Cocoa Bean Production
Introduction
Cocoa beans, the essential ingredient of chocolate, are the seeds of a small tree known botanically as Theobroma cacao, the second word of which is the common name applied to the tree by agriculturalists. However, in English it is usually called 'cocoa'. The tree was already being cultivated in its native continent, South America, where it is still part of the natural flora, when the Spaniards first went there in the sixteenth century. It is now grown in all the wet tropical forest regions, mostly within 17 degrees of latitude of the equator.
C
ocoa trees are small, growing up to about 20 feet (6m) in height in the shade of the big trees of the wetter areas of the tropical forests. The leaves are evergreen, resembling a laurel leaf in shape, and up to about 8 inches (20 cm) long. Cocoa is an unusual tree in several ways. It has two kinds of branches, the chupons which grow vertically upwards for about 5 feet (1.5m) and bear leaves arranged in a spiral, and the fan branches, up to five of which grow out horizontally like the spokes of a wheel from the top of each chupon where its vertical growth stops. This is called a jorquette. The leaves on the fan branches are arranged in two rows, one on either side of the branch. This dimorphic growth results in a clear distinction between the fan branches and the vertical growth of the main stem, particularly in the young tree. The main stem usually reaches higher than the 5 feet (1.5m) or so to the first jorquette as a result of a bud appearing just below the fan branches; this grows up vertically as another chupon from near the top of the previous one. The comparatively horizontal fan branches with their alternate arrangement of leaves grow and branch to form the leafy head of the tree which, in a cocoa plantation, joins with those of its neighbours to give a dense canopy. The heavy continuous shade of a well-grown planting of cocoa trees prevents to a large extent the growth of weeds beneath. Cocoa flowers are small, a little more than half-an-inch across, with petals varying from white to pink in different varieties. The minute fertilized ovary, however grows over a period of nearly six months into a huge, waxy looking, oval cocoa pod which can be as much as 8 inches (20cm) long. A further unusual feature is that many of the flowers, and hence the pods, are borne on the trunk or main branches of the tree below the leafy branches. Flowers continue to be borne often in clusters on the same spot on the stem, originally the site of a leaf stalk. This gradually becomes thickened and is known as a flower cushion. A mature tree can be an arresting sight with its raised flower cushions spaced on the bare trunk, some only a foot (30 cm) above ground level, bearing tiny pink flower and pods it various stages of their growth.
Ripe pods have a waxy coating over the wall of dense tissue, which is lignified to a varying extent and sometimes more than 0.5 inch (I cm) thick. It has proved impossible to find an economically worthwhile use for this material. Inside the pod, there are some 30 to 40 seeds embedded in a mildly sweet mucilaginous pulp. Each seed, or bean as it is called because of its resemblance to the typical leguminous bean seed, consists of two convoluted and swollen seed leaves or cotyledons and a small germ or embryo plant, all enclosed in a skin or testa. The cotyledons serve both as the storage organs containing the food for the development of the seedling and as the first two leaves of the plant when the seed germinates. Much of the food stored in the cotyledons consists of a fat known as cocoa butter, which amounts to about half the weight of the dry seed. Cocoa butter is an unusual fat in being quite hard at temperatures below 90°F (32 °C), softening over a comparatively small range of temperature, and is quite liquid at our blood heat. It is these properties, which allow chocolate to be quite hard and breakable at cooler temperatures and to melt completely in the mouth.
Botanical types
There are two appreciably different types of cocoa, the Forastero, which has purple cotyledons, and the Criollo, which has white cotyledons. The colour is given by anthocyanins, the group of chemicals, which give most blue and red flowers their colours. These are present in the cotyledons, confined in special pigment cells comprising about 10% of the storage cells. Their function in the seed is not known though it has been suggested that they have a protective role. In Criollo cocoas, the coloured anthocyanins are replaced by leuco forms. Nowadays, a very large proportion of the world's cocoa crop is Forastero and it is difficult to obtain pure criollo cocoa. There is a third type, generally described as Trinitario, which has, often within the same pod, beans with cotyledons ranging from almost white to a full purple colour. Trinitario cocoa appears to have originated by hybridization between Forastero and Criollo cocoas. This hybrid mixture was extensively planted in Trinidad after the island's Criollo plantations had been devastated in the eighteenth century. In the following century, this small island was becoming a major producer of cocoa and the hybrid mixture, which was found to be successful, was quite widely planted in various countries. Consequently, it has become known as a cocoa type by the name of the island. As would be expected of a hybrid mixture, there is quite a wide variation between individual trees.
The colour of the cotyledon is the main difference between Criollo and Forastero cocoas. It is also a very important one because the anthocyanins are involved in the production of the unique flavour of cocoa. The purple anthocyanins are associated with the stronger, more astringent and robust flavours. It is not surprising that Criollo, without these anthocyanins, is an altogether milder cocoa. Chocolate made from it is of a light brown colour quite like a milk chocolate, and has a pleasant flavour of a nutty type with only a gentle indication of what is now considered a typical chocolate flavour .Nevertheless, Criollo cocoa used to be regarded as the superior quality and was much in demand. However, it is a less vigorous plant than the Forastero and is more vulnerable to some diseases. Developments in processing and of new products both enabled the less desirable features of the Forastero to be minimized and use made of their stronger chocolate flavour, so that the tendency to replace Criollo by higher-yielding Forastero has been encouraged. The third type, the Trinitarios, while including pale beans within their pods, produce a larger proportion of beans with the purple colour. Certainly, they can have sufficient of the purple anthocyanins to show the strong chocolate flavour of the Forastero but it is refined and displays in addition the so-called ancillary flavours. The Trinitarios, derived from both the main types, thus include the most fully flavoured cocoas which some now regard as the superior cocoas of the highest quality. They continue to be grown in some areas. However, the popularity with the growers of the Forasteros, which are more robust and higher yielding than even the Trinitarios, combined with their suitability for some popular products, which are now being consumed in great quantity, has resulted in their becoming by far the larger proportion of the cocoa crop.
