Appendix I - Fruit and vegetable processing flow-sheets

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Processing of mango bars

Ripe fruit is used; the mangos are washed, peeled and cut into pieces with a stainless steel knife. Pulp extraction is carried out with a hand-driven or electrical juice extractor. Sugar, lemon juice (or citric acid) and potassium metabisulphite are then added to the pulp so that mixture contains 25% TSS (total soluble solids) as determined by a refractometer.

The composition of ingredients is as follows:

The pulp thus prepared is heated for two minutes at 70-80 C. It is then poured into aluminium trays coated with glycerine (this facilitates the removal of the dried pulp). The prepared pulp should be placed on trays at the rate of 15 Kg per square metre.

The trays are brought to a sun or solar dryer. The drying is completed when the product has the consistency of leather (about 15% moisture content). The yield ratio between raw material and finished product is about 12:1. Two or three layers of dried product are piled one on top of the other and cut into small squares (4 X 4 cm). Each square is wrapped in cellophane paper, packed in cellophane bags then labelled and stored in a dry place.



Processing of dried mango slices

Half-ripe fruits, without fibres, are used.

The mangos are washed, peeled and cut into 6-8 mm thick slices with a stainless steel knife. To obtain finished products with good quality and long storage life, the mango slices are soaked for 18 hours in a solution containing:

* - boiling water: 1 litre;

The slices thus prepared are drained and placed on glycerine coated aluminium trays, which are placed in a sun or solar dryer.

The drying is completed when the product has a moisture content of 15%. The dried slices (150 g) are packed in cellophane bags, labelled and stored in a dry place.

Mango bars and mango slices:

Storage life: about 9 months.

Remark: without preservative (potassium metabisulphite), the storage life of the products is relatively short.



Processing of mango juice

Fully ripe fruit is used. The mangos are washed, peeled and cut into slices with a stainless steel knife. Pulp extraction is carried out with a hand-driven or electrical juice extractor.

Boiling water, lemon juice and sugar are added to the pulp so that the mixture contains 12% TSS (total soluble solids) as determined by a refractometer and pH of 3.5 to 3.8. The composition of ingredients is as follows:

Bottles are filled and capped with a manual capper. Pasteurization times is related to the size of bottles.

Size of bottles in litre Pre-heating Pasteurization time in minutes
0.33 YES 20
0.50 YES 25
0.75 YES 30

Allow the bottles to cool in the same container till the following morning then wash, label and store them.

Storage time: about 12 months

Processing of mango jam

Both ripe and underripe fruit is used.

The mangos are washed, peeled and cut into small slices with a stainless steel knife. The amount of sugar required represents 60% of the weight of the mangoes prepared.

The cooking is done in two stages:

1ST STEP consists in adding 70% of the amount of sugar calculated, plus 2 spoons of lemon juice per Kg of mango. Stir well during the entire cooking until 50 Brix of solids by refractometer is reached.

2ND STEP consists in adding the remaining 30% of the sugar plus 2 spoons of lemon juice per kg of mangos. Stir well during the entire cooking, until 67-68 Brix of solids by refractometer is reached.

The jars are filled while the mixture is hot ("hot-fill" process). During the operation the jam must be stirred with the handle of a wooden spoon in order to eliminate the air that has entered the jars. The jars are closed with screw-tops. Jars cooling, washing and labelling are the last stages before storage.



Processing of peeled tomatoes

For the preparation of peeled tomatoes, fully ripe but still hard, long and/or oval tomatoes are used.

After washing, green tomatoes or those showing mouldy patches, black spots or presence of worms are picked out. The remaining tomatoes are dipped in boiling water for about one minute, then cooled in water at room temperature. Scalding facilitates the bursting of the skin.

The jars, previously washed, are filled by hand. To eliminate the gaps created during filling, tap the bottom of the jar. Then add a small spoonful of lemon juice or vinegar. The filling is completed by adding the hot pulp. The jar is tightly closed with a screw-top. Before counting the pasteurization time, wait till the water comes to the boil.

Pasteurization time is related to the size of the jars.



Processing of tomato pulp

For the preparation of tomato pulp, fully ripe but not spoilt tomatoes are used.

After washing, the tomatoes are drained in order to eliminate the water on the surface. Sorting is done before the tomatoes are cut into halves to facilitate crushing and to detect any possible disease or decay inside.

A manual or electrical juice extractor is used to separate the pulp from the seeds and the skin. The pulp is transferred to a pot and heated until 8-90 Brix of solids by refractometer is obtained.

