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Tocopherol and fluorescence levels in deep‐frying oil and their measurement for oil assessment
Author(s) -
Miyagawa Kuniko,
Hirai Kazuko,
Takezoe Reiko
Publication year - 1991
Publication title -
journal of the american oil chemists' society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.512
H-Index - 117
eISSN - 1558-9331
pISSN - 0003-021X
DOI - 10.1007/bf02657761
Subject(s) - tocopherol , food science , chemistry , fluorescence , coating , deep frying , chemiluminescence , vitamin e , decomposition , moisture , olive oil , chromatography , antioxidant , organic chemistry , physics , quantum mechanics
This study examined how tocopherol retention is affected by the presence or absence of food coatings, and also tested the measurement of fluorescent substance levels in cooking oil to evaluate oil deterioration. Potato slices were tempura‐fried (with a coating) or french‐fried (without a coating). The three tocopherol isomers decreased with heating time, and better retention was found in the tempura process. The decomposition rates of tocopherol were in the order γ> δ ≥α for the three isomers for both processes over repeated fryings. The fluorescence of frying oil increased 15‐and 17‐fold after tempura‐and french‐frying, respectively, for 32 consecutive times. Changes in the amounts of tocopherol and the fluorescence correlated well with the changes found by the chemiluminescent intensity and five conventional methods of oil quality measurement. These results indicated that tocopherol retention is affected by the food coating, and that measurements of vitamin E loss and fluorescence increase in oil should be useful for assessing the progressive deterioration of frying oil with its repeated usage.