Identification of Wild Yeast Strains and Analysis of Their β-Glucan and Glutathione Levels for Use in Makgeolli Brewing

Abstract

Makgeolli, also known as Takju, is a non-filtered traditional Korean alcoholic beverage that contains various floating matter, including yeast cells, which contributes to its high physiological functionality. In the present study, we assessed the levels of β-glucan and glutathione in various yeast strains isolated from traditional Korean Nuruk and selected a β-glucan- and glutathione-rich yeast strain to add value to Makgeolli by enhancing its physiological functionality through increased levels of these compounds. Yeast β-glucan levels ranged from 6.26% to 32.69% (dry basis) and were strongly species-dependent. Dried Saccharomyces cerevisiae isolated from Nuruk contained 25.53 µg/mg glutathione, 0.70 µg/mg oxidized glutathione, and 11.69 µg/g and 47.85 µg/g spermidine and L-ornithine monohydrochloride, respectively. To produce functional Makgeolli, a β-glucan- and glutathione-rich yeast strain was selected in a screening analysis. Makgeolli fermented with the selected yeast strain contained higher β-glucan and glutathione levels than commercial Makgeolli. Using the selected yeast strain to produce Makgeolli with high β-glucan and glutathione content may enable the production of functional Makgeolli.

In Vitro Study of Probiotic, Antioxidant and Anti-Inflammatory Activities among Indigenous Saccharomyces cerevisiae Strains

“…Until now, few studies reporting the effect of source (or strain) of yeast as important factors affecting the β-glucan content are available [74,75]. The amounts of β-glucans extracted from the four selected strains is highly variable among them (Figure 5), demonstrating that the β-glucan content of a yeast is strain/species dependent [76,77]. Two indigenous strains showed a content significantly higher or similar (TA4-10 and 4LBI-3, respectively) than the content found in the commercial probiotic strain Sb, while LL-1 strain exhibited the lowest amounts of β-glucans (7.83 ± 0.68% w/w).…”

Isolation of thermotolerant yeast Pichia kudriavzevii from nuruk

“…Nuruk is a traditional Korean fermentation starter that contains a variety of microorganisms [9][10][11] including yeasts and other fungi, and bacteria [12]. Yeasts isolated from nuruk have been used to produce an alcoholic beverage and traditional fermented foods [13]. Non-conventional yeast species such as Pichia stipitis [14], Kluyveromyces lactis [15], Candida thermophila [16] and Kluyveromyces marxianus [17] have advantageous characteristics such as tolerance to acid or heat, or the ability to metabolize carbohydrates that Saccharomyces cerevisiae does not naturally metabolize [18].…”

Diversity analysis of Saccharomyces cerevisiae isolated from natural sources by multilocus sequence typing (MLST)

“…Even though many microorganisms are involved in Makgeolli fermentation, S. cerevisiae strains are considered the main determinants of the quality of the final product and to contribute to the diversity of Korean traditional alcoholic beverages [18,19]. Hence, it is very important to identify and classify natural S. cerevisiae strains for their industrial application [20]. Many studies have selected S. cerevisiae strains from natural sources, mainly Nuruk, based on the alcoholic fermentation characteristics of the strains.…”