Raw materials are one of the most important aspects to consider in fruit and vegetable processing. The fruit and vegetables themselves are the raw materials, the reason for the development of preservation processes. Due to the great number of species suitable for industrialization, only a few will be mentioned, and of these, greater emphasis will be placed on the ones most commonly used.
The objective of this manual is not to specifically define each of the species. Rather, it is to provide the necessary elements and principles to allow the producers of raw material of any nature to explore the possibility of engaging in processing activities.
When speaking about raw materials, especially those used by industrial firms and particularly cottage industries, it must be considered that they may have two different origins: they may either grow spontaneously or be cultivated.
In both cases, the quality of the raw material is crucial to the fulfilment of the goals pursued in the processing and preservation of the product, and also determines the level of profit. The material must therefore be of good quality and its industrial performance, which is strongly dependent on the quality of the raw material, must be high. In addition to this, the raw material must meet certain basic sanitary quality requirements.
As stated previously, the quality of a processed product essentially depends on the quality of the raw material. On the other hand, the quality of the raw material also depends on the way that it is handled during the production process.
This is partly true in the case of species that grow in the wild. It is partly true because harvest and post-harvest handling also influences the quality of a product. This is the case of species that are highly sensitive to post-harvest handling like berries, for instance.
However, it is not only the harvest and post-harvest processes that have an impact on the quality of the raw material. The entire production process is important, from planting or sowing to harvesting. And even before sowing, the selection of the soil, of the genetic material to be planted and of the geographical location, will undoubtedly have a significant impact on the final outcome, on the quality of the raw material, and on the processed product.
Of course, some species and specific cultivars or varieties within them, are highly susceptible to environmental conditions, while others are much more resistant to the conditions of the ecosystem in which they grow.
Some of the vitally important factors in the handling of crops or natural resources are presented in the following paragraphs:
- Utilization of cultivars or varieties suitable to the characteristics of the specific environment.
- Technical management of the levels of fertilization required for an appropriate plant growth, reconciling yield with a number of quality-related factors which depend on soil nutrient levels and on the plant. For instance, a proper balance between soil nitrogen and phosphorus, in many vegetables will determine the quality of their colour, texture, and development, and their preservation capacity in the post-harvest stage.
- The control of the plant's water resources is a factor which largely determines final quality. A material that has been somewhat deprived of water will not be suitable for processing. Its sugar and organic acid levels will not allow for healthy development.
- The management of all aspects related to plant health is crucially important in the case of a raw material that must meet minimum quality requirements to be processed, as health standards will determine final quality. For example, certain products intended for dehydration present very serious defects when processed from a fungi infested raw material. Plant health becomes a basic priority in post-harvest preservation. This is a very important aspect of processing in small-capacity cottage industries, where part of the harvested material must often be stored with no refrigeration for a short period of time.
Harvest and post-harvest care is an aspect of paramount importance, as fruits and vegetables are usually rapidly perishable. Therefore, since industrial performance depends on post-harvest quality, special care must be taken in the period between harvesting of the material and the beginning of processing.
The harvesting method employed and the duration of the harvesting period will also influence the quality of the raw material. Hand harvesting obviously seems more suitable for small plots of land, as those which will be the object of the activities of a small enterprise or a home processing system. In this case, care must be taken to make sure that the harvest operation is performed properly, at the right time and in a way that will not affect the product.
The transportation of the material to the farm and its preservation, the use of containers that will not spoil the material, and transportation from the farm to the plant are factors that also influence the quality of the material to be processed. Very sensitive materials, with a high respiration rate must be processed rapidly or must be stored at relatively low temperatures. Less sensitive materials, on the other hand, do not require such care. Pulses, for instance, must be harvested, transported and subjected to processing very rapidly, for they tend to ripen very quickly.
The post-harvest of such raw materials must be strictly controlled, for they belong to rapidly perishable species. Of course, the idea is to process high quality material, but it is also important to process the greatest amount possible of harvested material. Processing is an alternative way to preserve these products so rich in extremely valuable nutrients, like vitamins, minerals and fibres. Processing must therefore be placed at the service of the preservation of materials that is normally lost in great amounts for want of care.
