Thermal resistance characteristics of bacillus cereus, Escherichia coli O157:H7, and listeria monocytogenes in a multi-grain soy milk product

Abstract

This study determined the thermal resistance of Bacillus cereus, Escherichia coli O157:H7, and Listeria monocytogenes in multi-grain soymilk and proposes processing conditions that meet the national standard for retort food products in Korea. D and z values were calculated from thermal inactivation kinetic curves after heating at 55, 60, and 65°C. The D value for B. cereus at 55°C was the highest (22.8 min), followed by that for E. coli O157:H7 (18.8 min) and L. monocytogenes (17.6 min). At 60-65°C, the order was L. monocytogenes (D60-65°C=3.4-0.9 min), E. coli O157:H7 (3.0-0.3 min), and B. cereus (1.2-0.3 min). The z values for these species were 5.2, 5.5, and 7.7°C, respectively. The Korean national standard for retort food products was achieved by thermal processing at 124±2°C for 0.3-2.2 min. This study provides useful data for ensuring both the microbiological safety and product quality of multi-grain soymilk products.