While still hot, the pulp is bottled with the help of a ladle and a funnel (previously "boiled" for few minutes in water). Acid correction is done with a small spoon of lemon juice.

The bottles are closed with a capper. The pasteurization is performed within the same duration as the jars of peeled tomatoes and under the same conditions. Cool overnight. Washing and labelling are the last stages before storage.

Storage life: about 12 months.




Processing of dried carrots

Roots with red cores and not woody are good for drying. Varieties such as "Chantenay Red Core" and "Imperator" are best for drying.

After removing the stalks and tips, wash the carrot, scrape, then cut into slices of about 56 mm thick using stainless steel knives. All green parts, if any, have to be removed.

For blanching, the slices are dipped for 3 minutes in boiling water containing 50 g salt per litre of water, followed by cooling in running water. In some processes, depending on the finished product specifications / customer standards, sulphiting is also carried out. This step is by dipping in a solution containing 3 g potassium metabisulphite per litre of water, during 3 min.

The product is then evenly spread on the trays of a dryer. The carrots are dried when the prepared MW material / dry products ratio is about 12: l (moisture content about 6%).

Cooling, packing, labelling and storage of dried products are performed according to same recommendations as for the other products.



Processing flow-sheet for apricot drying/dehydration

In order to obtain a high quality finished product, it is essential, among other points, that raw material characteristics fulfil the following requirements:

Fruit must be cut in halves with a knife; do not "separate" the two halves by hand.

Conventional sulphuring before drying is performed by exposing fruits on drying trays to fumes of burning sulphur in "sulphuring cells":

2 g of sulphur for each kg of prepared fruits; sulphuring time: 60 to 90 minutes.

In order to reduce SO2 content in finished product and to provide an alternative to sulphuring cells for small scale / farm operations, dipping apricot halves in various preservative solutions ("wet sulphuring") may be used.



Processing flow-sheet for dried/dehydrated plums (prunes)

The lowest acceptable degree Brix for raw materials is 21 with an average at 24 Bx and a maximum at 30 Bx.

Mechanical drying installation (tunnel) can handle up to 8-11 t/day raw material.

Initial air temperature is 55 C and final air temperature is 72-75 C.

Plums are dried down to 23-24% moisture in the first step.

After storage, commercial practice is to re-process the prunes by immersion in warm water (80 C), containing 2% sodium sorbate, during 10 min and thus rehydrating products up to 26-28% or to 30-32% moisture; this treatment provides a ready-to-eat product which is very appreciated.



Processing flow-sheet for dried/dehydrated apples

a) Wet sulphuring: dipping slices for 10 minutes in a solution containing: 0.5% Potassium metabisulphite (K2S2O5) + 0.2% Citric acid.

b) Dry sulphuring: keeping slices (on drying trays, in sulphuring cells) exposed to fumes of burning Sulphur

2 g Sulphur for each kg of apple; sulphuring time: 30-40 minutes.

- Resulphuring has to be performed by exposing dried apple in bulk to fumes of burning sulphur in order to avoid insect infestation.



Processing flow-sheets for dried/dehydrated leeks

* It is necessary to separate the white parts of the vegetables from the green ones by cutting manually.

The following step - cutting operation - is then done separately for each colour.

Sorting and sieving steps require elimination of "fines" and a control of adequate separation by colour.



Processing flow-sheet for dried/dehydration potatoes

* Optimal blanching time is 2-5 min according to variety.

** Optimal dehydration temperature is 65 C.

An alternative treatment is with slices soaked in a 10-fold weight solution of 5% (w/w) sodium chloride (salt) + 1% K2S2Os for 16-18 h, at ambient temperature (around 20C) and then dried.



Flow-sheet for processing of dried onions

Varieties with pungent flavour are the most appreciated; both coloured and white onions may be used.

After removing the tops, roots and outer integuments, onions are washed thoroughly and then cut into slices of 3 mm thick. It is preferable to cut at right angles to the core of the onions. After cutting onion slices are carefully washed. Blanching is not practiced (it makes the onion lose its flavour).

The use of preservatives is not necessary; therefore, after washing and draining, the slices are spread evenly on the trays of a dryer. The onions are dried when the ration of prepared raw material to dry product is about 9:1 (moisture content about 5%).

Cooling, packing, labelling and storage follow the same operations as described in other flowsheets.

The dried product may be ground into powder (which tend to agglutinate without any anticaking agent).

The dryer used for onions must be reserved especially for onion (flavour / odour contamination possible to other products).

Storage life: about 12 months.



