Thermal resistance of alicyclobacillus acidoterrestris spores in different heating media

Abstract

Summary The aim of this work was to study the influence of temperature (85, 90, 95 and 100 °C), total soluble solids (SS: 10 and 20°Brix or % by weight of sucrose) and pH (3.5 and 4.0) on decimal reduction time (D-value) of the Alicyclobacillus acidoterrestris strain DSM2498 spores in apple juice, orange juice and malt extract broth (MEB). The effects of SS and pH on D-values and z-values in each media were insignificant (P > 0.05). In apple juice, orange juice and MEB, z-values of A. acidoterrestris for pH 3.5 and pH 4.0 were 12.2 ± 1.3-14.2 ± 3.2 °C, 11.2 ± 0.3-9.4 ± 0.0 °C and 11.9 ± 0.8-10.3 ± 0.4 °C, respectively. z-values of apple juice, orange juice and MEB samples with SS = 10°Brix and SS = 20°Brix were 14.1 ± 3.2-12.2 ± 1.3 °C, 10.2 ± 0.7-10.5 ± 1.1 °C and 11.3 ± 1.5-10.9 ± 0.2 °C, respectively. However, D-values of all samples were affected by temperature significantly (P < 0.01). Average D-values of apple juice, orange juice and MEB were 101.2 ± 14.7, 34.4 ± 7.9, 20.3 ± 4.9 and 4.3 ± 1.3 min for 85, 90, 95 and 100 °C. This study demonstrated that A. acidoterrestris spores exhibited high resistance to thermal processing applications. pH and SS of the media did not affect thermal resistance. © 2009 Institute of Food Science and Technology.