Abstract
The browning of KORI-TOFU is accelerated at the relative humidity of above 85%. The pigment produced and lipid were extracted with ether and the composition of the ether extract was compared with that of unbrowned one. Linoleic acid and linolenic acid decreased, while carbonyl compounds, consisting mainly of hexanal and 2-nonenal, increased. Increase of nitrogen content was observed by 8 to 20 times as much as the unbrowned one. On analysis of hydrolysate of the residue, not only the basic amino acids, but also others decreased.
On standing the mixture of fatty acid and milk casein, browning occurred readily when the fatty acid was highly unsaturated. The mixture of autoxidized soybean oil and amino compound such as amino acid or milk casein also browned. In both cases the browning was accelerated at high relative humidity as seen in the case of KORI-TOFU, It is apparent from these experiments that the browning of KORI-TOFU is caused by the interaction between oxidized oil and protein, and the influence of reducing sugars may not be considered because its content is negligible.
