Accessing the growth of heat-resistant mold ascospores in potato dextrose agar, isolated from a processed fruit jam—Dependence of temperature, pH, and sugar concentration

Abstract

Heat-resistant molds (HRM) pose a significant threat to food industries due to their ability to survive in high temperatures (pasteurization range) and grow in a variety of environments. To understand how inhibiting variables affect HRM growth, this study evaluated the impact of high sugar concentration (50–60°Brix), low pH (3.5–4.5), and temperature (5–15) on the time (tv) to develop detectable colonies (colony diameter = 2 mm) of three HRM strains (Byssochlamys nivea, Byssochlamys fulva, Neosartorya fischeri) isolated from mixed fruit products. The study found that all HRM strains had relatively short periods of time to develop detectable colonies at 50°Brix, while no visible growth was observed at 60°Brix. Byssochlamys nivea was found to be the most susceptible to low temperatures, requiring up to 43 days to develop detectable colonies at 10°C and unable to grow at colder temperatures. The tv varied from 6 to 27 days based on pH and isolates. HRM's resistance to high sugar concentrations and ability to grow in cold environments pose a threat to the microbiological safety of fruit products. The evaluated data were fitted to several statistical distribution models to support further research on the quantitative microbiological risk in processed fruit products. This study provides valuable insights into how inhibiting variables affect HRM growth and can inform efforts to minimize their impact on fruit-based product quality and safety.