Fruit ascorbic-acid addition

Vitamin C occurs as L-ascorbic acid and dihydroascorbic acid in fruits, vegetables and potatoes, as well as in processed foods to which it has been added as an antioxidant. The only wholly undisputed function of vitamin C is the prevention of scurvy. Although this is the physiological rationale for the currently recommended intake levels, there is growing evidence that vitamin C may provide additional protective effects against other diseases including cancer, and the recommended dietary allowance (RDA) may be increased in the near future. Scurvy develops in adults whose habitual intake of vitamin C falls below 1 mg/d, and under experimental conditions 10 mg/d is sufficient to prevent or alleviate symptoms (Bartley et al., 1953). The RDA is 60 mg per day in the USA, but plasma levels of ascorbate do not achieve saturation until daily intakes reach around 100 mg (Bates et al., 1979). Most of the ascorbate in human diets is derived from natural sources, and consumers who eat five portions, or about 400-500 g, of fruits and vegetables per day could obtain as much as 200 mg of ascorbate. 

Mycotoxins are toxic secondary metabolites produced by fungi growing within or on foods. They can be a serious threat to human and animal health (Nagler el al., 2001). Table 11.4 details mycotoxins associated with soft drinks and fruit juice manufacture and raw materials. Patulin is the most common mycotoxin associated with fruit juice, particular ly apple juice (Pitt Hocking, 1997). It commonly occurs if juice is produced from stored apples. Mould growth in infected apples increases with time, raising levels of patulin. The use of windfall apples for juice is also a factor. Avoidance of windfall apples, filtration of juice and pressing quickly after harvest are all methods to reduce the incidence of patulin in juice. Patulin can be destroyed by fermentation to cider or by the addition of ascorbic acid (Marth, 1992). Within Europe, the European Union has set a limit of 50 ig/kg for patulin in both apple juice and cider. A recent survey of apple products in Chile found that 28% of samples of juice and concentrate exceeded this limit (Canas Aranda, 1996). 

Supplementation with the antioxidant vitamins ascorbic acid (250 mg) and mixed natural tocopherols (50 IU on alternate days) may be beneficial. Higher doses may vitiate the impact of lipid lowering therapy. Other naturally occurring antioxidants such as resveratrol, 3-catechin, selenium, and various carotenoids found in a variety of fruits and vegetables may provide additional antioxidant defense. Homocysteine, which initiates proatherogenic changes in endothelium, can be reduced in many patients by restriction of total protein intake to the amount required for amino acid replacement. Daily supplementation with up to 2 mg of folic acid plus other B vitamins is also recommended. 

Recently, workers using serum ascorbic acid values as the reference of their estimation of ascorbic acid requirements in monkeys and baboons found that captivity and handling increased the ascorbic acid requirements (51,52). They concluded that captive monkeys required 20 mg of ascorbic acid/d in addition to fruit supplements. No differences were measured in the response of serum ascorbic acid after supplementations of 5 or 10 mg of ascorbic acid/kg of body weight/d in the baboon. 

Selected graded fruit is peeled and sliced or diced, and sugar is added either as sugar syrup containing ascorbic acid or dry sugar previously blended with crystalline ascorbic acid, after which the fruit is compactly packaged, quickly frozen, and held in a frozen state until thawed by the consumer. The addition of 300-500 mg of L-ascorbic acid... 

Hexopar inositol nicotinate nicotinic acid, hexoprenaline [ban, inn] (hexoprenaline hydrochloride [jan]) is a P-ADRENOCEPTOR agonist selective for the P2-subtype that therapeutically can be used as a BRONCHODIIATOR in ANTIASTHMATIC treatment, hexoprenaline hydrochloride hexoprenaline. hexuronic acid ascorbic acid, hexylcaine [inn] (hexylcaine hydrochloride [usan]) is an ester series LOCAL ANAESTHETIC, used by topical application for the local relief of pain, hexylcaine hydrochloride hexylcaine. hexylresorcinol [usan] is a urinary ANTISEPTIC and an ANTHELMINTIC. It inhibits melanosis (blackspot) in shrimps, and is used as a food additive for prevention of enzymic browning in shrimps and fruits, hexyltheobromine pentifylline. 

Ascorbic acid browning is also inhibited by the addition of sulfite (Wedzicha and McWeeny, 1974). The same holds for polyphenol oxidase-catalyzed oxidation of natural phenols in fruit. The mechanism of the inhibition is by reaction of oquinone intermediates with sulfite, which leads to nonreactive sulfocatechols (Wedzicha, 1995). 

Preparation of the fruit. Since the early research of Webb et al. (33) several workers have recognized the problem of artefact formation during work-up of grapes. Accordingly, these investigators have employed additives such as NaF and ascorbic acid or SO. and sorbic acid to minimize microbial and oxidative degradation of the juice (2,10,34). 

Table 62.1 presents the chemical characterization of natural (without additives) camu-camu pulp. Except for ascorbic acid, the values were similar to those found by other authors (Zapata and Dufour, 1993). As can be observed, no sucrose was present and the reducing sugars content was low, distinguishing it from other acid fruits. 

The standard addition method can be efficiently implemented in a flow system with multi-site detection, as demonstrated by the amperometric determination of ascorbic acid in fruit juices [87], Only one sample aliquot was inserted, and the sample zone was monitored under two different conditions, before and after the standard addition by confluence. Measurements related to the first and second detection sites were normalised and the matrix effect was efficiently circumvented. About 55 samples were rim per hour, yielding precise results in agreement with a reference procedure. 

It is frequently u.sed as an additive to foods where it enhances the nutritious qualities. It may be added to restore loss of vitamin due to the food processing or to increase the natural amount of the vitamin present. In either ca.se the term nutrification has been used to describe its addition. Thus, L-ascorbic acid is added to fruit juice to fortify that which is naturally pre.sent or it may be added to artificial fruit drinks to improve taste and the nutritiousness of the drink. 

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