Fruit juices and nectars

This chapter will not provide the background to the production of fruit juices and nectars, as that is dealt with elsewhere in this volume. However, fruit juices and nectars represent the largest volume of non-carbonated beverages that are sold in almost every marketplace. It is therefore appropriate that some aspects of these products, particularly those relating to processing and packaging, are mentioned here. 

Fruit juices and nectars are highly susceptible to fermentation and other forms of microbial spoilage and with few exceptions it is essential that some form of pasteurisation is employed when these products are packaged. The exceptions that are seen usually relate to freshly squeezed orange (or other) juices that are processed directly from fresh fruit and packaged immediately. These products have a very short shelf life, usually a few days, and are maintained by storage at temperatures between 0 and 5°C. 

There is also a market for reconstituted fruit juice made from concentrate and not further processed but maintained, during its short shelf life, by refrigeration. 

For all other fruit juice and nectar products either frozen storage or in-pack pasteurisation will be used, although some manufacturers who employ a hot fill process. 

---

Annex II lists foodstuffs for which only certain of the annex I additives may be used. Such foodstuffs include cocoa products and chocolate products, fruit juices and nectars, jam, jellies and marmalades and partially dehydrated and dehydrated milk, which are the subjects of EU vertical standards, and a number of other foods including frozen unprocessed fmit and vegetables, quick-cook rice, non-emulsified oils and fats, canned and bottled fruit and vegetables, bread made with basic ingredients only, fresh pasta and beer. 

Typical flash pasteurisation operations for fruit juices and nectars will employ a plate pasteuriser with heat recovery and final product cooling. Typical flash pasteurisation conditions will use temperatures between 85 and 95°C with holding times varying between 15 and 60 s. Selection of the appropriate conditions will depend on the product, including the level of microbial load pre-pasteurising. If enzyme deactivation is required as well as microbial removal then a temperature between 90 and 95°C will normally be used. At these temperatures, holding times are normally reduced to around 15 s. 

UK Fruit Juices and Nectars Regulations 2003, Statutory Instrument No. 1564, HMSO, London. UK Soft Drinks Regulations 1964 (as amended), Statutory Instrument No. 760 HMSO, London. 

Although there are only a limited number of methods that have been validated specifically for soft drinks, there are around 80 validated methods available for the analysis of fruit juices, most of which would work equally well for soft drinks. These methods are published in the International Fruit Juice Union (IFU) handbook of analytical procedures, which offers the best reference collection of methods for the analysis of fruit juices in the world, with new methods added on a regular basis (Anon, 2004a). The IFU s collection of analytical methods covers most of the main procedures required to assess the quality and authenticity of fruit juices and nectars. The methods are hsted on the IFU s website (http //www.ifu-fruitjuice.com) at the time of writing they cannot be purchased directly from there, but they can be obtained from the Swiss Fruit Union, Zug, and details of how to do this are given on the website. It is possible that at some time the methods will be made available directly from the website. 

Anon (2004a) IFU Compendium of Analytical Methods for Fruit Juices and Nectars, Swiss Fiuit Juice Union, Zug, Switzerland. 

Moy and Speilmann (90) recently reported on the economic feasibility of vacuum puff freeze drying of tropical fruit juices and nectars. They considered the process economically feasible if production rates were 250,000 or 1,000,000kg of dried nectar base per year (two plant sizes) with an assumed level of 35% sucrose (wet weight basis) blended with the juice or puree before dehydration. One assumption made in their study was that a marketing share equivalent to 0.5% of the annual orange juice volume in the U.S. was attainable. 

Trace elements levels in soft beverages, fruit juices, and nectars are usually controlled by manufacturers for different reasons, not only related to toxicity. For... 

Kirca, A., Ozkan, M., and Cemeroglu, B. (2006). Stability of black carrot anthocyanins in various fruit juices and nectars. Food Chem. 97, 598 05. 

M. Gensler, H.-L. Schmidt (1994) Isolation of the main organic acids from fruit juices and nectars for carbon isotope ratio measurements. Anal. Chim. Acta 299. 231-237... 

Pectinases, cellulases and hemicellulases are used for clarification of fruit juices, juice extraction, improvement of cloud stability of vegetable and fruit juices and nectars, liquefaction and maceration of fruits and vegetables, reduction of cooking time of pulses and improvement of rehydration characteristics of dried vegetables. The chemical basis of these treatments and of the consequential changes in sensory and nutritional quality are discussed. 

Governments throughout the world advocate the inclusion of fruit juices in a healthy diet. A juice that is 100% derived from its parent fruit or fruits is almost universally regarded as a healthy and nutritious part of a human diet. The main emphasis in health-promoting dietary recommendations is increased consumption of fruit and vegetables. According to the CODEX General Standard for Fruit Juices and Nectars, an authentic fruit juice product... 

Tchango, J., TailUez, R., Njine, P.E., and Homez, J.P. 1997. Heat resistance of the spoilage yeasts Candida pelliculosa and Kloeckera apis and pasteurization values for some tropical fruit juices and nectars. Food Microbiol 14, 93-99. 

Enzymes could also be used to modify insoluble biopolymers and this is very important to the food industry. Examples include pectinase use in fruit juice and nectar production, food (e.g., fish, meat, and plant) protein hydrolyses, the production of yeast hydrolysates, the hydrolysis and recovery of proteins from by-product sludges, the recovery of meat scraps from bones... 

Cunha SC, Fernandes JO, Ferreira IMPIVO (2002) HPLC/UV determination of organic acids in fruit juices and nectars. Env Food Res Technol 214 67-71... 

---