Fruit juices and purees

Antioxidant capacity can be measured by several techniques, each of which has its own limitations. Antioxidant capacity of fruit juices and purees was evaluated by the DPPH method (which measures the radical-scavenging activity against a nonphysio-logical free radical), and treatment of these products with PEF or HHP resulted in losses... 

Determination of cations is one of the most important analyses for the routine quality control of fruit juices and purees. Weak cation exchangers are in general highly selective with respect to the H+ ion ... 

Hammond, D.A. (1996) Methods to detect the adulteration of fruit juice and purees, in Food Authenticity (eds RR. Ashurst and M J. Dennis), Blackie Academic Professional, Chapman Hall, London. 

Hammond, D.A., Correia, P., Day, M.P. Evans, R. (1998) 13C-IRIS—A refined method to detect the addition of cane/corn derived sugars to fruit juices and purees . Fruit Processing 3 86-90. 

One of the most useful methods involves the use of L-ascorbic acid as a reducing agent. This is practiced extensively in the commercial production of fruit juices and purees. The ascorbic acid reacts with the o-quinones and changes them back into o-diphenols (Figure 10-14). 

Saravacos, G. D. 1970. Effect of temperature on viscosity of fruit juices and purees. J. Food Sci. 35 122-125. 

Pectin esterase from Aspergillus niger Pectin methyl ester —r Pectinic acid + CH3OH Removal of pectin sheaths from plant fibers removal of cloudiness in fruit juices and beer production of fruit juices and purees. 

Some citrus fruit juices and purees (especially those of grapes) contain naringin, a dihy-drochalcone with a very bitter taste. Treatment of naringin with combined preparations of a-L-rhamnosidase and P-D-glucosidase yields the nonbitter aglycone compound naringenin (cf. 18.1.2.5.4). 

Hajare and others 2007), and high-pressure processing induce small or no losses of carotenoids in intact fruits and vegetables and their juices and purees. 

Packing of wine, water, fruit juices, tomato puree ( bag in box ) Packing of fertilizers and herbicides Packing for cooked meat... 

Capillary viscometers are ideal for measuring the viscosity of Newtonian fluids. However, they are unsuitable for non-Newtonian fluids since variations in hydrostatic pressure during sample efflux results in variations in shear rate and thus viscosity. This unit contains protocols for measuring the viscosity of pure liquids and solutions (see Basic Protocol) and serums from fruit juices and pastes (see Alternate Protocol). 

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. 

Carbohydrase (Rhizopus oryzae var.) Produced as a powder or a liquid by controlled fermentation using Rhizopus oryzae var. Soluble in water, but practically insoluble in alcohol, in chloroform, and in ether. Major active principles (1) a-amylase, (2) pectinase, and (3) glucoamylase (amyloglucosidase). Typical applications used in the preparation of starch syrups and fruit juices, vegetable purees, and juices and in the manufacture of cheese. 

To maintain cloud stability in fruit juices, high-temperature-short-time (HTST) pasteurization is used to deactivate pectolytic enzymes. Pectin is a protective colloid that helps to keep insoluble particles in suspension. Cloudiness is required in commercial products to provide a desirable appearance. The destruction of the high levels of pectin-esterase during the production of tomato juice and puree is of vital importance. The pectinesterase will act quite rapidly once the tomato is broken. In the so-called hot-break method, the tomatoes are broken up at high temperature so that the pectic enzymes are destroyed instantaneously. 

Worldwide, more than a thousand cultivated varieties of plums are pitted and dried to make prunes, which are usually eaten as a single-fruit snack. Prune juice and puree are also versatile as consumer and industrial products. Prunes are frequently used in cooking for both sweet and savory dishes, as well as with yogurt. Stewed or in a hot compote, prunes are favored as a dessert. They have a wide variety of uses in traditional meals, snacks, and side dishes. 

