Study of thermal stability of ascospores Aspergillus (Neosartorya) fischeri depending on the concentration of soluble solids in apple juice

Abstract

Kinetic studies of the thermal inactivation of test crop spores are necessary to develop optimal heat treatment regimes for fruit juices. The purpose of the work is to study the dynamics of changes in the thermal stability parameters DT and z depending on changes in the soluble solids content in canned fruit products using the example of certain types of apple juice products with a pH of 3.80. The regularity of thermal inactivation of ascospores of the mesophilic mold Aspergillus fischeri in concentrated apple juice (JAC) with a soluble dry matter (RSV) content of 70%, in restored apple juice with RSV – 11.2%, and in restored apple juice with pulp with RSV – 16% was studied. The parameters of thermal stability were determined by the capillary method at temperatures of 80, 85, 90, and 95 °C. It was experimentally established that the heat resistance of A. fischeri spores in clarified apple juice was DT 95 °С = 0.16 min, and the parameter value z = 6.76 °C, in apple juice with pulp parameters: DT 95 °C = 0.24 min, z – 7.12 °C, in YaKS – DT 95 °C = 0.39 min, and z – 7.8 °C. The dynamics of thermal stability parameters D and z of A. fischeri mold fungus spores (test cultures) versus RSV concentration of juice products was established. The research results showed that with an increase in the concentration of RSV, the thermal stability of spores increases exponentially. The rate of increase in thermal stability decreases with increasing concentration of RSV. Since the concentration of RSV affects the rheological properties of the product (viscosity), this leads to a change in the kinetics of heating in products with convection heat transfer. Therefore, an increase in the concentration of RSV should inevitably lead not only to an increase in the thermal stability of spores of microorganisms, but also to a shift in the region of optimal modes of heat treatment of products toward an increase in the thermal load to ensure regulatory requirements for microbiological safety.

Soil-Borne Neosartorya spp.: A Heat-Resistant Fungal Threat to Horticulture and Food Production—An Important Component of the Root-Associated Microbial Community

“…Subsequently, simply editing the environment of fungal growth may be enough to stop its growth altogether. Previously mentioned variables, such as °Brix/acidity ratio [ 99 ], pH [ 100 ], °Brix [ 101 ], alternating temperatures, and the concentration of soluble dry matter can all be altered to elicit a reaction from fungi [ 102 ]. There are also studies that show the prospect of using the UV-C light as a form of non-thermal food processing.…”