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Fermentation is one of the oldest forms of food preservation technology in the world. Indigenous fermented foods such as bread, cheese and wine, have been prepared and consumed for thousands of years and are strongly linked to culture and tradition, especially in rural households and village communities. Fermented foods are popular throughout the world and in some regions make a significant contribution to the diet of millions of individuals. For instance Soy sauce is consumed throughout the world and is a fundamental ingredient in diets from Indonesia to Japan. Over one billion litres of soy sauce are produced each year in Japan alone. 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 areas these products constitute over 50% of the diet. Fermentation is a relatively efficient, low energy preservation process, which increases the shelf life and decreases the need for refrigeration or other forms of food preservation technology. It is therefore a highly appropriate technique for use in developing countries and remote areas where access to sophisticated equipment is limited. There is tremendous scope and potential for the use of micro-organisms towards meeting the growing world demand for food, through efficient utilisation of available natural food and feed stocks and the transformation of waste materials.

There is a danger that the introduction of 'western foods' with their glamorous image will displace these traditional fermented foods. Although fermentation of foods has been in use for thousands of years for the preservation and improvement of a range of foods, the microbial and enzymatic processes responsible for the transformations were, and still are, largely unknown. Because of the tremendously important role indigenous fermented fruits and vegetables play in food preservation and their potential to contribute to the growing food needs of the world, it is essential that the knowledge of their production is not lost. Moreover, it is essential to increase the knowledge and understanding of the methods of preparation, in order to improve the efficiency of fermentation, especially the traditional processes as the yields of traditional fermentation processes are often low and sometimes the products are unsafe. This chapter discusses potential areas for improvement of indigenous fermented fruit and vegetable products. It can be divided into four main areas:

8.1 Improving the understanding of fermented products

For fermented products such as cheese, bread, beer and wine, which are produced on a commercial scale, a good understanding of the microbial processes has been developed. However with many of the fermented products in Africa, Asia and Latin America, knowledge of the processes involved is poor. It is likely that the basic principles apply across the board, but production conditions vary enormously from region to region, giving rise to numerous variations of the basic fermented product. It is not the intention or the desire to standardise the process and thereby lose this huge diversity, rather it is to harness the tremendous potential these methods have to contribute to increasing not only the quantity, but quality of food available to the worlds population.

There are two main reasons for gaining a better understanding of indigenous fermented products:

8.1.1 Documenting the traditional knowledge

Fermentation is one of the oldest food processing technologies in the world. The knowledge of how to make these products has often been passed down from parent to child (usually mother to daughter) and belongs to that undervalued body of "indigenous knowledge". Most of this knowledge has not been documented and is in danger of being lost as technologies evolve and families move away from traditional food preservation practices.

The collection and preservation of indigenous knowledge is of interest to governments, historians, anthropologists and scientists, to name but a few. Several individuals and organisations are actively involved in research in this area:

Several research institutes and scientists in Africa, Asia and Latin America are recording information on traditional fermented foods. Dr Karki in Nepal and Hamid Dirar have been extensively quoted in this book and their work on fermented products in Nepal and Sudan is of great importance.

Intermediate Technology has been collecting information about traditional food products from Africa, Asia and Latin America. The first volume of products was published in 1997 (Fellows, 1997). This included the following fermented food products: kenkey, ogi, injera, fermented sweet bread, sorghum beer, palm wine, banana beer, pineapple peel vinegar, lime pickle, tamarind pickle, mango pickle, gari, vegetable pickle, coconut toddy, yoghurt, ayib and dawdawa. Volume 2 will be published in 1999 and regional publications on the traditional food products of Bangladesh, Southern Africa and the Andes are planned.

The European Union has just completed an audit of the traditional food products of Europe. The results have been published in a series of publications (Cowan, 1998).

The Special Programme on Biotechnology and Development Cooperation for the Netherlands Government was established in 1992 to improve the access of developing countries to biotechnological expertise and innovation with a focus on using biotechnology for the benefit of small-scale farmers and producers. Part of the programme involved a competition to identify farmers' existing biotechnology practises. This programme resulted in the collection of valuable information about traditional fermented food products (Bunders et al, 1996).

Finally, the Food and Agriculture Organisation of the United Nations sees the value in collecting and preserving this source of knowledge. This book is an example of their work.

8.1.2 Developing a scientific understanding of the microbial processes

Most traditional fermented products are made by natural fermentations carried out in a non-sterile environment. The specific environmental conditions cause a gradual selection of micro-organisms responsible for the desired final product. This is appropriate for small-scale production for home consumption. However the method is difficult to control and there are risks of accompanying micro-flora causing spoilage and unsafe products.

If the processes are to be refined, with a view to production on a larger scale, it is essential to have a scientific understanding of the fermentation processes. This can be developed by:

This research is capital intensive and usually requires scarce foreign exchange. It requires the use of sophisticated equipment and reagents backed with a consistent energy and water supply which are not always available in developing countries. To meet the current and future challenges in developing countries, it is important that these countries develop the capabilities to benefit from improvements in fermentation methodologies.

