Thermal inactivation of Byssochlamys nivea in pineapple juice combined with preliminary high pressure treatments

摘要

Byssochlamys nivea is a thermal resistant filamentous fungi and potential micotoxin producer. Recent studies have verified the presence of ascospores of such microorganism in samples of pineapple nectars and juices. Although the majority of filamentous fungi have limited heat resistance and are easily destroyed by heat, Byssochlamys nivea ascospores have shown high thermal resistance. The aim of this work was to evaluate the application of linear and Weibull models on thermal inactivation (70, 80 and 90°C) of Byssochlamys nivea ascospores in pineapple juice after pretreatment with high pressure (550MPa or 650MPa during 15min). Following the treatments, survival curves were built up for each processing temperature and adjusted for both models. It was observed that the survival curves of B. nivea ascospores at 70°C after both previous treatment and at 80°C after 550MPa for 15 minutes fitted well in linear and Weibull models. In the others treatments, the Weibull model showed better fit. On 90°C ascospores inactivation (control), without previously high pressure treatment, the Weibull model also showed a better adjustment, presenting a larger R2 and a smaller RMSE. In the others controls treatments (70 and 80°C without previously high pressure treatment), it was verified the activation of B. nivea ascospores, then it was not possible to adjust the models. Thus, a 5-log reduction (t5) treatment, as recommended by the Food and Drug Administration, on Byssochlamys nivea ascospores in pineapple juice was observed in this work at 90°C/15.38min with previously high pressure treatment of 650MPa for 15min.