The basic characteristics of a number of fruits suitable for processing and their most important processes are illustrated in the following paragraphs.
These species grow in areas characterized by a temperate climate, that is, where temperatures are never extremely cold.
They include the following species which have an actual and potential economic importance.
SPECIES |
SCIENTIFIC LATIN NAME |
Apple |
Pyrus malus |
Pear |
Pyrus communis |
Peach |
Prunus persicae |
Plum |
Prunus domestica |
Curuba |
Passiflora mallisima |
Passion-fruit |
Passiflora lingularis |
Blackberry |
Rubus Glaucus |
Cherimoya |
Annona cherimola |
Feijoa |
Feijoa selowiana |
Strawberry |
Fragaria x Annannassa |
Tree tomato |
Cyphomandra betacea |
Tropical and subtropical fruits include members of the Anacardiaceae family, which comprises about 59 genera and 400 species. Such species are generally found in tropical areas and in high temperature zones throughout the world, as in the Caribbean, Brazil, Central America and Africa. Some plants are considered to be of economic importance, such as mango (Mangifera indica L.), pistachio (Pistacia vera L.) and cashew nut (Anacardium occidentale L.).
These fruits are generally very fragile and sensitive, and therefore require special handling and proper storage conditions. Nevertheless, they are in great demand all over the world and sell at rather high prices, mainly due to the fact that very few countries offer appropriate conditions for their cultivation.
These fruits may be broken down in two groups:
- Fruit trees growing in warm climates of a short, medium and long growth period, of which the following are of great economic importance today.
SPECIES |
SCIENTIFIC (LATIN) NAME |
Mango |
Mangifera indica L. |
Guava |
Psidium guajava |
Pineapple |
Ananas comosus |
Papaya |
Carica papaya |
Coconut |
Cocos nucifera |
Lulo |
Solanum nucifera |
Maracuya |
Passiflora edulis |
- Fruit trees growing in warm climates of a short, medium and long growth period, and of potential economic importance:
SPECIES |
SCIENTIFIC (LATIN) NAME |
Mangosteen |
Garcinia sp. |
Carambola |
Averhoa carambola |
Tamarind |
Tamarindus indica L. |
Sapote |
Matisia cordata |
Guava (Coronilla) |
Psidium araca |
Soursop |
Annona muricata L. |
Breadfruit |
Artcarpus altilis |
Tacay or Inchi |
Cardiodendron sp. |
Caimaròn or uvilla |
Pouroma sp. |
Borojò |
Borojoa patinoi |
In the following paragraphs, some general background information will be provided for some fruits with an industrial potential.
Banana
Only a very small part of the banana production is preserved by means of drying, freezing and canning, although such preservation processes are quite important in the areas where these fruits are grown extensively.
The most common industrial forms are dehydrated bananas and banana flour. The latter is produced from fully developed green bananas. Such products are mostly manufactured in Ecuador, Brazil and Costa Rica, among other Latin American countries. Most banana flour is processed with drum dryers, as with spray drying great quantities of product are lost because the material sticks to the equipment. It should be noted that while banana products like flour and pancakes are processed from a well developed and green raw material, in the case of dehydrated bananas the raw material must be ripe.
The varieties most used for dehydrated and dried products are Gros michel, Cavendish, Lady finger and Plantain.
Citrus fruits
The industrialization of citrus fruits requires a raw material with a uniform shape and size. The varieties with a thin and sufficiently hard rind are preferred, as those with a soft rind, like mandarins, require special handling in the preparation and juice extraction processes.
The products obtained from citrus fruits include orange juice in the concentrated and frozen form, and by-products like essential orange oil, washed pulp juice, frozen concentrate, concentrate for animals and d-limonene.
For juice processing, it is essential to use varieties with a high juice content and a good Brix°-acidity balance. The colour is an especially important quality standard in concentrated orange juices, and in the preparation of citrus product bases. Juices squeezed at different times are usually combined to obtain a product with a balanced colour and taste.
