occupy almost 80% of its volume. They are responsible for the cross striated appearance of the muscle fibre. Each myofibril is about 1 mg in thickness and may run the length of muscle fibre. The cross striated myofibrils remain embedded in the cytoplasm of the muscle fibre called sarcomplasm. The myofibrils are surrounded by a complex system of membrane tubules. The longitudinal tubules called sarcoplasmic reticulum run parallel to myofibrils. Another series of tubules run transversely as invaginations of the sarcolemma. The sarcoplasmic reticulum and T tubules are arranged in a sequence and play an important role in generating Ca++ fluxes in the excitation contraction mechanism. Sarcoplasm also contains glycogen particles, lipid droplets etc.
At low magnification (2000×), myofibrils, the intracellular contractile elements, show characteristic banded or striated pattern (Fig. 4). This situation arises due to the orderly arrangement of dark or A band and light or I band. A clear area in the centre of dark band called H zone is bisected by a dark M line. The light or I band is also bisected by a dark Z line. The distance between two adjacent Z lines is called sarcomere. In fact, the sarcomere is the functional unit of myofibril.
At 20,000× magnifications, the myofibril itself is seen to be composed of a number of thick and thin filaments. Thick filaments traverse the entire width of A band whereas thin filaments extend from Z line to the edge of H zone. Thus, only thick filaments are present in the H zone. These thick and thin filaments consist of contractile proteins myosin (Fig. 5) and actin (Fig. 6) respectively.
Connective tissue serves as the major supportive element of the animal body. It envelops the muscle fibres (endomysium) and bundles (perimysium) and finally the entire muscle (epimysium) connective tissue fibres form the bulk of tendons and ligaments. The tendons attach muscle with bone whereas ligaments connect two bones or support organs. Connective tissue consists chiefly of a mucopolysaccharide matrix in which fibres of collagen, elastin and reticulin are embedded. Collagen fibres predominate over those of reticulin and elastin. Adipose tissue is a specialized type of connective tissue, which is primarily made up of cells storing fat droplets. It is seen around kidneys, omentum and in and around various muscles and organs.
Smooth Muscles
Smooth muscles are found in the gastro intestinal tract, blood vessels, lymphatics and skin in close association with the connective tissue layers. These are involuntary in nature. Smooth muscle fibres are long, unevenly thickened in the centre and tapering on both the sides. The myofibrils are homogenous and do not show alternating dark and light bands like those of skeletal muscle. There are no Z or M lines. The sarcoplasmic reticulum is also not much developed.
Cardiac Muscles
The cardiac muscles found in the heart are also involuntary. Their muscle fibres are rounded to irregular in shape and give off branches, which get mixed up with those of nearby fibres. The nuclei are placed in the centre of the fibre. Myofibrils depict striations similar to skeletal muscle. The sarcoplasm shows numerous and much more mitochondria than the skeletal or smooth muscles. The intercalated discs are present at the position of Z lines.
Composition of Muscle Tissue
Muscle tissue contains approximately 75% water and 25% solids, of which 19% are proteins. Lipids constitute about 2.5 to 5% of muscle. Chemical composition of a fresh animal muscle is presented in Table 1. For simplification, meat can be taken as the postmortem aspect of a muscle.
Water
This is the largest component comprising two third to three fourth of the muscle tissue. Due to polar behaviour, water molecules are attached with the electrically charged groups of muscle proteins. About 40.5% of the total water in muscle is so tightly bound that it is almost impossible to dislocate it. The attraction of molecules keeps on decreasing as the distance from the reactive groups increases. Thus, most of the water exists in immobilised and free forms. When pH of meat is more than isoelectric point, the enhanced negative charge increases the interfilamental space resulting in retention of excess water. It may be noted that almost 70% of water content in fresh meat is located within the myofibrils. Further, an increased water holding capacity is associated with juiciness and tenderness of cooked meat.
Myofibrillar Proteins
These proteins constitute contractile part of the muscle and make up about 60% of the total protein in the skeletal muscle. Thick filaments constitute the A band of the sarcomere and consist of the protein myosin. There are 00 400 molecule of myosin in each thick filament. Myosin is a long asymmetrical molecule containing a globular head and two identical polypeptide chains. It has a relatively high charge and shows a strong affinity for the divalent cations, calcium and magnesium. Tryptic digestion splits myosin into two large pieces heavy and light mesomyosin. Heavy meromyosin head portion carries the ATPase activity and possesses actin binding ability. This ATPase activity of myosin is stimulated by Ca++ ions and inhibited by Mg++ ions.
The thin filament constitutes I band of the sarcomere and extent on either side of the Z line beyond I band also into the A band between the thick myosin filaments. Actin is the main protein of the thin filament. Actin occurs in two different forms. Globular or G actin is a monomere form, each molecule of which binds one molecule of ATP or ADP with high affinity. Further, each molecule of G actin binds one Ca++ ion very tightly. At high ionic strength and usually in the presence of ATP, G actin is polymerised to a high molecular weight fibrous or F actin. At low ionic strength, F actin depolymerises to yield G actin usually with bound ADP.
Actinin is a globular protein having similar amino acid composition as actin. It has two subunits. The alpha actinin is a constituent of Z line and has been shown to accelerate the polymerisation of G actin to F actin. The beta actinin regulates the length of thin filament.
Myofibrillar proteins are of special interest to the technologists because they contribute to approximately 95% of the water holding capacity, 75% of the emulsifying capacity and to a large extent the tenderness of meat.
Sarcoplasmic Proteins
These proteins make up about 30 35% of the total proteins in the skeletal muscle. They contain hundred of enzymes for the normal functioning of muscle cell. Sarcoplasmic proteins have mostly glycolytic enzymes and associated proteins like creatine kinase, lactic dehydrogenase, myoglobin, aldolase etc. In general, these proteins are very susceptible to heat.
Myoglobin is a conjugated protein consisting of a prosthetic heme moiety and a protein moiety (globin). It provides red colour to the muscle and serves as a carrier of oxygen to the muscle fibre. It is the most important pigment of meat colour. Cytochrome enzyme, flavin etc. contribute very little to meat colour. The amount of myoglobin present generally shows considerable variation.
Stroma or connective tissue proteins
The connective tissue is composed of an amorphous ground substance or matrix in which formed elements mostly fibres and a few cells are embedded. The ground substance is a viscous glycoprotein solution.
