Steam and hot water surface pasteurization are both promising technologies that are capable of achieving more than 5 log reductions in target pathogens as well as greatly reducing populations of spoilage microorganisms on the surface of fruits and vegetables. However, hot water immersion treatment of fresh produce appears to be a gentler process and has better control over the surface temperature of produce during treatment as compared to steam treatment. Steam processes are acceptable treatments for produce intended for further processing due to thermal damage of the produce surface. The VSV process produces good results with a number of commodities with bacterial reductions up to 4.8 log CFU/ml (Table 21.8), depending on the fruit or the vegetable. The VSV is a rapid process requiring less than 2 seconds for treatment and with little or no thermal damage.
Even though highly promising, surface pasteurization technology is in need of further research to determine thermal penetration profiles and heat sensitivity at different temperatures for individual commodities. There is also a need to obtain thermal inactivation data for human pathogens of concern, attached to surfaces of commodities that have subsurface sites (e.g., pores) and other sites providing protection as well as exposed sites. Furthermore, research is needed to determine the temperature-time effect of surface pasteurization on sensory qualities, storability, and processability of fresh produce at different maturity stages. Results from such research would enable the development of cheap, safe, and environmentally sound disinfection treatments for controlling pathogens and/or spoilage microorganisms on fresh produce.
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