Fermented and vegetables. A global perspective. Chaper 1.

Fermenting fruits and vegetables can bring many benefits to people in developing countries. Fermented foods play an important role in providing food security, enhancing livelihoods and improving the nutrition and social well being of millions of people around the world, particularly the marginalised and vulnerable.

Eight hundred million people do not have enough food to eat. If we include those not free from hunger the figure rises to 1.2 billion people. This is one fifth of the World's population. A further two billion people are deficient in one or more micro-nutrients (Anon, 1996). In the seventies, food security was viewed mainly in terms of food supply at the global and national levels. Since then there has been a major shift in understanding of food security with more emphasis on access to food rather than purely on production. The Food and Agriculture Organisation of the United Nations (FAO), amongst other influential organisations, has recognised that the problem of food security cannot be tackled in isolation. Moreover that it is an integral component of other development issues. FAO highlights the fact that the world food insecurity problem is a result of undemocratic and inequitable distribution of and access to resources rather than a problem of global food production (Anon, 1995), (Anon, 1996).

Fermentation technologies play an important role in ensuring the food security of millions of people around the world, particularly marginalised and vulnerable groups. This is achieved through improved food preservation, increasing the range of raw materials that can be used to produce edible food products and removing anti- nutritional factors to make food safe to eat.

Fermentation is a cheap and energy efficient means of preserving perishable raw materials. When harvested, fruit and vegetables, undergo rapid deterioration, especially in the humid tropics where the prevailing environmental conditions accelerate the process of decomposition. There are several options for preserving fresh fruit and vegetables including drying, freezing, canning and pickling. However many of these are inappropriate for use on the small-scale in developing countries. For instance the canning of vegetables at the small-scale has serious food safety implications and contamination with botulism is a possibility. Freezing of fruits and vegetables is not economically viable at the small-scale. Fermentation requires very little sophisticated equipment, either to carry out the fermentation or for subsequent storage of the fermented product. It is a technique that has been employed for generations to preserve food for consumption at a later date and to improve food security. There are examples from around the world of the role fermented foods have played in preserving food to enhance food security.

Fermented foods for survival in Sudan

About 60% of the fermented foods of Sudan are famine or survival foods. Many of the fermented foods have been developed in Western Sudan in the Kordofan and Darfur regions, which are traditional famine areas. The strong link between fermented foods and food shortages is revealed by the fact that when a family becomes rich a number of fermented foods are no longer prepared. The techniques used are very effective methods of food preservation. The products can be preserved for years through the double action of fermentation itself (which produces anti-microbial acids) and sun-drying. Sudan is probably the hottest and driest country in Africa. Through the years women have made full use of this free solar energy. Shade temperatures in the summer reach 45-50^oC and the hot sands outside the shade reach more than 70^oC. Dried and fermented foods together with the seeds and fruits that can be gathered from the wild have saved lives especially those of children in the past and in the present in times of shortage (Dirar, 1992). During the 1983-85 famine, relief workers found that people had survived by producing specific traditional fermented food products, especially Kawal (Arthur, 1986).

Gundruk: an important fermented product in Nepal

Gundruk is a fermented and dried vegetable product. It is produced by shredding the leaves of mustard, radish and cauliflower leaves and placing them in an earthenware pot to ferment. After five to seven days the leaves are removed and dried in the sun. Gundruk is a very important food product in Nepal ensuring food security for many Nepali communities especially in remote areas. It is served as a side dish with the main meal and is also used as an appetiser in the bland, starchy diet. The annual production of gundruk in Nepal is estimated at 2,000 tons and most of the production is carried out at the household level. Gundruk is also an important source of minerals particularly during the off-season when the diet consists of mostly starchy tubers and maize which tend to be low in minerals (Karki, 1986).

Fermentation can salvage waste food which otherwise would not be usable as food by changing the consistency of the product and making it digestible. This increases the range of raw materials available as food.

