SUCROSE AND ULTRA HIGH PRESSURE INACTIVATION OF SACCHAROMYCES CEREVISIAE AND LISTERIA INNOCUA

Abstract

D-values for ultra high pressure inactivation of Saccharomyces cerevisiae and Listeria innocua were evaluated in commercial applesauce with selected concentrations of soluble solids ranging from 13 to 60%. Applesauce with S. cerevisiae was compressed to 300 MPa and immediately decompressed (identified as 0 s) or held at 300 MPa for 30-s intervals for 150 s at room temperature. Applesauce with L. innocua was treated at 375 MPa for 0 to 300 s at room temperature. D-values for both microorganisms at soluble solids concentrations of 13, 20 and 30% were calculated. D-values for inactivation of S. cerevisiae were 26.3, 29.9 and 46.5 s in applesauce adjusted with sucrose to 13, 20 and 30% soluble solids, respectively. D-values for inactivation of L. innocua were 40.2, 55.2 and 120.6 s in applesauce also adjusted with sucrose to 13, 20 and 30% of soluble solids. Ultra high pressure treatment of commercial applesauce inoculated with S. cerevisiae or L. innocua adjusted to 40, 50 or 60% soluble solids reduced an initial inocula of 107to 106by less than 1 log. Soluble solids concentrations greater than 30% provide a baroprotective effect on inactivation by high pressure treatment. The use of ultra high pressure technology by the food industry to inactivate microorganisms may be limited in food models with high soluble solids concentrations. Soluble solids adjusted with sucrose concentrations greater than 30% protect against the destruction of microorganisms. An effective pressure treatment that ensures the microbial stability of foods depends on an understanding of the relationship between microorganisms and food components.