Since vitamin C is the most important nutrient in citrus fruit juice, it should be present in great concentrations in the form of ascorbic acid. Another processing requirement is that the raw material must not have an excessively bitter flavour, or that it does not acquire a bitter flavour as a result of thermal processing.
Citrus fruit segments are another derived product. When citrus fruit segments are packaged, it is extremely important for the raw material to have a firm and seedless texture, as deseeding is a very time-consuming and expensive process which spoils the fruits, making them less attractive to consumers.
Grapefruit, mandarin and orange segments are in greatest demand. These fruits must preferably be fully ripe.
Fig
Figs are very suitable for being canned, dehydrated, presented as paste and processed into frozen products or into compote. In their fresh state, however, they spoil rapidly.
They are difficult to transport and cannot adapt to storage conditions, not even if they are refrigerated.
Figs intended for dehydration must be left to fall from the tree when they are ripe. They must be picked from the ground frequently, to prevent hardening of the skin, the growth of fungi and attacks by insects.
Tree tomato
This fruit is characterized by the fact that it has an ovoid-apiculate shape, that it is green in colour when unripe and reddish-orange when ripe. It is between 6 and 9 cm long, and its widest part measures between 4 and 6 cm. Its average weight may range between 70 and 80 grams. Its skin is thin, smooth and resistant, the pulp has a very pleasant and peculiar flavour, and many seeds are concentrated in the middle of the fruit.
This fruit is currently used to make home-made compotes, to make drinks by homogenizing the pulp with water and sugar, to produce spicy sauces, and as seasoning to prepare certain dishes.
Carambola
The carambola is also known as star-fruit; it also has other specific names, according to geographic location. It originated in Ceylon and in the Moluccas, and has been grown in Asia for a very long time. It may be propagated in tropical and subtropical climates and is grown in Australia, the Philippines and other islands of the South Pacific, Central America, South America, the islands of the Caribbean, Africa, Israel and subtropical areas of the United States.
The carambola tree is relatively small and is 6 to 9 m high, its crown being between 6 and 10 m wide. Its leaves are dark green, its flowers have a colour ranging between pink and purple, and a diameter of 6 mm.
The shape of a carambola is between oblong and ellipsoidal, it is between 6 and 15 cm long, with 4 to 6 longitudinal sections, so that when it is cut into cross sections, the fruit has the shape of a star. Its skin is translucent, soft and waxy, and its colour ranges from white to a deep golden yellow. Its taste varies between sweet and sour. The carambola is used to produce juice, nectar, pulp and jam. It may also be preserved in syrup, after having been cut in cross sections.
Lulo (Naranjilla)
The lulo or naranjilla, as it is also known, grows better in the humid valleys of the Andes near Ecuador, at an altitude between 1,200 and 2,100 m.
In Ecuador, where it originates, the species is found throughout the country, from the Colombian border to the south, in the Loja province. In Colombia, the main production area is located between Cali and Ipiales.
The fruits are round or slightly oval-shaped, of an orange-yellow colour, with a short peduncle of sepals similar to those of the tomato, adhering to the fruit. As a result of the orange colour and the smooth and resistant aspect of the skin, as well as the predominantly sour taste of the pulp, resembling that of an unripe orange, the fruit is commonly known as "naranjilla" (little orange).
The fruits weigh between 40 and 70 g, and their diameter is comprised between 4 and 5 cm. The internal part of the fruit resembles that of a tomato. The pulp is juicy, of a greenish color, and it is divided in four almost symmetrical sections. The seeds are smooth and roundish, with a diameter of 3 mm and light yellow in colour.
By industrially processing this fruit, the following products may be obtained: nectars and juices, frozen pulps, 65 Brix° concentrate, jams and jellies.
Blackberry
Numerous species of blackberries or brambleberries have been found to grow in the high areas of tropical America, especially in Ecuador, Colombia, Panama, Central American countries and Mexico.
The Rubus and Rosa genera, which belong to the Rosaceae family, are very similar, which is why the blackberry plant rather resembles wild rose plants, with thorns and composite leaves behind five leaflets. The differences between these genera lies in the fruit, as blackberries look like oblong or thimble-shaped strawberries, and when they are ripe they acquire a black, red or purple color.
