Preparation of fruit juice

fruit juice

i. Selection of fruit:
All fruits are not suitable because of difficulties in extracting the juice or because the juice is of poor quality. The variety and maturity of the fruit and locality of cultivation influence the
flavour and keeping quality of its juice. Only fully ripe fruits are selected. Over ripe and green
fruits, if used, adversely affect the quality of the juice.

ii. Sorting and washing
Diseased, damaged (or) decayed fruits are rejected or trimmed. Dirt and spray residues of arsenic, lead etc., are removed by washing with water or dilute hydrochloric acid (1 part acid 20
parts water).

iii. Juice extraction
Generally juice is extracted from fresh fruit by crushing and pressing them. Screw type juice extractors, basket presses or fruit pulpers are mostly used. The method of extraction differs from fruit to fruit because of differences in their structure and composition. Before pressing, most fruits are crushed to facilitate the extraction. Some require heat processing for breaking up the juice – containing tissues. In case of citrus fruits, the fruit is cut into halves, and the juice extracted by light pressure in a juice extractor or by pressing the halves in a small wooden juice extraction. Care should be taken to remove the rind of citrus fruits completely otherwise it makes the juice bitter. Finally, the juice is strained through a thick cloth or a sieve to remove seeds.

All equipments used in the preparation of fruit juices and squashes should be rust and acid proof. Copper and iron vessels should be strictly avoided as these metals react with fruit acids and cause blackening of the product. Machines and equipments made of aluminium, stainless steel etc. can be used. Extracted juices should not be unnecessarily exposed to air as it will spoil the colour, taste and aroma and also reduce the vitamin content.

IV. Deaeration
Fruit juices contain some air, most of which is present on the surface of the juice and
some is dissolved in it. Most of the air as well as other gases are removed by subjecting the
fresh juice to a high vacuum. This process is called deaeration and the equipment used for the
purpose is called a deaerator. Being a very expensive method, it is not used in India at present.

V. Straining (or) Filtration
Fruit juices always contain varying amounts of suspended matter consisting of broken
fruit tissue, seed, skin, gums, pectic substances and protein in colloidal suspension. Seeds and
pieces of pulp and skin which adversely affect the quality of juice, are removed by straining
through a thick cloth or sieve.

Removal of all suspended matter improves the appearance but often results in disappearance of fruity character and flavour. The present practice is to let fruit juices and beverages retain a cloudy or pulpy appearance to some extent. In case of grape juice, apple juice and lime juice cordial however, a brilliantly clear appearance is preferred.

VI. Clarification
Complete removal of all suspended material from juice, as inlime juice cordial, is known
as clarification which is closely related to the quality, appearance and flavour of the juice.

The following methods of clarification are used (a) Settling (b) filtration (c) freezing (D) cold storage (e) high temperature (f) chemicals such as gelatin, albumen, casein, mixture of tannin and
gelatin (g) enzymes such as pectinol and filtragol.

VII. Addition of sugar
All juices are sweetened by adding sugar, except those of grape and apple. Sugar also acts as preservative for the flavour and colour and prolongs the keeping quality. Sugar based products can be divided into 3 groups on the basis of sugar content.
a. Low sugar – 30 per cent sugar or below
b. Medium sugar – sugar above 30 and below 50%
c. High sugar – 50% sugar and above
Sugar can be added directly to the juice or as a syrup made by dissolving it in hot water,
clarifying by addition of a small quantity of citric acid or a few drops of lime juice and filtering.

VIII. Fortification
Juices, squashes, syrups etc. are sometimes fortified with vitamins to enhance their nutritive value, to improve taste, texture or colour and to replace nutrients lost in processing. Usually ascorbic acid and Beta-carotene (water – soluble form) are added at the rate of 250-500 mg and 7-10 mg per litre, respectively. Ascorbic acid acts as an antioxidant and beta-carotene imparts an attractive orange colour. For a balanced taste some acids are added. Citric acid is often used for all types of beverages and phosphoric acid for cola type of drinks.

IX. Preservation
Fruit juices, RTS and nectars are preserved by pasteurization but sometimes chemical
preservatives are used. Squashes, crushes and cordials are preserved only by adding
chemicals. In the case of syrup, the sugar concentration is sufficient to prevent spoilage. Fruit
juice concentrates are preserved by heating, freezing or adding chemicals.

X. Preservation by Bottling
Bottles are thoroughly washed with hot water and filled leaving 1.5-2.5 cm headspace. They are then sealed either with crown corks (by crown corking machine) or with caps (by capping machine).

Individual Beverages
1. Juices
Juices are of two types
a. Natural juice (pure juice):It is the juice, as extracted from ripe fruits, and contains only
natural sugars.
b. Sweetened juice: It is a liquid product which contains at least 85% juice and 10% TSS.
Pure fruit juices such as apple juice and orange juice are commercially manufactured. Apple
juice is generally bottled while other juices are canned.

Example Apple juice

fruit juice
Apples → Washing with 1.5% Hcl – Grating (apple grater)→ Crushing for juice extraction
→ Straining → Clarification (By enzyme (or) gelatin) → Filtration→ Heating at 82-85o
C → Filling hot into cans →Sealing → Processing at 100 oC for 15 min. → Cooling → Storage.

Citrus juice

fruit juice
Mandarin and sweet oranges → Washing → Peeling (By hand) → Separation and cleaning of segments → Juice extraction (Screw type extractor) → Straining → Heating at 80 oC– Bottling (or) canning (Baby food cans) → Crown corking (or) can sealing →Pasteurization →Cooling → Storage.

Example for sweetened juice
Mango juice

fruit juice
Mangoes (ripe) → washing → peeling  s tone rem oval →s training of pulp – addition of
water (1 lit pulp 0.5 lit H2O) → mixing with syrup → Homogenization → Heating at 85o
C →Filling hot into cans → sealing → Processing at 100 oC for 20 min → cooling → storage.

2. Ready-to-serve (RTS)

fruit juice
This is a type of fruit beverage which contains atleast 10% fruit juice and 10% total
soluble solids besides about 0.3 per cent acid. It is not diluted before serving hence it is known
as ready to serve. Commercially RTS beverages (with 13% TSS and 0.3 % acid) can be prepared by using SO2 -70 ppm or benzoic acid 120 ppm.

For example: Papaya RTS
Ripe fruits → Washing → Peeling → Cutting into halves → Seed removal → Passing
through pulper → Pulp → Mixing with strained syrup solution (Sugar + Water acid, heated just
to dissolve) Homogenisation → Bottling → crown corking → Crown corking → Pasteurization
(about 90 oC for 25 min) – Cooling → Storage.

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