Optimization of fermentation conditions for 3-methylthio-1-propanol production by Saccharomycopsis fibuligera Y1402 in tobacco matrix

3-methylthio-1-propanol (3-Met) is widely used as a flavoring substance in food flavoring. In this study, the fermentation conditions of Saccharomycopsis fibuligera Y1402 for 3-Met production were optimized in the tobacco matrix. Firstly, the optimization of the culture medium components and culture conditions was carried out through a single factor design. Then, a Plackett-Burman design was used to screen out factors that most significantly affected the production of 3-Met by S. fibuligera Y1402. The steepest ascending path design was used to identify the most significant response region. The optimal conditions for the production of 3-Met were determined using the Box-Behnken experimental design and response surface analysis. These conditions included a particle size of tobacco between 60 and 80 mesh, ammonium sulphate as the nitrogen source with a concentration of 2.4 g/L, L-methionine (L-Met) concentration of 3.1 g/L in the nutrient solution, an incubation time of 145 h, a moisture content of 83%, an initial pH of 5.5, a temperature of 29 °C, and an inoculation size of 1.6%. Under these conditions, the production of 3-Met reached 342.07 mg/g of tobacco. When the culture was scaled up, the conversion yield of 3-Met reached 1.07 g/g of tobacco. This suggests that fermenting this strain can increase the amount of 3-Met in tobacco leaves. This research offers a reference value for employing this strain to enhance the flavor components of crushed tobacco leaves, low-quality tobacco leaves, or tobacco stems, facilitating the processing of inferior tobacco leaves.