Collagen is the main fibrous protein the muscles and significantly influences the meat toughness. It makes upto 40 60% of the total stroma protein and 20 25% of the total protein in the body. A fine network of collagen fibres is present in almost all tissues and organs including skeletal muscles. It is the most common constituent of tendons. White coloured collagen fibres are straight, inelastic and non branching. These fibres shrink or shorten at a temperature of 60°C but higher temperatures or boiling causes transformation to water soluble gelatin. Acid or alkali treatment results in the marked swelling of these fibres. Collagen is the only protein possessing a fair amount of hydroxyproline (approximately 14%) and low concentration of hydroxylysine. The smallest unit of collagen molecular structure is tropocollagen which aggregate to form more massive structures the fibril, primitive fibre and mature fibre. High tensile strength and insoluble nature of mature collagen fibres is due to increased inter molecular linkages.
Reticulin is composed of small fibres, which resemble that of collagen except for its intimate association with a lipid containing myristic acid. Reticular fibres form a network around blood vessels, neural structures, epithelium etc.
Elastin is common in ligaments and its yellow fibres can be easily stretched. Elastin fibres are branched and do not hydrolyse on boiling. Elastin contains two unique amino acids desmosine and isodesmosine which contribute to its highly insoluble nature. The nutritive value of elastin is practically nil due to its resistance to digestive enzymes.
Processing of Meat and Meat Products
Basic meat plant operations such as cutting, trimming, deboning and grinding do not constitute meat processing. In fact, processing refers to any treatment including salting which brings about a substantial chemical and physical change in the natural state of meat. Processing invariably imparts considerable shelf stability to meat. As a matter of fact, many processing techniques evolved in the pursuit of preservation.
Basic Processing Procedures
1. Comminution All processed meats can be classified as either non comminuted or comminuted products. Non comminuted products are generally processed from intact cuts. These products are usually cured, smoked and cooked, e.g. ham and bacon. Comminution refers to subdivision or reduction of raw meat into meat pieces or particles. The degree of comminution or particle size varies with the processing characteristics of products. Such meat particle size reduction helps in the uniform distribution of seasonings and eliminates the toughness associated with meat of old animals and lowers the fuel cost for cooking. Comminution is done with the help of meat mincer for coarse ground products whereas bowl chopper is also employed for making fine meat emulsion.
2. Emulsification A mixture of two immiscible liquids where one liquid is dispersed as droplets in another liquid is called emulsion. An emulsion has two phases a continuous phase and a dispersed or discontinuous phase. These phases remain immiscible due to the existence of an interfacial tension between them. The emulsion remains unstable if interfacial tension is very high. The emulsion can be stabilised by reducing the interfacial tension with the help of emulsifying agents or emulsifiers. Homogenized milk is a good example of true emulsion in which fat droplets are dispersed in an aqueous continuous phase. The size or diameter of dispersed fat droplets in a true emulsion ranges from 1 to 5 micrometer (mm).
Meat emulsion comprises of a dispersed phase of solid or liquid fat droplets and a continuous phase of water containing salt and proteins (Fig. 1). Here, continuous phase can also be referred as a matrix in which fat droplets are dispersed. Due to the presence of matrix, many people call meat
Emulsion as a multiphase system. For practical purposes, meat emulsion is an oil in water emulsion where solubilised meat proteins act as emulsifiers. The fat droplets are usually larger than 50 mm in size and remain coated with a soluble protein either myofibrillar or sacroplasmic. The amount of fat that can be incorporated in a stable emulsion depends on fat particle size, meat pH, temperature during emulsification and the amount and type of soluble proteins. It is very important to maintain low temperature during emulsion formation in order to avoid melting of fat particles, denaturation of soluble proteins and lowering of viscosity. This is done by adding ice flakes instead of chilled water during chopping.
For the preparation of a good meat emulsion, lean meat is first chopped with salt to extract salt soluble proteins and then fat and other ingredients are added. Salt soluble proteins have a relatively high emulsifying capacity. Once a good meat emulsion is formed, it has to be protected during cooking or heat treatment. The emulsion breakdown can occur due to sudden exposure to high temperature because of coalescence of finely dispersed fat particles into larger ones (fat pockets). The encased or moulded emulsion is first exposed to heat at 55°C so as to coagulate the coating proteins and stabilize the emulsion.
3. Meat extension A lot of non meat food items can be incorporated in meat products. These are generally termed as extenders, although these may be specifically referred as fillers, binders, emulsifiers or stabilizers depending on the purpose of their incorporation in the basic meat formulation. In developing countries, soya products, potato starch and flours of wheat, rice, pea, corn etc. are used as fillers to reduce the cost of formulations. Several milk products such as skim milk powder dried whey, sodium caseinate etc. are frequently used as binders. Some gums like sodium alginate, carrageenan, gum arabic etc. may be used to stabilise fragile meat emulsions. Due to high cost, extension of meat should be taken up on a large scale in order to ensure the availability of meat products to the masses.
4. Preblending It refers to the mixing of a part or all the curing ingredients (salt, nitrite, nitrate etc) with ground meat in a specified proportion. This process allows better extraction of proteins, which in turn helps in the formation of stable emulsion. It permits control of product composition by adjusting the desired fat content. Besides, processors get enough time for the analysis of meat samples.
5. Hot Processing It refers to the processing of carcass as soon as possible after slaughter (certainly within 1 2 hours) without undergoing any chilling. The term pre rigor processing is used when muscular meat is processed in a pre rigor condition. Though hot processing of meat has been a common practice in India, it is rather a new development in western countries. This technique has many advantages. It accelerates the processing steps and entire processing time is reduced to a great extent. There is improvement in the cooking yield and sensory quality of the product. In addition, there are financial benefits due to reduced chiller space and labour requirement. Thus, lot of energy is saved if hot processing is adopted at a pilot scale.
6. Cooking Meat and meat products are cooked by any one or a combination of three methods dry heat, moist heat and microwave cooking. Dry heat cooking is an accepted method for relatively tender cuts of meat such as pork chops, leg and chops of lamb, ground and comminuted meats etc. The product yield is relatively high due to comparatively less shrinkage. Dry heat cooking involves either broiling, roasting or frying. In broiling, meat held on a wire grill is exposed to heat from above as in electric and gas oven or below as in charcoal broiler. Meat is required to be turned for uniform and sufficient cooking of all sides. Roasting is also practised on tender cuts of meats such as pork shoulder and loin shoulder, rack and loin of lamb and cured ham etc. The roast piece, at least 8 cm thick, is adjusted in open roasting pan with fat side up and placed in hot air oven at 115 150°C. Cooking temperature and time varies according to the cut. Roasting generally gives good browning and improves the flavour of the product. Frying deep fat or shallow pan is also classified under dry heat cooking. This method is especially suitable for thin cuts of meat such as sliced steaks, mutton chops, chicken meat pieces etc.
