Antifungal activity of s-methyl butanethioate against Botrytis cinerea, preparation of slow-release fresh-keeping card and its application to control gray mold of peach fruit

Peach fruit is highly susceptible to decay caused by Botrytis cinerea . Volatile compounds have attracted considerable attention due to their safety and practical application advantages. S-methyl butanethioate, a volatile organic compound, is biosynthesized by microorganisms and plants. In this study, fumigation with synthetic s-methyl butanethioate at 50, 100, 200 and 300 μL/L effectively inhibited mycelial growth and conidial germination of B. cinerea and disease incidence of gray mold on peach fruit in a concentration-dependent manner. Furthermore, s-methyl butanethioate induced conidial apoptosis by causing the accumulation of reactive oxygen species (ROS) and exacerbating mitochondrial damage. To address the limitations in solubility, stability, and volatility of s-methyl butanethioate, a slow-release fresh-keeping card was prepared by embedding s-methyl butanethioate into β-cyclodextrin. Scanning electron microscopy (SEM) and Fourier transform-infrared spectroscopy (FT-IR) confirmed the successful embedding of s-methyl butanethioate into the cavity of β-cyclodextrin, forming the encapsulated structure of the inclusion complex. Notably, the release of s-methyl butanethioate from the fresh-keeping card was delayed for 15 d and the antifungal effect was stronger than direct fumigation with s-methyl butanethioate. Moreover, the fresh-keeping card application prevented surface damage to peach fruit caused by direct fumigation. Therefore, the fresh-keeping card loaded with encapsulated s-methyl butanethioate not only enhanced stability but also extended antifungal efficacy, outperforming the traditional un-encapsulated form. Therefore, this study demonstrates that fresh-keeping card loaded with natural components might serve as an alternative to synthetic chemical fungicides for controlling postharvest diseases of fruit and vegetables.