Preferential substrates for an effective Fusarium lipase and importance of a balanced lipid population in bread making

Lipases have been used in bread making over the past 25-30 years to improve dough handling and bread quality. It is generally accepted that their improving impact results especially from hydrolysis of galactolipids, and to a lesser extent also of phospholipids. Lipases are suggested to be clean label alternatives for surfactants since they in situ generate lysolipids which are structurally very similar to surfactants. Nonetheless, the mechanisms behind the improving effects of bread making lipases are still unclear. In this study, an effective bread making lipase from Fusarium oxysporum expressed in Aspergillus oryzae was applied in bread making in concentrations ranging between 5 and 3,000 ppm. Addition of at least 20 ppm was necessary to obtain a significant increase in loaf volume. Maximum volume increases (8-13%) were reached for concentrations between 20 and 1,000 ppm. When lipase concentration was increased further to 1,500 ppm, loaf volumes decreased significantly. Supplementation with 3,000 ppm Fusarium lipase yielded loaves which were 12% smaller than the control breads. Furthermore, (non-)fermented dough samples with and without Fusarium lipase in concentrations of 20, 200 and 3,000 ppm were prepared. Dough lipid population analyses pointed out that triacylglycerols, monogalactosyldiacylglycerols and N-acylphosphatidylethanolamine were quickly hydrolyzed and were the preferred substrates for the effective Fusarium lipase. In fermented dough samples containing 3,000 ppm lipase, not only all investigated lipid classes were affected but also lysolipids, produced through lipase action, were further degraded. These results, in combination with the inferior loaf volume, emphasize that the balance between endogenously present lipids and their hydrolysis products is of major importance in bread making and that overdosing of lipases should be avoided.status: publishe