Molecular Oxygen and Reactive Oxygen Species in Bread-making Processes: Scarce, but Nevertheless Important

Abstract

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.

Hydrolytic enzymes and their directly and indirectly effects on gluten and dough properties: An extensive review

“…It can be noted that the cross‐linking between starch–protein is in charge of bread staling. The antistaling effect of cellulase could be according to the enzyme cell wall degradation, and monosaccharides and oligosaccharides resulting from the enzyme action which cause an alteration in water distribution between starch–protein matrix (Yurdugul et al., 2012; Decamps et al, 2016; Joye et al, 2009).…”

Dietary cholesterol oxidation products: Perspectives linking food processing and storage with health implications

“…Heating provides energy to overcome the activation energy of hydrogen abstraction, which facilitates the production of free radicals, thus promoting cholesterol oxidation (Decamps et al., 2016). Simplified model systems, including solid, aqueous, and lipid model systems, were used for studying the effects of temperature, time, and food matrix on COPs formation (Medina‐Meza & Barnaba, 2013).…”

Oxidizing agent‐assisted extrusion cooking of yellow peas and the techno‐functionality of the resulting extrudate flours

“…In addition to the oxidizing agents such as BP and ADA, flour is traditionally aged naturally through oxidation with oxygen in the air. Oxygen plays an important role in flour maturation through the oxidation of the free sulfhydryl groups of flour proteins to disulfides, which strengthen the gluten network (Campbell, 2003;Decamps et al, 2016;Wieser, 2003) and produce bread with greater loaf volume (Delcour & Hoseney, 2010;Dobraszczyk, 2003;Wang & Flores, 1999).…”

“…The injected air, when dissolved in the melt, may act as an oxidizing agent. Oxidation of flour proteins promotes the formation of disulfide bonds among protein polymers (Campbell, 2003;Decamps et al, 2016;Wieser, 2003) leading to a greater extent of protein aggregation (Huang et al, 2006;Wu et al, 2009;Xiong & Guo, 2021). As a result, protein-water interactions may drop, raising the amount of available water to interact with starch (Aluko et al, 2009;Beck et al, 2017).…”