Preliminary evaluation of oyster mushroom-supplemented yoghurt fermented with Lactobacillaceae strains: Lactic acid bacteria viability and inhibitory effect on Escherichia coli

Abstract

Members of the Lactobacillaceae family are well-established as beneficial microorganisms with significant functional value in the food and pharmaceutical industries. To ensure optimal health benefits, maintaining probiotic viability in the intestinal environment is crucial, a process that can be supported by prebiotic supplementation. The high cost of commercial prebiotics, like inulin and fructo-oligosaccharides, necessitates exploring affordable local alternatives. Oyster mushroom (Pleurotus ostreatus) is a potential source of non-starch polysaccharides, particularly β-glucans, known for their prebiotic and antibacterial properties. This study aimed to assess the impact of white oyster mushroom on the quality of yoghurt fermented with a mixed Lactobacillaceae starter culture, focusing on visual and physical characteristics, physicochemical characteristics (total protein and total solid) preliminary sensory acceptability, as well as its influence on LAB (lactic acid bacteria) growth and inhibitory effect against Escherichia coli (E. coli). An experimental design was employed, including the preparation of oyster mushroom, yoghurt formulation with three levels of supplementation, and evaluation of physicochemical, sensory, microbiological, and antimicrobial properties. Preliminary sensory acceptability involved 37 panelists, and LAB viability was assessed using total plate count on MRS agar. Inhibitory effect was evaluated against E. coli using the well diffusion assay. Statistical analysis was performed using one-way ANOVA followed by Dunnett’s post hoc test, and the E. coli inhibitory effect was analyzed using one-way ANOVA followed by Tukey’s multiple-comparisons test. Oyster mushroom supplementation significantly increased total culturable LAB viability at YOM 3% and YOM 5%, whereas a significantly larger inhibition zone against E. coli was observed only at YOM 5%. These findings provide preliminary evidence that oyster mushroom supplementation may support the growth of the mixed starter culture and produce limited inhibitory activity against E. coli, although its strain-specific prebiotic effect and broader antimicrobial potential require further confirmation.