Das Reduktionsvermögen pflanzlicher Lebensmittel und seine Beziehung zum Vitamin C

Absorption Rate of Oxygen by Orange Juice: Effect of Catalysts - Effects of Catalysts

“…Filtered orange juice + 20 p. p, m. stannous ion 5. Filtered orange juice + ascorbic acid preparation (21) is supported by observations of Tillmans, Hirsch, and Siebert (24). A study of the close relationship between the reducing value of fruits and vegetables when titrated by 2,6-dichlorophenol indophenol (15, 23) and the vitamih C values reported in the literature, and the relationship of ascorbic acid to vitamin C is suggestive of a method to determine the vitamin C values of orange juice.…”

The isolation and identification of vitamin C

“…The similarity, however, between the reducing substance which Tillmans considered to be vitamin C and hexuronic acid was thus indicated then. Later (Tillmans et al, 52,53,54,55,56) when he had worked out his thesis in greater detail and became acquainted with the work on hexuronic acid he actually suggested that vitamin C was probably identical with it. Very soon after the appearance of Tillmans' last series of publications, King and Waugh"' 57 claimed to have isolated a crystalline substance from lemon juice, by the decitration and lead acetate method mentioned previously, which, in their opinion, was hexuronic acid and which was antiscorbutically active.…”

The use of homocysteine in the estimation of dehydroascorbic acid

“…In the one, developed by Roe and his colleagues (Roe & Kuether, 1943;Roe, Mills, Oesterling & Damron, 1948), the dehydroascorbic acid is condensed with 2:4-dinitrophenylhydrazine and the product treated with sulphuric acid to give a red colour, the intensity of which is measured photoelectrically. In a second technique (Tillmans, Hirsch & Siebert, 1932;Eekelen, Emmerie, Josephy & Wolff, 1933;Bessey, 1938), dehydroascorbic acid is measured as acorbic acid after reduction with hydrogen sulphide and removal of excess of reductant. Disadvantages are associated with both methods; they are nonspecific for dehydroascorbic acid, timeand labourconsuming, and in the method involving reduction with hydrogen sulphide it may be difficult to ensure the removal of excess of reductant before estimating the ascorbic acid formed with 2:6-dichlorophenolindophenol.…”