Yeast-Bacterial Interactions during Malolactic Inoculations Affecting Anthocyanin Adsorption and Content in Shiraz Wine.

Wine color is an important sensory attribute originating from the anthocyanins present
in grape skin. The present study is aimed toward assessing the involvement or interference of the
bacterial cells (Oenococcus oeni and Lactobacillus plantarum mixed culture) on adsorption of
Shiraz anthocyanins during co-inoculation with yeast. The yeast-bacterial interactions during co22 malolactic fermentation (Co-MLF) resulted in higher glucosides and vitisin B, lower coumaryl and
caffeyl anthocyanins when compared to sequential malolactic fermentation (Seq-MLF) and
alcoholic fermentation (AF) wines. However, the detailed profiling of lees revealed that there are
no significant differences in the anthocyanin adsorption pattern between AF and MLF
inoculations, even though such significant differences were observed in wine. Lees mainly
contained acylated anthocyanins of peonidin and malvidin, indicating hydrophobic interactions
involved in adsorption. Overall, yeast-bacterial interaction during MLF has a drastic influence on the final wine composition, with adsorption being one of the minor variables governing the
anthocyanin changes. Further, the incorporation of L. plantarum strain for co-inoculation resulted
in higher pyranoanthocyanin and hence, could be a strategy to tackle loss of color during co inoculation.