M. Ritz et al., Inactivation of Listeria monocytogenes by high hydrostatic pressure: effects and interactions of treatment variables studied by analysis of variance, FOOD MICROB, 17(4), 2000, pp. 375-382
High hydrostatic pressure is regarded as possible alternative method for fo
od preservation. One of the primary considerations for industrial applicati
ons is the ability of this method to eradicate pathogenic micro-organisms.
This study subjected L. monocytogenes suspensions, in a phosphate buffer (p
H 7.0) or in a citrate phosphate buffer (pH 5.6), to high hydrostatic press
ure treatments relative to the following variables: pressure (200-600 MPa)
treatment time (3, 10 and 20 min), temperature (4, 20 and 40 degrees C) and
the pH of the suspension medium (5.6 and 7.0). An optimal design of 40 run
s was obtained using the Fedorov algorithm and responses were studied by an
alysis of variance in terms of cell survival on plate count agar. Efficienc
y was determined by log(10) comparisons of the numbers of live cells before
and after treatment. A statistically significant relationship was found be
tween the four variables considered (pressure, pH, treatment time and tempe
rature), their interactions (treatment time vs pressure, pH vs treatment ti
me, pH vs pressure, pressure vs temperature, treatment time vs temperature)
and the inactivation of L. monocytogenes. R-squared statistical analysis i
ndicated that the linear model used accounted for more than 98.5% of the va
riability in the inactivation of L. monocytogenes. (C) 2000 Academic Press.