There are believed to be as many as 300 species of blackberries of a relative importance throughout the world, according to the commercial value that they are attributed in the different areas.
The following industrialized products may be obtained from this fruit: nectars and juices, frozen pulps, 65 Brix° concentrate, jams and jellies, 33° Brix concentrates, wine and sulfite pulps.
Cashew
Cashew trees originate from the southern tropical regions like Mexico, Peru, Brazil, as well as Eastern India. However, they are grown in the tropical regions of America, Asia and Africa.
The cashew tree has an average size and can reach a height of 12 m. The fruit (apple) is rhomboidal in shape and is between 5 and 20 cm long, 4-8 cm wide, with a slight red, yellow, or red and yellow skin, which is thin and waxy. The pulp is soft, juicy, yellow, astringent and sour.
Cashews grow better in tropical climates at an altitude below 100 m. They tolerate different degrees of exposure to sunlight, but cannot withstand the cold or floods.
Cashew apples are rapidly perishable. However, the people of India and Latin America consume them in their fresh state and also process them into juices, wines and syrups.
Soursop and Cherimoya
These fruits are rapidly perishable, and must be hand harvested when completely ripe, to prevent them from falling from the tree branches and bruising. The ripe fruit is washed with chlorinated water to remove the soil and minimize the presence of bacteria. Once it is washed, the fruit is peeled and the pits are removed by hand, for there is no current alternative to this procedure.
Soursops and cherimoyas may be consumed as a dessert, although they are mostly used in the form of frozen pulp in foods like ice cream and syrups, and in drinks.
The diluted pulp may be used to produce nectars and juices with special characteristics. The frozen puree is sold with added sugar, up to 59° Brix. Storage life may be prolonged by adding ascorbic acid in concentrations of up to 10-30 g/100 kg. Other products include the combination of soursop pulp and refined tamarind puree and sugar cane or papaya juice.
Guava
The characteristics of a few varieties of this species have been established. Guava is an excellent source of ascorbic acid (vitamin C), and to a lesser degree, of vitamin A, phosphorus, pantotenic acid and B complex vitamins. Its seeds may find a potential application in the production of pectin and oils.
The fruits must have a nice colour, a pH near 3.4 and a solids content between 9 and 12%. The market requires large completely ripe fruits with a firm pulp. Their industrial potential derives from the fact that they may be used to make pulps, purees, powder for nectars, jams, jellies and sweets of 70-75 Brix° (ate).
Mango
Like many other tropical fruits, during thermal processing mangoes undergo chemical changes in terms of their nutritional and organoleptic properties, mainly flavour. It is therefore important to employ procedures that will not affect such thermolabile compounds to a significant degree, like freezing or carefully performed thermal techniques, even at a home-processing level.
Mangoes may be processed into different products, such as puree, frozen pulp, nectar, concentrated and frozen pulp and in a high-sugar pulp preparation known as "ate". Mango pulp may also be dehydrated to produce bars. Mango slices in syrup or in the dehydrated form are also consumed. This fruit is also excellent when pickled.
Papaya
In addition to being widely consumed as fresh fruit, papayas have other applications as food products.
Like other tropical fruits, papayas are prepared and preserved according to different methods. Nectars or juices may be produced by using papaya puree, which either alone or in combination with different-flavoured fruits makes a very tasty product. Papaya pulp is also a very popular product.
Tamarind
This species belongs to the leguminosae family, and every part of the tamarind tree, namely the wood, bark, leaves and fruits, may be used in many different ways. The tamarind has been utilized as medicine since ancient times, for its pulp can combat scurvy and has laxative properties, while its leaves have diuretic properties. However, the tamarind is mostly used as food. The seeds, the soft leaves and the flowers of fully grown trees are utilized in salads and to make soups. Unripe and tender husks are used as seasoning in boiled rice, fish and meats.
The pulp obtained from a ripe fruit is an agroindustrial product of considerable economic value in many parts of the world.