The preparation of cocoa beans
Cocoa pods are harvested when ripe by cutting the woody stalk. This is easily done with the pods borne low on the trunk, but less so with the pods on the upper branches where it is necessary to use a special knife fixed on a long pole. The thick-walled pods are opened to release the seeds, either by cutting with a knife or cracking with a simple wooden club. The former requires care in practice to avoid piercing the pod wall too deeply and cutting into the shells of some of the beans. The pods generally change colour as they ripen, green pods become a golden yellow, while the red immature pods of other varieties become orange-yellow. The crop does not all ripen at the same time so that harvesting has be carried out over a period usually of several months.
There are some 30 to 40 seeds, cocoa beans, in a cocoa pod. Unlike seeds of most temperate plants, they are not long-lived and do not dry out naturally. Indeed, if these large seeds are not planted within a week or two, they fail to germinate. In the ripe pod, the moisture content of the beans is in the region of 65% and they are embedded in a sugary, mucilaginous pulp, Such materials are of course, very liable to decay, especially at tropical temperatures, and the sticky pulp is both difficult to remove mechanically and difficult to dry.
It is fortunate both for cocoa growers and, as has subsequently been realized, for chocolate manufacturers and consumers that there is a simple solution to this difficulty. When the beans in their surrounding pulp are removed from the pod and left for a few days, yeasts and bacteria develop, causing fermentation and the breakdown of the sugars and mucilages in the pulp, which can then drain away as liquid. Subsequently, the beans can be spread out in the sun or dried in mechanical driers down to a moisture content of about 7%. These are the processes of fermentation and drying, by which, the vulnerable moist seeds are prepared for transport and storage, the first stages of their journey into chocolate.
These processes of preparation are essential for another reason. If Forastero beans are carefully cleaned of pulp and dried without any fermentation of the surrounding pulp, the dry cotyledons within the bean are not the brown or purple-brown colour of fermented cocoa beans but an unattractive dark slaty grey. When such beans are made into chocolate, this same colour persists and the taste is not like that of chocolate at all. Chocolate made from slaty, unfermented beans tastes extremely unpleasant, being very bitter and astringent without any apparent chocolate flavour. The grower of cocoa therefore, as well as producing the beans, carries out the first and most vital stage of flavour development.
Criollo cocoa, eventhough it is milder, also requires fermentation to develop its flavour. However, much less fermentation can be sufficient and this seems to be possible with little more than heaping the beans for a few nights before much drying has taken place. It, therefore, seems to have been no accident that Criollo was the variety first in cultivation. Criollo beans are not unpleasant to the taste even without undergoing fermentation, whereas severely underfermented Forastero cocoa is most unpleasant. The milder Criollo cocoa, therefore, was the early standard and the Forastero was then regarded as a coarse cocoa of poor quality. However, with proper fermentation, the Forastero flavour can be very attractive in many products and, with the added advantage of better yields, this chocolate flavour and the more complex Trinitario chocolate flavours have become predominant. Now, the very limited amount of pure Criollo still grown would not be regarded by most consumers as making the best chocolate.
Fermentation
Fermentation is carried out in a variety of ways, but all depend on heaping a quantity of fresh beans with their pulp sufficiently for the microrganisms to produce heat, which raises the temperature, while limited access of air is allowed to the beans. It can, as is usual on small farms of a few acres in West Africa, be done in heaps enclosed by banana leaves or, as is normal on plantations with their larger production, in boxes with the beans covered with banana leaves or sacking. The boxes must have provision for the liquefied pulp, the sweating, to drain away and for some entry of air, either by means of small holes in the bottom of the box or preferably through a floor of slats each separated by about 0.25 inch (6mm). Heaps can be used to ferment anything from around 200 to about 3000 Ib (90-1100kg) of wet cocoa beans, although intermediate amounts are desirable. Boxes should be at least 2 feet 6 inches (0.75m) across and should not be filled to much more than this depth. The required quantities of cocoa beans can take a considerable time to collect, but it is essential to use ripe pods and desirable to open all the pods and fill the box or heap on a single day. This can necessitate holding some of the harvested pods for a few days. There is some evidence, notably from comparing practices in some areas where Trinitario is grown, that holding unopened pods for a few days results in better flavour development. Recent work on behalf of the Cocoa, Chocolate and Confectionery Alliance has confirmed this conclusion in West Africa and Malaysia. Some drying of the beans in the unopened pods results in more air reaching among the beans so that the fermentation starts more actively.
