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To process and preserve fresh produce successfully, the spoilage agents must be destroyed without ruining the nutritional value or palatability of the produce itself.
Unfortunately, fruit, vegetables and root crops are the only natural source of the essential vitamin C in our food. This vitamin is easily destroyed, especially where processing makes use of heat. In order to retain the maximum amount of vitamin C in processed food, it:
The best methods for small-scale processing are: drying, chemical preservation and heat processing.
11.3.1 Drying. All living materials require water for survival. Fresh produce contains up to 95 percent water and thus is sufficiently moist to support both enzyme activity and growth of micro-organisms. The aim in drying is to reduce the water content of the produce to a level insufficient for enzyme activity or the growth of micro-organisms. The critical level is about 10-15 percent moisture, depending on the commodity. If too much water is removed, the product becomes brittle and is easily shattered.
Produce can be dried by using solar or artificial heat. Solar (sun) drying is cheap but is not so easily controlled as dehydration by more sophisticated means. In some countries, heat from burning agricultural waste is used for drying, as in copra driers, which have also been used for drying root crops.
Drying by direct exposure to the sun has a number of disadvantages:
Recently much research has gone into the design of solar driers for fresh produce in order to overcome these problems. Solar driers can be:
The rate of loss of vitamin C from the produce is reduced when the indirect solar drying method is used.
Drying should be as rapid as possible in order to maintain quality and minimize vitamin loss. The rate of drying depends on:
- Fruit and vegetables may be treated with sulphur dioxide before drying in order to prevent enzymatic browning; it also slows breakdown of vitamin C and kills some micro-organisms;
- Most vegetables except onions and garlic are blanched by dipping them in hot water for a few minutes before drying; this stops the action of enzymes which may not be killed by the sun-drying process;
- Green vegetables retain their colour better during drying if about 0.25 percent of bicarbonate of soda is added to the blanching water, but this will speed up the loss of vitamin C;
- Dried cassava forms an important part of the staple diet in parts of Africa and Latin America; the dried product may be in the form of chips, granules or flour; in some areas the grated cassava root is fermented for a short time before being dried by artificial heat or sunlight;
- Dried vegetable products are subject to severe insect infestation, and some may be affected by exposure to light during storage; dried produce must be stored in a very dry atmosphere, in insect-proof containers and away from light. ·
11.3.2 Processing using chemicals. Chemicals used in processing include sugar, salt, vinegar and chemical preservatives such as sodium meta-bisulphite. The principal products are:
Preserves with sugar. This is based on using a high concentration of sugar with fruit pulp or juice to create a product in which it is difficult for moulds and yeasts to grow. It includes:
Pickled vegetables. Young fresh vegetables of many types as well as some fruits can be preserved by pickling in vinegar. The prepared vegetables or fruit are first soaked for a few days in a strong salt solution (brine) and then packed into jars which are then filled with cold vinegar. The vinegar is usually flavoured by steeping the desired spices in it for one or two months. The jars should be closed with plastic-lined covers.
Preservation with salt. This method is usually used for preserving green beans. Young green beans and salt are placed in alternate layers in large glass or earthenware jars, the top layer being of salt. The jars are closed with moisture-proof covers and then they are stored on stands.
Fermented products. In several countries vegetables are subjected to lactic acid fermentation in brine, such as sauerkraut in Germany, made from shredded cabbage, and takuwan in Korea, using radishes. In the Pacific islands, a fermented product is made by burying peeled starchy produce in pits lined with Heliconia or banana leaves. The product, known as masi or ma, is mostly made from breadfruit, but green bananas, cassava roots or taro may also be used.
11.3.3 Heat treatments. For many years fruit and vegetables have been preserved by heat, using canning or bottling methods. The object is to kill the enzymes and micro-organisms by heating the produce in liquid in cans or jars. The containers are then sealed while still hot to prevent contamination of the sterilized contents. Although moist heat inactivates enzymes and kills most micro-organisms, some bacteria, such as Clostridium and Staphylococcus are heat-resistant and are capable of growing and producing poisons in canned or bottled foods. Clostridium produces a toxin which causes botulism, a fatal food poison.
Acid foods, such as fruit, inhibit the growth of Clostridium and prevent the formation of the poison.
Non-acid foods such as peas and beans and almost all vegetables can be preserved only by heat at the high temperatures achieved in steam-pressure vessels. For this reason, heat-processing methods are not recommended for processing any vegetables under small-scale local conditions.
11.3.4 Information about processing. Detailed information on the methods used in fresh-produce processing is normally available from national departments of agriculture or of food technology, through local department advisers or extension officers.
