Effect of Exogenous Lipase on Dough Lipids During Mixing of Wheat Flours

Abstract

Cereal Chem. 75(5):595-601In control dough, endogenous wheat lipase was inactive, because the triacylglycerol (TAG), 1,2-diacylglycerol (DAG 1,2 ), and 1,3-diacylglycerol (DAG 1,3 ) fractions of nonpolar lipids were not affected by mixing. Conversely, the free fatty acid (FFA) and monoacylglycerol (MAG) fractions decreased, mainly due to the oxidation of polyunsaturated fatty acids (PUFA) catalyzed by wheat lipoxygenase. Addition of exogenous lipase to flour (15 lipase units [LU] per gram of dry matter) resulted in substantial modification of nonpolar lipids during dough mixing. Due to the 1,3 specificity of the lipase used in this experiment, the TAG and DAG 1,3 fractions decreased, whereas the MAG and FFA fractions increased. The DAG 1,2 fraction increased at the beginning of mixing and decreased after 40 min of mixing. Moreover, part of the PUFA released by lipase activity was oxidized by wheat lipoxygenase, resulting in major losses of PUFA. Conversely, the net content of the saturated and monounsaturated fatty acids (SMUFA) remained constant, because the free SMUFA content increased primarily at the expense of the esterified forms. For a constant mixing time of 20 min, increasing the amount of lipase added to dough (from 2.5 to 25 LU/g of dry matter) resulted in a linear decrease in the TAG fraction and a linear increase in the SMUFA content in the FFA fraction. At the same time, the PUFA content of the FFA fraction increased only for additions of lipase to flour of >5 LU/g of dry matter, due to partial oxidation by wheat lipoxygenase.

Neutral lipids in non‐starch lipid and starch lipid extracts from Portuguese sourdough bread

“…These hydroperoxides, and intermediary free radicals formed during mixing, can co-oxidize several compounds -and are often transformed into a variety of aldehydes and oxygenated FA. Furthermore, endogenous lipases -which hydrolyze TAG, DAG, and MAG of NL fractions, will consequently lead to increases in MAG and FA fractions [56,57].…”

Enzymes in Breadmaking

“…Undoubtedly, lipase functionality comprises several aspects (Castello et al 2000, Poulsen andBorch Sse 1997). By analyzing the biochemical changes induced by the exogenous lipases, Castello et al (1998Castello et al ( , 2000 proposed a more indirect impact of lipases on the gluten. At the same time, the level of emulsifying molecules increases, which may result in an increased stability of the gas cells (Castello et al 1998(Castello et al , 2000.…”

Foam formation in dough and bread quality

“…Phospholipids can impact on breadmaking quality, though not individually, as it has been shown that there appears to be synergistic effects in phospholipid mixtures that most strongly affect loaf volume (Helmerich and Koehler, 2005). Modifi cation of the lipids by lipase (Castello et al , 1998) has been found to improve the breadmaking properties (Weegels and Hamer, 1992), suggesting that the foaming activity of the intrinsic lipids has considerable room for improvement. In general, the foaming properties of the non-polar lipids similar to those present in wheat are not particularly good.…”

“…The balance of foaming and non-foaming lipids is likely to be infl uenced by wheat variety, environmental conditions and processing conditions (including milling) (Morrison and Barnes, 1983). Lipases have been used to hydrolyse di-and tri-acyl lipids into monoglycerides and lysolipids (Castello et al , 1998); this has increased loaf volumes and crumb structure, and has been offered as a replacement for emulsifi ers (Weegels and Hamer, 1992;Monfort et al , 1999). The effect is probably based on the fact that the hydrolysis products are more soluble, surface active and foam active than the substrate lipids, and lower the surface tension more effectively (Primo-Martin et al , 2006).…”