Investigation of sorption isotherms of wheat germ for its effect on lipid oxidation

Abstract

This research aimed to investigate the oxidation and sorption isotherm properties of wheat germ and to determine monolayer moisture content (m0) in particular, because it has a limiting effect on lipid oxidation. This research comprised two stages. The first stage was the determination of sorption properties and m0 at three temperatures (15, 25, and 35°C). The second stage of the research was to investigate lipid oxidation properties of stored wheat germ at two different temperatures (4 and 25°C) and m0 for 28 days. As a result, it was determined that wheat germ has a Type II sorption isotherm, Halsey is the best fitting sorption equation, and the average m0 is 4.25 g moisture per 100 g dry matter. Furthermore, the free fatty acid and peroxide value of wheat germ oil increased with increasing storage moisture content and temperature, determined as 12.63% and 5.01 mEqO2/kg on average, respectively. In conclusion, storage of impermeably packaged wheat germ at low temperature and m0 content is an applicable method for decreasing rancidity and prolonging shelf‐life.