Development of a yeast co-culture inoculum for improved red wine metabolome from Punjab MACS Purple variety of grapes

This study explored the fermentation characteristics and sensory properties of wine produced from Punjab Purple grape juice using Saccharomyces cerevisiae strains MK680910 and MK680911, both individually and as a co-culture. Wines were fermented under optimized conditions adjusting °Brix, inoculum size, and oleic acid concentration determined through Response Surface Methodology (RSM). The predicted ethanol yields closely aligned with experimental values, reaching 9.478 % (v/v) for MK680910 and 10.078 % (v/v) for MK680911. Co-culture fermentation was optimized as 18°Brix, 6.2 % (v/v) inoculum, and 9 mg/L oleic acid. It was completed in 7 days compared to 9 days for individual strains, achieving the highest fermentation efficiency (90 %) versus 86 % for MK680910 and 85 % for MK680911. A post-fermentation micro-oxygenation (MOX) treatment applied to enhance colour stability, phenolic composition, and sensory complexity by controlled oxygen exposure revealed that an incremental monthly MOX treatment @ 0.025 LPM over three months significantly increased total phenolic content and colour intensity, particularly in co-culture fermented wines. These wines also exhibited higher acidity, total phenols, antioxidants, anthocyanins, and ethanol levels, along with lower residual sugars and pH, contributing to superior wine quality. GC-MS analysis revealed an increased complexity of volatile compounds in wines prepared using co-culture compared to those from individual cultures. The PCA analysis of the GC-MS analyzed compounds revealed presence of major components belonging to esters, alcohols, furfurals, phenolics, ketones and terpenoids. Thus, a combined approach of co-culture fermentation, oleic acid supplementation, and micro-oxygenation presents a promising strategy for enhancing red wine quality through increased metabolomic complexity and refined sensory attributes. • RSM optimized Co-culture fermentation and subsequent MOX treatment improved fermentation efficiency and wine complexity. • Co-culture wine scored high on sensory scale. • GC-MS and PCA analysis showed improved diversity of volatiles in co-culture wine.