Bones and hides

A wide range of "waste" products are fermented to produce edible food products in Sudan. These includes bones, hides and locusts. Fresh bones are fermented into a variety of products. "Dodery" is produced by chopping bones into small pieces and placing them into fermenting vats. They are subsequently covered in water, left for three days, removed, crushed into a paste and mixed with the ash from burnt sorghum stalks. The mixture is returned to the fermenting vat for a further two to five days. The final product is rolled into balls and has a shelf like of up to two months. Another product "Kaidu digla" is made from the vertebrae of the backbone. These are chopped into smaller pieces and then sun-dried. After drying they are pounded with stones; mixed with water and salt; moulded into balls and allowed to ferment (Dirar,1992).

Use of waste products in Indonesia

In Indonesia a variety of waste products are fermented to produce nutritious food products. Tempe-bongrek is a protein rich food made in Indonesia by fermenting peanut and coconut press-cake, remaining after oil extraction. The product is similar to traditional tempeh produced from the fermentation of soya beans. The production of tempeh- bongrek is a mould fermentation, initiated by inoculation of the soaked, acidified press-cake with Rhizopus species. The inoculated cakes are placed on banana leaves or plastic sheets in a dark room for about 2 days. An incubation temperature of 37ºC is optimal for the mould and prevents the growth of P. cocovenenans, which produces bongkrek toxin. A pH of less than 6.0 also prevents the development of bongkrek toxin. Ontjom is produced from waste groundnut press cake, tapioca waste and the solid waste of tahu. Ontjom is prepared using a mixed culture of micro-organisms with Rhizopus or Neurospora species predominating. Ontjom is mainly produced in west Java where it is consumed as a side dish in the form of deep fried slices. It forms an important daily food item for the west Javanese, particularly those from the lower income groups. Fresh coconut residue, left over from the production of coconut cream or milk, can be fermented by Bacillus subtilis, in an alkaline fermentation, to produce semayi, which is widely consumed in Indonesia (Steinkraus, 1996).

Pineapple peel vinegar

A considerable amount of the fruit can be wasted in the peeling and preparation of pineapples in Latin America. Through fermentation, a product can be produced from the peelings, that would otherwise have been discarded. The peelings are placed in containers of water and sugar and yeast are added. They are allowed to sit for about 8 days, after which a pineapple peel vinegar is produced. The product is of a distinct, light pineapple flavour and can be used in the same way as other vinegars.

Many fruits and vegetables contain naturally occurring toxins and anti-nutritional compounds. These can be removed or detoxified by the action of micro-organisms during fermentation. For instance the fermentation process that produces the Sudanese product Kawal removes the toxins from the leaves of Cassia obtusifolia and fermentation is an important step in ensuring that cassava is safe to eat.

Removing cyanide by fermentation

Cassava contains a naturally occurring chemical: cyanogenic glucoside. When eaten raw or improperly processed, this substance releases cyanide into the body, which can be fatal. Correct processing removes this chemical. The cassava is first peeled (as about 60-70% of the poison is in the peel) and then soaked in stagnant water or fermented in sacks for about three days. It is sometimes grated or rasped as this helps to speed up the fermentation process. At the beginning of the fermentation, Geotricum candida acts on the cassava. This tends to make the product acidic, which finally kills off the micro-organisms as they cannot exist in such a medium. A second strain of micro-organisms (Cornibacterium lactii), which can tolerate the acidic environment then take over and by the third day 90-95% of the dangerous chemical will have been hydrolysed. The cassava also develops its characteristic flavour. The product is then sieved and the fine starch particles are fried in an iron pan alone over a flame or with some palm oil. During this process most, if not all the remaining toxins are given off. The liquor from a previous fermentation is used as a starter, thereby reducing the period of fermentation to about 6-8 hours.

The production of fermented fruit and vegetable products provides income and employment to millions of people around the world.

Food processing is probably the most important source of income and employment in Africa, Asia and Latin America. The Food and Agriculture Organisation of the United Nations has stated that value added through marketing and processing raw products can be much greater than the value of primary production (Anon, 1995). For instance in sub-Saharan Africa more than 60% of the workforce is employed in the small scale food processing sector, and between one third and two thirds of value added manufacturing is based on agricultural raw materials (World Bank, 1989), (Conroy et al, 1995). This is particularly important as agriculture and the formal sector are unable to absorb the growing labour force in many countries.