Moist heat cooking is recommended for relatively tough cuts of meat. In this method, hot water or steam is continuously kept in contact with meat for cooking, so that moisture loss does not take place beyond a particular stage. Pressure cooking, stewing, simmering etc. are popular moisture cooking procedures. Higher cooking temperatures can be achieved in pressure cooking facilitating the tenderization of tough cuts of meat. In stewing, tough meat pieces are first browned in small amount of fat and then covered with water along with curry stuff and allowed to cook at simmering temperature in covered container. The final product becomes tender along with a curry. Simmering involves cooking in hot water at a temperature of 70°C for considerable time. Braising utilizes both dry heat as well as moist heat for proper processing of meat products. Several meat cuts like pork chops and steaks, mutton breast and shanks etc. are first fried in a frying pan and then put in a covered container along with water and seasoning for cooking at 80 90°C.
Microwave cooking is relatively a recent development. Microwaves are high frequency, non ionizing electromagnetic waves which are generated by magnetron vacuum tube within the oven. These waves are channelized into the oven cavity through a wave guide. A stirrer fan distributes the microwaves evenly. The microwaves penetrate the food from all directions simultaneously upto a depth of 2 4 cm causing water, fat and sugar molecules to vibrate at a very high speed. The vibrations cause tremendous friction which produces heat for cooking the food. The spread of heat throughout the three dimensional space in the food itself is called volume heating. Contrary to conventional heating, food is first to be heated in the microwave cooking, which then transmits heat to container and oven environment. It saves a lot of time, taking only 25% time as compared to conventional thermal oven. Microwaves can pass through glass, pottery, wood and paper but reflected by metal. So, metallic utensils cannot be used in the microwave oven. There are some other disadvantages also. Food has to be frequently turned to ensure proper heating and browning of food does not take place in this cooking.
Fraudulent Substitution of Meat and its Recognition
Adulteration of meat involves substitution of costly or superior quality with cheaper, undesirable or inferior quality meat. It is a fraudulent practice that is objectionable on the grounds of health, religion and economics. It is punishable under Prevention of Food Adulteration Act, 1955.
The substitutions generally practised are mutton for goat meat (Chevon), beef for buffalo meat, rabbit meat for chicken etc. The instances of dog or cat meat or even veal as goat meat have also come to light. In United Kingdom, substitution of beef with horseflesh is the most likely one to be encountered whereas in Australia, the possibility of substitution of beef with Kangaroo meat cannot be ruled out.
Recognition of Fraudulent Substitution or Adulteration
It is necessary to assure the wholesomeness of meat to the public, which besides other measures may necessitate the authentic identification of species of meats.
Histological Methods
The diameter and number of muscle fibers, determined by a fibreoptic microscope, can also lead to species identification. Diameter of muscle fibres of buffalo is more than ox, whereas muscle fibres of buffalo are smaller in size and polygonal in cross section as compared to large and irregular muscle fibres of ox. As far as other species are concerned, the size of muscle fibres decreases in the following order pig, buffalo, sheep, goat, poultry.
Electrophoretic Methods
Electrophoretic methods have been found to achieve the separation of proteins by their differential migration through a supporting medium under the influence of an electric field. The protein bands thus resolved are visualized for characteristic pattern by direct observation or densitometeric scanning.
Polyacrylamide disc electrophoresis In this method, mito chondrial preparation of goat, sheep, cattle and buffalo meat has been used for the identification of the particular species of fresh meat. The species are identified according to the band pattern.
Polyacrylamide gel electrophoresis initially introduced as starch gel electrophoresis, it was improved with Polyacrylamide gel. Here buffer consisting of 0.5M NaCI and 0.034M EDTA is used at pH 5.4. After electrophoresis and staining, band pattern is observed for identification. It is applicable to meat cooked at less than 80°C for 10 minutes. However, every time we have to run the standard alongwith the sample.
Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS PAGE) when electrophoresis of different meat samples is performed in a polyacrylamide gel alongwith sodium dodecyl sulphate, proteins run according to their molecular weights. The resultant band patterns can be observed for species specificity. SDS PAGE electrophoresis yields not only excellent results for globular proteins in native state but also for the highly helical rod shaped molecules like myosin. This method is useful for cooked meat and meat products. However, complexity of bands in high molecular weight region hinders the identification especially in closely related species.
Isoelectric Focusing
This method utilizes differences in the isodectric point of fresh meat proteins for meat differentiation. Tissue sections are placed directly on the surface of agarose gels and the proteins are eluted electrophoretically. This is a speedy method with high resolving power.
Enzyme Linked Immuno Sorbent Assay (ELISA)
ELISA is an important qualitative immunological tool, which is not monitored by precipitation. In this test, antigen antibody interaction occurs in a monomolecular layer immobilized on an inert surface and is followed by means of an enzyme chemically bonded to one of the immuno reagents. This is a rapid test and the results are obtained in 2 3 hours. The test is very sensitive also because even 2 per cent adulteration can be recognized by this test.
It should be noted that no single test is good enough to differentiate all types of meats. Physical, chemical and anatomical methods are more suitable for raw meat whereas, comminuted meat products require sophisticated techniques such as Ouchterlony method, SDS PAGE, Isoelectric focusing, ELISA etc. However, Ouchterlony method cannot distinguish between closely related species such as sheep and goat, cattle and buffalo etc. The effectiveness of ELISA and SDS PAGE is hampered by the cumbersome process of isolating species specific serum. A new method called Random Amplified Polymorphism DNA (RAPD) Fingerprint Technique generates specific DNA fingerprint pattern for differentiation of red meats in a short time. Besides, some developed countries have patented field identification test kits. Such a kit is very much required in our field conditions also.
Processing of Some Convenience Poultry Products
Chicken is the major species of poultry in India. It is consumed far and wide in many forms of traditional and processed products. Convenience products do not require any preparation prior to consumption. The common traditional products are tandoori chicken, chicken sheek kabab, chicken shami kabab, chicken curry, chicken kofta, chicken tikka, chicken samosa etc. Other poultry products such as barbecue, chicken patties, chicken sausages etc. also have a good market in urban areas. The methods of preparation of some convenience poultry products have been described in this chapter.
