Fruit Juice Processing and Equipment

All the processes for fruit juice products require that the juice or pulp is first extracted from the fruit. The following are the manufacturing stages:

Juice Extraction

In the case of citrus, this is easily done with a hand presser or a revolving citrus ‘rose’, Figure 1. Other fruits such as mango, guava, soursop, etc require pulping – that is, after peeling and stone removal, the flesh of the fruit is pushed through a perforated metal plate.

For this process, there is a range of equipment available from the small ‘Mouli Legume’ and several versions of handpowered pulper/sieves, all of which force the fruit pulp down through interchangeable metal strainers, Figures 2 and 3.

At slightly higher production levels, it is necessary to use a power source, and the multi-purpose Kenwood Chef food mixer, is strongly recommended. This has a pulping attachment rather similar to the Mouli Legume and in addition can be used for liquidizing etc.

For large-scale production, an industrial pulper-sieving machine is necessary. This also acts by forcing the fruit pulp through a fine cylindrical mesh. These cost, however, is quite expensive.

Preparation

When the juice or pulp has been collected, it is necessary to prepare the batch according to the chosen recipe. This is very much a matter of choice and judgement, and must be done carefully to suit local tastes. Juices are sold either pure or sweetened. Fruit squashes would normally contain about 25% fruit material mixed with a sugar syrup to give a final sugar concentration of about 40%. These are diluted with water prior to use and as the bottle is opened, partly used and then stored, the addition of a preservative is necessary (for example 800ppm sodium benzoate). Cordials are simply crystal clear squashes.

Another range of products that has proved popular is fruit nectars which are consumed on a ‘one shot’ basis. Essentially, these consist of a 30% mix of fruit pulp and sugar syrup so as to give a final sugar level of about 12-14%. All fruits contain sugar, usually around 8-10%, with variations not only from fruit to fruit but also in the same fruit grown in different parts of the world. The addition of sugar to give the recommended levels must take into account the sugar already in the juice. However, the amount of sugar added in practice is finally decided by what the purchasers actually want.

In all cases, sugar syrups should be filtered through muslin cloth prior to mixing to remove
particles of dirt which are always present.

Pasteurization

All the products mentioned above need o be pasteurized at 80-95°C for 1-10 minutes prior to filling hot*. At the simplest level, this may be carried out n a stainless steel, enameled or aluminum saucepan over a gas flame, but this can result in localized overheating at the base of the pan, with consequent flavor changes.

To avoid the use of large expensive, stainless steel pans, a large aluminum pan can be used to boil sugar syrup. A given amount of the syrup is then mixed with fruit juice in a small stainless steel pan and this increases the temperature to 60-70°C. The juice/syrup mixture is then quickly heated to pasteurizing temperature.

The next industrial jump in pasteurization is, unfortunately, expensive in that it involves the purchase of a double-jacketed steam kettle in stainless steel and a small boiler.

Filling & Bottling

In all cases, the products should be hot-filled. A stainless steel bucket, drilled to accept a small outlet tap, has proved to be a very successful filler. Output can be doubled quite simply by fitting a second tap on the other side of the bucket. This system has been used to produce 500-600 bottles of fruit juice per day.

After filling hot, the bottles are capped and laid on their sides to cool prior to labeling.

*Care is needed when producing pineapple juice due to a heat resistant enzyme in the juice. The enzyme damages skin after prolonged contact and workers should therefore wear gloves to protect their hands. The juice must be heated to a higher temperature for a longer time to destroy the enzyme (eg boiling for 20 minutes).

Quality Control

As in all food processing enterprises it is necessary to ensure that the fruit products are correctly formulated and priced to meet the customer’s requirements, and that production costs are minimized to ensure that a profit is made. The quality of each day’s production should be monitored and controlled to ensure that every bottle of juice has the correct keeping and drinking qualities. In particular the following points should be observed:

  • Only fresh, fully ripe fruit should be used; mouldy or insect damaged fruit should be thrown away. All unwanted parts (dirt, skins, stones etc) should be removed.
  • All equipment, surfaces and floors should be thoroughly cleaned after each day’s production.
  • Water quality is critical, if in doubt use boiled water or add one tablespoon of bleach to each gallon of water to sterilize it. If water is cloudy, a water filter should be used.
  • Pay particular attention to the quality of re-usable bottles, check for cracks, chips etc and wash thoroughly before using. Always use new caps or lids.
  • The concentration of preservative should be carefully controlled for correct preservation of squashes and cordials, and may be subject to local laws. Check first and use accurate scales to measure the preservative.
  • The temperature and time of heating are critical for achieving both the correct shelf life of the drink and retaining a good color and flavor. A thermometer and clock are therefore needed.
  • The correct weight should be filled into the bottles each time.

These factors are important because a customer will stop buying the products if the quality varies with each purchase.

Checklist of Required Equipments

  • Kenwood chef major and continuous juice separator
  • Boiling pans should be made of aluminum, enameled metal or stainless steel. For larger quantities it is necessary to buy equipment which does not cause burning or sticking of the product to the bottom of the pan.
  • Stainless steel steam jacketed kettles, that is, a double walled pan are suitable and can be obtained with capacities from 5-500 liters
  • Checklist for equipment required
  • Peeler
  • Knives (stainless steel)
  • Cutting boards
  • Juice extractor
  • Thermometer
  • Analytical balance
  • Stainless steel saucepan
  • 10kg scales
  • Measuring cylinder
  • Capping machine
  • Wooden spoons
  • Plastic funnels
  • Plastic buckets
  • Strainers
  • Cleaning equipment (brushes, scourers, cloths, hosepipes etc) 2 gas cylinders, 2- or 3- ring burners.

Building with large preparation table, smaller table for gas burners, shelves for products, sink, draining board, taps, cupboard for labels and dry ingredients.

The working area should have the following features:

  • Sloping concrete floor and proper drainage for washing down each day.
  • A potable water supply.
  • Preferably electricity.
  • Screened windows and doors to reduce insects.
  • No horizontal ledges, window sills, or rafters where dust, bird droppings etc can collect.

source: practicalaction.org, photo from enzymeindia.com

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