Biotechnologies need to be developed which are affordable by the poor, since it is they who are likely to benefit most by improvements to the traditional processes.

8.2 Refining the process

The art of traditional processes needs to be refined to incorporate objective methods of process control and to standardise quality of the final product without losing their desirable attributes such as improved keeping quality, taste and nutritional qualities.

Science based fermentation research has often focused mainly on improving the metabolic properties of the micro-organisms used as a starter culture, using the techniques of selection, mutation and genetic modification. To achieve this a full understanding of the fermentation process is needed. The properties of the starter culture must be known and culture conditions must be controllable. This means that science based fermentation research currently has little to offer traditional food processing (Broerse and Visser, 1996).

8.2.1 Process control

Once the details of the fermentation process and the microbes involved are known and understood, it is possible to begin to refine and improve the process. The commercially produced products, such as bread, wine, soy sauce and pickles are all examples of processes which have been studied and optimised. Recently traditional fermented products in Africa have been industrialised. In Nigeria, Dadwa (a fermented legume product) is now made by Cadburys and in Zimbabwe, traditional fermented milk is made industrially and sold as "Lacto" (Okafor, 1992).

The areas where the efficiency and yield of food fermentation processes can be increased are:

Techniques to control the fermentation processes could include the development of pure starter cultures. Developing these by laboratory selection or genetic engineering is not viable. A more feasible approach would be to exploit the ecological principle of inoculum enrichment by natural selection. Another approach to stabilise fermentation under nonsterile conditions is the use of multi-strain dehydrated starters which can be stored at ambient temperature. These are already used for the manufacture of tempeh (Nout, 1992).

8.2.2 Quality control

The aim of quality control is to ensure that every batch of food produced has a satisfactory and uniform quality. This does not necessarily mean that it is the highest quality possible but that it reaches the standard the customers are willing to pay for (Fellows, 1996) .

Inadequate quality control can have an adverse effect on local demand for the product. This is particularly a problem for small-scale traditional production. In modern industrial applications, the fermentation equipment and processes are controlled using expensive technology, resulting in a consistent product of a known quality. Traditional practises take place in a less predictable environment. This can result in mistakes including sour beer and mouldy pickles.

It is often felt that traditional products made at the small scale are unhygienic and unsafe. This is sometimes true. However the case is often overstated. Many fermented foods are inherently safe due to low moisture contents or high acidity. Lime pickle from India and Gundruk from Nepal are good examples. Several of the steps in traditional processing are designed to reduce contamination. These include boiling, adding salt and sun drying.

Quality control procedures are essential for the production of safe products and contribute to the success of small food processing businesses. Appropriate quality control procedures need to be developed and implemented. These procedures need to be developed with the processors who must understand and apply them. The quality of food is highly subjective. What is acceptable to one customer is not acceptable to another. It is important to carry out participative research to identify ways to improve the quality control procedures for fermented food products.

The sort of areas that should be investigated include:

8.3 Disseminating improvements

Documentation of the traditional methods of food fermentation and research to identify improved methods of production are meaningless if the results are not disseminated to those who are likely to put them into practice.

There is a danger of mystifying the fermentation process by enrobing it in scientific theory. What was once a simple process carried out by any family member, in the confines of the household, using locally available equipment and materials, could become a process to be feared. It is important to be realistic and to ensure that the improvements recommended are ones which can easily be put into practice. The aim is not to deter the production of fermented foods at the small scale, but to encourage their production and consumption on a larger scale.

Fermented foods often have a stigma attached to them – they are considered as poor mans food. As soon as a family can afford to buy processed foods, they move away from carrying out home fermentation. This is a pity, because as we have seen earlier, fermented food products have many nutritional advantages which surpass western-style fast foods and processed foods. Where cultural values attached to the fermented food are strong, it is unlikely that there will be an image problem. For example, kimchi is considered part of the national heritage in Korea. It is a vital ingredient of all meals and as such is a highly valued food. This is reflected in the amount of research carried out on the product and the detailed understanding of the process, which already exists.

It is not difficult to gain access to village people, both to collect the traditional information and to disseminate improved practices. Numerous organisations are involved in field projects. They can be used to organise training sessions and group meetings for the dissemination of new methods, for example, for the use of pure starter cultures.

One of the problems likely to be encountered is gaining access to starter cultures and other improved methods. Agricultural extension services should take a responsibility for the promotion and the supply of starter cultures at a price which is affordable.

8.4 Creating a supportive environment for production of fermented food products

Developing countries need to build their resources of trained, knowledgeable individuals, who are able to apply the basic microbiological principles to the production of fermented foods. Extra support should be made available to train professionals in this discipline.

Fermented foods should be recognised as part of each countries heritage and culture and efforts made to preserve the methods of production. A recognised body (government or non-government) should take the responsibility for the collection of details and the promotion of fermented food products. Consumers need to be made aware of the numerous benefits of fermented foods and their prejudices against fermented foods, especially those traditionally produced at the home scale, dispelled.

Many traditional fermented foods are produced from minor or wild fruits and vegetables, many of which are being lost through deforestation and loss of biodiversity.

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