Improvement of myrtle wine quality by proline under tannic acid stress: Combined E-nose and HS-SPME-GC-MS analysis

Tannic acid can inhibit Saccharomyces cerevisiae metabolism and cellular integrity during myrtle wine fermentation. Proline has been shown to significantly mitigate the stress effects of tannic acid on the S. cerevisiae. This study aimed to investigate the effects of proline on the volatile profile and sensory properties of tannic acid-rich myrtle wine. The results indicated that proline significantly increased the contents of ethanol, organic acids, and phenolic compounds in myrtle wine. GC-MS analysis showed a 15.8% increase in total VOCs in the proline-treated group (PG) compared with the control group (CG), with rOAV analysis identifying isoamyl acetate, ethyl isovalerate, ethyl octanoate, and phenylethyl acetate as potential aroma-active compounds contributing to fruity and floral characteristics. E-nose showed that the response values of W5S, W1S, W2S, W2W, and W3S sensors in PG were increased by 76.2%, 16.2%, 96.4%, 41.25%, and 9.8% compared with CG, respectively. Ultimately, sensory analysis revealed that proline substantially improved the overall sensory quality of myrtle wine. These findings provide valuable theoretical guidance for enhancing the quality of myrtle wine.