Agro-processing of field crops: Peppers & Tomatoes

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February 24, 2020

Agro-processing of field crops: Peppers & Tomatoes

By Theresa Siebert (ARC – Institute for Agricultural Engineering)

Farmers worldwide are searching for new opportunities to grow markets, turnover and profits, and one way of doing this is by adding value to farm produce through further agro-processing, explains Theresa Siebert (ARC – Institute for Agricultural Engineering)

The General Principles involved in Agro-Processing

Most value-added food products available to the consumer have been processed in some way, and two main types of processing can be identified:

Primary processing: This type of processing includes the simplest of processes such as washing, peeling, chopping, ageing, the milling of wheat for flour production, and the processing of sugarcane;
Secondary processing: This type of processing includes the conversion of primary processed products into more complex food products and includes procedures such as mixing, depositing, layering extruding, drying, fortifying, fermentation, pasteurisation, clarification, heating,

Without food processing, we would not have the convenience of a large variety of food products available in food outlets. Advantages of food processing include:

It allows for the year-round availability of food that has only a limited growing season, or is not grown in certain areas due to soil and climate factors;
Processing extends the shelf-life of products, such as canned fish and UHT milk;
Food processing improves the safety of our food supply through processes intended to destroy harmful bacteria and packaging helps in the prevention of food

Agro-Processing of Peppers:

In the food processing industry, peppers are divided into two basic categories, namely hot (spicy/pungent) varieties and the sweet (mild) varieties. Hot peppers include cayenne peppers, chillies, hot banana peppers and Jalapenos while the sweet peppers include the bell peppers, paprika, pimento, sweet banana peppers and sweet cherry peppers.

Processing Opportunities of Peppers:

Dehydrated chilli peppers: Chillies are hot, pungent peppers that can be preserved by dehydration. Chilli peppers are suitable for both sun and artificial drying methods. The mature chilli pods are dehydrated to a final moisture content of 3% for safe long-term storage. The dried pods may also be ground into a powder to produce red pepper (Cayenne pepper);
Fresh cut bell peppers: Minimally processed refrigerated bell peppers are washed, sorted and packed in a ready-to-use state either as whole fruit or in slices;
Pepper salsa: Bell peppers can be preserved in the form of a sauce known as Salsa is a spicy sauce that is served with meat and Mexican food. It is best served fresh, but can be frozen for later use. Peppers are chopped with tomatoes, onions, garlic and spices such as fresh parsley, basil or oregano;
Pickled bell peppers: Peppers can easily be pickled in a brine or vinegar solution, alone or with other vegetables and seasoning. The variety of coloured peppers available make for attractive pickles. Certain varieties can be pickled as whole pods, while larger peppers are cut into strips;
Pickled chilli peppers: Similar to bell peppers, fresh chilli peppers can also easily be pickled in a brine or vinegar solution, also alone or with vegetables and seasoning;
Frozen bell pepper pieces: Bell peppers are one of the few vegetables that can be frozen without Bell peppers are frozen in sliced or diced form and will keep for about nine months to a year;
Canned red or green chilli peppers have a storage life of several months and are used as a convenience product when the fresh product is out of season. Chillies are usually canned without packaging

Dehydrated Chilli Peppers

Agro-Processing of Tomatoes:

In South Africa, only about 10 % of the tomato crop is processed, of which 85 % is destined for the tomato sauce market and 10 % for frozen tomato products. In contradiction to these figures, the USA processes 50 % of its tomato crop while Europe is currently agro-processing 30 % of its tomato crop. Seen in the light of South Africa’s annual import of about 1,300 tons of tomatoes, the question arises whether this is not perhaps an under-utilised opportunity for South African (and African) producers and processors in the tomato industry.

Opportunities of Tomatoes:

Tomato chutney: Chutney is a sweet, tangy condiment that is served with curries, hot & cold meat and savouries. Tomato chutney may be prepared from both green and ripe tomatoes, along with onion, sugar, vinegar and various other ingredients, including spices. It is packaged in glass bottles and has a shelf life of several months at cool temperatures;

Tomato juice: Tomato juice is the un-concentrated, strained liquid extracted from ripe tomatoes. It is thus free of skin, seed and coarse particles, but contains insoluble solids in suspension. It may or may not be seasoned with Tomato juice has a bright red colour and is opaque with a typical cooked tomato taste. It is high in nutrients, especially vitamin A;
Tomato leathers (fruit rolls): Fruit leathers are dried sheets of fruit pulp with a soft rubbery texture and sweet taste, characteristic of the fruit Tomato fruit can be used to produce fruit leathers, whether alone or in mixtures combined with apples, various berries, apricots, peaches, plums, mangoes, guavas, pineapples and granadillas. Layers of different coloured leathers can be pressed together to form a sandwich. The single layers can be cut in various shapes or strips that can be rolled up;
Tomato powder can be manufactured from either tomato paste or concentrated tomato juice. The tomato juice is spray-dried or the pulp can be drum dried to produce tomato powder. Tomato powder is a concentrated product with a very strong flavour;
Tomato sauce (Ketchup) is made from strained, pulped tomatoes and additions such as spices, salt, sugar, vinegar, onions, garlic and contains no less than 12% tomato The principles of manufacturing ketchup are based on the preparation of a tomato puree or paste. The percentage of tomato solids in the final formulation (i.e. yield) is related to the insoluble cellular materials released during pulping;
Tomato pulp: Two types of tomato pulp are produced. The first type of pulp is made from whole tomatoes and the second type is made from tomato by-products from other processes, including skins and cores from canning and partially extracted tomatoes from juice Tomato pulp is one of the ingredients used in both tomato soup and condensed tomato soup;
Tomato jam is produced from green or ripe tomatoes. Jam is a product which consists of whole fruit, pieces of fruit, fruit pulp or fruit puree of one or more types of fruit with fruit juice or concentrated fruit juice as an optional ingredient, and may contain permitted food additives and sweeteners;
Sun-dried tomatoes are produced by drying ripe tomato slices under shade cloth, out of direct sunlight. Tomatoes are dried in the form of halves, quarters or slices. The final product has a brown colour, distorted shape and does not rehydrate well;
Tomato paste is a concentrated tomato pulp product in which the tomato solids have been increased to 24- 30%. Higher concentrations are also The term “tomato puree” is also used for tomato concentrates produced by the evaporation of strained tomatoes but is generally less concentrated (>8.5% total solids) than tomato paste;
Canned tomatoes: Tomatoes can be canned whole or sliced or chopped for the canning of stewed Desirable characteristics of a processing tomato includes an intense, uniform red skin and pulp colour, a high total solids content with a good flavour and firm meaty texture. A round-shaped tomato with smooth skin is preferred since cracks and cavities complicate washing and peeling.