Fruit juice

There is a growing trend in urban centres of Afghanistan for higher juice consumption and this market may become much larger in future. Apple, pomegranate and apricot fruit are the most popular juices to date, but others may increase in popularity.

Juice is made using traditional methods in many companies, but is not widely sold as a juice. Juice can also be made from a mixture of fruits, although this is not widely done at present. Juice manufacturers face competition from producers who buy imported flavour concentrates and dilute them to make ‘fruit drinks’ that are much cheaper. The marketing of fruit juices should therefore focus on the fact that they are made from fresh fruits with no additives. There is also competition with Afghanistan and foriegn or exported juices that are sold in paperboard cartons. However, the cost of equipment to form and seal the cartons is too high for small-scale producers and they are only sold under licence. Cheaper alternatives including plastic pots with sealed foil lids are available as alternatives to bottles. Some processors have also found a market selling juice in polythene sachets.

Preservation is due to pasteurisation and the natural acidity of the juice. Some types of juice (e.g. melon juice) have low levels of acid and this can be increased by adding citric acid to give a pH below 3.5-4.0. Although some producers add a preservative such as sodium benzoate to ensure a long shelf life, this is not necessary if juice is properly processed. Unopened bottles should have a shelf life of 3-9 months, depending on the storage conditions and quality of the package. Juice production can be spread over a larger part of the year by processing a sequence of fruits or by part-processing pulps and storing them in 1000-2000 ppm. sodium metabisulphite solution. The sulphur dioxide is driven off during pasteurisation.

Juice can be extracted from fruits in a number of ways, depending on the hardness of the raw material. Soft fruits such as berries or tomatoes can be pressed in a fruit press, or pulped using a juicer attachment to a food processor.

Steamers, such as those used for blanching, can also be used to ‘dissolve’ some types of cut soft fruits such as melon. Tomatoes can be heated in a wire basket in boiling water for 10 minutes to loosen the skin before pulping. Citrus fruits are usually reamed to extract the juice without the bitter pith or skin. Harder fruits are peeled and pulped using a liquidiser and pressed to extract the juice. Tomato and other fruit juices can be prepared using a pulper-finisher that separates skins and seeds from the pulp. When a clearer juice is required it is necessary to filter it through a fine cloth or stainless steel juice strainer. A crystal clear juice requires a filter press, which is a considerable investment for a small-scale processor.

Press factors influencing juice yield and quality.
Factor	Effect
Fruit immature	Resistance to juicing, low yield
Fruit inadequately crushed	Resistance to juicing, low yield
Fruit over mature	Undesirables extracted, poor quality
Fruit over comminuted	Undesirables extracted, poor quality
Excessive pressure	Undesirables extracted, dark juice
Excessive time in press	Dark, over extracted juice
Short press cycle	Low yield, lighter juice character
Long press cycle	Low throughput, over extraction
Cold Press	Lower yield, lighter character
Hot press	Higher yield, stronger, darker character
Enzyme treatment	Higher yield, stronger character
Pressing aid added	Higher yield
Press cake redistributed	Increased yield
Delayed or extended pressing	Dark juice, incipient spoilage

After safety concerns comes economic and quality considerations. A product can be perfectly safe and completely fraudulent. As the sale of a product labelled fruit juices may in fact consist of no or little actual fruit components. Thus the development of standards for fruit juices is incorporated into most country’s regulatory codes. These regulations include the processing employed, the amount of fruit content required for various juice designations (Table 2), the soluble solids and acid levels, amount of added substances allowed such as sugar, acid, water, preservatives and reasonable sanitary standards.Some of the important juice quality factors are listed below:

Some quality criteria for juicing.
Factor	Criteria	Rationale
Maturity	Ripeness	Optimum quality
Solids	Adequate level	Affects yield, flavour
Acidity	Appropriate pH level	Flavour, sugar/acid ratio
Colour	Fully developed	Juice appearance
Defects	Appropriate level	A few can be tolerated
Size/shape	Uniform	Ease of handling/juicing
Specific chemicals	Past analyses	Reflect handling/quality
Pesticide residues	Regulatory control	Legality of product
Foreign matter	Appropriate level	Reasonable limits
Microbial count	Low total, no or few pathogens	Safety/stability of juice
Aflatoxin level	Below proscribed limits	Juice safety