1971 年 37 巻 1 号 p. 40-43
In a previous paper, the results indicated that the role of unsaturated carbonyls in the discoloration reaction seemed more important than those of the saturated carbonyls. While NONAKA reported that half-aldehydes longer than glutaraldehydic acid were presumed to be important precursors of the browning in fish oil.
In this study, to make the effect of half-aldehyde on browning clear, the browning potentialities of azelaaldehydic acid (AZA) and its methyl ester (MAZ) were examined in comparison with those of common aldehydes in autoxidized oil, propanal and 2-hexenal, by the model systems with volatile bases.
AZA and MAZ were prepared from oleic acid by ozonolysis (Fig. 1).
As shown in Figs. 2 and 3, in both reactions with ammonia and trimethylamine, the most rapid browning occured with 2-hexenal and the browning potentialities of AZA and MAZ were relatively low and equal to or less than that of propanal.
Subsequently, the brown discoloration between ammonia and methyl ester of cuttle-fish liver oil, both autoxidized (carbonyl value 377) and unoxidized ones contain-ing authentic aldehydes equivalent to carbonyl value of autoxidized oil, were examined. The results showed that the browning of autoxidized oil was far more extensive than those of the others (Fig. 4). In these experiments, of the aldehydes examined, 2-hexenal also exhibited higher browning potentiality than AZA.