Pigments oxidation

Excess NaOH is used to start the reaction and not over 35% of the chromium is added as dichromate. At the end of the reaction, the thiosulfate is removed by filtration and recovered. The hydrous oxide slurry is then acidified to pH 3—4 and washed free of sodium salts. On calcination at 1200—1300°C, a fluffy pigment oxide is obtained, which may be densifted and strengthened by grinding. The shade can be varied by changes in the chromate dichromate ratio, and by additives. 

CS023 Tanaka, T., Y. Betsumiya, C. Mine and I. Kouno. Theanaphthoquinone, a novel pigment oxidatively derived from theaflavin during tea-fermentation. Chem Commun 2000 2000(15) 1365-1366. 

Because they are important, the phenolics and their roles in wine have been studied considerably (I), but more needs to be known. Since different classes of phenols behave quite differently in the various roles as pigments, oxidation substrates, flavors, etc., separate consideration and analysis is essential to completely understand them. Every individual phenol should be separately determined precisely and quantitatively. Chromatography may solve these problems, but for now, chromatography and other detailed separatory methods have drawbacks, particularly for economical application to many individual wine or grape samples. 

Ethoxyquin Ethoxyquin, 6-ethoxy-l,2-dihydro-2,2,4-trimethylqumoline (Figure 4), is used as an antioxidant in animal feeds primarily to protect carotenoid oxidation. It may also be used in fish products, fish oU, poultry fats, potatoes, apples, and pears during storage and especially to protect pigment oxidation in ground chili and paprika (93). Ethoxyquin may act as a free radical terminater. Dimerization of the radical may inactivate the antioxidant (94). 

Bleaching Pigments, oxidation products, trace metal, traces of soap... 

Pigments Oxidation Products Residual Phosphatides Residual Metals Soaps... 

Colour fading from pigment oxidation in fresh meat, the effect of illrrmination on the appearance of orange juice, the effects of varying coffee and milk concentration on coffee appearance and measuring breakfast cereals by grinding to a defined particle size are given as examples of the types of problems encountered in food colour appearance measurement. The effect of the illuminant on the calculated CIELAB colour values for a variety of food spectra is also presented. 

The non-TAG portion of soybean oils includes phospholipids, free fatty acid, chlorophyll pigment, oxidation products, and other unsaponifiable components such as tocopherols, sterols and hydrocarbons. Some of these minor components negatively affect oil quality, while some may play a positive role in nutrition and function. The goal of refining is therefore to remove the undesirable components and, at the same time, to maximize retention of the beneficial components. 

Coleman, H. M. 1961. The mechanism of meat-pigment oxidation. The effect of solutes on the hemoglobin-oxygen equilibrium. Food Research 16, 222. 

Substances of biological origin (e.g., blood, proteins, and pigments) Oxidation products of residual soil or antioxidants... 

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