Glycerol Production by Fermenting Yeast Cells Is Essential for Optimal Bread Dough Fermentation

Abstract

Glycerol is the main compatible solute in yeast Saccharomyces cerevisiae. When faced with osmotic stress, for example during semi-solid state bread dough fermentation, yeast cells produce and accumulate glycerol in order to prevent dehydration by balancing the intracellular osmolarity with that of the environment. However, increased glycerol production also results in decreased CO2 production, which may reduce dough leavening. We investigated the effect of yeast glycerol production level on bread dough fermentation capacity of a commercial bakery strain and a laboratory strain. We find that Δgpd1 mutants that show decreased glycerol production show impaired dough fermentation. In contrast, overexpression of GPD1 in the laboratory strain results in increased fermentation rates in high-sugar dough and improved gas retention in the fermenting bread dough. Together, our results reveal the crucial role of glycerol production level by fermenting yeast cells in dough fermentation efficiency as well as gas retention in dough, thereby opening up new routes for the selection of improved commercial bakery yeasts.

Effect of pentoses, hexoses, and hydrolyzed arabinoxylan on the most abundant sugar, organic acid, and alcohol contents during rye sourdough bread production

“…Among alcohols, significant amounts of glycerol (0.25%) and ethanol (1.86%) were identified. According to the literature, a high amount of glycerol was the result of yeast (Aslankoohi, Rezaei, Vervoort, Courtin, & Verstrepen, 2015) and hetero‐fermentative LAB activity (Brandt & Ganzle, 2015) as well as lipid hydrolysis by lipases which are both found in rye flour (Banu, Vasilean, & Aprodu, 2011). Ethanol was produced by yeasts present in the flour and added as an ingredient of LV2 cultures (Lefebvre et al, 2002; Van der Meulen et al, 2007) as well as by hetero‐fermentative LAB (Corsetti & Settanni, 2007).…”

Metabolite Analysis Allows Insight into the Differences in Functionality of 25 Saccharomyces cerevisiae Strains in Bread Dough Fermentation

“…Production of more glycerol has been suggested to lead to a decrease in the ratio of reduced form of nicotinamide adenine dinucleotide (NADH) over oxidized form (NAD + ) in the cells. The yeast might balance this ratio through conversion of more acetaldehyde to acetic acid and NADH (Aslankoohi et al 2015).…”

Contribution of the tricarboxylic acid (TCA) cycle and the glyoxylate shunt in Saccharomyces cerevisiae to succinic acid production during dough fermentation

“…Δidh1Δidp1, which might be due to the changes in the ratio of NADH/ NAD + upon a slightly higher production of acetic acid in this sample compared to the wild-type reference strain S288C. Aslankoohi et al (2015) showed that overexpression of GPD1 and a rise in the level of glycerol during dough fermentation has a positive influence on dough stability during fermentation. However, the highest glycerol content observed in this study (5 mmol/100 g flour) is well below the levels they obtained in their GPD1 overexpression strain (12 mmol/100 g flour).…”