Executive Summary
Human pathogens can be present sporadically on fresh fruits and vegetables. CPS funded research has explored die-off rates for pathogens present on commodity surfaces and factors that can enhance pathogen persistence:
- Human pathogens on fresh produce surfaces generally demonstrate bi-phasic die-off patterns, i.e., rapid initial die-off followed by a prolonged period of decline thereafter out to a point where sample enrichment methods are required to enable detection.
- The over-riding objective of E. coli O157:H7 and other human pathogens have to existence on fruit and vegetable surfaces is to survive and they express genetic and physiological defense mechanisms to combat environmental conditions that might otherwise kill them.
- Salmonella spp., E. coli O157:H7,other STECs and Lm can not only persist but grow on fresh fruits and vegetables, but the rate of growth is dependent on the commodity, holding temperatures, competing microorganisms, available nutrition, and pH.
- Treatment of fruits with waxes or fungicides does not by itself impact Lm survival.
- Time at an elevated temperature and pH are important variables in supporting Lm growth on whole fruits and vegetables. Models have been developed to help industry predict risks associated with growth of Lm.