There can be many participants in any given marketing system. Here are the main ones.
12.1.1 Farmers. Most small farmers are mainly concerned with the growing of crops, and their awareness of marketing as a tool to increase income is non-existent or is limited to what they learn from other small farmers or from villagers nearby.
To many small farmers, marketing may mean the sale of produce to a trader or its consignment to a commission agent. They would sell directly to consumers or to a wholesale market only if the farm is close to such outlets. As their production increases, farmers acquire other sources and information about marketing systems, but in developing countries very few growers have either sufficient production or sufficient knowledge to take advantage of the marketing choices available.
12.1.2 Traders. The role of traders is essentially to act as the link producer and distributor. They are mostly entrepreneurs whose income depends on matching the supply of produce with the demand of the market. They range from small family groups on a local level to large international companies dealing with export and import of produce in many countries.
The marketing of fruit and vegetables in developing countries is marked by a large number of small traders. They play an indispensable role in the marketing system. Their importance is, however, not always appreciated and their profits are often considered excessive, largely because farmers and government officers are unaware of the traders' costs. The proportion of the retail price that comes to the trader is generally much lower than that received by the farmer.
12.1.3 Commission agents. The role of specialized commission agents is to take produce owned by a farmer or a trader and sell it for the best price possible. They may find a buyer in an organized wholesale market or by direct contact with distributors. The proceeds of the sale, minus deduction for the agreed commission, are then passed back to the former owner. Commissions commonly range from 4 to 10 percent of the price obtained.
The commission system has advantages for the farmer, who is likely to get a higher price than he would if selling to an intermediate trader, even though the farmer carries the risk of loss always present in the marketing of perishables. The farmer's confidence in the agent rests on the knowledge that the agent's income depends on his getting the best deal for the farmer.
12.1.4 Retailers. Market demands for all commodities are essentially determined by retailers, who therefore have great influence on market prices. What the retailer buys reflects the quality and quantity of what he thinks his customers will buy. In most developing countries, the quality of produce varies so widely that sales potential exists for most grades of produce. Farmers and traders should maintain contacts with retailers to be aware of market preferences so that they can arrange production and post-harvest handling practices to provide produce of the desired quality.
The prices paid by retailers will depend on the number of competing buyers in the wholesale market and on the volume of produce available: this is the law of supply and demand. Although retailers try to buy produce at the cheapest possible price, most of them will apply a standard mark-up and thus will obtain their usual profit margin regardless of the wholesale price.
There are several common types of markets, each filling a specific role.
12.2.1 Farmer markets. These markets are simple retail operations where farmers sell produce directly to consumers. They occur in towns or cities and may be in a covered market hall or on an open street, on a daily or a weekly basis. Such markets have histories of dozens or hundreds of years.
By selling directly to consumers, farmers can ask and get much higher prices (and in cash) than they would by selling to traders. To deal with retail customers takes time, however, and moves only small quantities of produce. Losses can be high from customers' pinching and prodding of produce, which then must be discarded if sufficiently damaged. The industrious farmer can spend his time more profitably elsewhere.
12.2.2 Assembly markets. An assembly market is much like a farmer market except that producers deal with traders instead of directly with consumers. It is a farmer market on a wholesale level. Traders find assembly markets convenient in saving themselves expense and time they would need to travel to farms to collect produce.
Assembly markets tend to start from a natural need by buyers and sellers, and their location will usually be determined by proximity to good transport, whether road, rail or water, so that traders can quickly move their purchases onward to markets.
The operation of an assembly market can be simple, but a successful one will soon attract people providing services such as weighing, packaging, loading equipment and perhaps even banking. The building of a marketing hall will move the buying and selling under cover and out of the weather, and may attract other services like packing and storing.
Assembly markets can be operated by farmers through some cooperative association, by municipal or central government bodies or by a number of large traders. There is, however, the danger that sectional interests taking control of operations can put other groups or persons at a disadvantage.
12.2.3 Wholesale markets. The wholesale market provides a convenient point for the gathering of large amounts of produce from many sources and for its division into small assortments to meet the needs of retailers. In developing countries, incoming produce is most commonly owned by a trader or may be consigned by a large farmer or a cooperative, whereas in developed countries most produce is consigned by farmers.
The need for a wholesale market arises naturally as the population of a town increases and thus becomes remote from producing farms. The simplest wholesale markets exist in small towns, where incomes are relatively low. They may function only weekly, where farmers or traders bring in only small quantities of produce of every size and quality. Facilities may be minimal, and prices correspondingly low. Retail merchants may compete with private customers and will generally get better prices because of bulk purchasing. Many such retailers are street hawkers, though others may operate stalls in the market itself, keeping longer hours than does the wholesale operation. Such combination markets are common in African towns.
