In this article we will discuss about how to extract fruit juice.
Introduction to Fruit Juice Extraction:
A wide range of drinks can be made using extracted fruit juice or fruit pulp as the base material. Many are drunk as a pure juice without the addition of any other ingredients, but some are diluted with sugar syrup.
The types of drink made from fruit can be separated into two basic types:
(i) Those that are drunk straight after opening.
(ii) Those that are used little by little from bottles which are stored between uses.
The first type should not require any preservative if they are processed and packaged properly. But the latter group must contain a certain amount of permitted preservatives to have a long shelf-life after opening. The different types of drink are classified according to the following criteria (Table 9.2).
Each of the above products is preserved by a combination of natural acidity, pasteurization and packaging in sealed containers. Some drinks (syrups and squashes) also contain a high concentration of sugar which helps to preserve them.
For all the fruit based beverages, the first stage is the extraction of juice or pulp from the fruit.
Any fruit can be used to make fruit juice, but the most common ones include pineapple, orange, grapefruit, mango and passion fruit. Some juices such as, guava juice are not filtered after extraction and are sold as fruit nectars.
The following are the key manufacturing stages:
Select mature, undamaged fruits. Any fruits that are mouldy or under-ripe should be sorted and removed. Wash the fruit in clean water. Peel the fruit and remove stones or seeds. If necessary, chop the fruit into pieces that will fit into the liquidizer or pulper.
There are several methods to extract juice depending on the type of fruit you use. For citrus fruits which are naturally juicy, the best option is to use a hand presser or a revolving citrus ‘rose’. Some fruits such as melon and papaya are steamed to release the juice. Apples are pressed and fruits such as mango, guava, pineapple and strawberry must be pulped to extract the juice.
The fruit pieces are pushed through a perforated metal plate that crushes and turns them into a pulp. Some fruits can be pulped in a liquidizer and then filtered to remove the fruit pieces. There is a range of equipment available that varies in size and in the type of power supply (some are manual while the larger ones require electricity). For the small scale processor, the Mouli Legume or a hand-powered pulper/sieve which force the fruit pulp down through interchangeable metal strainers is sufficient.
To make a clear juice, the extracted juice or pulp is filtered through a muslin cloth or a stainless steel filter. Some of the larger filter presses have a filter included. Although juice is naturally cloudy, some consumers prefer a clear product. It may be necessary to use pectic enzymes to break down the pectin and to help clear the juice. Pectic enzymes may be difficult to find and expensive and therefore should only be used if really necessary and readily available.
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 judgment 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 sugar syrup to give a final sugar concentration of about 40%. Squashes are diluted with water prior to use and, as the bottle is opened, partly used and then stored, it is necessary to add a preservatives.
All the products mentioned above need to be pasteurized at 80-95°C for 1-10 minutes prior to hot-filling into bottles. 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 (e.g. boiling for 20 minutes). The pasteurization process may be holding method or flash process (low temperature preservation methods).
(6) Filling and Bottling:
In all cases, the products should be hot-filled into clean, sterilized bottles. A stainless steel bucket, drilled to accept a small outlet tap, is very effective bottle filler. After filling hot, the bottles are capped and laid on their sides to cool prior to labeling.
The freshness and quality of the expressed fruit juice is central to the quality of the final product. 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:
1. 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.
2. All equipment, surfaces and floors should be thoroughly cleaned after each day’s production.
3. Water quality is critical. If in doubt use boiled water or add one tablespoon of bleach to 5 litres of water to sterilize it. If water is cloudy, a water filter should be used.
4. 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.
5. The concentration of preservatives 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.
6. 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.
7. 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.