The pulp of the fruit is slightly difficult to extract due to its low water content and, because it is sticky. To remove it, the fruit is normally subjected to a steam bath for several hours. A syrup of about 13.2° Brix may thus be obtained.
Vegetables may be divided into the following categories, on the basis of their capacity to adapt to different climates:
Group A: Vegetables that adapt well to temperatures ranging between 18 and 27°C. They do not tolerate frost. This group includes sweet corn, beans, lima bean, tomato, bell pepper, squash, cucumber and melon.
Group B: Crops characterized by a long growth period, which thrive in areas where the temperature is above 21°C. This group includes the watermelon, sweet potato, eggplant and chili pepper.
Group C: Tropical species growing in very humid areas where the temperature is high. This group includes the "bilimbi".
Group D: These vegetables thrive in areas where the mean monthly temperatures range between 15 and 18°C. They are intolerant to temperatures between 21 and 24°C, and tolerate weak frosts. This group includes spinach, lettuce, broccoli, beetroot, Brussels sprout, cabbage, radish, rhubarb and watercress.
Group E: These vegetables thrive in areas where the temperature ranges between 15 and 16°C. They do not tolerate temperatures between 21 and 24°C. They may be damaged by frost when approaching maturity. This group includes the cauliflower, artichoke, lettuce, green pea, white potato, celery, carrot, chicory, endive, parsley and chard.
Group F: These vegetables adapt well in areas where the temperature ranges between 13 and 19°C. They are tolerant to frost. This group includes the onion, asparagus, garlic, leek and shallot. Some of the vegetables suitable for industrial processing are presented in the following paragraphs.
Tomato (Lycopersicon lycopersicum)
The tomato is a plurannual or perennial plant cultivated as an annual, which belongs to the Solanaceae family.
The fruit is a berry with 2 to 9 loculi. The fruits with many loculi generally have an irregular shape. Their weight ranges between 40 and 300 g.
The tomato is one of the vegetables that enjoys the greatest consumption, both fresh and as a preserve, paste, juice and dehydrated product.
Bilimbi
The bilimbi may be found throughout South-eastern Asia and across Malaysia, which is its region of origin. However, the bilimbi is only known as a species crop. The bilimbi was introduced in Australia, the Caribbean, South and Central America, Florida and Hawaii.
The bilimbi tree can reach a height of up to 18 metres, although it is usually 15 metres tall or less. The bilimbi fruit is cylinder-shaped, between 5 and 7.5 cm long, although its length is usually 5 cm. It is yellow-greenish when ripe, and its skin is thin and soft. Its pulp is green, soft, juicy and very sour, with few seeds.
The bilimbi adapts better to heat, grows well in humid tropical areas, and cannot tolerate freezing temperatures. Young trees may be damaged by temperatures between -1 and -2°C.
The bilimbi is not an important product on the world market as a fresh fruit, although it is processed into jellies, sauces, pickles and - juices.
Eggplant (Solanum melongena)
Eggplant is native to India. It is a perennial solanaceous plant, but is cultivated as an annual.
Its fruit is spherical, elongated and pear-shaped or cylindrical. Its colour is purple when it is ripe, due to the presence of anthocyanin. Some varieties have white fruits. Its pulp is cream coloured and crumbly.
Eggplant may be used for the preparation of preserves in brine and oil, in frozen vegetable mixes, and pickled.
Bell pepper - Chili pepper (Capsicum spp)
There are two types of pepper, the sweet and the hot pepper, the former being used more extensively.
It is a perennial solanaceous plant, grown as an annual. The fruit comprises a composed pericarp, an endocarp and seeds. Inside, it is divided into lobuli. The shape and size of the fruit varies according to the different varieties.
The colour of the fruit is determined by lycopersicine and carotene, and the yellow by the xanthophyll. The scent is determined by its ethereal acid content. The fruit also contains carotene or provitamin A.
Its pungency (degree of spiciness) is determined by the alkaloid called capsicine, whose content ranges from slight traces to 0.71%, mostly concentrated in the pulp.
The product may be consumed directly, or in the form of preserves, pickled peppers or powder.