Many large cities in Asia and Latin America have reached the stage of economic development where they can benefit from a wholesale market exclusively for fruit and vegetables. Higher incomes in cities always result in greater demand for fresh, high-quality produce, and retail operations reflect what customers expect in quality and variety. The size and diversity of a central wholesale market mean that it can satisfy the needs of retailers and their customers.
The influence of a wholesale market extends beyond its location. It supplies produce to retailers in surrounding districts and to other wholesalers in more distant places. Prices set by supply and demand at the wholesale market also have an importance beyond the market itself as they become a reference point for the setting of prices for transactions of farmers, traders and consumers on other markets. Wholesale markets may also play an additional role as the receiving and marketing centre for imported produce.
12.2.4 Retail outlets. As cities grow and exercise more economic power, the trend in retailing is away from street stalls and hawkers and toward fixed shops and supermarkets.
Hawkers. Although they have been part of market systems for centuries, hawkers are actively discouraged in many countries as being traffic hazards and as not contributing much to overall marketing schemes. Hawkers do, however, benefit lower-income consumers by selling at low prices much low-quality produce which might otherwise be a dead loss. Any reduction in their numbers should be the result of more efficiency and better prices in retail outlets and not of official harassment.
Public markets. Public retail markets have varying degrees of importance, ranging from being the major source of produce for consumers to being a minor supplement to its sale in shops. The usually low prices reflect low overhead and operating costs, but the confinement of produce retailing to central market districts means that customers must travel some distance to market. The emergence of small fixed shops will eventually divert customers away from central markets, even if they must pay higher prices.
Retail shops. Prices of produce in retail shops reflect a greater variety of goods of a higher standard of quality than those found in public markets. Competition between retailers is based mainly on attracting customers by concentration on shop decoration, presentation of produce and personal contact between staff and customers. Such shops are likely to be situated in or near residential neighbourhoods.
Supermarkets. Retail shops can efficiently and quickly turn over large quantities of produce but, with increasing costs that inevitably follow economic development in communities, retail shops are pressed to sell ever greater quantities in order to retain profitability. Thus supermarkets with their greater financial resources can move into produce-selling at a relatively small increase in overhead costs. Supermarkets can and do negotiate directly with growers for supplies of fresh produce, thus eliminating middleman costs entirely and selling produce at prices matching those of farmer markets. In developing countries, however, produce in supermarkets is generally more expensive than in open markets, largely because of packaging, high-quality produce, and the attraction for the usually affluent customer of easy parking and one-stop shopping.
The aim of a commercial marketing strategy is to sell a commodity at the time and place that can bring the highest possible return. To develop a marketing strategy for fruit and vegetables is much more complex than for, say, manufactured goods because of the fragility and perishability of fresh produce. These factors place limits on the time produce can be held, the distance it can be moved and the handling costs that customers will be expected to bear. Such market uncertainties bring a speculative element into trading activities and thus the attendant risk of market manipulation.
Since trading of fruit and vegetables in most countries operates as a free market, the law of supply and demand regulates the market price. This means that the price will increase if the supply falls below market demand and will decrease if the supply exceeds the demand.
The supply of a commodity is calculated from the total quantity of produce that is grown and from the period during which it is available. The quantity on a particular market is determined by the area under cultivation, the productivity of the crop and the amount of that crop brought in from other areas.
The supply of most commodities moving to markets in developing countries usually varies over a year, but there is considerable potential for change by manipulating both production and transport factors to level and extend the supply.
13.2.1 Changing production volume. Changes in fruit and vegetable growing patterns will best come about through market forces. For example, when a market is under-supplied with a product, the resulting high prices will encourage farmers to increase the area planted with this crop and decrease that of a low-return commodity. Such changes can occur more readily with annual crops like vegetables than with fruit from trees which take years to come into production.
To bring about changes in cultivated crops is more difficult in farming communities that are poorly educated and have little concern with marketing. The opposite can happen if farmers become too conscious of market trends and readily change crops if they have a poor market return. This can start a lopsided cycle of overproduction and falling prices followed by underproduction and rising prices and so on.
13.2.2 Transport to other markets. Problems of over- and under-supply can be more quickly balanced by transporting produce between districts with surplus or scarcity. A knowledge of prices is essential for profitable trade between such districts, and this a strong argument for the establishment of an organized market information system.
