Improvement of stability and antioxidant activity of wheat germ by mixed fermentation versus single fermentation

Wheat germ is a high-nutrient by-product from the milling industry with very limited optimal consumption due to its short shelf life. The severe activity of endogenous lipase and lipoxygenase is associated with the release of fatty acids which are responsible for the rancidity and shelf-life deficiency. Reducing these enzymes activity is essential for prolonging the wheat germ shelf-life. For this purpose, the mixed and simple fermentation of different wheat germ concentrations (10, 15 and 20% w/v wheat germ in distilled water) with Lactobacillus plantarum and Lactobacillus acidophilus was investigated to improve the stability of wheat germ by restraining the activity of the enzymes. Fermentation noticeably reduced the activity of the enzymes in all samples (ranges from 50 to 82.15% for lipase and 55.34 to 72 for lipoxygenase in different treatments), but the mixed-fermented wheat germ with the maximum concentration (20%) achieved the highest reduction level in both enzymes inactivation. Fermentation also resulted in an obvious increase in antioxidant activity from 51.18% in raw wheat germ to more than 72.73% in different samples, which mixed fermentation of 20% wheat germ suspension with the value of 89.76 was ranked first.