Evaluation of Oxidative Deterioration of Lipid in Dried Foods Using the Solid Sample Fluorescence Spectrophotometry

Abstract

Protein-bound fluorescence was examined for dried foods containing lipids such as soybean flour, peanut flour, Kori-tofu (dried soybean curd), and Yuba (dried soymilk skin) by solid sample fluorescence spectrophotometry. All samples gave fluorescence spectra with the excitation wavelength at 430-440nm and the emission wavelength at 500-510nm, and the fluorescence intensity were increased during storage. Formation of the fluorescence was derived from lipid peroxidation in foods because it was inhibited by extraction of lipids or addition of BHT. Although the fluorescence intensity depended on varieties of dried lipid foods, it was positively correlative to carbonyl value of extracted lipids. These observations showed that determination of protein-bound fluorescence intensity is simple and available for evaluating the oxidative deterioration of lipids in dried foods.