Carrot (Daucus carota)
The carrot is an umbelliferous biannual root. It is rich in calcium, phosphorus, iron and carotene (vit. A).
This root is mainly used to prepare pickles and dehydrated products, and is employed in soup mixes, preserves and frozen products, either alone or in combination with other foods. Carrots may be consumed cooked, in syrup and in the form of juice and jam.
Green pea (Pisum sativum)
The green pea originated in Ethiopia and in Mediterranean Europe. It belongs to the Fabaceae family (ex Leguminoseae). It is a climbing, herbaceous annual and requires an amount of water equivalent to 45 cm.
Horticultural green peas may be consumed directly, or as preserves or frozen products. In agriculturally advanced countries, preserved and frozen peas are increasingly taking the market share of fresh peas. Dried grains are used to prepare pre-cooked flours and soups.
Dry bean (Phaseolus vulgaris)
The dry bean is native to Mexico, Peru and Bolivia and originates from the Phaseolus aborigeneus.
It is a leguminous plant, which reaches between 105 and 120 cm, and is distributed extensively on the superficial layer.
The fruit is a pod composed by a pericarp and seeds. For green beans, it is preferable to avoid the formation of parchment between the fleshy parts of the pericarp. The formation of "strings" or "fibres" in the seams of the pod should also be avoided. The dried fruit may be used to prepare soups and dried vegetable mixtures, it may be pickled or employed in the preparation of acidified preserves.
Horticultural beans are consumed directly, both in the green pod as grains and therefore half-ripe, or as preserves. They may also be consumed in the frozen form. Green beans have a low-calorie content, and a high nutritional value because they contain vitamins, minerals and carbohydrates.
Onion (Allium cepa)
Onions are bulbous vegetables, important both in terms of domestic consumption and export. The bulb is consumed in its tender state, raw, ripe, pickled or in form of powder. At a nutritional level, it stimulates appetite even if its calorie content is normal, its protein and dry material content is low, and its vitamin level is not very high.
The bulbs may be red, white or yellow in colour.
Leek (Allium porrum)
The leek originated in the Near East. It does not form bulbs. It is consumed on a small scale in soups, contains less volatile oils than garlic and onion, and is rich in organic sulphur. It is mainly used as a dehydrated product in the preparation of sauces and soups.
Garlic (Allium sativum)
Garlic is native to Southern Europe and Central Asia. It is an annual, of the Amarylidaceas family. The bulb is characterized by antiseptic, diuretic, expectorating, anti-scurvy and antirheumatic properties. It is consumed directly, in the dehydrated form, and may be used in the preparation of pickles and sauces.
Asparagus (Asparragus officinalis)
The asparagus is a perennial vegetable, which contains a high level of thyamine, riboflavine and ascorbic acid. It is consumed in the direct form or as a preserved product. It is native to Europe, the Caucasus and Siberia.
The asparagus belongs to the Liliaceas family. It is made up by a mass of rhizomes with buds on the tip, which give origin to the edible spears. The stalk or turions have a diameter between 6 and 23 mm and grow from buds on the rhizomes. This vegetable is especially used for making dehydrated products and soups.
Artichoke (Cynara scolymus)
This crop is indigenous to Southern Europe. Although it is considered to be a perennial plant, it actually is not, for after it blossoms it dies and is replaced by a shoot. The artichoke belongs to the Compuestas family.
Artichokes are consumed cooked, and the edible portion is the base of the bracts and the heart. Such parts may also be preserved.
Parsley (Petroselium crispum hortense)
Parsley is used as seasoning in soups and sauces. It is a biennial plant and belongs to the family of Umbeliferas.
Coriander (Coriandrum sativum)
This crop is native to southern Europe. It belongs to the family of Umbreliferae. Its leaves are used for seasoning, and its seeds are used to make liquor.
Sweet basil (Ocicum basicilicum)
The green or dried leaves of this plant are used as aromatic flavouring. The crop belongs to the Labiadae family.
