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close this book Food Chain No. 13 - November 1994
View the document Greetings
View the document The ancient art of biotechnology
View the document Equipment
View the document Booklines
View the document Fermented foods in Sudan
View the document Mursik - fermented miIk in Kenya
View the document The production of Hate de coco
View the document Resource page
View the document Bakers' yeast
View the document Recipe page
View the document Acknowledgments

The ancient art of biotechnology

There are hundreds of traditionally fermented foods and it would be impossible to cover all the products here. This article presents a broad overview of the range and variety of traditional fermented foods from different regions of the world and readers will undoubtedly recognise many of the foods listed.

CEREALS

Most of the traditional fermented foods are made from cereals. All the major cereal grains can be processed using traditional biotechnology. One particular type of fermented cereal is porridge.

Different types of porridge are made from a wide range of cereal grains. Uji (from Kenya) or ogi (from Nigeria) is an important weaning food as well as a breakfast food. It is made from maize, sorghum or millet flour. The basic process involves the grain being steeped in water for one to two days. This aids germination of the grain, similar to the process of malting in brewing. The steeped grain is then milled and water is added to extract the starch in solution. The starch is left to separate out from the water and then allowed to ferment naturally - a step which can take two to five days. The paste or slurry is diluted with water, boiled to the consistency of porridge and then sweetened before consumption usually for breakfast although there are different customs for different regions.

LEGUMES/NUTS/OILS

Fermented legumes, oilseeds and nuts are commonly used as condiments. Some examples are iru from the locust bean, ogiri from the castor seed and soy sauce from the soy bean Iru or dawadawa is a condiment used in many African dishes especially those of Nigeria. Its high protein content makes it a valuable component in the diets of poor families Iru is prepared from the locust bean which is more commonly known as carob - the alternative chocolate. Traditional in' processing is still carried out at a domestic level. However, its popularity as a condiment has resulted in a modern product, which is similar to a stock cube, being developed in Nigeria.

Traditionally, in' is made by boiling the dried locust beans for about 24 hours. With the addition of ash the seed coats are removed. The seeds are then boiled again for about two hours. While the seeds are still very hot they are drained, transferred to a basket and covered with leaves. This helps to retain heat and create a humid atmosphere. The beans are allowed to ferment for two to three days, after which time the leaves are removed and the seeds are crushed to a paste. Various shapes can be moulded from the paste and finally the paste is sun dried.

ROOTS

Roots and tubers are important constituents in the diets of millions of people and traditional biotechnologies have been developed to help preserve them and add variety to the diet. However there are only a few types of root crop which have been fermented and these include cassava and potato.

Two types of fermented cassava are gari fufu. A product of fermented potato is the alcoholic spirit, potcheen. Cassava is one of the most important crops in the world, being the staple food for millions of people. Cassava needs to be processed because fresh cassava contains a chemical substance which, if consumed, can lead to cyanide poisoning. Long term consumption of poorly processed cassava can result in the incidence of goitre.

It is important to note that fermentation does not detoxify cassava; detoxification is achieved in the earlier processing stages of grating and washing. The role of fermentation is to introduce variety into cassava diets while at the same time helping to preserve it.

Gari and fufu are products of the natural fermentation of cassava. The main differ ence between these two products in terms of processing is that hari is prepared by allowing washed, grated and pressed cassava to ferment in cloth sacks. The fermentation step for fufu on the other hand, is carried out by submerging cut pieces of washed and peeled cassava in water until fermentation has proceeded to give the desired flavour.

Gari is finally obtained by sieving out the coarse fibres and then frying the pulp. For fufu, the fermented pieces are also sieved but then pressed and made into small balls which are boiled and mashed into a dough.