Processing of dried tomatoes

For the preparation of dried product, tomatoes should be ripe, of good red colour and should be firm.

Tomato pigments are stable because they are rich in carotene; therefore, pre-processing, such as blanching and sulphiting, is not necessary. Alternatively the slices may be dipped for 3 min in a solution containing 0.7% K2S2O5 plus 10% salt.

Washing and sorting are followed by cutting in halves lengthwise to eliminate the liquid and the seeds. The seeds as well as the ones from tomato pulp processing can be used again as seeds if they have not gone through a heat treatment.

Empty the tomatoes and then cut them lengthwise into slices of 6 to 8 mm thickness and place them in dryers.

The tomatoes are dry when the raw material / dry product ratio is about 25:1. On an average, 40 g of dried products are obtained from I Kg of fresh tomatoes. The yield depends on the dry tomato residue and the degree of drying.

The last operations before storage are: cooling (half an hour at room temperature), bagging (in 100 g cellophane bags, closed to avoid humidity) and labelling.

The product must be kept in a dark place to reduce infestation by photophylic insects.

The dried slices may be reduced to flakes by rubbing through a sieve of about 10 mm mesh. This gives a better looking product which is easy to handle. The product may also be ground into powder but this will tend to cake and the colour is less appealing than the flakes.


Three processing recommendations made in this flow-sheet have to be followed, among others, for all dried/dehydrated products:

  1. Let finished products cool down to room temperature for half an hour before packing/bagging;
  2. Always store dried/dehydrated products in a dark place.
  3. Place dried/dehydrated products in packing materials which have enough barrier effect against moisture transfer and close well.



Flow-sheet for orange juice processing

Fruit to be used for juice production should be from a well run cultivation, freshly picked and well ripened.

The fruit is first sorted to remove rotten and other unfit items. It then passes through a soak tank of disinfectant and water and then to a brush-washer where rapidly revolving brushes and sprays wash the fruit very vigorously and thoroughly. The brush-washed fruit is again sorted and conveyed to the juice extractor, or halved and juiced.

The pulpy juice flows into the mesh screen finisher for the removal of seeds, heavy pulp and skin portions. The finished juice passes on to the blending, mixing and heating tanks where the requisite amount of sugar syrup is added, if sweetened juice is to be produced. Blended juice is pasteurized and filled into sterilised cans. Filled cans are sealed, cooled, labelled and packaged for marketing.



Flow-sheet for processing mango juice

Fruit to be used for juice production should be factory ripened. Fully mature, unripe mangos are harvested and shifted to the cannery where they are allowed to ripen in a closed atmosphere. Usually it takes about three to four days to ripen the fruit.

Fruit is then sorted and sound ripe mangos are passed to a soak tank of antiseptic and water, and then to a brush washer where rapidly revolving brushes and sprays wash the mangoes. The washed fruit is conveyed to the preparation tables where it is hand peeled. In some cases, the washed unpeeled fruit is steamed and pulped, but for a quality product it should be peeled.

The peeled mangos are steamed and pulped. The coarse pulp thus obtained is sieved with the help of a finisher and conveyed to the blending, mixing and heating tanks where the requisite quantity of sugar syrup is added. The juice is then pasteurized, filled into the steamsterilised cans and sealed. The sealed cans are water-cooled, labelled and packaged for sale.



Flow-sheet for processing of pineapple juice

Canned pineapple juice is now third to canned tomato juice and orange juice in terms of volume (world production). It is an excellent juice for canning, since it retains its fresh flavour and aroma remarkably well and is of an acidity and sugar content such that it is properly balanced in flavour.

Pineapple juice is a by-product obtained during the canning of pineapple slices or rings in syrup. The principal raw materials from which pineapple juice is prepared are the shredded meat obtained from the inner portion of the peels left after the peeling of the pineapple, the small pineapple that is too small for canning, the trimmed cores and the juice drippings from the crushed pineapple.

Small pineapples are peeled. The peeled, small pineapple cores and eradicated meat are shredded; the juice is extracted and then passed through a finisher. The juice thus obtained is blended with sugar syrup, pasteurized and filled into sterilized cans. The cans are sealed hot ("hot-seal" process), cooled, labelled and packaged.



Simplified flow-sheet for tomato juice processing

A hand-operated or an electrical juice extractor could be used. Refining is an optional step and will be performed if an additional centrifugal refiner is available as equipment.

Citric acid or lemon/lime juice will be added in bottles just before filling. Salt may be added to enhance taste.