The fermentation begins with yeasts converting the sugars in the pulp to ethyl alcohol. This produces the initial anaerobic conditions, but then bacteria starts to oxidize the alcohol to acetic acid and further to carbon dioxide and water, producing more heat and raising the temperature by more than 18oF (10oC) during the first 24 hours to over 104oF(40°C) in a good active fermentation. As the pulp starts to break down and drain away during the second day, bacteria further increase, lactic acid is produced and the acetic acid bacteria are, under the slightly more aerobic conditions, more actively oxidizing alcohol to acetic acid. By this time the temperature should have reached almost 122 °F (50oC). In the remaining few days of a normal Forastero fermentation of five or six days, bacterial activity continues under conditions of increasingly good aeration as the remains of the pulp drain away allowing air to diffuse between the beans. The high temperature is maintained by the bacterial activity. In box fermentations, it is usual to turn the beans. In the colder cocoa-growing regions, this is done after 1 or 2 days and again after 3 or 4 days, but in the Far East, the practice of turning every day has developed. Turning is often done by shovelling the beans into another box set in front of and below the one used previously. The process of turning has the immediate effect of increasing the aeration and consequently the bacterial activity, which is reflected in a rapid rise in temperature that may exceed the cooling effect of turning. One of the purposes of turning is to secure an even degree of fermentation but it has found that there is considerable variation between different parts even where turning has been carried out. Turning is also recommended for heap fermentations where it would be expected that aeration would not be as good as in a suitably ventilated box. In practice, it is doubtful whether West African heaps are turned more than once, and many are not turned at all. Such evidence as there is suggests that the relatively smaller bulks fermented in heaps may receive quite similar aeration to the larger amounts in boxes. However, there is clearly a greater risk that a few beans in a heap, which is not turned at all, will receive virtually no fermentation. Certainly, a very small percentage of slaty and scarcely fermented beans is not unusual even in good West African cocoa.
Although five or six days can be regarded as the usual period for Forastero cocoa in the fermentation heap or box, there is appreciable variation in the practice. The West African heap is normally opened after about 5 days; in Trinidad the period used to depend on the judgment of the estate for each fermentation. It was usually within the range of five to seven days. Grenada differed in fermenting for a longer period, usually nine to eleven days. Criollo, on the other hand needs much less fermentation and two days usually suffices. Surprisingly, although Trinitario cocoa requires the longer fermentation for its purple beans, the Criollo type beans do not appear to be over-fermented. There is evidence from taking samples at daily intervals from a Trinitario fermentation heap that the most important changes, especially the reduction in astringency and the increase in potential chocolate flavour, mainly occur during the first few days. Moreover, there is little doubt that some fermentation activity takes place during drying before the moisture content is reduced too much. Unless drying is very rapid, deficiencies in the fermentation are remedied to some extent during the first days of drying.
The chemical changes within the cocoa bean depend on the cells of the cotyledon dying so that the cellular membranes break down and allow the different constituents, which are kept separate in the living tissue to come into contact. Death, which takes place during the second day, is caused primarily by the acetic acid, which is then being produced in the pulp. The high temperature is also a contributory cause of the death of the cells. The anthocyanins and other polyphenolic compounds in the pigment cells can then diffuse out into the adjacent main storage cells where they meet various enzymes that bring about hydrolytic reactions while the conditions within the bean are anaerobic. These include the breakdown of the coloured anthocyanins of the Forastero beans so that there is some bleaching of the cotyledons at this stage. As more air reaches and enters the beans, oxidative or browning reactions start to predominate and the tissue darkens. This stage occurs in the latter part of a normal Forastero box fermentation of 6 or 7 days and can continue during drying, provided this is not carried out too rapidly. At the same time as these more visible reactions are taking place, various other chemical changes, which are not fully understood but certainly involve the polyphenols take place and are essential for the development of chocolate flavour.
Drying
When fermentation is completed, the beans are removed from the box or heap for drying. They are then reasonably free of adherent pulp but still have a high moisture content and are somewhat soft. In areas where the weather is comparatively dry at harvest time, the beans are usually dried by being spread out during the day in layers a few inches thick on trays or mats, which are exposed to the sun. The layers of beans are raked over at intervals, usually heaped up at night and protected when it rains. The trays can, as in the West Indies, be whole floors either with the roof on wheels to be pushed back when it is dry and closed over the floor at night or when it rains. Alternatively, the floors themselves are arranged on wheels so that several can be run under a roof, one above the other to save space. In some West African countries, the beans are spread on mats made of split bamboos, which are placed on low platforms. These can be rolled up to protect the beans and can be carried into the nearby huts when it rains. Such mats have the advantage that raking about tends to dislodge any fragments left adhering to the shells of the bean, and these tend to fall away from the cocoa between the strips of bamboo. It usually takes about a week of sunny weather to dry down to the 7% moisture content needed to prevent mould growth during storage.
Where the weather is less dry and sunny at harvest time, drying is done artificially. In the simplest form, the beans are spread over a surface, which is heated from below by the flue gases from a wood fire, wood being the only local fuel. More complex drying equipment involves the use of heat exchangers so that warm and clean air can be blown through the layer of beans spread on a perforated surface or in a rotating cylinder. Modern equipment can give complete combustion of oil, or of solid fuel including wood, so that the flue gases can be used to dry the beans after some admixture of air. Such equipment is widely used by the large plantations in the Far East. Artificial drying introduces two problems. The beans can be dried too quickly so that the enzymes within the bean are inactivated by lack of moisture before the various changes have been completed. To some extent, this can be overcome by ensuring that the chemical processes have gone sufficiently far before the beans are removed from the fermentation heap or box, although it is normal with sun drying for some of these processes to take place during the first few days of drying. The second problem is that the smoke may find its way on to the beans. This is liable to produce an unpleasant smoky or hammy taste, which cannot be removed from the resulting chocolate by processing. While it is comparatively easy to design a drier in which the smoke is kept away from the cocoa, when it is operated for a number of years under the conditions on many cocoa farms and estates which lack skilled maintenance facilities, the risk of smoke reaching the cocoa beans too often becomes a reality. This is the reason why cocoas from some areas are in less demand and consequently command lower prices.
