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Every parent in the world knows how to process foods they do it every day when preparing meals to feed their families. But 'food processing' as a scientific and technological activity covers a broader area than food preparation and cooking. It involves the application of scientific principles to slow down or stop the natural processes of food decay caused by micro-organisms, enzymes in the food, or environmental factors such as heat and sunlight, and so preserve the food. Food processing also uses science together with the creative imagination of the processor to change the eating quality of foods and provide people with interesting variety in their diets (as seen in the hundreds of different types of foods such as pickles, cheeses and biscuits that individual processors make throughout the world).

So the reasons for processing foods may vary. In some countries the main aim is to preserve basic foods such as cereals, root crops or vegetables against periods of shortage; i.e. to increase the food security of populations throughout the year.

Others wish to process foods to create employment and to generate additional income, either as a little extra money to supplement family incomes or to establish and expand a recognized food processing business. Small-scale food producers often start by working from home using domestic equipment; they often have little money to invest in equipment and little access to credit. However they must be able to produce uniform quality foods under hygienic conditions.

Some people will see food processing as their main source of income. They are entrepreneurs who will take out a loan to buy specialized equipment and secure working capital and, if successful, they will develop business and marketing skills to expand and diversify their enterprise.

Food processing as a business

For those who earn an income from food processing there are special problems which make this type of business different to most others: many raw materials are highly perishable and will spoil quickly after harvest or slaughter unless properly processed. They may also be highly seasonal which means that they can only be processed for part of the year, or alternatively they are part-processed for intermediate storage until they are needed.

Added to this, foods are biological materials whose composition varies as a result of the actions of weather, pests and diseases. This can mean unpredictable supplies and costs for raw materials. Some processed foods also have a seasonal demand (such as for festivals and ceremonies), which further complicates the business of food processing.

Even after processing, foods do not keep indefinitely. The 'shelf-life' of processed foods can vary from a few days to several months or years. The distribution and sales methods used by the processor must be suited to the expected shelf-life of the food and carefully organized so that customers receive the food before it spoils.

Packaging is an important means of controlling the shelf-life of foods, but there are universal problems in finding suitable packaging materials in developing countries. This is one of the most important constraints on small-scale food processors. The technically advanced plastic films, cartons and cans usually have to be imported, and even if foreign exchange restrictions or available supplies permit, they can be very expensive. Traditional alternatives such as leaves, clay pots etc. do not perform as well technically and are often perceived by customers as inferior. This puts the business at a marketing disadvantage compared to equivalent imported products.

In all food processing activities there is the overriding concern to avoid food poisoning. Food is the only commodity that people buy every day and take into their bodies. Processors and processing methods must meet strict standards of cleanliness and production control to avoid the risk of harming or even killing their customers by allowing the growth of food poisoning organisms in their products.

In no other type of business do processors operate under these multiple complex technical constraints. However, they do share with other types of small business the difficulties of operating in a frequently hostile economic environment. In the majority of developing countries the bulk of food processing enterprises are on a small scale and are located in the informal sector. They are rarely formed into associations and have little economic power or ability to seek such assistance as may be available. They will often need intermediaries, such as extension agents, to guide them to appropriate solutions for their own individual problems.

The larger, formal food processing sector may receive government support in the form of subsidies, foreign exchange allowances, price stabilization or guarantees and access to specialist advice. In contrast, the small-scale informal sector has no political influence, despite its combined voting power, and is therefore subject to the vagaries of the national (and often international) economic climate.

Support to small-scale processors

Despite these combined problems, many governments and development agencies are promoting food processing as a means of alleviating poverty in rural and pert-urban areas. The reasons are not hard to find: food is familiar to the target groups, the raw materials are readily available (often in surplus), the technology is suitable for small-scale operation and is accessible and affordable, equipment can often be manufactured locally, creating further employment, and the products, if chosen correctly, have a widespread demand. Compared with some other technologies, small-scale food processing is particularly suitable for women and it has few negative environmental effects.

The selection of suitable products for small-scale manufacture, and then the process by which to make them, requires very careful consideration. It is not sufficient to assume, as many 'advisers' do, that simply because there is a surplus of a raw material each year that a viable food processing venture can be created to use up the excess. There must be a demand for the processed food which has been clearly identified before a process is set up. Otherwise the most likely result is to produce a processed commodity that no one wants to buy and substantial financial losses to those involved.

In general the types of products that are suitable for small-scale production are those for which a high value can be added by processing. Typically, cereals, fruits, vegetables and root crops have a low price when in their raw state, but can be processed into a range of baked goods, snack foods, dried foods, juices, pickles, chutneys etc. which have a considerably higher value. The high added-value means that the amount of food that must be processed is relatively small, and hence the size and type of equipment required can be kept at affordable levels.

