In the last several decades, food industries have increasingly used lipases as a result of the functional versatility of these enzymes and their potential beneficial effects in terms of processing and product quality. This review article discusses lipases and their functional effects during cereal-based food processing with a focus on the production of bread and cakes. Their dough and batter intermediates, respectively, are essentially semi-solid foams that upon baking are converted into solid cellular sponges. In both cases, the lipid fraction(s) from wheat (in the case of bread and cake), egg and/or bakery fat (in the case of cake) exert major roles in gas incorporation and stabilization in the cited semi-solid foams. An up-to-date overview on the (potential) substrates, the different lipase enzymes, their action mechanism, their functionality, and how they impact bread and cake quality is presented. We also hypothesize on how the observed effects can be interpreted in terms of the altered lipid chemistry.

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Glucose oxidase (GO) and pyranose oxidase (P2O) improve dough stability and bread quality. We here studied whether their mode of action resides in cross-linking of proteins and/or arabinoxylan (AX) molecules through the production of H2O2. Evidence for both was deduced from a decrease in extractability of protein and AX from dough made with P2O, GO, or H2O2, using sodium dodecyl sulfate containing buffer and water, respectively. The addition of H2O2, P2O, or GO to a glutathione solution sharply decreased its sulfhydryl (SH) content. P2O or GO can trigger protein cross-linking through the formation of disulfide (SS) bonds. As a result thereof, SH/SS interchange reactions between low molecular mass SH containing compounds and gluten proteins can be hampered. Furthermore, a decrease in the level of monomeric ferulic acid (FA) esterified to AX in dough points to a role of FA bridges in cross-linking of AX molecules. Our results indicate that the molecular mechanism of dough and bread improvement by P2O and GO resides in cross-linking of gluten proteins and AX by formation of H2O2. They furthermore show that the extent of cross-linking upon addition of P2O or GO strongly depends on the concentration (and production rate) of H2O2.

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In bread making, O2 is consumed by flour constituents, yeast, and, optionally, some additives optimizing dough processing and/or product quality. It plays a major role especially in the oxidation/reduction phenomena in dough, impacting gluten network structure. The O2 level is about 7.2 mmol/kg dough, of which a significant part stems from wheat flour. We speculate that O2 is quickly lost to the atmosphere during flour hydration. Later, when the gluten network structure develops, some O2 is incorporated in dough through mixing-in of air. O2 is consumed by yeast respiration and in a number of reactions catalyzed by a wide range of enzymes present or added. About 60% of the O2 consumption in yeastless dough is ascribed to oxidation of fatty acids by wheat lipoxygenase activity. In yeasted dough, about 70% of the O2 in dough is consumed by yeast and wheat lipoxygenase. This would leave only about 30% for other reactions. The severe competition between endogenous (and added) O2-consuming systems impacts the gluten network. Moreover, the scarce literature data available suggest that exogenous oxidative enzymes but not those in flour may promote crosslinking of arabinoxylan in yeastless dough. In any case, dough turns anaerobic during the first minutes of fermentation.