Abstract:

In order to explore the inactivation effect of high hydrostatic pressure on naturally occurring microorganisms in
pickled radish, the numbers of aerobic bacteria, mold and yeast as well as coliform in pickled radish were measured after
pressure processing at various pressure levels (300–600 MPa) for 5–25 min, respectively. The traditional linear models,
Weibull and Log-logistic model were used to fit the survival curves of aerobic bacteria in pickled radish processed by high
hydrostatic pressure. The results showed that microbial inactivation was improved with an increase in pressure level and
processing time. Both mold and yeast were more sensitive to pressure processing and could be inactivated by 500 MPa
pressure for 5 min. Modeling analysis showed that the coefficient of determination (R2) were higher than 0.99, indicating
that the Weibull model fit the kinetics curve of aerobic bacteria inactivation well. The Weibull model was more simple and
flexible compared with the Log-logistic model. The value of scale factor b of the Weibull model increased with increasing
pressure, while the value of shape factor n decreased.

Key words: high hydrostatic pressure, pickles, inactivation kinetics, Weibull model, Log-logistic model