The enumerated populations were then expressed as log CFU/ml.
The growth/death kinetic parameters of each of the test organisms
were characterized using the freeware DMFit (Version 2.1) of the
Institute of Food Research, Reading, UK. The freeware fitted the
enumerated populations into the model developed by Baranyi and
Roberts (1994) and was able to calculate for, when applicable; the
lag time(tlag), growth rate (kG) ordeathrate (kD), and final population
(yf) per test organism. In the inactivation studies, death rates were
expressed in terms of D values, which are equivalent to the length of
time of necessary for the organisms to be reduced by 1 log cycle or
90%. The D values were calculated by obtaining the negative reciprocal
of the kD of the inoculatedmicroorganisms in the irradiated and
heated apple juice. Data obtained from independently replicated
experiments were subjected to single factor analysis of variance
(ANOVA) using the general linear model procedure (PROC GLM) of
the SAS Statistical Software Package version 8.0 (Cary, NC, USA). The
Duncan’s multiple range test (DMRT) was used for post-hoc determinations
of significant differences at 95% level of significance