Interdistrict trading can be organized on a long-term basis using information on annual market trends or in response to a short-run supply in a market. For example, a severe storm can so damage a crop that supplies to local markets are severely cut and prices rise quickly. Traders familiar with regional prices can soon restore equilibrium by transporting supplies of the scarce commodity. By the same means, farmers aware of prices can save themselves the effort and expense of consigning produce to glutted markets.
An efficient packing house can often provide the focus for effective interdistrict trading because of its ability to grade, pack and arrange transport for produce needed elsewhere.
13.2.3 Seasonal supply. The harvest period of seasonal crops like most fruit and vegetables can be short, with limited quantities of the crop available at the beginning and end of the season and the peak production period coming in between.
The rewards of being able to market a crop outside the normal harvest period are appealing both to farmers and traders because of the higher prices accruing to out-of-season crops. Pre-harvest manipulations can spread out harvesting periods, and post-harvest techniques can extend the marketing period.
13.2.4 Pre-harvest manipulations
Growing locations. Within a given country, a greater range of harvest dates can be established by taking advantage of different climatic conditions. In the extreme, this means that in a large country like Australia freshly harvested potatoes are available year-round because they are grown in areas of a wide range of altitude and latitude. Even in small countries there is some flexibility: Thailand has little variation in latitude, but onions are grown in three areas spanning only an 800 m difference in altitude. The three different harvest periods combined with a simple post-harvest storage programme allow the marketing of onions for nine months of the year.
Farming practices. To profit from high, early-season prices, farmers are tempted to harvest produce earlier than normal. This practice is wrong and should be discouraged as such produce is not fully mature and is therefore of poor eating quality.
Some manipulation of harvesting dates is possible by the judicious use of irrigation late in the growing season. Water applied at the proper time hastens the maturation of many crops and thus they can be harvested earlier but at full maturity. This maturation technique cannot advance harvest dates by more than two weeks, but that can be sufficient to justify early-season prices.
Conversely, the optimum harvest date can be delayed by restricting the use of water. This technique can be useful for a late-maturing district growing a commodity with a very short storage potential where it is profitable to market as long as possible after other districts.
Cultivar selection. The harvesting period can also be adjusted by selecting crop varieties which have different growing periods. Where early harvesting is required, a variety with a short growing period could be selected, and vice versa for late-harvest varieties.
Cultivar selection cannot be done at random. Each variety has unique characteristics and will differ from others in some aspect of appearance or taste. Customers may not like a new variety, and its price may have to be marked down in order to sell.
Post-harvest technique. The ability of a farmer or trader to delay the marketing of produce or to trade on distant markets can be greatly enhanced by the use of post-harvest technology. The wide range of techniques now available to delay ripening, to inhibit ageing and to control pests and diseases is discussed in Chapter 9.
The ability of a grower or an organization to plan and act on an efficient marketing strategy for fruit and vegetables will be greatly aided by access to accurate, adequate and timely information on all aspects of the commodities being traded. Although every person in marketing is in the course of his work collecting and analysing information, no individual has the resources to gather information on all markets of current and potential interest. The breadth and diversity of market information can be collected and processed only by some system.
In addition to supplying data to market operators, a market information system performs a valuable public service by making market transactions more transparent. Its best result will be its moderating influence on price fluctuations, as farmers and traders can act more confidently to balance supply and demand and make it more difficult for dishonest or deceptive practices to go unnoticed.
13.3.1 Users of market information. All sections of the fruit and vegetable industry will benefit from a market information system, although each group will use it differently:
13.3.2 Type of market dab required. Information required by persons or organizations will depend on the size and complexity of their operations and on their ability to assimilate and use the information. The type of data gathered by the system therefore needs to be tailored to the needs of the users. A system that is too complex will probably at first be underutilized, thus in effect wasting the time, effort and money spent in gathering the data. On the other hand, a system that is too simple will not do the job of developing efficient marketing. Systems being initiated should thus take into account the increasing capability of its users as they gain experience.
13.3.3 Market price. Market price is the most important information required by market operators. Price data need to be collected from all the major types of trading outlets, and the system should therefore include prices paid at the farm gate, assembly markets, central wholesale markets and retail outlets. If substantial import or export of produce takes place, separate records of those prices should be maintained.
13.3.4 Source of data. Price data must be qualified by the location where obtained. Although some averaging or amalgamation of data is inevitable and it is often desirable to calculate a national average price for commodities, it is essential that districts with distinctive trading patterns retain their identity in the information system. Similarly, for exports and imports, the prices obtained and prices paid for produce at or from different countries should be separately reported.