The cut test
Cocoa grading schemes in producing countries are based on a visual assessment of quality by means of a procedure known as the cut test. The procedure has been laid down as an international cocoa standard and its text is included in a pamphlet, Cocoa Bean-Chocolate Manufacturers Quality Requirements, available from the Cocoa Chocolate and Confectionery Alliance in London. The cut test involves cutting at least 100 beans lengthways to reveal in section the greater amount of the middle of the cotyledons. These are examined individually and the percentage of beans of the various categories determined. When a measure of the degree of fermentation is required, three additional categories are used. The first is fully fermented beans, which are brown in colour with the convolutions of the cotyledons tending to separate when the bean is properly dry. If there is some blue or purple colour evident, then these beans, which are partially fermented, are classified as partly brown-partly purple. If all the cut surface is blue or purple without any brown patches, and the cotyledons are pressed tightly together, the bean is classified as fully purple. The least fermented beans, which are defined in the ordinance are slaty in colour. This is because the pigment cells have not released their contents, and none of the chemical changes of fermentation have taken place.
In practice no fermentation is uniform, and since too much fermentation results in a loss of both the strength and quality of flavour, the ideal degree of fermentation shown in the cut test is some 70-80% of the beans fully fermented and 20-30% partly brown- partly purple. Slaty beans should be absent, their presence indicates a lack of sufficient turning, and any more than about 5%, depending on the degree of fermentation of the rest of the beans, will be reflected as some astringency apparent in the chocolate. Fully purple beans are those in which the anthocyanins have been liberated from the pigment cells by the acetic acid of fermentation, but very little further chemical change has taken place. These beans also should not be present, and they have an effect on flavour, which is similar to although slightly less extreme than that of the slaty beans. While this cut test is useful in defining the degree of fermentation of a cocoa, it has been found to be extremely difficult to define these categories of beans in such a way that examiners working in different places can separate the categories in the same way, to produce similar numerical results on the same cocoa. As an alternative, a chemical measure of the amount of anthocyanin was tried, since fermentation involves its breakdown. The quantity of anthocyanin, however, in the slaty and fully purple beans is so much greater than that in the partly purple beans that the results simply reflect the few unfermented beans present. One fully purple bean contains more anthocyanin than about 30 partly purple beans. Consequently, the cut test which also reveals defects other than the degree of fermentation, remains the accepted test in spite of its limitations.
The other categories defined in the model ordinance are mouldy beans, where mould is visible on the cotyledons. These are especially undesirable even as few as 3% can give an unpleasant musty or mouldy flavour to chocolate. Insect-damaged beans are those where the bean has been penetrated by an insect, which feeds on the cotyledon. These should not be present. Any number will involve loss of material and a risk of contamination with fragments of the insect. Also, certain beetles, when present in large numbers, can result in an undesirable stale taste. Germinated beans are those where the seed has started to grow before being killed by the fermentation, and the shell has been pierced by the growth of the first root. In the dry germinated bean, the embryo plant usually drops out, leaving a hole, which makes the bean more easily attacked by insects and moulds. Flat beans are those which have begun to form, but have not developed or filled out. There is no useful cotyledon in them so they simply add to the shell, which is waste. They should be excluded from the fermentation.
Sources of cocoa bean supplies
1. Bulk cocoas
Much of the world's supply of cocoa is grown in West Africa. Just before the beginning of this century, cocoa was brought to the Gold Coast, now called Ghana, from the island of Fernando Po (now called Biyogo). It was a purple-seeded variety of Forastero known as Amelonado. This proved to be well suited to the conditions where the indigenous farmers established small farms of a few acres on land which they cleared from the forest, leaving a few big trees to give some shade to the cocoa trees. At first, the quality of this cocoa was poor because of the lack of experience and care in preparation, but an effective grading system was introduced and applied when the farmers brought their cocoa for sale to the buying firms and later the Government buying centres. This was based on the cut test, and undue numbers of defective beans were penalized. As a result, a remarkably uniform quality of cocoa was exported which was free of major defects such as mouldy flavours. Also, in spite of the absence of any requirement in the grading regulations for limiting the partly brown-partly purple beans, it was found in practice that fermenting sufficiently well to keep the slaty beans down to below 3% resulted in the average level of fermentation, as shown by the numbers of brown and purple beans, usually being sufficiently good.
Satisfactorily fermented Amelonado cocoa, as grown in West Africa, has a full almost heavy chocolate flavour of a relatively simple kind, without undue acidity or bitterness or the various ancillary flavour effects, which are characteristic of Trinitario cocoa. Cocoa from Ghana and Nigeria was almost all from the Amelonado variety, which is, at least in the trees grown there, unusually uniform genetically and produces a uniform type of flavour. This West African cocoa has also developed an enviable reputation for freedom from mould and other taints. This has been assisted by the relatively dry climate. The rainfall is actually less than that previously been considered the minimum needed for successful cocoa growing. Consequently, it is comparatively easy to dry cocoa in the sun sufficiently to inhibit mould growth, and the absence of artificial drying obviates the risk of smoke contamination. In addition, the use of fresh banana leaves for the fermentation heap eliminates the risk that an inadequately clean box will introduce taints. The uniformity of the flavour of the cocoa, with its freedom from undesirable taints combined with the suitability of its comparatively simple but full chocolate flavour for the manufacture of milk chocolate, has resulted in its becoming most acceptable to manufacturers for general use. At the same time, the West African crop has increased in quantity with the result that this cocoa has become the world's bulk cocoa against which other cocoas are judged. Although it is not generally regarded as the highest quality of cocoa, good West African with its uniform and full chocolate flavour is not merely a bulk filler, to which other more flavourful cocoas must be added, but a type of cocoa which is well suited for making certain products and particularly milk chocolate, which is now consumed in large quantity.
