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

Abstract

In Greek-style yogurt production, every kilogram of product yields 2 to 3 kg of acid whey (YAW); this coproduct’s composition and low pH pose challenges for its proper valorization and reinsertion into the food supply chain. However, 240 mL of YAW contains over 9 g of lactose and represents a good source of minerals; these traits can be leveraged to develop nutritious fermented beverages. The purpose of this study is to investigate the aerobic fermentation of dairy sugars by different yeasts by characterizing these processes and their products. This will determine whether such methods provide viable options for the production of acetic-acid-containing beverages from YAW. To achieve this, yeast nitrogen base was used to prepare four growth media formulations, each supplemented with lactose, glucose, galactose, or a 1:1 mix of glucose and galactose (GLU:GAL), and each adjusted to a pH of 4.20. Fermentations were performed by pure cultures of S. cerevisiae, K. marxianus, B. claussenii, or B. bruxellensis, and were held at 25 °C with agitation at 185 rpm. For each treatment, density, pH, and microbial enumeration were measured over time to obtain process profiles, while ethanol, organic acids, and sugars were analyzed at the beginning and the end of each fermentation via HPLC, to determine resulting products. ANOVA and Tukey’s honest significant difference test at a significance level of 0.05 were used to compare residual sugars and fermentation products. Variable rates of sugar consumption were observed for each species. In GLU:GAL, B. claussenii consumed all of the glucose, left behind most of the galactose, and produced a high concentration of acetic acid. These results suggest the potential to develop versatile processes that target glucose for acetic acid production, while leaving available galactose to confer products with prebiotic properties. The development of processes for the conversion of YAW into beverages with organic acids and other healthful components not only aligns with consumers’ demands for better-for-you products, but also promotes the valorization of this otherwise underutilized dairy coproduct.

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.…”

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].…”

Leveraging Milk Permeate Fermentation to Produce Lactose-Free, Low-In-Glucose, Galactose-Rich Bioproducts: Optimizations and Applications

“…Mainly, B. claussenii has demonstrated the potential to make beverages from lactose-containing streams [21]. Furthermore, Rivera Flores, et al [22] observed the sugar utilization profile of a commercial strain of B. claussenii and found that it yielded various products when cultured under different conditions of oxygen and sugar availability [22,23]. Their results showed that under anoxic conditions, it metabolized all the available lactose into ethanol, whereas it metabolized only glucose and preserved nearly all galactose when presented with the two monosaccharides [22].…”