Thermal Food Processing

pH-Assisted Thermal Processing 587
At present it is well known that the majority of the microorganisms show
their maximum heat resistance at neutral pHs, decreasing with an increase in
acidification. The magnitude of the effect of pH will depend on the microbial
species and other factors, such as food composition, type and concentration of
acid, or even the sporulation temperature in the case of bacterial spores.
pH influences not only heat resistance, but also bacterial growth, and most
importantly, it influences very much the growth of the survivors to a heat treatment.
Hence, the combined effect of the pHs of the heating medium and recovery
medium may lead to synergistic reductions of the viability of microbes.
The huge amount of data on the effect of pH on microbial growth and heat
resistance has allowed for the development of large databases and mathematical
models that enable prediction of the behavior of microorganisms under certain
conditions. These data sets are available for food microbiologists, manufacturers,
risk assessors, and legislative officers.
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