Vegetables and fruits

About 2.0% of H2PO4 anions are present in natural citrus fruit juices, as well as about 0.02% glucose-6-phosphate and other sugar phosphates. Other phosphorus compounds present in relatively minor quantities are nucleic acids, ATP, phospholipids and B group vitamins. 

Respiration and other metabolic reactions continue at least for a while after the harvesting of fruit and vegetables. During ripening, the fruit enters the climateric phase in which there is enhanced respiration with ATP, RNA and protein synthesis, the production of ethylene and in some cases changes in the content of sugar phosphates. 

Very useful effects can often be obtained by treatment of fruit and vegetables with added phosphates. These effects include stabilisation against bacteria and rancidity, enhancement of colour, and desirable effects on tenderness and firmness. For example, small additions of Na4P20v to peas and beans prior to canning lead to a more tender product due to the sequestering of calcium ions. 

The addition of 0.1-0.2% of sodium polyphosphates will stabilise the colour of strawberries, tomatoes, cherries, and so on, and the use of such compounds prior to canning or freezing will help keep vegetables green [52]. 

Sodium polyphosphate is used to increase the yield of pectin extracted from citrus pulp and apple pommice. It is useful in the manufacture of jams, where it improves clarity by preventing the formation of insoluble calcium and magnesium pectates. 

We know that much of the recent compunction for consumers to choose organic food has been driven by media attention to food scares , which have popularised the focus on food safety and health. Issues such as salmonella in eggs, E. coli food poisoning and the BSE disaster have all taken their toll on consumers confidence in the food industry. 

At the same time these issues have underscored and publicised the choice of organic foods as a viable alternative. 

Throughout this chapter there will be an obvious view taken from the supermarket s perspective. Not only is this chapter written by a supermarket representative, but multiple retail sales of organic foods account for 69% of the total UK sales of organic foods, estimated to be worth 269 million (Soil Association 1999a). 

As far as UK production is concerned, the Soil Association s Food and Farming report estimates there to be about 3000 hectares of organic fruit and vegetable production in the UK (see Table 5.2) which represents only 5% of the total production area. This includes protected cropping. 

Crop Area under cultivation (ha) Estimated tonnage Value ( m) 

It is difficult to be specific about microbial damage in fruit and vegetables because there is usually a succession of micro-organisms and each commodity will differ. However, numerous different types of spoilage can be recognised. 

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Fruit and Vegetable Products. Sorbates are appHed at 0.05—0.1 wt % as a fungistat for pmnes, pickles, reHshes, maraschino cherries, oHves, and figs (64,112). The same levels extend shelf life of prepared salads such as potato salad, cole slaw, and tuna salad (99). In fermented vegetables, sorbates protect the finished product by retarding yeasts during fermentation or in the cover brine (r65,r72—r74,r94). 

Canned Fruits and Vegetables. The use of citric acid to bring the pH below 4.6 can reduce heat treatment requirements in caimed fmits and vegetables. In addition, citric acid chelates trace metals to prevent enzymatic oxidation and color degradation, and enhances the flavor, especially of caimed fmits. 

Sample pre-treatment. Novel procedures of electrochemical sample treatment have been proposed to decrease the signal interference with native cholinesterase inhibitors present in fruits and vegetables. Polyphenolic compounds were removed by electrolysis with soluble A1 anode followed by the oxidation of thionic pesticides with electrogenerated chlorine. The procedure proposed makes it possible to decrease the background current and the matrix effect by 80-90%. Thus, the detection limits of about 5 ppb of Pai athion-Methyl and Chloropyrifos-Methyl were obtained in spiked grape juice without any additional sepai ation or pre-concentration stages. 

While there is limited evidence to suggest that consumption of diets high in fruit and vegetables is associated with a reduction in risk of breast cancer, the... 

It is important to note that diet is a complex mixture that contain compounds with varying activity. Chemical stimulators of colon cancer growth include bile acids, 1,2-diglycerides and prostaglandins which stem from consumption of fat. In contrast, fruits and vegetables contain substances such as carotenoids, flavonoids and fibre, which may inhibit cancer cell growth, and the risk of colon cancer appears to be mirrored by the ratio of plant sterols to cholesterol in the... 