A second general statement, which is particularly relevant for those with little previous experience of food processing, is that the product selected should have minimal inherent risk of food poisoning. Acidic foods (such as yoghurt, pickles, fruit juices, jams) and most types of dried foods have a low risk of transmitting food poisoning micro-organisms. In contrast low-acid foods such as meat, milk, fish and some vegetable products are much more susceptible to transmitting food-borne illness through poor hygiene of workers or incorrect processing conditions.

Some types of process have a larger inherent risk of causing food poisoning than others. Canning, bottling, chilling or freezing of low-acid foods are each more risky than, for example, acid fermentations, drying or concentrating foods. In addition some processes are much more expensive to set up and operate than others: for example, canning and freezing are more expensive than drying, bottling (e.g. fruit juices) and baking at a small scale.

However an individual producer should not base a decision to produce a food on availability of raw materials, cost of equipment and risk of food poisoning alone. He or she should conduct local market surveys to find out which processed foods are in demand and how much people will pay for them throughout the year. The scale of production is then set to meet a pre-determined proportion of this demand. From this scale of production, together with technical advice on the best way to process the food, it can be decided what size and type of equipment is required. One function of this guide is to show what equipment is currently available and the approximate price of each piece. These costs are needed to calculate the approximate capital required for equipment (and if necessary the loan required) in a feasibility study of any proposed production before getting precise details from equipment manufacturers.

Another function of this guide is to prompt ideas for local adaptations of equipment to meet particular needs. If a processor has a problem in finding suitable equipment it is not necessary to 'reinvent the wheel' to find a solution, but similarly it is not always necessary to go to the expense and time involved in importing equipment. It is hoped that this book can give ideas from which a processor and a perceptive workshop owner can produce equipment that will provide an appropriate answer to the problem.

We recognize that knowledge of these appropriate technologies alone will not ensure their adoption. Proven prototypes may be needed for demonstration and those who are convinced of the effectiveness of a technology may need financial support to acquire and promote it. This in turn may require the collaboration of national food research institutes and university food science and technology departments for development and testing of technologies for local needs.

However, knowledge is a pre-requisite to such development and it is hoped that this publication will have a role to play in disseminating information about food processing technologies.

Appropriate food technology implies affordable, locally produced and locally repaired, reliable technology that has a suitable scale and complexity of operation for the people who will operate it. It will help increase incomes and improve (or at least avoid worsening) income distribution.

In practice, however, it is likely that the consequences of introducing a new technology are largely unpredictable. It is true that potential adverse effects of a new technology on poor producers can be predicted to some extent and therefore avoided by careful studies before a project is implemented. But the large number of factors that are in play during a technological change prevent an accurate prediction of the final outcome and of who will benefit. There is therefore a need for sensitivity and understanding of the social and cultural context in which the introduction is planned.

If a demand exists for the products of technologies described in this guide, the changes will come. It is the concern of implementing agencies to try to ensure that the change benefits disadvantaged groups rather than further threatening their livelihoods.

We are aware that it is the staff of implementing agencies who will read this book and not the ultimate intended beneficiaries - the small-scale food processor. There is therefore a responsibility to evaluate carefully the technologies described to ensure their effectiveness for each individual processor who is being assisted.

The criteria that will help in deciding whether to recommend a technology are complex and inter-related but are likely to include the following:

· technical effectiveness (whether the equipment will do the job required at the indicated scale of production),

· relative costs for both purchase and maintenance of equipment and any ancillary services required,

· operating costs and overall financial profitability,

· health and safety features,

· conformity with existing administrative or production conditions,

· social effects such as displacement of a workforce,

· training and skill levels required for operation, maintenance and repairs,

· environmental impact such as pollution of air or local waterways,

· flexibility to perform more than one function,

· compatibility with other parts of a process.

However, it must be stressed that each of these factors is an aid to judgement by staff on the spot and not simply a checklist. Each will have a different weighting in different circumstances and there can be no simple solution to the difficult task of weighing up all factors in a particular situation and making the 'best-fit' from the available technologies.

The technologies and equipment described in this book will undoubtedly affect the economic status of many people, and not always positively. However, in comparison with large-scale, automated technologies used by food processors in industrialized countries, those presented here are relatively benign. The loss in productivity by using predominantly manual procedures is insignificant compare to the under-utilization and high investment costs of larger automated equipment. The gain in employment and sparing use of resources makes these technologies more sustainable and therefore more valuable to the small-scale processor and ultimately to the national economy.

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