Pearling Affects the Lipid Content and Composition and Lipase Activity Levels of Wheat (Triticum aestivum L.) Roller Milling Fractions

Abstract

Wheat bran contains most of the dietary fiber, vitamins, minerals, and antioxidants of the grain. Unfortunately, it readily deteriorates upon storage because it has high lipid contents and lipase activity levels, which can cause rancidity and, hence, when used in food systems, inferior product quality. We here examined the lipid composition and the lipase activities of wheat bran and the impact of pearling prior to milling thereupon. The lipid content of the outer bran layers (2.31% on a dry matter [dm] basis) is lower than that of regular bran (3.81% dm). Nevertheless, these layers have the highest concentration of free fatty acids (FFA, 0.56% dm), which is ascribed to lipid hydrolysis. Indeed, the lipase activity levels in the peripheral layers were three times higher than in the bran itself. Abrading these tissues by pearling prior to milling yielded a bran fraction with about 30% lower FFA content and 30% lower lipase activity level. Pearling offers opportunities to lower the FFA content and lipase activity levels in wheat bran and, hence, to contribute to an improved storage stability of bran.