Tandoori Chicken
Broilers at 6 weeks of age are preferred for tandoori chicken because of their tender meat and ability to sustain roasting. Dressed chickens with intact skin are rubbed with 4 per cent salt along with spices and seasoning and kept for 15 minutes. After draining, the carcasses are thoroughly marinated with sauce on the surface and in the interior. A marination time of 1 2 hours is allowed. The formulation of sauce depends on the consumers preference for taste and other sensory attributes. In general, dry and ground spices along with condiments are blended with vinegar (10%) and curd (10%).
The marinated chickens are roasted in a tandoori oven under smokeless, moderate and uniform heat for 20 30 minutes depending on the temperature of oven and size of the broilers. Care must be taken to keep the chickens away from the direct fire and avoid burning or blistering of the skin or extremities. During roasting, chickens are occasionally removed from the oven and pasted with sauce or fat with the help of a brush. The doneness of tandoori chicken is tested by twisting one of the drumsticks when it dissociates easily from the joint. By this time, it also acquires slightly smoked flavour.
Chicken Barbecue
Broilers with about 750 g dressed weight are preferred for barbecuing. The dressed chickens are longitudinally halved for this purpose after removing the neck portion. The chicken halves are marinated with sauce containing spices, salt and seasonings according to the consumers taste and preference and allowed to stay for an hour. The sides are then placed on the oven for barbecuing during which these are periodically turned and basted with sauce with the help of a brush to avoid drying. The cooking should proceed slowly at moderate temperature so that tender, golden brown and slightly smoked flavoured barbecue is obtained.
Chicken Seekh and Shami Kababs
Culled or spent chicken meat can be utilized for preparing sheek kababs. Lean meat is minced through 8 mm plate of a meat grinder. Wheat flour (3 per cent) and whole egg liquid (5 per cent) should be incorporated as binders to provide sufficient strength to the mince. Fat, salt, dry spices and seasonings are added as per consumers preference. The mince is pasted around specially made iron bars (seekh) and cooked over moderate and uniform heat, turning the bars and basting with vegetable oil from time to time till doneness with brown colour is achieved.
In the preparation of shami kababs, meat chunks and water soaked black gram dal are simmered in water for nearly 15 minutes before grinding. It is seasoned with salt, dry spices and condiment paste. Some people also add liquid egg to the mince. It is made into round cakes, which are shallow, fried with edible oil on a girdle till both the sides are brown.
Chicken Kofta
Meat from spent or culled chicken can be utilized for preparing kofta (meat balls). Lean meat is coarse ground through 8 mm plate of a meat grinder. Ten to fifteen per cent vegetable oil is added to it.
Wheat flour (3 per cent) in combination with whole egg liquid (5 per cent) are incorporated to provide sufficient binding strength. Seasonings, salt and spices can be mixed as per consumer preference. The dough is rolled into 15 g balls with hands. The balls are deep fat fried for 5 minutes. Cooked balls, packed in polyethylene pouches have a keeping quality of 8 to 10 days at 4oC.
Role of Meat and Poultry Products in Human Nutrition
We have already discussed the nutritive value of fresh meat and chicken in chapter 2 and 13 respectively. Meat is a very well recognized nutritious food due to abundant high quality protein, B complex vitamins and important minerals especially iron. However, all the nutrients contained in fresh meat do not reach the consumer. Several of them could be partially lost in the processing. The extent of nutrient loss will depend on the processing steps undertaken during the manufacture of a particular product. Hence, there is a need to have a fresh look at the nutritive value of meat and poultry products. Although variety range of processed meat products is very high, relevant information is available only generally prepared products (Tables 1 and 2).
Most processing procedures involve cooking, which brings about a number of changes in meat. Cooking coagulates and denatures the meat proteins altering their solubility. It inactivates or destroys the indigenous proteolytic enzymes. Cooking invariably decreases the water content of meat, lowering the water activity level. It intensifies the flavour and modifies the texture. In addition, considerable number of micro organisms is killed enhancing the storage life of meat.
Smoking and cooking take place simultaneously in most cured meat products. During smoking, carbonyl groups present in smoke react with amino groups of protein whereas, phenols and polyphenols in smoke could react with sulphydril group of protein. Both the reactions cause some loss of available amino acids thereby decreasing the nutritive value of protein. Water soluble vitamins may also be affected to some extent. In fact, some destruction of thiamine (Vitamin B1) is inevitable, although effect on riboflavin (Vitamin B2) and niacin may be very little. Smoking process can be nutritionally advantageous because it helps to stabilise the fat soluble vitamins due to anti oxidant properties. Canning process is particularly detrimental to the water soluble vitamins present in meat. In canning, about 20 40% of thiamine, 10% each of riboflavin and niacin, 20% of biotin and 20 30% pantothenic acid are destroyed.
Processing changes the nutritional characteristics of fresh meat to some extent. The percentage of protein is slightly decreased whereas that of fat and minerals is increased. The percentage of minerals is generally increased due to added salt and seasonings. Besides, processed meats have more caloric values as compared to fresh meat due to the addition of fillers, binders and other extenders in the form of cereal flours or skimmed milk powder and frequently some fat.
Inspite of some processing losses, meat and poultry products are rich sources of vital nutrients. Meat products depict a lot of variation in the amount of the protein but most of the products are rich in protein content, which is of very high quality due to the availability of essential amino acids. In fact, meat products could meet a major portion of recommended dietary allowance (RDA) of 56g protein per day as prescribed by the National Research Council. Since protein is needed to make up the day to day wear and tear of body tissues in adults and large amount of protein can be stored in the body, consumption of meat products can ensure its availability to a large extent. Besides, protein supports the growth in children and pregnant ladies. Consumption of enough protein products with high biological value becomes an absolute necessity. Since meat products contain ample amount of fatty acids that are essential in the diet of human, the recommended dietary allowance of fat is relatively less, it can be easily met. However, it should be emphasized that people with genetic disposition for obesity should restrict the consumption of animal fat.
