Heat inactivation of Escherichia coli O157:H7 in apple cider in the presence of glycerol monolaurate and a synthetic antimicrobial peptide, PR-26

The effect of moderate temperatures in combination with glycerol monolaurate and an antimicrobial peptide, PR-26 on E. coli O157:H7 in apple cider was determined. A five-strain mixture of E. coli O157:H7 was inoculated into apple cider (pH 3.53) containing 0.01% PR-26 or 0.02% glycerol monolaurate or a combination of 0.01% PR-26 and 0.02% glycerol monolaurate. The apple cider was incubated at 40, 45 or 50C for 30 s, 5 min, 10 min, and 15 min. At each of the specified time intervals, the surviving population of E. coli O157:H7 was determined. At all the three temperatures, there was no significant difference (P > 0.05) between the E. coli O157:H7 populations of the control and the treatment containing PR-26. However, the treatments containing glycerol monolaurate alone or combination of glycerol monolaurate and PR-26 resulted in significant reductions (P < 0.05) in E. coli O157:H7 counts. Results indicate that addition of glycerol monolaurate (0.02%) to apple cider and heating at 50C for 5 min can reduce E. coli O157:H7 by 5.0 log CFU/mL.