During the years around I960, Ghana and Nigeria were producing half the world's crop, but since then other areas have greatly increased production and Ghana's crop is now much reduced. The Ivory Coast, the next country west of Ghana, has produced a similar cocoa from the same Amelonado variety, although more recently there has been a great deal of planting of a more variable but more vigorous and earlier-bearing hybrid Forastero cocoa, which is now contributing substantially to the Ivory Coast crop. This is based on selection of cocoas collected in the region of the Upper Amazon Rivers in South America. This hybrid cocoa, when prepared in a similar way to the Amelonado, is similar in flavour although it does tend towards somewhat sharper overtones of flavour and is not as uniform as is the Amelonado. The same cocoa is also now planted to some extent in Ghana and Nigeria. However, the Ivory Coast has not organized such an effective grading scheme as these two countries have applied for many years at the stage when the farmer first brings his beans for sale. The result is that a great deal of Ivory Coast cocoa is badly prepared, being inadequately fermented and dried. It often includes mouldy beans and is not free from taints, which can be described as dirty foreign flavours. In consequence, Ivory Coast cocoa is less desirable for chocolate manufacture, but the Ivory Coast is now West Africa's biggest producer and one of the two biggest in the world.
A moderately big West African cocoa producing area is Cameroun. Here again the cocoa is mainly Amelonado, although there has been some planting of Trinitarios, but the area suffers from a much heavier rainfall, which necessitates artificial drying. This leads to occasional smoke contamination of the beans. Unfortunately, smoky beans are not easy to detect, except by tasting the cocoa after roasting, and, since the contamination may only be present in a proportion of bags of a consignment, even after careful checking of samples, the smoky taint may not be found until the consignment is being used in manufacture.
The world's other big producer of bulk cocoa is Brazil in South America, whose produce is often referred to as Bahia cocoa. This name is based in the state in which most of the cocoa is grown. Here, there is extensive growing, both in small farms and big plantations, of a similar Amelonado cocoa. In fact, it is believed that West African Amelonado came originally from the Brazilian cultivation. More recently hybrid Forasteros, including the Upper Amazon hybrids have been planted. Brazilian cocoa, however, has tended to be less fermented with distinctly fewer brown beans than West African and is quite distinctly more acidic. In addition, artificial drying is the practice and as in Cameroun, it is not always done satisfactorily. There is a similar, ever-present risk of finding smoky flavours. This risk can be reduced for the manufacturer by a recent development, the initial processing of the bean within the producing country, which is, however, in some other respects less desirable for the manufacturer. This involves the producing country roasting the cocoa beans, removing the shells, and grinding the beans into the liquid stage known as cocoa puree or cocoa liquor. Hence the industry term 'origin liquor' for cocoa bought in this form. Since the grinding inevitably involves mixing, it is easier to check effectively for smoke by testing samples of the origin liquor. The procedure of selling cocoa as origin liquor has advantages in avoiding the transport of the waste shell and saving some space, but it prevents the chocolate manufacturer exercising a control over a quality of the beans or carrying out the roasting process, the precise operation of which does affect the development of the flavour.
The Dominican Republic is another producer, big for the West Indies, of a bulk cocoa, but here there is a tradition of minimal fermentation. The proportion of slaty and fully purple beans is quite high and the cocoa is, as would be expected, distinctly astringent, dark-coloured, and poor in chocolate flavour. In the Far East, New Guinea and Malaysia have more recently become substantial producers. New Guinea contains a good deal of Trinitario cocoa as well as hybrid Forastero from the Upper Amazon. Without a long tradition of fermenting cocoa, this source produces very variable results, including a good deal of unsatisfactory cocoa caused by mould, smoke and other dirty unpleasant flavours. It all tends to be weak in chocolate flavour and somewhat acidic, but some New Guineas are quite strong in some of the desirable ancillary flavours of the Trinitario. Malaysia, which includes Sabah, is the most recent additional producer of bulk cocoa, and is rapidly becoming one of the bigger producers. The cocoa is virtually all the selected hybrid Forastero from the Upper Amazon and most is grown on large estates. Fermentation is based on the box practice of the West Indies but does involve more aeration with frequent turning of the beans and usually very rapid artificial drying. Smoke contamination is unusual but the cocoa is mostly altogether too sharp and acidic and lacks sufficient chocolate flavour.
2. Flavour cocoas
The other main type of cocoa grown is the Trinitario, itself a hybrid mixture of Criollo and Forastero, which, together with the small amounts remaining of Criollo cocoa, produces the fine or flavour cocoas. These have flavours ranging widely from the pale nutty Criollos to the full but titillating flavours of some of the Trinidad estates. The latter can produce cocoas, which have a strong, but not overpowering chocolate flavour showing depth and fullness together with various attractive ancillary flavours reminiscent of raisin and of wines.
The development of these flavours is variable and appears to depend on a number of factors which are not well understood. Even cocoa from a single small estate usually develops its characteristic flavour to a variable extent. It is apparent that the kind of cocoa grown is important and, where the flavour potential of particular selections of cocoa is being examined, it should be remembered that the cocoa bean is a seed and the pollen parent may be expected to make as big a contribution to the flavour potential of the cotyledons as the tree which bears the pod. There is some reason to believe that a mixture of genetic types like that of the Trinitario populations is essential for this type of flavour development. The right fermentation is certainly necessary to develop these flavours properly and the same objective as for bulk cocoa of mostly, but not all, brown beans is probably right. However, assessment of the degree of fermentation by the cut test does not enable the better flavours to be selected. Certainly, defective beans should be absent and normally are in cocoa from the better estates. But some cocoas with an apparently ideal degree of fermentation are dull in flavour while others with what appears to be a distinctly different degree of fermentation have been found to be well developed in flavour. There is, in fact, no substitute for tasting after roasting as a method for determining the flavour quality of Trinitario cocoas.