Meat products contain enough of vital minerals such as iron, sodium, potassium and phosphorus. However, these are particularly deficient in calcium. Much of the requirement of iron, which is an absolute necessity for health upkeep, can be made available by the meat products. Anaemic patients are usually recommended a liver diet because of its high iron content. A regular intake of iron is must for the proper synthesis of haemoglobin, myoglobin and certain enzymes due to very limited capacity to store iron in the body. All the water soluble vitamins are present in meat products but thiamine, riboflavin and niacin are present in significant quantities. Liver containing meat products are extremely rich in vitamin A content.
Sausages
Fresh Sausages
Fresh sausages are one of the most popular, best selling items at the meat counter. The processing procedure is very simple and, with proper observation of certain rules. The making of fresh sausage can be a very profitable part of a meat processor's operation.
Material used in fresh pork trimmings, usually with a ratio of 50% lean to 50% fat meat. However, a more desirable sausage both in appearance and flavour can be made by adding 10 25% additional lean meat, although one government regulation specifies that the ratio of lean and trimmable fat should be 50/50.
Low Temperatures Are Important
Fresh sausage is a very perishable item the fat part of the pork trimmings may turn rancid very rapidly with too high temperatures during both the processing procedure and through the marketing channels. Even at 40°F, development of rancidity and bacterial growth in fresh pork is much more rapid than at 32° F. So trimmings should be as fresh as possible. Use them right from the cutting floor, if this is possible and promptly chill to 30° 32°F or use freshly frozen thawed trimmings.
Cause of the development of rancidity in pork is the chemical reaction of oxygen in the air with the unsaturated fatty acids present in pork fat. The lower the temperature, the slower the development of this rancidity. Therefore, the temperature of the pork and the sausage made from it should never go much above 32° F for any length of time. After sausages have been made they can be held in cold storage and through shipment to the grocer at low temperatures. Dry Ice may be used to keep pork at low temperature during the chopping and mixing operations.
Practice Strict Sanitation
Contact of the pork fat with certain metals, such as iron or copper, also increases the rate of development of rancidity. So use only stainless steel utensils and equipment in handling pork. Furthermore, strict sanitation must be practiced with regard to utensils, equipment, and the entire sausage making area. If equipment is used that has been used for curing meats, even a trace of sodium nitrite coming in contact with the pork could affect the flavour and bloom of the sausage reaching the customer. Bloom is that fresh pink colour of the finished product, which some customers look for at the meat counter. In some cases, traces of sodium nitrite in the finished sausages have caused them to turn red when fried.
Destruction of Trichinae
The Meat Inspection Division (MID) is concerned with protecting public health by setting up regulations that assure destruction of live trichinae in pork flesh when pork products are processed for the consumer. Trichinae are the live parasites that can invade pork flesh and, if not destroyed before being consumed, can cause the serious disease known as trichinosis in humans. However, in the case of fresh pork sausage, which MID classifies as a product, which is customarily well cooked in the home or elsewhere before being served to the consumer, MID requires no treatment of such products for the destruction of trichinae.
Avoid Smeary Texture
Pork sausage is made by using either a meat grinder or a rapid high speed meat chopper. In order to produce the best product and to avoid a smeary texture, the meat grinder should have sharp blades and be in good working condition and the high speed meat chopper should not be overloaded when chopping pork for sausage. If a badly worn meat grinder with dull blades is used, it breaks up the fat cells and crushes rather than grinds the lean meat portion so that smeariness results.
Use of Spices
There are three options to the sausage maker in the type of spices he may use Dry soluble spices, natural spices, or strongly flavored southern style spices.
Dry soluble spices are a mixture of extracted oils and oleoresins of the natural spices with sugar or salt as the carrier. These will help preserve the bloom in sausage and are the best type of spices for sausages packaged in window type containers where the consumer can see the product.
Natural spices, especially the herb type, may discolour the meat giving it a grayish cast but many consumers prefer this kind of spice flavouring regardless of colour because of its rich flavour. If natural spices are used, they must be purified and sterilized to avoid contamination of the meat.
Southern style seasoning is hot and very strongly flavoured with red pepper and paprika imparting a reddish colour to the mixture. Again, the hot, strong flavour and the reddish colour in fresh sausage are preferred by some consumers.
Standard spice formulas are given in Table 1 for the three kinds of sausage seasoning mentioned above.
Shelf Life
As stated above, fresh pork sausage is very perishable. The keeping quality of freshly made sausage is 5 6 days. Certain natural spices, e.g., rosemary and sage, have some antioxidant properties and will help extend the shelf life of sausages longer than those made only with dry soluble seasonings. An extract of herbs such as sage and rosemary is permissible and is commonly used it is available as a patented, proprietary product. It is claimed that using this extract increases the shelf life of fresh sausages 16 20 days, extending its keeping quality from 5 6 days to upto 30 days with proper handling in making the sausage and if kept under proper refrigeration.
Antioxidants are permitted in fresh pork sausages. If used, shelf life can be extended from 5 6 days to 16 20 days.
Casings and Stuffing
Fresh pork sausage is stuffed into sheep, hog, or artificial casings. Small casings (20/22 sheep or 28/32 hog) are used for links with the links usually made in 3½ in. lengths. For larger casings for sausage of 1 Ib weight, artificial cellulose casings are well liked for their uniformity however, hog or sheep casings are still used by many for the larger 1 Ib links (or rings). Bulk sausage may be packaged in cloth bags, in larger sized hog or sheep casings, or in cellulose casings. For consumer use, these are usually 1 lb in weight for institutional use, they are the same diameter but are longer and of larger weight.
Processing Procedure
Check condition of meat grinder for sharpness and cleanliness and meat mixer for cleanliness (particularly if it has been used in curing meats).
Trimmings should be free of bones, sinews, blood clots, and skins. Trimmings should also be chilled to about 33°F at the start of processing.
Mix together salt, corn sugar, and seasonings (from Table 2).
Grinding Method
Grind chilled trimmings through the l l ½ in. plate of the grinder. Then transfer to mechanical mixer, add salt mixture and ice and mix for 2 min. Remove from mixer and grind again using either the or in. plate of the grinder.
Rapid Meat Chopper Method
A rapid meat chopper operates at speeds up to 3000 rpm and will reduce meat pieces to particle size very rapidly. Use well chilled meat pieces or trimmings. Fill chopper bowl only half full, add salt mixture and ice and let machine run until meat is reduced to desired size. Pulverized Dry Ice may be added to the chopped ingredients along with chopped ice to keep meat temperature down to 28° 32°F. Transfer meat mixture to mechanical mixer and mix approximately 1 2 min to assure proper distribution of salt and flavouring and also to increase the binding capacity of the soluble proteins in the Meat.
