Citric acid lowers heat resistance of Clostridium sporogenes PA 3679 in HTST white asparagus purée

Abstract

SummeryThe heat resistance parameters ( D , and z) of Clostridium sporogeries PA 3679 spores were determined from 121 to 145°C (HTST conditions) in Sgrensen 0.067 M phosphate buffer (pH 7.0) and in asparagus purte at natural pH (5.8) and at increasing levels of acidification (pH 5.5, 5.0 and 4.5) using citric acid as acidulant. The thermal resistance of the spores was higher when suspended in phosphate buffer pH 7.0 than in asparagus purte at all pH levels. The D, values obtained in asparagus puree decreased as the acidification level of the heating medium was increased by the addition of citric acid. The most evident effect was observed at the lower temperatures assayed. There was a general increasing trend in the value of the z parameter as the pH level of the heating medium rose ( z~~~.~ = 12.9"C; ZpH7.0 = 14.S"C). The differences found were significant between z values for pH 4.5 and those calculated for pH 5.8 and 7.0.

Study of the combined effect of electro-activated solutions and heat treatment on the destruction of spores of Clostridium sporogenes and Geobacillus stearothermophilus in model solution and vegetable puree

“…However, the obtained Z values for the tested purees in this work appeared to be higher than that of the control (NaCl), one could say that the heat resistance of spores increased due to the mixing with EAS. However the temperature and time needed for equivalent reduction was also observed to decrease ( [55]. Later they also found that a combination of asparagus glucono-δ-lactone and citric acid gives Z values of C. sporogenes that can reach up to 25 °C [56].…”

“…Among these factors, we can cite the type of the heating medium, strain type and the heating method used (dry or moist heat) [8,55].…”