An attempt was made in the past by one manufacturer to overcome this problem of variation in the flavour development of Trinitario cocoa by having unfermented cocoa shipped to his factory and carrying out a fermentation there. It did not prove satisfactory and was discontinued after a few years.
Prior to the beginning of this century, most of the cocoa used by chocolate manufacturers was either Criollo or Trinitario. The main use was for plain chocolate, where blends of different proportions of a number of origins would be used to produce a variety of flavour effects. In milk chocolate, these interesting flavour effects would be much less apparent and it was found that the simple full chocolate flavour of the Amelonado bulk cocoa produced a satisfactory result and avoided the need for the careful lasting and selection, which is involved in the use of fine cocoas. Some plain chocolate also is made from bulk cocoa, and has a distinctly full and heavy chocolate flavour, although some manufacturers reduce the strength by modifications to the processing. Sometimes, a proportion of flavour cocoa is added to modify and brighten the flavour, while in other plain chocolates, where the heavier effect of the full Amelonado chocolate flavour is not wanted, the chocolate is made from a blend of fine cocoas. In such a chocolate, a small proportion of a good bulk cocoa may usefully be added if the chosen flavour cocoas are lacking insufficient simple chocolate flavour to carry the ancillary flavours. In this way, a suitable bulk cocoa can serve as a flavour cocoa.
Trinidad has for a long time been a producer of good Trinitario flavour cocoa showing, with the right processing to develop it, a bright full chocolate flavour made more interesting by fruity and winey overtones. It also produces cocoa, which cannot be described as good; indeed it is found that the flavour-cocoa-producing areas produce a much wider range of flavour quality than most bulk cocoa areas. Grenada produces an essentially similar cocoa to Trinidad, although the ancillary flavours tend not be as strong, Jamaica is a small producer of a similar type of cocoa which is rather more acidic. Here, the cocoa is collected from the farmers and fermented in a few central fermentaries but there is some variation in the flavour. Most of the south and Central American countries, which grow cocoa, apart from Brazil, are also growers of Trinitario. Venezuela produces various cocoas of the Trinidad type. Recognizable differences occur between the productions of the various river valleys in the mountains along its northern coast. It is interesting that geographically Trinidad is the eastern end of this mountain range. Ecuador is now mainly a bulk cocoa producer, but used to produce a very characteristic cocoa known as Arriba, which appeared to require less fermentation, to such an extent that the best Arriba with its unique strong floral flavour usually had at least 5% of slaty beans.
Sri Lanka (Ceylon), now only producing a small quantity, was unusual in that the beans were washed after fermentation. This resulted in the shells being both lighter and much more easily broken, facilitating the entry of insects and making uniform roasting difficult. Java, now part of Indonesia, was one of the larger producers of white-seeded Criollo cocoas, and Western Samoa, two small islands in the Pacific Ocean, still produces some Criollo. New Guinea, where the earlier plantings were of Trinitario, produces substantial quantities of a flavour cocoa, as well as a great deal of poor-quality cocoa. This flavour cocoa is rather weak in chocolate flavour with an interesting acidity, and occasional shipments show strongly developed ancillary flavours of various types.
Good flavour cocoas command higher prices than the bulk cocoas, but the proportional difference has declined with the increasing importance of bulk cocoa to manufacturers. Moreover, the quantity of flavour cocoas required is relatively small and most manufacturers, certainly for milk chocolate use, would not willingly replace their bulk with flavour cocoa. There is, consequently, no possibility that a major bulk cocoa producing country would receive a relatively higher price by altering its bulk cocoa to show flavour cocoa characteristics. The premium for flavour cocoas over bulk cocoas does depend on there being a sufficient demand for the particular flavour cocoa. Within the field of bulk cocoas, relative prices reflect both the useful yield expected by the manufacturers and experience of the quality as it affects the flavour of cocoa from the area. The shell has to be removed and so the slight differences in its average weight will affect the yield of dry cotyledon or nib, as it is called at this stage. A further important character is the amount of fat in the cocoa bean. This is because chocolate, which needs sugar to balance the flavour of the cocoa, requires more fat than that which is sufficient to liquefy cocoa nib simply by grinding to release its fat . So additional fat is required in chocolate manufacture and the higher the fat content of the cocoa beans used, the less extra fat will suffice. However, the differences in the fat contents between cocoas from different areas are relatively small.
Experience of the quality of supplies of bulk cocoa also affect acceptability. Ghana, the generally preferred standard for bulk cocoa, produces a relatively uniform cocoa with a strong chocolate flavour, which is free from serious defect. Nigeria has a similar reputation, but its cocoa has marginally more shell and less fat. A small reduction in price, compared with the price of good Ghana cocoa, is based on this difference in yield. Ivory Coast cocoa is slightly lower again in yield, but, more seriously, it suffers from the presence of mould and other undesirable flavours. There is, therefore, a larger discount in the Ivory Coast price, and bulk New Guinea is cheaper still because, as well as giving a lower yield as a result of a high shell content, the presence of undesirable flavours including mould and smoke is relatively common.
Shipment of cocoa beans
Cocoa beans are transported and stored in hessian sacks, which are strong, can easily be stacked and can be sampled by means of a sampling stick, which can be pushed between the woven threads. The hessian allows water vapour to pass through, so that the cocoa beans gradually come into equilibrium with the humidity in which they are stored. This can have the advantage of allowing an odd damper bag to dry a little, but is part of the reason for the need to dry cocoa beans down to between 6 and 7% of moisture to allow for some slight uptake while stored in the producing country, where relative humidities even within stores tend to be fairly high.
