Heat resistance and the effects of continuous pasteurization on the inactivation of Byssochlamys fulva ascospores in clarified apple juice.
OBJECTIVE
To determine thermal resistance, the effect of pasteurization temperature variations (c. 2 degrees C) in a continuous system in the number of decimal reductions (n) of a Byssochlamys strain in clarified apple juice (CAJ).


RESULTS
Thermal destruction kinetics of Byssochlamys fulva IOC 4518 in thermal death tubes were determined at 85 degrees , 90 degrees , 92 degrees and 95 degrees C by using Weibull distribution frequency model. Three processes with different heating and holding temperatures (A: 94 degrees , 92 degrees C; B: 95 degrees , 93 degrees C; C: 96 degrees , 94 degrees C, respectively) were performed in a continuous system. Process time was 30 s. delta (time of first decimal reduction) values were: 42.98, 8.10, 3.62 and 1.81 min. Variable n ranged from 0.16 to >4.78 for process B (equivalent to industrial). Variable n (0.95-2.66 log CFU ml(-1)) were obtained in CAJ bottles processed under condition B, while process A resulted in total heat-resistant mould (HRM) survival and process C in total HRM destruction.


CONCLUSIONS
This study demonstrates that small variations in temperature during the CAJ pasteurization could result in elimination or survival of HRM due to its nonlogarithmic behaviour.


CONCLUSIONS
This was the first study to use Weibull frequency method to model inactivation of HRM in fruit juices. Temperature variations could culminate in the presence of HRM in pasteurized juices even when low counts (<10 spores per 100 ml) were present in the raw materials.
Sant'ana
A S
AS
Department of Food Science, Faculty of Food Engineering, State University of Campinas, Rua Monteiro Lobato, Campinas, SP, Brazil. assantana@usp.br
Rosenthal
A
A
Massaguer
P R
PR
D001628:Beverages / Q000382:microbiology*; D055323:Byssochlamys / Q000254:growth & development*; D015169:Colony Count, Microbial; D005506:Food Contamination / Q000032:analysis*; D005519:Food Preservation / Q000379:methods; D006358:Hot Temperature; D027845:Malus / Q000382:microbiology*; D013172:Spores, Fungal / Q000254:growth & development*; D013997:Time Factors