13.3.5 Trading volume. The volume of produce presented for trading in different markets is of considerable importance since volume is a direct determinant of market price. Data on arrivals in assembly and wholesale markets, outgoing dispatches to other markets and traders, and stock being held in a market should be collected.
13.3.6 Marketing costs. Costs and charges incurred at various stages of the marketing chain could be reported with information on market charges, costs of transport, and stock held.
13.3.7 Coverage of data. Ideally, price and volume information on all produce should be reported daily, but a lower frequency will undoubtedly be more realistic for most countries, owing to the limited resources that can be allocated to information services. If the system is to be of any value to the produce industry, reporting must be done at least once a week.
There will be the need for some sort of codification of markets in the information that is distributed. A central wholesale market has sufficient turnover to be included as an entity, but smaller local markets will need to be grouped into categories based on the kind of market activity. In the same way, there will be some regional grouping of markets into zones, but care must be taken to preserve unique trading features or commodity profiles of different districts.
For commodities which have particular importance to a country but are produced and traded across different market zones, it may be convenient to maintain a separate record of each commodity so that the market price and movement can more easily be followed.
13.3.8 Market reviews. The publication of daily or weekly market information in price and volume of produce traded is useful for a continuing assessment of market strategies, but it can also be adapted for long-term planning by analysing market trends on a quarterly, semiannual or annual basis and for making comparisons with performance in previous years.
If an information service is starting from scratch, it is advisable to limit its scope to a few major commodities and a restricted trading path while aiming to generate daily information to be disseminated the same day or at latest the next day. The goal should be to supply a regular and reliable service that its users see as performing a useful function. Only when the service is operating efficiently should it seek to expand its range of commodities and markets.
Daily reports could be displayed at markets participating in the service, with duplicated sheets distributed to traders and to other interested agencies.
The reports could contain information on:
Price. the highest, the lowest, and the most frequently occurring prices of each unit sold, with reference to the varieties and grades of commodity traded on each market. The most-frequent (or modal) price is important as the barometer of market trends.
Supply. the volume of produce available for trading in the various produce grades; where an accurate measure is not possible, a standardized ranking system could be used, such as a l-to-5 scale, with 3 as the average supply and 5 as great oversupply.
Movements: for larger markets, particularly in cities, arrival and dispatches of loads (including imports) in terms of volume or of number of loads;
Summary. general comments on any significant change in trading pattern or any factors, such as weather or traffic conditions, likely to affect trade soon.
The collection of information should be entrusted to one person well versed in fruit and vegetable trading. It is important that subjective assessments be consistent from day to day, and different observers will naturally show variation in their judgements.
The methods available to improve a marketing system are almost infinite. The key to successful marketing improvement is to determine which of these methods are most suitable for a particular marketing situation.
Any marketing improvement programme must be preceded by a study of the existing marketing situation. Then goals for improvement can be established, to be followed by a plan for action. Such a study is best conducted by a government-sponsored group with considerable knowledge of fruit and vegetable marketing, but it should not be directly involved in the ownership or management of existing marketing operations. The active cooperation of fruit and vegetable marketing groups is, however, essential to assist in the study.
The evaluation must identify the size and shape of:
The social and economic targets to be achieved need then to be defined, and the deficiencies in the present system ranked in order of importance with respect to these goals. The seriousness of each deficiency in technical terms should also be given with an assessment of possible technical solutions.
The development plan can be short, medium or long term. It may span the total marketing system, but it usually embraces only specific commodities or a subsystem of the marketing chain. It should describe various options to improve marketing in terms of social and economic costs and benefits and their feasibility. The action plan should provide a timetable for the various components:
Although the government may hold responsibility for coordinating such a plan, the follow-up work should be passed on to industry people such as a market authority or farmers' association, and this could include responsibility for financing parts of the plan. An overdependence on government control and funding can run counter to the efficient management of a commercial enterprise.
The lack of qualified personnel is a major constraint to market improvement in developing countries. A prerequisite of any marketing development programme is the presence of people experienced in all aspects of fruit and vegetable marketing. Personnel helping to implement the improvement programme must be qualified in the various supporting technologies and management systems. Experience and knowledge will be required in order to implement:
Farmers and traders will need training not only in the introduced technologies but also in the need for continuing improvements in marketing.
Training of all personnel associated with marketing operations needs to be a national priority if marketing development is to succeed. Training must, however, be considered a long-term activity: initial training must be followed by work experience and further training at increasingly advanced levels.
Additional training must also be given to officers of extension services, who must themselves acquire enough knowledge of marketing activities to assist farmers.
Traders and post-harvest handling groups will also need to be well informed.