Characterization of Thermally Induced Gelatinization of Corn Starch and Its Effect on Storage Viability of Yeast.

Abstract

Scalding treatment significantly influences starch physicochemical properties, which in turn affect yeast viability. However, the relationship between the degree of starch gelatinization and yeast preservation remains unclear. This study investigated the structural and physicochemical properties of corn starch following gelatinization at different processing temperatures (50°C-90°C) and their effect on the storage survival rate of Saccharomyces cerevisiae Y10. As the temperature increased, a reduction in crystallinity and setback value was observed. The moisture content and water mobility increased progressively as the temperature rose from 50°C to 70°C, and remained stable at higher temperatures. Concurrently, water activity reached its maximum (0.483) at 70°C. No significant differences in reducing sugar content were observed among treatments. Structural characterization suggested that treatment at 70°C induced moderate swelling and rupture of starch granules, forming a porous microstructure. Meanwhile, the gelatinization treatment at 70°C was observed to yield the highest rate of yeast survival, at 15.00%. Correlation analysis suggested that survival rate was positively correlated with moisture content (r = 0.99, p < 0.001), while showing significant negative correlations with peak viscosity (r = -0.96, p < 0.001) and crystallinity (r = -0.91, p < 0.001) in the range of 50°C-70°C. In conclusion, gelatinization at 70°C significantly enhanced yeast survival during storage by optimizing the moisture distribution and structural matrix of the starch substrate. This study elucidates the relationship between starch gelatinization and yeast viability, providing a theoretical basis for optimizing the process of starch-based yeast viability preservation. PRACTICAL APPLICATIONS: This research is primarily applicable to starch-based yeast starters and provides a foundation for developing ready-to-use, room-temperature-stable dough starters suitable for home baking and commercial bakeries. Furthermore, these findings contribute to the production of fermentation agents with longer shelf lives and stable activity (such as those used in sourdough, yeast starters, fermented dough, and rice wine).