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. Itwas 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 apar with the commercial wine, aswell as wineswithout malolactic fermentation, in terms of phenolic compoundsand 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.