Impact of the film‐forming dispersion pH on the properties of yeast biomass films

Abstract

BACKGROUND: Yeast biomass, mainly composed of proteins and polysaccharides (mannans and ⊎-glucans), has been proposed to develop films. pH can affect the solubility of polysaccharides, the structure of the cell wall, and the interactions between proteins. Considering the potential impact of these effects, the pH of yeast film-forming dispersions was studied from 4 to 11. RESULTS: In tensile tests, samples increased their elongation by increasing pH, from 7 ± 2% (pH 4) to 29 ± 5% (pH 11), but Young's modulus was not significantly modified. Regarding thermal degradation, the maximum degradation rate temperature was shifted 46°C from pH 4 to 11. Differences in water vapour permeability, colour, opacity, and roughness of films were also found. According to the results of differential protein solubility assay, hydrophobic interactions and hydrogen bonding were promoted at pH 4, but disulfide bonds were benefited at pH 11, in addition to partial ⊎-glucan dissolution and break-up of the alkali-sensitive linkage in molecules from the cell wall. CONCLUSION:The results lead to the conclusion that film-functional characteristics were greatly benefited at pH 11 in comparison with the regular pH of dispersion (pH 6). These results could help in understanding and selecting the pH conditions to enhance the desired properties of yeast biomass films.

Energy Harvesting from Sugarcane Bagasse Juice using Yeast Microbial Fuel Cell Technology

“…During this death phase, yeast does not generate protons or electrons. The low pH of the medium also has an impact on the life cycle of yeast (Delgado et al, 2021).…”