Effect of pectinase produced by Bacillus velezensisW17-6 on methanol content and overall quality of kiwifruit wine

Kiwifruit, a climacteric-fruit susceptible to rapid deterioration, attains considerable value upon transformation into kiwifruit wine, thereby increasing its added value. However, a noteworthy challenge arises from its high pectin content, which negatively affects byproduct quality, necessitating pectinase treatment during processing. Commercial pectinases exhibit heightened pectin esterase activity, giving rise to safety apprehensions due to augmented methanol content during kiwifruit pectin hydrolysis. In this study, Bacillus velezensisW17-6 was screened for its high pectinase activity coupled with low pectin esterase activity. The resultant crude pectinase named PBV was acquired through fed-batch-fermentation and partial purification. Subsequently, PBV was deployed in the fermentation of Xuxiang kiwifruit wine, and its impact on overall quality was assessed through diverse analyses. The results indicated that Xuxiang kiwifruit wine with PBV treatment outperformed counterparts treated with commercial pectinases. PBV treatment not only yielded superior clarity (83.75%±0.47%) and juice yield (81.60%±0.47%) but also increased the total flavonoids content in Xuxiang kiwifruit wine by 1.2 times compared to commercial pectinase. Notably, the methanol content of PBV-treated Xuxiang kiwifruit wine was significantly lower at 36.13±1.83 mg/L than that of wines treated with two commercial pectinases. PBV-treated kiwifruit wine also exhibited elevated concentrations of volatile compounds such as phenethyl alcohol, ethyl undecanoate, lauric aldehyde, isobutyric acid, and myrcene. Impressively, PBV-treated kiwifruit wine surpassed other wines in both electronic and artificial sensory analyses. In summary, PBV exhibits substantial potential in the production of low-methanol, high-quality kiwifruit wine, enhancing the flavor and nutritional value while minimizing methanol production and improving the safety profile.