Non-anthocyanin polyphenolic transformation by native yeast and bacteria co-inoculation strategy during vinification.

Background: Co-inoculation has been adapted by many wine-producing countries because it enhances the success of malolactic fermentation and reduces the fermentation cost, as well as time. However, wine phenolics have been sparsely highlighted during co-inoculation, even though polyphenols are an important parameter affecting wine colour, astringency and aroma. In the present study, we investigated the impact of co-inoculation on non-anthocyanin polyphenol profile for two different grape varieties.

Results: Co-inoculation of native yeast strain (AAV2) along with Oenococcus oeni was adapted for Cabernet Sauvignon and Shiraz wine. It was observed that the co-inoculation had minimal yet significant impact on the phenolic composition of wines for both the grape varieties. Color loss, as well as fruity aroma development, was observed in co-inoculated wines. The wines were on a par with the commercial wine, as well as wines without malolactic fermentation, in terms of phenolic compounds and overall organoleptic acceptance. Principal component analysis and hierarchical cluster analysis further suggested that the varietal influence on phenolic composition was dominating compared to inoculation strategies. Among the varieties, the inoculation strategies have significantly influenced the Cabernet wines compared to Shiraz wines.

Conclusion: The results of the present study demonstrate that the phenolic compounds are not drastically affected by metabolic activities of malolactic bacteria during co-inoculation and, hence, are equally suitable for wine fermentation. © 2017 Society of Chemical Industry.