Protective effect of wheat gluten peptides against ethanol-stress damage in yeast cell and identification of anti-ethanol peptides

In the study, the protective effects of wheat gluten hydrolysates (WGH) on the ethanol-induced injury in yeast cells were investigated, and the peptides that enhanced the resistance to 10% (v/v) ethanol-stress were identified. Results showed that the growth and viability of yeast under ethanol-stress were significantly enhanced by WGH, and it indicated that there were high activity fractions in WGH. Interestingly, eight wheat gluten peptides (WGP) were obtained and identified as EP, LL, LW, LPL, LML, LLL, LLW, and EFPL, respectively, and five (LL, LLL, LW, LML and EP) of them worked best. Furthermore, WGP could enhance the yeast resistance to ethanol-stress, and the WGP apparently maintained the morphology and structure (especially the cell walls and membranes) of yeast under ethanol-stress. Further studied found that WGP (especially LL and LW) contributed to increasing cell wall integrity and cell membrane fluidity while also reducing cell membrane permeability. TEM analysis found that due to the existence of LL and LW, both the thickness of cell wall and the integrity of cell membrane were enhanced, on the contrary, the cell membrane degradation and cytoplasmic efflux were reduced. These results revealed that WGP could be considered as an effective protector of yeast against ethanol-stress damage.