Vitamin methods

Harris, Leslie J.; Mapson, L. W.; Wang, Y. L.

doi:10.1042/bj0360183

Cited by 33 publications

(13 citation statements)

References 3 publications

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“…It was found that the reducing substances present reacted with indophenol dye, both at pH 3-5 and 1.4, at a rate indistinguishable from that of ascorbic acid (Table 5). This gives further evidence for the view that in such foods there are no significant amounts of indophenol-reducing substances other than ascorbic acid (Birch et al 1933; Harris & Olliver, 1942; Mapson, Experimental details. The technique used was as follows.…”

Section: Fresh Fruits and Vegetablesmentioning

confidence: 77%

“…Likewise there is no evidence that the chemical method is any less satisfactory when used for fruits or vegetables as normally canned, or as cooked by either boiling or steaming. Examples of this kind of correspondence between the chemical and biological data have been cited in previous papers (Harris & Ray, 1933 6 ; Birch, Harris & Ray, 1933; Harris & Olliver, 1942).…”

mentioning

confidence: 69%

“…Its velocity constant at pH 1.4 or 3.5 was identical with that of ascorbic acid. Harris & Olliver, 1942). It was, nevertheless, of interest to determine the precise value of the velocity constant.…”

Section: J Harris Anl L W Mapson I947mentioning

confidence: 99%

“…Methods are already available for estimating it and ascorbic acid in VOl. I Ascorbic acid by ' continuous-$ow method 25 presence of each other (Harris et al 1942; Mapson, 1942). Thiosulphate is said to be present in urine, and methods have likewise been described for its differential estimation (e.g.…”

Section: J Harris Anl L W Mapson I947mentioning

confidence: 99%

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Determination of Ascorbic Acid in Presence of Interfering Substances by the ‘ Continuous-Flow’ Method

Harris

Mapson

1947

Br J Nutr

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Section: Fresh Fruits and Vegetablesmentioning

confidence: 77%

mentioning

confidence: 69%

Section: J Harris Anl L W Mapson I947mentioning

confidence: 99%

Section: J Harris Anl L W Mapson I947mentioning

confidence: 99%

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Determination of Ascorbic Acid in Presence of Interfering Substances by the ‘ Continuous-Flow’ Method

Harris

Mapson

1947

Br J Nutr

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“…Potentiometric estimations were made by the method of Harris, Mapson & Wang (1942) for true vitamin C, with certain modifications advantageous when apparent vitamin C is present . Dehydroa8corbic acid.…”

Section: Eetinwtion8mentioning

confidence: 99%

Vitamin C in the walnut (Juglans regia)

Wokes

Melville

1948

Biochemical Journal

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The cultivation and analytical data of blackcurrants and raspberries in Tasmania

Hill¹

1951

J Sci Food Agric

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347of pasteurization needs to be considered with due caution in view of the deterioration in flavour which usually accompanies high-temperature holding-pasteurization.Addition to the juice of an antioxidant would be desirable if one could be found that would be suitably effective. Ascorbic acid in the concentrations used by the author had some deterrent action but did not completely suppress formation of turbidities.A satisfactory explanation of the phenomena of oxygen absorption by apple juice and subsequent oxidation of the juice in accordance with the evidence presented requires careful consideration. I t must be borne in mind that both oxidizing and reducing enzyme-systems exist in apple juice and that the net degree of oxidation of the juice will depend not only on their relative concentration and activity but also on the relative concentrations of oxygen donator (in this case molecular oxygen) and oxygen acceptor (probably tannin). At ordinary temperatures there is probably some fixation of molecular ozygen on the juice colloids and eventually, through the agency of the apple-juice oxidase system, oxidation of tannin to phlobaphene may occur. The phlobaphene undoubtedly is relatively less soluble than its tannin precursor, a haze develops in the juice, which eventually coagulates as more tannin is oxidized and is thrown out of solution as a sediment in the bottle. When oxidation of tannin by dissolved oxygen is complete and the phlobaphene rendered insoluble, the juice then exhibits strong reducing-properties. Early pre-heat treatment of the juice disturbs the equilibrium of the oxidation-reduction system and although the oxidase is not inactivated at temperatures of 145-150' F. it is possible that such temperatures favour activity of the reducing system.Whether this system is responsible for liberation of some of the ' bound ' oxygen is a matter of conjecture, insufficient information as yet being available to lend support to this hypothesis.I t is hoped that publication of these results will stimulate further research on both deaeration and oxidation and lead eventually to discovery of a suitable method for prevention of oxidation turbidities in apple juice.A description is given of the berry fruit-growing industry in Southern Tasmania. The methods of harvesting and conditions of transportation are described. Analyses of blackcurraits and raspberries, made during the 1948, 1949 and 1950 seasons, are presented with a view to providing information of assistance in determining the amounts of these fruits in pulps and jams.The analytical figures detailed below are the results of a chemical survey extending over the 1948, 1949 and 19jo seasons. The need for composition figures for Tasmanian berry fruits for use in connexion with the analysis of jams has been apparent for some time. In addition

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Vitamin methods

Cited by 33 publications

References 3 publications

Determination of Ascorbic Acid in Presence of Interfering Substances by the ‘ Continuous-Flow’ Method

Determination of Ascorbic Acid in Presence of Interfering Substances by the ‘ Continuous-Flow’ Method

Vitamin C in the walnut (Juglans regia)

The cultivation and analytical data of blackcurrants and raspberries in Tasmania

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