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Elucidating the role of wheat endogenous lipids in bread making
L. R. GERITS (1), B. Pareyt (1), J. A. Delcour (1). (1) KU Leuven, Leuven, , Belgium

Wheat endogenous lipids, although minor constituents of wheat flour, largely impact bread making. By adding lipases with different specificities to a bread making recipe and analyzing the lipid composition with HPLC-ELSD, we recently demonstrated that lipids promoting the lamellar mesophase or the hexagonal I mesophase positively impact bread LV. However, less is known on the exact mechanism(s) by which endogenous lipids actually improve LV. High specific LV has been related to proper gas cell stability. Therefore, we here set out to study the mode of action by which endogenous wheat lipids impact gas cell stability upon addition of lipases with a known positive effect on LV or surfactants such as diacetyl tartaric esters of mono- and diglycerides (DATEM) and sodium stearoyl lactylate (SSL). We elaborated on both direct [dough liquor (DL) lipid composition] and indirect (gluten network properties) gas cell stabilization mechanisms. Dough resistance to extension was higher when adding DATEM (0.31 ± 0.03 N) or SSL (0.34 ± 0.04 N) than for control dough (0.23 ± 0.03 N). Remarkably, lipase addition had no such impact. It was demonstrated for the first time that the lipid composition of dough with added lipases at the end of mixing was mostly similar to that of control dough. We hypothesized that dough rheology is probably only impacted by lipid components that are readily available at the start of mixing and, thus, not by the components formed by lipases as they are only released during fermentation. Lipase use increased DL lipid levels from 0.96 ± 0.09 % (for control dough) to 3.09 ± 0.17 % after the fermentation phase. This increase originated from an increase in lysolipids, but also from a more unexpected increase in the levels of all other polar lipids. Logically, formation of hexagonal I mesophases by the lysolipids allowed emulsifying other lipids.

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