Cabbage (Brassica oleracea var. capitata var. subauda)
Cabbage is a very important vegetable due to its high yield. It is used directly in soups or stews and is processed into a fermented product. The crop is native to Asia Minor and the eastern Mediterranean region.
Cauliflower (Brassica oleracea var. botrytis)
Cauliflower may be consumed directly or pickled. It is indigenous to the island of Cyprus. It may be used to prepare pickles, alone or in combination with other vegetables.
Cucumber (Cucumis sativus)
Cucumber is consumed directly in salads and pickled. It is not very important from a nutritional point of view, as it has a 95-96% water content and few vitamins. It originated in the humid areas of India, and was later exported to China and South-eastern Asia. Cucumber may be used to make dehydrated products, it may be preserved in oil or vinegar or be processed into naturally fermented pickles.
Pumpkin (Cucurbita spp)
Pumpkin is important in terms of its composition and of its relatively high yield. It may be consumed directly in stews and in pies or in syrup. It is native to Central and South America. The plants are annuals and bear large fruit that may even weigh 50 kg. Their pulp has a variable thickness and may be white, off-white, yellow, etc. in colour. The pulp may be used to make pies or it may be preserved as acidified and sterilized pieces in syrup.
Zapallo hoyo and zucchini (Cucurbita spp)
The so-called zapallos tiernos include hoyo, zucchini and hoyito. They may be consumed when they are still unripe in soups or stuffed. Their vitamin and sugar content is lower than in that of pumpkins.
These vegetables have an elongated shape, their surface is rough and they are dark green in colour. Zucchini may be preserved as dehydrated products or in oil, after having been sterilized.
As shown in pictures 29 to 53, the great diversity of raw materials existing both in this region and in the rest of the world, is such that it would be impossible to engage in an exhaustive analysis of all of the species suitable for industrialization.
In the specific case of vegetables, practically all species may potentially be subjected to industrialization processes, with the exception of lettuce, which can only be fermented. The rest of the species, however, are all suitable for processing.
In the case of fruit, the number of both tropical and subtropical species that may potentially be subjected to processing greatly exceeds that of species not suitable for industrialization.
Picture 29. Fruits from dog rose, a wild rosaceous plant growing in south-central Chile. (G. Paltrinieri)
Picture 30. Miniature squashes cultivated in Mexico. (G. Paltrinieri)
Picture 31. Recently harvested broccoli. (G. Paltrinieri)
Picture 32. California-type bonnet peppers. (G. Paltrinieri)
Picture 33. Italian-type tomatoes ready to be harvested. (G. Paltrinieri)
Picture 35. Garlic in plastic nets ready for the market. (G. Paltrinieri)
Picture 34. Cases of recently harvested tomatoes. (Fernando Figuerola)
Picture 36. Onions in nets ready for the market. (G. Paltrinieri)
Picture 37. Bilimbi fruit ready for processing. (G. Amoriggi GUY/86/003)
Picture 33. Carambola fruit washed and ready for sorting. (G. Paltrinieri)
Picture 39. Mangoes ready for processing. (G. Paltrinieri)
Picture 40. Cashew with its false fruit hanging from it, i.e. the nut. (G. Paltrinieri)
Picture 41. Raspberries in trays ready for processing. (G. Paltrinieri)
Picture 42. Passion fruit. (FEDERACAFE, Colombia/RLC)
Picture 43. Sweet oranges. (FEDERACAFE, Colombia/RLC)
Picture 44. Cherimoya packed for the market. (FEDERACAFE, Colombia/RLC)
Picture 45. The pineapple has many industrial uses. (FEDERACAFE, Colombia/RLC)
Picture 46. A whole and half a guava fruit. (FEDERACAFE, Colombia/RLC)
Picture 47. Tree tomato fruit. (FEDERACAFE, Colombia/RLC)
Picture 48. Lulo fruit. (FEDERACAFE, Colombia/RLC)
Picture 49. Wild blackberries (G. Paltrinieri)
Picture 50. Papayas. (G. Paltrinieri)
Picture 51. Curuba fruit. (FEDERACAFE, Colombia/RLC)
Picture 52. Maracuya fruit. (G. Paltrinieri)