Thus, it is uncertain to what extent the apparent protective effects of fruit and vegetable consumption on risk of stomach cancer can be attributable to their phytoestrogen content. This appears not to have been studied directly, and other constituents such as ascorbic acid (vitamin C), a-tocopherol (vitamin E) and /1-carotene may be potentially protective. 

The most severe environmental problem of fruit and vegetable processors is the potential for water poUution if the liquid wastes are not handled properly. Cooking can cause odors, which are usually controlled by using furnaces as afterburners. 

Pickled fruits and vegetables, vegetable sauces and seasonings, and salad dressings... 

Scurvy results from a dietary vitamin C deficiency and involves the inability to form collagen fibrils properly. This is the result of reduced activity of prolyl hydroxylase, which is vitamin C-dependent, as previously noted. Scurvy leads to lesions in the skin and blood vessels, and, in its advanced stages, it can lead to grotesque disfiguration and eventual death. Although rare in the modern world, it was a disease well known to sea-faring explorers in earlier times who did not appreciate the importance of fresh fruits and vegetables in the diet. 

From the practical point of view, the principal variation of environment which is definitely under the control of the cultivator, is, of course, the alteration in the composition of the soil, which is brought about by scientific manuring, llie analysis of fruits and vegetables will give the ordinary agriculturist much information as to the necessary mineral ingredients to be added to the soil but in the case of essential oils, the conditions are entirely different. The various parts of the plant tissue are affected in different ways by the same mineral salts, and successful development of the fruit or any other given part of the plant may have little or no relationship with the quantity or quality of essential oil produced. So that it is only by actual distillations of the plant, or portion of the plant, coupled with an exhaustive examination of the essential oil, that informative results can be obtained. 

Tressler, D. K. and Joslyn, M. A., Fruit and Vegetable Juice Processing Technology, Avi. Westport (1968)... 

Fruits and vegetables which give off heat of respiration need to have perforated cases so that air may pass through the product. 

It will be noted that fruits and vegetables, with the exception of dried fruit and onions, are stored in high humidity to prevent drying out through the skin. Meats generally must be in drier air, or slime may form with the growth of bacteria. 

Frozen fruit and vegetables will be sealed in plastic bags and stored at -18°C or lower. The humidity at this temperature is not important. 

The successful and profitable control of frozen food quality requires workable standards of product quality and condition and suitable methods for determining the degree of product conformance with standards. The frozen fruit and vegetable industry has developed rapidly during the past 20 years and serious concentration upon the development of adequate standards and objective methods for quality measurement is necessary. Such standards and methods should be placed on a uniform basis the country over and given official and legal status. 

Because of their highly perishable nature, frozen fruits and vegetables are very sensitive to mishandling during distribution, especially in connection with maintaining proper conditions of temperature. 

Much valuable research has been devoted to developing the basic principles for the production of frozen fruits and vegetables of high and uniform quality. If this knowledge could be applied to its fullest extent, there would be little need for concern over the quality of such foods. Before this can be done, those responsible for quality control must be provided with suitable standards of quality and condition, and objective methods of analysis which will clearly indicate conformance or nonconformance to the standards. Responsibility for this resides with the research food technologist or chemist. It constitutes a rich field for profitable and practical research. 

There is yet much to be done in establishing standards and objective methods in which one may have complete confidence. The frozen fruit and vegetable industry has developed rather rapidly during the past 20 years and it is now time for individuals and organizations responsible for the conduct of frozen food research to concentrate... 

To illustrate how some filth elements may be detected, measured, and evaluated in fruit and vegetable products, let us consider tomatoes, which are subject to at least three types of depredation worms, flies, and mold. 

Moisture Determinations. Because the moisture content of many fruits and vegetables is an index to maturity and quality, moisture determinations are employed extensively in the grading of raw fruits and vegetables, and in some cases— for example, tomato products—the finished item may be sold on the basis of moisture content. 

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