The study examined the effect of Lactobacillus plantarum together with Saccharomyces cerevisiae on cider quality through simultaneous and sequential inoculation strategies to evoke malolactic fermentation. The antioxidant activities and flavor compound profiles of apple ciders fermented with mixed cultures of commercial wine yeast (S. cerevisia SY) and autochthonous bacteria (L. plantarum SCFF107 and L. plantarum SCFF200) were assessed. The antioxidant ability results indicated that apple ciders fermented with the simultaneous inoculation method had a higher DPPH radical scavenging rate and total antioxidant capacity, especially for SIL107 cider (simultaneous inoculation with S. cerevisiae SY and L. plantarum SCFF107), which exhibited the highest DPPH free radical scavenging activity (78.14% ± 0.78%) and the highest total antioxidant ability (255.92 ± 7.68 mmol/L). The results showed that ciders produced by mixed inoculation with L. plantarum improved flavor because of their higher contents of volatiles such as esters and higher alcohols and higher contents of non-volatile compounds like organic acids and polyphenols in comparison with the single culture of S. cerevisiae, especially for the simultaneous inoculation method. In addition, irrespective of the inoculation mode, compared to the single culture of cider, L-malic acid degraded dramatically in the presence of L. plantarum during alcoholic fermentation, accompanied by increases in lactic acid. What is more, sensory evaluation results demonstrated that ciders produced by mixed cultures gained higher scores than ciders fermented by the single culture of S. cerevisiae, especially in the simultaneous inoculation mode, in terms of the floral, fruity, and overall acceptability of the cider. Therefore, our results indicated that simultaneous inoculation with L. plantarum was found to compensate for some enological shortages of single S. cerevisiae fermented ciders, which could be a potential strategy to enhance the quality of cider products.

This study aimed to investigate the impact of different strains of Lactiplantibacillus plantarum on malolactic fermentation (MLF), antioxidant activity, and aroma of ciders. A commercial strain of Saccharomyces cerevisiae and six indigenous L. plantarum strains were co-inoculated into apple juice to induce simultaneous alcoholic fermentation (AF) and MLF. The findings indicated that despite belonging to the same species, the different L. plantarum strains significantly differed (p < 0.05) in terms of antioxidant activity and aroma compounds in the ciders. MLF induced by L. plantarum resulted in the substantial consumption of malic acid and increased levels of lactic acid in the ciders, with strain-specific effects observed, particularly with L. plantarum SCFF284. In addition, ciders produced from mixed fermentations exhibited higher levels of antioxidant activity than those from pure S. cerevisiae fermentation (p < 0.05), especially for LAM284. Furthermore, ciders produced from mixed fermentations exhibited higher levels of aroma compounds, such as ethyl acetate and isoamyl alcohol, and also received higher sensory scores compared to ciders produced through pure S. cerevisiae fermentation (p < 0.05). These results highlight the effectiveness of MLF induced by L. plantarum in enhancing the antioxidant activity and aroma profile of ciders.