Fate of Bacterial Pathogens and Indicator Organisms in Liquid Sweeteners

Abstract

The survival of pathogenic and indicator microorganisms in liquid sweeteners was studied. Seven sweeteners—liquid sucrose, 42% high-fructose corn symp (HFCS), 55% HFCS, 25 DE (dextrose equivalent) com syrup (CS), 36 DE CS, 63 DE CS, 50% medium invert sucrose, and 65% high-maltose com syrup (HMCS) were inoculated with Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, and coliforms at a level of 105 cells per g. The inoculated products were stored both at or near their normal holding temperatures (32 to 46°C) and at 26.7°C (the lower limit during transportation). In most of the products the number of microorganisms fell below the detection limit in less than 3 days when the sweeteners were stored at their normal holding temperatures. However, in liquid sucrose S. aureus survived up to 2 weeks. When the products were stored at 26.7°C, the reduction in the number of microorganisms occurred at a slower rate. At 26.7°C the fastest rates of reduction were observed in 42 and 55% HFCS and in 50% medium invert sucrose. In these products the number of bacteria fell below the detection limit in 3 to 6 days. The slowest rate of the reduction was observed in the liquid sucrose, in which S. aureus survived up to 1 month. These results indicate that incidental contamination of liquid sweeteners with microbial pathogens will not present a public health or regulatory hazard.