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A kinetic study of oil deterioration during frying and a comparison with heating
Author(s) -
Houhoula Dimitra P.,
Oreopoulou Vassiliki,
Tzia Constantina
Publication year - 2002
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/s11746-002-0447-0
Subject(s) - chemistry , conjugated system , conjugated diene , oleic acid , cottonseed oil , conjugated linoleic acid , polar , reaction rate constant , organic chemistry , food science , linoleic acid , fatty acid , kinetics , biochemistry , copolymer , polymer , physics , quantum mechanics , astronomy
The thermooxidative alterations of cottonseed oil during frying of potato chips without oil turnover, in a temperature range of 155–195°C, were studied. The results showed that the content of polar compounds, conjugated dienes, conjugated trienes, and p ‐anisidine value ( p ‐AV) increased linearly with the time of frying at a rate depending on temperature. The rate constants showed a significant but low increase with temperature, except for the rate constant of conjugated trienes that was not correlated to frying temperature. The alterations induced by heating the oil were also measured and compared with those observed in frying at the same temperature. The major difference observed between frying and heating was related to the p ‐AV increase, which presented a considerably higher rate during heating. The FA content, as a function of process time during frying at 185°C, showed a significant increase in palmitic acid (C16∶0) and a significant decrease in linoleic acid (C18∶2). Oleic acid (C18∶1) also showed a small but significant decrease. The same results were obtained for the oil heated at 185°C. Examination of p ‐AV or conjugated dienes with polar compounds showed that both p ‐AV and conjugated dienes had a linear relationship with total polar compounds, with correlation coefficients of 0.946 and 0.862, respectively.