VEGETABLES

Fermentation is a traditional way to preserve vegetable surpluses and the products a used for a variety of purposes. Fermented vegetables such as pickles, gundruk and sauerkraut are used as condiments to e hance the overall flavour of the meal. Kawal, on the other hand, is used as a meat replacer in diets of poorer people and ferment' cassava leaves are made into a dish with meat or fish to accompany the staple cassava component of a meal. Nearly all types vegetable can be pickled; the better known ones include cucumbers, cabbage and olices. Pickling is still carried out at domes scale. However industrial scale process have been developed for most types pickles. Pickles are made by storing prepared vegetables in a weak brine solution sometimes dry salting. This provides a suitable environment for lactic acid bacteria grow which impart the acid flavour to the vegetable. Dill pickles have the additional flavour of dill which is added to the brine the start of fermentation.

Sauerkraut is pickled cabbage. Shredded cabbage is dry salted and put into barrels. brine is formed as liquid is drawn out of the cabbage. The barrel is covered with a plastic sheet and liquid, often brine, poured on the sheet to ensure that the cabbage completely submerged to prevent blackening Fermentation is often complete after one to two months although the time depends the temperature and concentration.

Gundruk, is an important condiment in Nepal and is obtained from the fermentation of leafy vegetables. To make gundruk, vegetables leaves are pounded by hand and then placed in an earthenware pot. The pot is filled with the pounded vegetable and then straw is placed on top During the day the pot is left outside in the sun which dries out the product, in the evenings the pot is placed near a heat source. Warm water is added periodically to keep the pot brim full and to keep the fermenting mass warm. After fermentation is complete the product is spread out on clean mats to dry in the sun. It is then stored and used as necessary

MEAT AND FISH

Meat and fish are important sources of protein in the diet but such foods are highly perishable in their fresh state. Fermentation provides a low cost way to preserve these foods and add variety to the diet. When considering meat and fish processing it is necessary to point out the greater risk of food poisoning if food processing is improperly carried out. In the fresh state, meat and fish have a neutral to alkaline chemical balance; conditions under which pathogenic bacteria thrive. Hence greater precautions must be taken when processing these foods. Fermentation, when properly carried out, results in an increased acidity in the food after a short period of time which inhibits the growth of food poisoning bacteria.

There are three basic types of fermented fish: sauces, pastes and salted. An example of a fish paste is bagoong which is produced in the Philippines. Salt is mixed with prepared fish to a ratio of about 1:3. It is then allowed to ferment until it has the desired characteristics. This may take one to two months.

Fermented meat products by comparison to the fermented products of other food commodities are less widely reported. Fermented meats include hams and some sausages and there is a wide range of fermented meat products from the Sudan. They include the fermentation of fatty strips of meat and other products from the intestines and offal.

FRUITS

The fermented products from fruits largely fall under the categories of alcoholic beverages and vinegars Virtually any fruit can be processed into an alcoholic beverage. The process is well known, being essentially an alcoholic fermentation of sugars to yield alcohol and carbon dioxide. The latter being an important characteristic of beers and champagnes.

Banana beer is made by allowing bananas to fully ripen before extracting the juice. The juice is allowed to ferment naturally for about three days Vinegar, an important condiment and preservative, is produced by an additional fermentation stage after the fermentation of sugars to alcohol. It is the acetic acid produced by the fermentation of alcohol (ethanol) which gives the characteristic flavour and aroma to vinegar.

A wide range of raw materials can be made into vinegar. Traditional vinegars include palm wine vinegar, and coconut vinegar produced from the sap of palm flowers. The sap readily ferments to toddy and by the addition of a vinegar starter (from a previous batch) vinegar can be made.

THE FUTURE

These are just a few examples of many hundreds of foods produced by biotechnology that are consumed all over the world. It is interesting to speculate on their origins but it is more important to look to the future. Indigenous knowledge and traditional biotechnologies cannot rest on their laurels. The introduction of 'western foods' with their glamorous image are now the most recent threat to those foods that have survived the test of time. To withstand this threat greater recognition must be given to indigenous knowledge.

Traditional biotechnologies are a good example of indigenous knowledge threatened not only by the introduction of Western style foods but also from modern biotechnology practices themselves If any advances in biotechnological practices are to 'withstand the test of time', to complement and not compete with indigenous knowledge and clearly to not marginalize rural people, then the technical, social and economic circumstances of rural people today need to be considered.