Fermented foods are popular throughout the world and the production of fermented food products is important in many countries in providing income and employment.

In Africa, fermented cassava products (like Gari and Fufu) are a major component of the diet of more than 800 million people and in some parts of Africa it constitutes over 50% of the diet (Oyewole, 1992). In Asia the preparation of fermented foods is a widespread tradition. Kimchi (a fermented cabbage product) is the major food product of Korea. Soy sauce (a fermented legume product) is economically important from Indonesia to Japan. Over a billion litres are produced each year in Japan alone. Over 2000 million litres are produced each year in Korea and over 150 million litres in Taiwan. Miso (a fermented legume product) is also very important in Asia with over 560,000 tons produced a year in Japan alone (Anon, 1982). In Latin America, fermented cereal products, alcoholic drinks and fermented milk products are three of the most important sectors of the economy.

The optimum health and nutrition of individuals is dependent upon a regular supply of food and a balanced diet. When diets are sub-optimal, the individual's capacity for work and achievements are greatly reduced. The most vulnerable groups are women, children and weaning infants. Availability of food, dietary restrictions and taboos, misconceptions, limited time available for feeding or eating compound to create a group of individuals who are nutritionally disadvantaged. Approximately 30% of women consume less than their daily requirements of energy and at least 40% of women world-wide suffer from iron-deficiency anaemia. Fermentation can enhance the nutritional value of a food product though increased vitamin levels and improved digestibility.

Fermentation processes can result in increased levels of vitamins in the final product. Saccharomyces cerevisiae is able to concentrate large quantities of thiamin, nicotinic acid and biotin and thus form enriched products.

Micro-organisms contain certain enzymes, such as cellulases, which are incapable of being synthesised by humans. Microbial cellulases hydrolyse cellulose into sugars which are then readily digestible by humans. Similarly pectinases soften the texture of foods and liberates sugars for digestion. Fermented foods are often more easily digestible than unfermented foods (Kovac, 1997), (Parades-Lopez, 1992).

Lactic acid fermented weaning foods are traditionally produced in developing countries, both to improve the safety of the food and to improve its digestibility. Starchy porridges are commonly fed to weaning infants in developing countries. The consistency of these gruels, combined with the small capacity of the infants stomach, means that it is physically impossible for the child to consume adequate energy to meet its high demands. By acidifying the porridge through lactic acid fermentation, starch is hydrolysed into shorter chains of glucose and dextrose, which reduce the viscosity of the porridge and increase its energy density. Thus the child is more able to meet its energy requirements.

There are many traditional beliefs about the medicinal properties of fermented food products. The Fur ethnic group in Sudan strongly believe that the consumption of fermented foods protects them from disease (Dirar, 1992). Koumiss (a fermented milk product in Russia) has been used to treat tuberculosis. Pulque (a fermented fruit sap) is felt to have medicinal properties in Mexico.

Fermentation is a traditional method of reducing the microbial contamination of porridges in Kenya (Watson, Ngesa, Onyang, Alnwick and Tomkins, 1996) A study in Tanzania has shown that children fed with fermented gruels had a 33% lower incidence of diarrhoea than those fed unfermented gruels, owing to the inhibition of pathogenic bacteria by lactic acid forming bacteria (Svanberg, 1992).

Fermentation can improve the flavour and appearance of food. One important area is the creation of meat-like flavour. Over the years, Sudanese women have developed products to replace meat in their diets. These include "kawal", fermented wild legume leaves, "sigda" (fermented sesame press-cake) and "furundu" (fermented red sorrel seeds). The strong flavours of fermented food products can enhance a dull diet. Fermented vegetables such as pickles, gundruk and sauerkraut are used as condiments to enhance the overall flavour of the meal. A small amount of pickle can make a bland starchy diet (like dahl and rice in Asia) much more appealing (Battcock, 1992).