Timing of inoculation of Oenococcus oeni and Lactobacillus plantarum in mixed malo-lactic culture along with compatible native yeast influences the polyphenolic, volatile and sensory profile of the Shiraz wines.

Malolactic fermentation (MLF) is a secondary wine fermentation resulting from lactic acid bacteria (Oenococcus
oeni or Lactobacillus plantarum), especially in cool climates. MLF reduces acidity, improves body, mouthfeel,
aroma complexity, and stabilizes the wine. Nevertheless, the traditional MLF using single culture is often
associated with stuck fermentation, increased volatile acidity and color loss in wine. Thus, studies on mixed
blend of L. plantarum and O. oeni to improve chemical and sensory profiles are gaining importance. The first
study on different timing of inoculation of dual malo-lactic culture for the vinification of Shiraz wine aims to
understand interactions between the wine cultures (Saccharomyces cerevisiae AAV2, L. plantarum Lp 1 and O. oeni
Oo 1). The wines were compared based on chemical properties, phenolic and volatile profiles, and sensory
analysis. The study highlighted that early or mid-inoculated MLF wines have higher anthocyanins, flavonoids,
syringol, esters, vanillate derivatives, benzaldehyde, and free terpenes compared to traditional MLF wines. The
wines were rated high for purple red colour, tannin, body, and overall acceptability. Hence, it was concluded that
the inoculation of Lp 1 and Oo 1, either after 7 or 14 days of alcoholic fermentation by yeast AAV2, yield the
desired quality Shiraz wine.