Effects of inoculation with lactic acid bacteria at different periods on physicochemical and sensory quality of ‘Cabernet Sauvignon’ dry red wine

Using ‘Cabernet Sauvignon’ wine grapes as raw materials, commercial lactic acid bacteria (LA, OE) were inoculated in the pre-, mid- and post- alcoholic fermentation, their effects on the malolactic fermentation process were compared, and the effects of inoculum with lactic acid bacteria at different periods on the physicochemical indexes, aromatic substances and sensory characteristics of wines were analyzed. The results showed that the malolactic fermentation was completed in the shortest time when lactic acid bacteria were inoculated at the pre-alcoholic fermentation period (LA: 12 d, OE: 14 d). There were no significant differences in residual sugar, total acid, alcohol content, colour and hue of wines inoculated with lactic acid bacteria at different periods (P>0.05), but the volatile acid content of wines inoculated with lactic acid bacteria at the pre-alcoholic fermentation period was significantly higher than that of wines inoculated at the post-alcoholic fermentation period (P<0.05). The wines inoculated with lactic acid bacteria at the pre-alcoholic fermentation period had the highest contents of total aroma substances, esters and higher alcohols, and the contents reached 1 182.46 mg/L, 291.47 mg/L and 550.16 mg/L for strain LA inoculation, and 985.95 mg/L, 192.83 mg/L and 563.49 mg/L for strain OE inoculation, respectively. A total of 20 kinds of aroma substances with odor active value (OAV)>1 were found, and the number of aroma substances with OAV>1 in the wine inoculated at the pre-alcoholic fermentation period was the highest of 18. The wines inoculated at the pre-alcoholic fermentation period had higher scores in terms of purity, intensity, harmony, persistence of aroma and aftertaste, but the differences in appearance were not significant. In conclusion, the wines inoculated with lactic acid bacteria at the pre-alcoholic fermentation had shorter malolactic fermentation times and better quality.