Characterization and emulsifying properties of extracts obtained by physical and enzymatic methods from an oenological yeast strain

Abstract

BACKGROUND Glycosylated compounds are one of the main fractions of the yeast cell wall. Thanks to their amphiphilic structure, they have been studied as stabilizers in food emulsions over a broad range of pH conditions with encouraging results. Nevertheless, extraction costs still represent an important limit for their application in the food industry. RESULTS In this research, four extraction methods were applied to yeast cells exploiting both physical (heating and sonication) and enzymatic approaches (use of three industrial enzyme preparations, namely Glucanex®, Sur Lies and Elevage). A fifth method involving a pure β‐glucanase enzyme (Zymolyase) was taken as reference. These extraction methods were applied to the oenological strain Saccharomyces cerevisiae EC1118, and their extraction yields and chemical properties (quantitative and qualitative determination of sugars and proteins) were studied. Emulsifying activities were determined at three different pH values (3, 5 and 7). Extractions with Physical, Glucanex and Sur Lies methods were the most successful approaches to obtain relevant amounts of yeast compounds with good emulsifying activities for 2:1 oil‐in‐water emulsions at pH 3 and 7 over 48 h. CONCLUSIONS These results indicate that there is the potential for the extraction approaches here proposed to become viable tools for the recovery of yeast compounds to be used as emulsifiers in foods. This approach can be considered as the starting point to explore the possibility to exploit yeast by‐products from the fermentation processes (e.g. fermentation lees from wine and beer making) as valuable compounds for food applications. © 2019 Society of Chemical Industry

Structural characteristics of Saccharomyces cerevisiae mannoproteins: Impact of their polysaccharide part

“…In more controlled systems, enzymatic extractions are usually performed with commercial enzymes. Nevertheless, besides βglucanases, other residual hydrolytic activities have been observed in these commercial cocktails, especially proteases and mannanases that can directly affect the mannoprotein structure (De Iseppi et al, 2019;Kath & Kulicke, 1999;Schiavone et al, 2014). As expected, mannoproteins extracted by physicochemical methods (heat, acid, and alkali extractions) also differ in molar mass range and composition from those extracted through enzymes (De Iseppi et al, 2019;Kath & Kulicke, 1999;Moine-Ledoux & Dubourdieu, 1999;Núñez et al, 2006;Saunier, Mercereaua, & Vezinhet, 1991).…”

Current and future strategies for wine yeast lees valorization

“…Recently, an improved method of extraction of MPs from enological yeasts to be used as emulsifiers was proposed by De Iseppi et al (2019). In this study, the MPs precipitation with ethanol was replaced with a dialysis step which allowed the inclusion of a soluble β-G fraction in the final extracts.…”

Yeast cells for encapsulation of bioactive compounds in food products: A review

“…Manos and polypeptide chain showed hydrophilic and hydrophobic properties, respectively. 54 Different strains of baker's yeasts have been used to extract mannoproteins to be applied in food products. [55][56][57] Dikit et al used S. cerevisiae KA01 isolated from palm wine and the emulsifier obtained from this strain had potential application in salad dressing.…”

“…The amphiphilic nature of cell wall due to the presence of mannoproteins made it a bio-emulsifier. Manos and polypeptide chain showed hydrophilic and hydrophobic properties, respectively 54. Different strains of baker's yeasts have been used to extract mannoproteins to be applied in food products [55][56][57].…”