Lipases in wheat breadmaking: analysis and functional effects of lipid reaction products

The baking activity of two different lipases was evaluated by a microbaking test on a 10 g flour basis, and the altered lipid composition of lipase-treated wheat lipids was quantitated. To identify and quantitate the various lipid classes, pure glycolipids and phospholipids were isolated from a wheat flour lipid extract by a silica gel batch procedure and silica gel column chromatography. These reference compounds were used to establish a high-performance liquid chromatographic method with evaporative light scattering detection, which was able to separate all of the wheat lipid classes and lipase reaction products. Wheat lipids, dough lipids, and dough lipids after lipase addition were quantitated using cholesterol as an internal standard. Especially digalactosyl diglycerides (-0.9 mmol/kg flour), monogalactosyl diglycerides (-0.4 mmol/kg), and N-acyl-phosphatidyl ethanolamine (-0.3 mmol/kg) were hydrolyzed, and a concomitant formation of digalactosyl monoglycerides (+0.6 mmol/kg), monogalactosyl monoglycerides (+0.6 mmol/kg), and N-acyl-lysophosphatidyl ethanolamine (+0.5 mmol/kg) was found. The lipase-induced changes of the lipid fraction caused increases in bread volume of 56-58%, depending on the type and concentration of the added lipase. The current results confirm the important relationship between the lipid fraction composition and the baking performance of flour.