Prior to use, empty bottles or jars (and crown-corks or caps) must be washed thoroughly, rinsed and then "sterilised" by keeping in boiling water for 30 min.

* Pasteurization is a very important step for the finished product shelf-life and must be carried out very carefully.

** DO NOT cool recipients after pasteurization in running water - there are risks of breakage; instead, leave recipients to cool down slowly overnight in the pasteurization pot.

* Pasteurization TIMES

Recipient countenance Preheating Pasteurization times
0.331 60 C 40 minutes
0.501 60 C 45 minutes
0.661 60 C 55 minutes
0.751 60 C 60 minutes



Flow sheet for processing of mango slices in syrup

Fully mature, unripe mangos are ripened in the cannery to optimum canning ripeness. Mangos high in flavour, with more flesh and low in fibre are always recommended for canning.

Sound ripe mangos are soaked in antiseptic and water, brush washed and then conveyed to the preparation tables and hand peeled. "Cheeks" of the peeled mangos are sliced off and longitudinally cut into two or three slices. Side cuts are packed separately. Slices are then conveyed to the filling tables where they are graded for size, colour and maturity and filled into sterile cans. Filled cans are syruped, steam exhausted, sealed, processed in boiling water, cooled, labelled and packaged.

Stones with the left over flesh are steamed and pulped and the pulp thus obtained is packed as such or converted into mango juice or nectar.



Flow-sheet for processing of pineapple rings in syrup

Pineapples are harvested when they have reached full maturity in order to obtain maximum flavour and quality. Usually the fruit is harvested when 20 to 25 per cent of bracts have turned orange in colour, and then transferred to the cannery in the shortest possible time. Fruit weighing 1.5-2.0 Kg are the best suited for canning as rings.

Fruit is size graded and the crown removed. It is then washed thoroughly and prepared, which includes peeling, coring, slicing and punching. Slices are then graded for size, colour and maturity. Slices should be free from peels and eyes. Each can is filled with slices of the same size and colour. The filled cans are syruped hot, exhausted, sealed, processed, cooled, labelled and packaged.



Flow-sheet for processing of tomato ketchup or sauce

Tomato sauce and tomato ketchup are popular condiments all over the world. Clean, wholesome tomatoes of intense red colour and of meaty, not watery texture are used for sauce making. High acidity and a rich tomato flavour are additional desirable qualities.

Sound tomatoes are washed very thoroughly, cored, sliced, heat crushed and pulped (through a pulper or juice extractor) to remove seeds and skins. Tomato pulp or paste is then cooked with the requisite quantities of spices, onions, garlic, sugar, salt and vinegar.

The whole mass is concentrated to a final TSS (Total Soluble Solids) of more than 25 per cent. The mass is finally passed through the finisher and filled into clean, dry bottles.

Bottles are cleaned, labelled and packaged for marketing. (Preservation is assured either by use of preservatives or by pasteurization).



Simplified technological flow-sheet for fruit jams processing

Jams may be made from practically all varieties of fruit. Various combinations of different varieties of fruit can be often be made to advantage, pineapple being one of the best for blending purposes because of its pronounced flavour and acidity.

Sound fruit is sorted, washed in running water or, preferably, brush-washed and prepared. The mode of preparation varies with the nature of the fruit. For example, mangos are peeled, steamed and pulped; apples are peeled, cored, sliced, heated with water and pulped; plums are scalded and pulped; peaches are peeled and pulped; apricots are halved, steamed and pulped; berries are heated with water and pulped or cooked as such.

Fruit pulp is cooked with the requisite quantities of sugar and pectin, and finished to 69% Total Soluble Solids (TSS). Permitted food colours and the requisite amounts of citric acid and flavouring are added at this stage. The product is packed in cans or glass jars, and cooled, followed by labelling and packaging.



Processing flow-sheets for manufacturing jams from berries


Flow-sheet for mango and guava processing - pulps and nectars


Technological flow-sheet for pineapple canning

Coring is a major limiting factor in the recovery of the fruit and in the whole processing operation. Trimming should be mainly to remove the deep "eyes".

Sugar syrup concentration is adapted to the type of finished products:

45-55 Brix for "Fancy" slices

30-35 Brix for "Choice" slices

20-25 Brix for standard slices

Removal of air is performed in continuous steam exhauster equipment for 7-9 min at 185212 F or discontinuously in boiling water.

Heat treatment is carried out in continuous rotary cookers at 212 F for 10-20 min.

Cooling is be done in rotary coolers in water for 10 min.



Flow-sheet for the processing of passion fruit

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