Difficulties, however, can still be caused by this moisture in commercially dry cocoa when it is transported to manufacturers in colder countries. The West African crop is mainly shipped during the northern winter months. Cocoa at 8% moisture is, for example, in equilibrium with a relative humidity of 70%. It may be loaded, usually filling the holds of the ship, at a temperature of about 85 oF (30°C). After a few days, the temperature both of the air and the sea will start to fall and, within a few more days, on reaching the North Atlantic it may be down close to freezing point. These are the conditions under which dew will condense on to the cold metal of the ship. But the bulk of cocoa will take quite a long time to cool appreciably so that it will keep the air around it warm and at its equilibrium relative humidity. This air will diffuse outwards and be cooled by the cold metal of the ship till its relative humidity reaches 100% and water starts condensing on the cold metal. A drop in temperature of only 12 oF (7oC) is sufficient for this air to become fully saturated. A stack of cocoa allows some movement of air in the spaces between the rounded bags and even between the beans. There is, therefore, in practice a distinct convection circulation of the warmed air up through the middle of the stack and down the outside, where it is cooled by the metal of the ship's side in contact with, and cooled by, the cold sea. This results in a steady movement of water evaporated from the more central part of the stack of cocoa beans on the cold metal of the ship where it is condensed, running off as liquid water, and giving up its latent heat to the metal, which remains at a low temperature because the heat is conducted away to the cold sea and air outside.
Although the cocoa beans are dry, even at 7% moisture the water in a hold containing 1000 tons of cocoa would as liquid water amount to 15 000 gallons. If the moisture content of the cocoa was reduced only a quarter percent, there would be 560 gallons available for condensation. Such amounts are liable to involve water literally raining down from the deck above and running down the walls of the hold without apparently reducing the average moisture content of the dry cocoa. There can easily be a sufficient quantity to wet patches of the dry cocoa in bags. Liquid water is taken up very quickly by cocoa beans, which can in a few minutes go from their dry condition to 20 or 30% moisture. At these moisture contents and temperatures around 75 °F (24 °C), moulds can develop in a few days. As a result, a number of shipments have arrived in Europe and North America with patches of beans, which have been wetted and spoilt by the growth of mould.
Precautions to prevent such damage must be taken in ships. The best precaution is to operate mechanical ventilation. This continually removes the warm air, carrying more moisture than it can hold when it cools, before the water can condense on to the cold surfaces. In addition, the bags are stacked so that they are not in contact with the cold metal and are not placed where any condensation water is likely to run down and wet the bags, and absorbent mats are spread over the tops of the stacks to catch drips from the deck head. But there can be problems in ventilating during bad weather, so that difficulties do arise at times. It is usual to leave channels for ventilation in large stacks. This helps the ventilation to cool the cocoa by removing the heat which with the rapid change which is possible in the external temperature, is the cause of the problem.
It has been suggested that mould growth can be a result of moisture migrating actually through the cocoa from the warm central area of the stack to the cool outer layers. There is, of course, a tendency for such a movement to take place, because the vapour pressure of water in air at a relative humidity of, for example 70%, which is in equilibrium with the dry cocoa at 8% moisture, is relatively lower at the lower temperatures near the outside of the stack. The cooler cocoa will therefore gradually absorb moisture vapour, which diffuses out from the air around the warmer beans. This is because the vapour pressure of the water in the warm air around the warm cocoa beans will be higher than that in the cooler air in equilibrium with the cooler cocoa. Water vapour will therefore diffuse out to the area of lower vapour pressure, raising this pressure above the vapour pressure in equilibrium with the cocoa there. Water will then be absorbed by the cocoa to bring it into equilibrium with its surrounding air and its moisture content will be raised while the vapour pressure of the air will be reduced. This process is caused by the difference in temperature between different parts of the stack due to the cooling of the outer layers and will continue as long as there is a temperature difference, unless the cooler cocoa has a moisture content sufficiently raised that its equilibrium vapour pressure is as high as that of the warmer cocoa.
However, this movement of water vapour by diffusion is a slow process and, eventhough it may be assisted by some movement of air, the uptake of wafer in the vapour state by cocoa beans takes days rather than the minutes involved in the uptake of liquid water. Instead of liquid water wetting relatively few beans, the vapour will be absorbed by any beans of moisture content low enough to have a vapour pressure below that of the air. In practice, the increase in moisture content by moisture migration is not more than 1 or 2%, even under the most favourable circumstances. This may be enough to allow moulds to grow, but their growth at this sort of moisture content is very slow indeed. Moreover, it would only be the cool cocoa that would be increased in moisture by this means. The low temperature would also delay growth. For example, beans at temperatures up to 60 °F (16°C) fully exposed to 90% relative humidity took several weeks to rise to 10% moisture content, eventhough their equilibrium moisture content in 90% relative humidity is as high as 13%, and these beans did not show any mould growth until they had been exposed for 7 weeks. This kind of moisture movement could not, therefore, cause mould damage to cocoa during even a slow voyage. The rapid uptake of substantial amounts of water into relatively few cocoa beans as a result of condensation on to the cold inner surfaces of the hold is, however, a constant risk when moving from tropical to colder regions. The necessary precautions must be taken against this risk.
A more recent development has been the introduction of containers. An early attempt to ship cocoa in bulk in a specially designed container proved unsatisfactory due to condensation. More recent trials have involved the normal hessian bags of cocoa being stacked into containers. It has been found possible to ship cocoa in the standard closed containers between West Africa and Europe during the warmer summer months, but during the winter, excessive condensation can be expected on the inside of the container in the same manner as in a ship's hold. Special containers have therefore been designed with grilles to allow ventilation air movement involving circulation to remove the warm air. Provided there is sufficient air movement in the ship's hold, such ventilated containers have proved satisfactory, again overcoming the difficulty of the temperature change by removing the warm moist air and gradually cooling the cocoa to remove the cause of the trouble.