Stuffing
Keep the stuffing table well iced to keep sausages cold. Immediately after mixing and grinding, stuff into casings using casings as described above suitable for the end product. Link and hang on sausage trees. Carry immediately to chill room (under 32° F) to dry casings and chill sausages. Casings should be dry before packaging fans may be used to help dry them. Chill sausages to 32° F before packaging when they are ready for shipment.
The best way to hold the bloom and prevent development of rancidity is to transfer them to a freezing temperature of 0°F after they are chilled and the casings dry.
Fish Products
Separating Fish Flesh from Bones and Skin Mechanically
The fish flesh separator works by squeezing the flesh from the skin and bones of fish and passing the flesh through perforations on a stainless steel plate or drum. The skin and bones do not pass through the perforations and are separated by the machine. The comminuted fish flesh can then be used in many food products e.g., fish sticks, sandwich spreads, hors d'oeuvres, etc.
The flesh separator has, (1) a stainless steel drum (approx 8½ in. in length and 6½ in. in diameter) perforated with closely spaced holes in. in diameter, and (2) a continuous rubber belt (approx 41 in. long and 8¼ in. wide) which runs over a series of moving rollers. Position of the rollers is adjustable to regulate the pressure exerted against the drum by the rubber belt.
Here is how the machine works Headed and gutted fish are fed into the machine and pass between the belt and perforated drum. Pressure applied by the belt on the fish forces the fish flesh through the perforations of the drum while the skin and bones pass to the waste discharge chute. The operator can adjust the pressure exerted by the belt to remove most of the light meat during the first pass through the machine. If it is desired to remove the remaining light meat and dark flesh under the skin, the waste can be passed through the machine again after pressure exerted by the belt has been increased. Alternatively, pressure exerted by the belt can be adjusted to the maximum so that one pass removes all the fish flesh both light and dark.
Following is a Table showing yield of flesh and waste for a number of common varieties of Pacific Ocean fish using the mechanical fish flesh separator.
Reducing Drip Loss in Fish Fillets
The loss of drip in fresh and thawed fillets is effectively controlled by the addition of small amounts of sodium tripolyphosphate (TPP) to the fillets prior to either their distribution fresh to retail or in preparation for freezing.
If fish fillets are treated with sodium tripolyphosphate, the surface layer of protein is modified so that its ability to hold water is greatly increased. This surface layer of modified protein prevents the escape of fluid from the interior of the fillet, with the result that drip formation is prevented.
Sodium tripolyphosphate can be applied to fillets by two methods fillets may be dipped in appropriate concentration of TPP solutions, or the solution can be sprayed directly onto the fillets.
Treatment for Freezing
With fillets that are to be frozen, the most effective dip solution is 12% TPP containing 4% salt. The drip during thawing of red snapper and sole fillets is reduced about 50% by TPP treatment before freezing.
Results of Tests on Fresh Fish
Tests show that the loss of drip in fresh (refrigerated) fillets can be effectively minimized by spraying with 7.5 10% TPP solution containing 2% salt. Treated fillets such as sole, ocean perch, cod, and halibut steaks lost no more than 0.5 1.0% drip during their effective refrigerated shelf life. Drip lost in untreated fish ranged from 3 to 6% during the same storage period.
Manufacturing Fish Flour (Fish Protein Concentrate)
Fish flour (fish protein concentrate) is an inexpensive source of protein of high quality and may find wide use in improving nutritional quality of many prepared dishes as well as improving the diet of people whose food is largely grains such as rice and corn.
Raw frozen fresh fish is used, such as hake or other less costly fish which is in plentiful supply. The frozen fish is ground up, then placed in an open stainless steel mixing kettle. To the ground, fish is added isopropanol solvent and extraction takes place, at well below the ambient temperature. The resulting slurry is separated in a centrifuge, and the isopropanol phase goes to solvent recovery while the solids enter a second stage extractor (a covered, jacketed mixing vessel). Here, extraction takes place at about 170°F, near the boiling point of the solvent. The phases are separated again, and third stage extraction proceeds at 170°F, using fresh (recovered) solvent. After final centrifuging, solid material goes to a vacuum tumbler dryer that removes residual solvent. Once dried, the fish solids enter a mill where they are ground to a light gray powder.
Salted and Pickled Fish
Salting Fish
There are two classes of commercial methods of salting fish brine salting and dry salting. The term dry salted refers to the method of salting and not to the procedure followed in packing or storing fish it should not be confused with dried, salted fish.
Brine Salting
Brine salting is of relatively little importance compared with dry salting, as the chief fish that is salted by brine is the alewife or river herring. The cleaned fish are placed in large vats partially filled with concentrated salt solution. A small amount of salt is put on top of the fish floating in the brine. The fish should be stirred daily to prevent the brine from becoming too dilute at any one point in the vat.
Dry Salting
The exact procedure to follow depends upon the kind of fish and the custom practiced in a particular locality. But, for general consideration, the following description is sufficiently detailed.
The round, gibbed, beheaded or split fish are washed and then packed in water tight containers with an excess of dry salt. The proportion of salt to fish varies greatly depending upon the kind of fish, the weather, and the custom of the salter, varying from 10 to 35% of the weight of the fish. Usually, the fish are rubbed in salt as they are packed and each layer of fish is then sprinkled with salt. After a few hours, sufficient pickle has formed to cover the fish which are not disturbed until they are completely salted. Then the fish should either be re packed in fresh pickle or removed and dried.
The dry salt method has been found to obtain more rapid penetration of salt into the fish and to inhibit decomposition more quickly. Evidently, in dry salting the brine remains more nearly saturated, probably because of the greater surplus and better distribution of the dry salt.
Salting of Cod, Lusk, Haddock, Hake, and Pollock
Cleaning
The fish are cleaned (eviscerated) at sea. The heads are broken off, the fish split open, and 2/3 of the backbone removed (that portion from the head to the lower end of the abdominal cavity). The fish are then washed.