As stated by Scott (1984), published information on mycotoxins in foods processed for human consumption is limited. Information on the extent that mycotoxins persist through processing is important for risk management by food processors and regulatory authorities. Whereas past research mainly focused on cereal processing, this chapter summarizes available literature on major categories of fruit products dried fruits, fruit juices, wine and cider as fermented fruit juices, and fruit purees and jams. 

Foo and Lemon (1997) assessed the acute effects of kava, alone and in combination with alcohol, on subjective measures of impairment and intoxication and on cognitive performance. This was a placebo-controlled study, with ten subjects in each of four conditions placebo, kava, alcohol, and kava plus alcohol. The placebo was pure fruit juice and fruit juice was added to kava and alcohol as well to maintain double blind conditions. A battery of tests was included to measure outcomes, including subjective measures of impairment and intoxication, and visual-motor and cognitive performance. These measures were performed before (time = 0), and 30, 60 and 90 minutes after consumption of the drinks. Each test trial took about 12 minutes. Kava consumption produced no significant effects on perceived or measured competence, while alcohol caused motor and cognitive impairments. However, when kava and alcohol were combined, kava potentiated both the perceived and measured impairment produced by the alcohol alone. This potentiation effect is in accord with the findings of Jamieson and Duffield (1990) on the positive interaction of ethanol and kava resin in mice. 

Electrodialysis has a number of other large-scale applications and these would include the manufacture of pure sodium chloride for table salt (in Japan, electrodialysis is the principal method, production exceeding 10 ton yr ), the demineralization of cows milk (for baby food), cheese whey and sugar solutions, the removal of excess acid from fruit juice and the isolation of organic acids from reaction streams. 

Sometimes the proposed method is an indirect procedure to monitor the excess of oxidant or the color change of an auxiliary reagent such as the method described for the assay of azathioprine, either in pure form or in pharmaceutical formulations the methods are based on the oxidation of the drug with excess N-bromosuccinimide or chloramine-T and determining the consumed reagent by the decrease in color intensity of celestine blue or gall-ocyanine, respectively. Another example is the determination of ascorbic acid in fruit juice and pharmaceuticals on the basis of its inhibition effect on the reaction between hydrochloric acid and bro-mate. The decolorization of methyl orange due to the reaction products was used to monitor the reaction at 510 nm. 

Chemical determination without separation can be exploited, especially in the analysis of pure or highly concentrated samples such as some foods (e.g., fruit juice and other liquid formula) and pharmaceuticals. Biological samples often contain imknown compounds that can cause nonspecific interference in less sophisticated assays. The chemical methods usually lack the specificity and sensitivity in the quantitative determination of vitamins in biological samples or differentiation between different vitamers. 

Paris does not mention what sugars constitute the 18%. However, if one supposes about 7.5% of the above to be glucose, Paris s observations agree with those of other workers on different fruit juices and on pure sugar solutions. 

Figure 10.211 Separation of aikaii and aika- purees diiuted 1 50 with deionized water iine-earth metais in various fruit juices and peaks (1) sodium, (2) ammonium, (3) potas-fruit pur s. Separator coiumn lonPac CS12A sium, (4) magnesium, and (5) caldum (repro-eiuent 20mmoi/L methanesuifonic acid flow duced with permission from Ref. [317]. rate 1 mUmin detection suppressed conduc- Copyright 1996, Eisevier B.V.). tivity samples various fruit juices and fruit...

Botanically, fruits are the matured ovary with, or without seeds, and sometimes with the remains of floral parts. The fruit wall, which may be either dry or fleshy is known as the pericarp and forms the edible part of most fruits. In the case of strawberries it is the swollen receptacle that forms the edible fruit. Most common fruits are used for dessert purposes, but what is not sold on the domestic market may be used as the starting material for several products of value in food processing. These include (a) fruit pieces, pulp, and puree (b) dehydrated fruit (c) fruit juices and concentrates (d) fruit powders (e) preserved fruits (canned or bottled) and (f) jams and jellies. 

---