The cocoa trade accepts that there is a loss in weight when cocoa is transported from the producing to the consuming countries. A loss of 0.5% of the weight is allowed in the London contract, and statistics of cocoa supply and usage include this 0.5% loss as a difference between production and consumption figures which is known as shrinkage. In fact, it appears to be an over-estimate. Careful measurements made a few years ago showed no average change when a number of bags in different parts of a stow were tested in West Africa and the same bags sampled and checked for moisture on arrival in England as part of an ordinary shipment. Much earlier, it was believed that cocoa as used in factories in Europe had a substantially lower moisture content in the region of 4 or 5%, presumably partly as a result of drying while in store. It was not then realized that the established method of sampling, which involved putting the sample of beans into a cloth bag, allowed appreciable drying before the sample was examined and tested in the laboratory. However, such inaccuracies, although no doubt explaining some perplexing differences between the results of a reliable method of moisture determination when used in different laboratories, did not affect the actual yield of dry roast nib from each bag of beans. This is determined by the accuracy of the weight of beans filled into the bag and their average moisture content at that time. It is unimportant as to how much moisture is lost subsequently, since a greater loss will merely reduce the amount of moisture lost during the roasting process, the product of which is dry roast nib, the characteristic ingredient of chocolate.
Infestation of cocoa
Once they have been dried, cocoa beans are not subject to deterioration, provided they are kept under good conditions. These should include an absence of the various insect pests, which feed on cocoa beans. Cocoa is particularly vulnerable to two small tropical moths belonging to the genus Ephestia. The larva stage, the caterpillar, enters a bean, usually where the shell is damaged, and feeds and grows there until it is ready to pupate. It then leaves the bean and usually finds its way out of the bag and up the wall of the store. Insect damage to cocoa beans is easily seen in the cut test where the droppings (frass) and woolly filaments produced by the caterpillar are obvious in the cut beans.
Various beetles and their larvae also feed on cocoa beans and can be recognised by the powdery frass they leave. Some only rarely enter the beans, feeding mostly on the residue of pulp adherent to the outside. Their presence can result in a consignment being described as severely infested, eventhough the cut test on a sample of beans does not reveal any insect damage. Control of light infestations is usually effected by spraying with an insecticide such as a pyrethrum type, which is virtually non-toxic, suspended in a non-tainting oil or in water. More severe infestations are better controlled by fumigation, either in suitable chambers or under gas-proof sheeting. The Ephestia moth, often known as the cocoa moth, is a particularly successful pest. Its habit of pupating away from its food enables the moths to emerge in considerable numbers to lay their eggs to continue infesting foodstuffs even after an infested consignment has been moved and 'treated to kill the insects. Control measures need therefore to be applied to the structure of the store as well as the actual consignment. One of the two species of Ephestia. E. elutella is more tolerent of the cooler temperatures of most consumer countries, and is particularly troublesome to manufacturers. Both species can feed on chocolate products as well as cocoa beans. A most distasteful appearance is produced when a larva finds its way into a product and feeds there.
Microbiology of cocoa
Cocoa beans are free from micro-organisms when they are inside the cocoa pod, but the pulp is an excellent medium for their growth and this is encouraged in the fermentation process. Yeasts and various kinds of bacteria proliferate and it is to be expected that even after drying there will be a great many micro-organisms, including moulds, adhering to the shell. In fact, cocoa shell is coated with very large numbers of harmless bacilli remaining from the fermentation and, depending on the hygiene of the drying process, there may also be some of the less resistant but potentially harmful bacteria. The bacteria are dormant while the bean is dry. The roasting process normally involves sufficient heat to kill all but the more heat-resistant of the bacilli. However, it is important to separate the intake of beans, which necessarily involves considerable evolution of bacteria-laden dust, from the handling of the beans after they have been roasted and from subsequent processes. Most of the bacteria on the beans are quite harmless and merely contribute to the bacterial count. However, it is possible for some contamination to occur with harmful bacteria like Salmonella, Fortunately, these are much more sensitive to heat and are normally killed in the roasting process. However, they are more resistant under dry conditions and there have been a very few instances where chocolate has been found to contain sufficient of these bacteria, believed to have been brought into the factory with cocoa beans, to cause some illness. Chocolate and most chocolate products are too dry and sugary to allow multiplication of bacteria, but chocolate does appear to allow bacteria in it to remain in a dormant, but potentially active, state for long periods and may exert a protective effect on bacteria in the stomach. If use is made of origin liquor, freedom from Salmonella depends on its manufacture and routine checks should be made of its bacterial condition. Somee factories actually heat-treat the cocoa liquor when producing origin liquor to ensure that the bacteria are controlled. Unfortunately, the high temperature needed to kill bacteria under the conditions within the liquefied cocoa has an adverse effect on the flavour.
Moulds attack cocoa beans and, as has been pointed out, are most objectionable since as few as 3% of mouldy beans can taint chocolate in a most unpleasant fashion, and this taint cannot be removed by processing. When it was found that some moulds could produce the highly toxic substance, aflatoxin, the question arose as to whether it was produced in cocoa beans. Numerous tests have been carried out but the presence of aflatoxin in cocoa beans has never been confirmed, although tests have been carried out actually on the mouldy beans on which Aspergillus glaucus, a species of mould capable of producing aflatoxin, has grown actively. There is evidence that the mould must have a particular medium on which to grow to produce the aflatoxin and it appears that the necessary medium is not provided by cocoa beans. Nevertheless, the objectionable effect of moulds upon the flavour of chocolate does necessitate constant attention to the prevention of moulds from growing on cocoa beans. This is achieved by drying reasonably rapidly after fermentation and avoiding subsequent uptake of water.