Salting
Butt Method
In summer all fish must be salted in butts or other water tight containers, but in winter they are often salted in kenches. A butt is a large barrel (formerly a molasses hogshead) and is about 3 ft in diameter and 4 ft high. The salters throw the cod face (flesh side) up into butts and sprinkle salt uniformly over each layer. When coarse salt is used, 6.5 7 bu are required for each butt of fish. If finer salt is used, a slightly larger quantity is often added and in hot weather more salt is required. The fish are piled high above the top of the butt and the last few layers which are exposed are placed with backs up. A pile of salt is placed on top of the fish. The salt and fish settle slowly and within a day or two sink below the top of the butt. After the fish have settled, a bushel or more of salt is placed on top. About 3 weeks' time is required for the completion of the salting process.
Kench Method
During winter or on board schooners, these fish are often salted in kenches. A kench is a regular pile of fish made by laying them on their backs with napes and tails alternating. A considerable quantity of salt is spread over each layer. The top layer of fish is turned with backs up. As the salt extracts the water from the fish, it runs to the floor and is drained off. Since the fish do not stand in brine, it is much more difficult to obtain uniform penetration of salt by the kench method therefore, there is much greater danger of spoilage (souring) by this procedure than by the butt method. About 20 lb of salt are used on each 100 lb of fish.
Drying
Water Horsing
When fish are to be dried, they are removed from butts or kenches and washed with sea water or brine to remove any objectionable slime. They are then hauled to a building or room having a good concrete floor. Here they are kenched on frames about 8 in. above the floor. Weights of various kinds are placed on the kenches to press surplus brine out of the fish. The fish drain and slowly dry in the kenches the longer they remain on kenches the less time they must remain on the flakes for final drying.
Drying on Flakes
After kenching, the partially dried fish are placed flesh side up on flakes for further drying. A flake is a rack or lattice bed about 3 ft wide constructed of triangular strips about 1 in. wide (at the base) and nailed about 3 in. apart to a substantial framework. These are built in the open air about 30 in. above the floor. The weather is watched carefully, and when a rainstorm is imminent the fish are collected in piles and covered with small rectangular boxes with peaked roofs called flake boxes.
The time, which the fish remain on the flakes, depends chiefly, upon the weather and the amount of drying and bleaching desired. When there is a strong dry wind, two lots may be dried in a single day but during bad weather, a week or more may be required.
The degree to which the fish are dried depends upon the trade. If they are to be sold in the southern states, they must be much drier than if they are to be marketed locally. Fish for export must be dried as completely as possible. For export, flake drying is usually insufficient in the moist New England climate where the bulk of the salting is done therefore, such fish are dried further in specially constructed, heated driers.
When sufficiently dry the fish are carted to a storehouse where they are kenched until needed for packing, or skinning and boning.
Skinning and Boning
The fish are sorted as to quality and size. The skin is pulled off and discarded. All of the bones still remaining are pulled out and the salted product is cut into strips to fit the boxes or cartons in which it is to be packed. Usually, fine salt containing 4% boric acid is sprinkled over the salt fish as it is packed.
Salting Mackerel
Salting of mackerel begins at sea aboard the fishing trawler. Each mackerel is split so that it will lie open and flat after the viscera has been removed. The splitting knife is held by the fingers and guided by the thumb and slides along the upper side of the fish. After splitting, each fish goes to a tray where the gibber opens the fish with a jerk causing it to break lengthwise along the lower end of the ribs. Viscera and gills are removed and the fish is thrown into a wash barrel partly filled with clean salt water the fish is thrown into the barrel open and face down. Here, the blood is soaked from the fish. They remain in the salt water until the splitting is finished, which may be 6 8 hours, or even longer. Then the deck is cleaned up and the men proceed to salting.
The mackerel are removed from the salt water by emptying the wash barrels onto the clean deck and are rinsed by throwing buckets of clean water over them. They are then dipped into fine salt, such as Liverpool No. 2, and placed in a barrel flesh side down, except that 2 3 bottom layers have the flesh side up. Coarse salts are not used as they give the fish a ragged appearance. The barrels of salted mackerel are then not disturbed until the vessel arrives in port. Here they are removed to a cool storehouse and remain until needed for market. From time to time, additional brine is added to the barrels to replace any loss by leakage or evaporation. This is important as any exposed fish soon rust and cannot be marketed.
Before marketing, the salted mackerel are carefully re packed and covered with fresh brine. Tops of the barrels are removed, the brine poured off and discarded, and the fish emptied out into a culling crib, a box of planed boards with slat bottom, usually about 5 ft long, 3 ft wide, and 8 10 in. deep on legs about 3 ft high. Here the mackerel are sorted into recognized trade grades and put into weighing tubs with perforated bottoms. Each tub holds about 100 lb and is weighed on a beam scale. After weighing, the fish are packed in barrels, kegs, or kits with the various grades packed separately. A small amount of salt is sprinkled on the bottom of the barrel or keg 2 3 layers of fish are placed flesh side up with the remaining layers placed flesh side down. A large handful of salt is sprinkled over each layer as it is packed with about 35 lb needed for each 200 lb barrel. When filled, the barrel is turned on its side and filled with strong brine.
Salting Salmon
In dressing salmon for pickling, first remove the head then split the fish along the back ending the cut with a downward curve at the tail. Remove the viscera and of the backbone scrape away the blood, gurry, and black stomach membrane. Thoroughly scrub and wash the dressed fish in cold water. Place them in pickling butts with about 15 lb of half ground salt to every 100 lb fish. Lay fish in a tier, flesh side up, sprinkle salt evenly over each tier and repeat until tank is full. Several boards are then laid across the fish with the boards weighted down in order to keep the fish sub merged in the pickle, which will form. Allow the fish to stand in the pickle about 1 week, holding the brine at about 90°F. Remove the fish from the pickle, rub clean with a scrub brush, and repack in market barrels, using 1 sack of salt to every 3 barrels of 200 lb fish. About 40 52 red salmon, 25 35 coho salmon, 70 80 humpback salmon, 10 14 king salmon, and 25 30 dog salmon will be required to fill each when packing a market barrel of dressed, salted salmon.
Salting Mullet
Dry Salting
The best method for curing mullet in the warm weather of the southern states is dry salting, a combination of salting and drying. If the fish are strictly fresh and handled carefully, the product will be of good quality. A recommended procedure follows.
Procedure
Split the fish along the back, mackerel style, so they will lie flat in a single piece, leaving the backbone in. Heads may or may not be removed. Roe is saved and salted separately. In cleaning the fish, they should be eviscerated and washed to remove all traces of blood from under the backbone and clear away the dark belly cavity skin. If heads are left on, clean out all traces of the gills. Score each fish longitudinally along the backbone and also through the flesh on the topside of the fish. Then, wash and soak in a light brine solution for about 30 min to remove all traces of blood and slime. Remove from brine and drain for about 15 min.
