Fermentation of Dairy-Relevant Sugars by Saccharomyces, Kluyveromyces, and Brettanomyces: An Exploratory Study with Implications for the Utilization of Acid Whey, Part I

Abstract

Acid whey from Greek-style yogurt (YAW) is an underutilized byproduct and a challenge for the dairy industry. One alternative is the fermentation of YAW by yeasts such as Saccharomyces, Brettanomyces, and Kluyveromyces spp., to produce new styles of fermented beverages. Previous research in our group suggested that the sugar profiles of the dairy coproducts impacted the fermentation profiles produced by B. claussenii. The present work aims to describe the fermentation of dairy sugars by S. cerevisiae, K. marxianus, and B. claussenii, under conditions comparable to those of YAW. For this purpose, four preparations of yeast nitrogen base, each containing 40 g/L of either lactose (LAC), glucose (GLU), galactose (GAL), or a 1:1 mixture of glucose and galactose (GLU:GAL), all at pH 4.20, were used as fermentation media. The fermentation was performed independently by each organism at 25 °C under anoxic conditions, while density, pH, cell count, ethanol, and organic acids were monitored. Non-linear modeling was used to characterize density curves, and Analysis of Variance and Tukey’s Honest Significant Difference tests were used to compare fermentation products. K. marxianus and S. cerevisiae displayed rapid sugar consumption with consistent ethanol yields in all media, as opposed to B. claussenii, which showed more variable results. The latter organism exhibited what appears to be a selective glucose fermentation in GLU:GAL, which will be explored in the future. These results provide a deeper understanding of dairy sugar utilization by relevant yeasts, allowing for future work to optimize fermentations to improve value-added beverage and ingredient production from YAW.

Sicilian Whey: Utilization of Ricotta Whey in the Production of Value-Added Artisanal Beers

“…This style of beer is characterized as a dark ale with the addition of lactose [45]. Lactose is not fermentable by the beer yeast, S. cerevisiae [46]; thus, lactose is not converted into alcohol and remains in the final beer, providing residual sweetness and body to the beer. This style of beer is typically brewed with pale malt with the addition of caramel and chocolate malts for flavor and color [47].…”

Cheese whey permeate as a precursor of lactose-free, galactose-rich bioproducts: an approach for optimization and application

“…Brettanomyces claussenii, a yeast found in the microbiomes of beverages like kombucha and ke r, has become popular in recent years due to its potential to ferment dairy substrates (Lawton et al, 2021). Our previous research found that, in a synthetic medium providing either an oxic or an anoxic environment, B. claussenii could convert the glucose from hydrolyzed lactose into ethanol, while leaving the galactose almost completely undisturbed for days after the fermentation had been deemed complete (Rivera Flores et al, 2021;Rivera Flores et al, 2022). This idiosyncrasy opens a door to other unique, attractive applications of fermentation as a means for the reutilization of WP.…”

“…To successfully synthesize ethanol while simultaneously retaining the most galactose, an important consideration is the dependency of the fermentation on parameters like degree of lactose hydrolysis and time. For instance, we learned that if no exogenous lactose hydrolysis occurred, then the fermentation by B. claussenii would yield no galactose (Rivera Flores et al, 2021). Thus, the effects of relevant fermentation factors on both responses needs to be studied more systematically to develop e cient processes that can allow for the optimization of each product.…”

Aerobic Cultivation of Mucor Species Enables the Deacidification of Yogurt Acid Whey and the Production of Fungal Oil

“…In recent years, scientists have conducted research investigating the conversion of YAW into food ingredients or other resources through various means. For instance, fermentations of YAW have been researched as potential strategies to produce bioderived resources such as ethanol, galactose, lactobionic acid, galactooligosaccharides, and medium-chain carboxylic acids [8][9][10][11][12]. Processing unit operations, including membrane filtrations, have also been studied to convert YAW into whey proteins, milk minerals, and monosaccharide products [6,13].…”