FOOD TECHNOLOGY-1

Module 4. Fruit and vegetable juice processing

Lesson 15
PROCESSING OF SELECTED FRUIT JUICES-II

15.1 Introduction

In the last lesson (Part-1) we dealt with Citrus fruit juices viz. Orange, Lemon, Lime, Grapefruit. In this lesson we will deal with Apple, Grape, Mango(pulpy) and other juices.

15.2 Apple Beverages

Apple juice, apple cider and vinegar are made from fruit, not suitable to be marketed as fresh product. The particulars of some Apple variants are depicted in Table 15.1. The flow chart for preparation of Apple juice is furnished in Figure 15.1.

Table 15.1 Particulars of some apple varieties

Fig. 15.1 Flow chart for preparation of Apple juice

15.3 Salient Features of Some Steps of Manufacture

15.3.1 Blending

A blend of tart and aromatic varieties gives more flavourful juice than single variety.

15.3.2 Crushing

The macerated apple pulp is covered with cotton press cloth and subjected to pressure in racks in a hydraulic press.

15.3.3 Repressing

The press cake may be broken up and pressed for a second time. The juice contains more or less finely divided pomace and cloths may be precoated with rice hulls.

15.3.4 Chemical preservation

Juice sold as fresh cider is generally bottled after 0.1% Na-benzoate has been added to protect product from bacterial or yeast spoilage. Sorbic acid or K-sorbate (0.05%) in combination with mild pasteurization may be employed.

15.3.5 Clarification of juice

Pectinase hydrolyses pectin, which releases particles that settles to the bottom. Tannin and gelatin are added to form a coagulum and then precipitate. Alternately, the juice may be heated to have the same effect.

Table 15.2 Composition of Apple juice

15.4 Type of Apple Juices

15.4.1 Unclarified juice

It is sold in fresh state or preserved by 0.1% Na-benzoate for prompt consumption. The juice has coarse particles removed by screening or settling.

15.4.2 Centrifuged apple juice

The pressed, screened juice is passed through a centrifuge. The juice is slightly clearer than unclarified juice, but more opaque than filtered juice.

15.4.3 Filtered apple juice

The juice is first treated to reduce pectinaceous matter. Then juice is filtered to remove all particles, giving brilliantly clear product. Filtered juice may be produced by (a) tannin and gelatin, (ii) enzyme treated, (iii) heat treated, or (iv) treatment with bentonite.

15.4.4 Untreated juice

The filtered juice has superior flavour with excellent body, if freshly pressed and screened juice is filtered and processed rapidly. Filter aid (0.5-2.0%) is added to juice and filtered. The juice carries slight haze but has full flavour of original fruit. It develops no objectionable sedminent during storage; however, slight increase in cloudiness may occur.

15.4.5 Opalescent juice

It is made by retaining the fine pulp particles suspended in the juice. It is preferred by some over the traditional clear juice.

15.5 Grape Juice

Scientific name of grape: Vitis vinifera

Varieties: Concord, Bangalore blue, Beauty seedless, Himrod, Anab-e-shahi, etc. The flow chart for preparation of Grape juice is furnished in Figure 15.2. The composition of grape juice obtained from some variants is shown in Table 15.3.

Fig. 15.2 Flow chart for preparing Grape juice

15.5.1 Salient Points on Juice Recovery from Different Varieties

15.5.1.1 Beauty seedless

No difference in juice yield (79%) either by cold or hot pressing. An increase of 5.50% in yield resulted due to pectolytic enzyme treatment.

15.5.1.2 Himrod

Hot pressing gave 4.5% higher juice recovery than by cold pressing (78.8%). Enzyme treatment enabled increase in juice recovery by 7.3% vs. by cold pressing.

15.5.1.3 Anab-e-shahi

An increase in 6-12% juice yield was there due to pectolytic enzyme treatment.

Table 15.3 Composition of cold and hot pressed juices

According to US grade A Unsweetened grape juice, it should possess

Min. 15° Brix and Min. acidity – 0.60% as tartaric acid

For Concord grape

Brix at harvest: 16-19°Brix
Total sugar: 14-16°Brix

Table 15.4 Composition of juice of different grape varieties

15.4 Mango

Mango is christened as the ‘King of Fruits’. Mangoes are grown in 83 countries and 63 countries produce more than 1000 metric tonnes a year. Total world production of mangoes in 2009-10 was 31.5 million tonnes.
India is by far the largest producer, accounting for nearly 55% of world production, followed by Mexico, Pakistan, Indonesia, Thailand and Brazil. The mango products have a share of 43-44% in the total production of fruit and vegetable products.

Generally 20 varieties are used; for processing the important ones include: Totapuri, Alphonso, Kesar, Dashehari, Pairi, Baneshan, Neelam and Fazli. Sindhu is a seedless mango variety. There is a concern of incidence of spongy tissue in Alphonso and fruit fly and stone weevil in Totapuri. The particulars related to pulp, peel, stone, etc. of some important Mango varieties are furnished in Table 15.5. The composition of few important varieties of Mango has been shown in Figure 15.6.

Table 15.5 Particulars for some mango varieties

Table 15.6 Composition of certain Mango varieties

15.5 Comparative appraisal of nutrient composition of some fruit juices

For comparison of the various compositional characteristics, the data for few fruit juices are depicted in Table 15.7.

Table 15.7 Composition of some fruit juices