Use dairy fine mined salt and dredge each fish in the salt, rubbing some into the scored cuts on each side. A shallow pan or box about 2 ft square is convenient for this operation. Pack the salted fish, layer by layer, into barrels or tubs with flesh side up except for the top layer, which is packed flesh side down. A little salt is sprinkled on the bottom of the container and over each layer of fish. Place a weight on top of the pack to keep the fish under the surface of the brine that forms. Allow the fish to cure in this brine 36 48 hours, after which they are removed and allowed to drain for 15 20 min.
The fish are now ready for the drying racks. These are frames of wood covered with wire mesh and standing on legs 3 4 ft high. Drying is done best in the shade under a roof without walls and so located that as much of a current of air as possible will pass over the fish. Oxidation or rusting sets in immediately if drying is done under the direet rays of the sun. The salted fish are laid on the recks skin side down, but are turned 3 4 times the first day. At night, to prevent spoilage through dampness, which causes souring, and molding, fish are taken to a sheltered cover (inside if possible). The time required for drying usually averages 4 days but is dependent upon weather conditions during the drying period and size of the fish. The dryer the finished product is the less danger there will be of reddening or rusting. If the surface looks dry and hard and the thumb can be pressed into the thick part of the flesh without leaving an impression, the fish can be considered cured.
Should high humidities make air drying impossible, the following procedure should be used When the fish are struck through, having absorbed enough salt for curing purposes, they should be taken out of the salt, scrubbed in brine, and piled in stacks with the flesh side down. Weight the stacks heavily in order to press moisture out of the fish. After 10 18 hours in stacks, repack the fish in dry salt, again weighted down, and put in storage in a cool, dry place.
Brine Salting
In an effort to stimulate production and use of brine salted mullet in the southern states, technologists of the U.S. Fish and Wildlife Service devoted considerable time to a study of methods of curing. Their recommended procedure may be summarized as follows
In the preparation of brine salted mullet, the fish should be dressed as soon as possible after removal from nets or seines (within 6 hours at the most). Split fish down the back and along the backbone the heads are cut through so that the fish can be laid out flat. The viscera can also be easily pulled out after cutting through the heads. Roe, in season, is usually separated and dried, sailed or smoked as a profitable by product. Gills are removed and the appearance of the product is improved if the black membrane of the belly cavity is also removed. Heads and foreparts of the backbone are often taken out of larger fish (those weighing more than l½ lb). After thorough cleaning, the fish are washed in clean sea water or light brine to remove blood and slime. Soaking for ½ hr in brine will make this cleaning easier.
The fish are now ready for salting. A mined or refined salt is preferable to sea salt, as it is cleaner and contains less chemical impurities. Ocean salts are also carriers of the bacteria that cause reddening of the fish. In packing, a heavy layer of salt is placed on the bottom of the barrel and covered by a layer of fish, open side up. Sprinkle layer of fish liberally with salt. Repeat fish and salt layers until container is full. The fish are usually packed fanwise with heads out and tails toward the center. Take care that the fish in the layers do not overlap. Every surface should be exposed to the action of the salt. Place the top layer of fish in the barrel cut side down, covers with salt, and places a weight on top of the filled barrel to keep fish submerged in the brine that forms. The fish should be struck through with the salt in 4 10 days, depending upon size of the fish. If possible, they should be held in a cool room at a temperature not exceeding 50°F during the striking through period.
Repacking can be done any time after the fish are struck. They are graded and sorted for size and condition, and any remaining blood, salt, scales, etc.. are rinsed off in the brine. Repacking is usually done in smaller kegs or barrels with a layer of salt on the bottom, and on the top with a light sprinkling between fish layers. After the containers are headed'' sufficient concentrated brine is added to fill the containers. The product should be refrigerated if it is to be stored for very long.
Bismark Herring and Variations
True marinated fish, according to the Germans, are those, which are cured with strong salt and vinegar pickles without being cooked. Examples of the German products are Bismark herring, mustard or Kaiser Friedrich herring, and Russian sardines.
Bismark Herring
These are prepared from herring of uniform size. The fish are first washed in a special washing machine, consisting of a large revolving drum equipped with a spray of water. The washed and scaled fish are then cleaned, beheaded, and boned. They are then rinsed with water and brushed inside to remove the black lining of the belly cavity. They are then placed in salt brine for 2 3 hours. Following this, they are put into a vinegar pickle (from 5 6% acetic acid) containing a moderate amount of salt. They remain in the pickle for 2 days after which they are packed tightly in boxes with slices of onion, and some pepper and mustard seed. A vinegar sauce (from 2.2 to 2.4% acetic acid) containing some sugar is added and the box is closed and wrapped for marketing. The herring are usually shipped immediately but, if stored, are kept in cool, dry rooms.
Mustard or Kaiser Friedrich Herring
These are prepared in exactly the same manner as Bismark herring However, a mustard sauce, instead of sweetened vinegar, is added when the fish are packed. The mustard sauce is usually prepared in special factories and is merely thinned preparatory to use in the marinating factory.
Other Variations
Other marinated fish are prepared by the addition of Remoulade, wine, bouillon, tomato, or Cumberland sauce to the vinegar prepared fish. Sauce prepared from the milts of herring constitutes another favorite marinade. In cutting the herring the milts are collected and mixed with vinegar sauce. When desired for use as the sauce, the milts are strained through a sieve so that the membranes are removed. As the herring are packed in boxes, any of a number of combinations of spices may be used, depending upon the preference of the packer. These include black pepper, pimiento, onion, clove, bay leaf. These are sprinkled over each layer of fish as they are packed. The milt sauce is added and the boxes are then closed and wrapped in the same way as plain Bismark herring.
Canned Marinated Herring
These are prepared by washing choice herring of uniform size in a revolving cylindrical screen, which also removes scales. The fish are then dressed by removing heads, tails, and bones by hand they are then rinsed and placed in about 75° brine for 2 3 hours. From the brine tanks they are transferred to a vinegar pickle of 5 6% acidity, containing considerable salt. After about 2 days the fish are ready to pack in cans, in which they are placed in layers, with onions, peppers, and mustard seed on each layer. A small amount of 2¼% vinegar and a little sugar is added to each can. Cans are exhausted, sealed, and processed.
