14C-6 |
Prediction of growth/ non-growth interface of some molds inoculated in spread milk jam. Influence of aw, pH, potassium sorbate concentration and inoculum size. |
C. CHAR, S. Guerrero, and S. M. Alzamora. Department of Industry, Natural and Exact Sciences School, Buenos Aires University, Ciudad Universitaria, Nuñez, Buenos Aires, 1428, Argentina ²Dulce de Leche ²is a typical argentine sweet spread prepared from milk concentrated by evaporation to about 70 % w/w total solids (aw ranging from 0.80 to 0.85) at atmospheric pressure with added sucrose, glucose, and vanillin. Growth of xerophilic and pathogen molds represents a severe problem in this type of products with high sugar concentration. The objective of this research was to analyze the influence of aw, pH, inoculum size and antimicrobial agent concentration on Penicillium simplicissimum , Eurotium chevalieri and Aspergillus fumigatus growth/non growth response in Dulce de Leche systems stored at room temperature during 120 days. ²Dulce de Leche ²systems with different water activity (aw0.85 or 0.80), pH (5.6 or 6.0), and potassium sorbate concentration (0, 500, 1000, 1500 or 2000 ppm) were poured into sterile Petri dishes which were inoculated in one central point with each 10 µL mold suspension (107conidia/ml). To study inoculum size influence systems with added antimicrobial (1000 ppm) or not were inoculated with 2.0, 5.0, 7.5 or 10 µL mold suspension. Each condition was assayed in triplicate. Growth /non-growth observations were made during the whole storage at room temperature. Logistic regression was used in order to obtain polynomial equations to mathematically model growth-no growth mold interface. In addition, critical storage times were calculated for 0.1 probability of mold growth. The probability of growth decreased as aw and inoculum size diminished and as antimicrobial agent concentration increased. The non-growth period did not significantly change with the inoculum size but potassium sorbate concentration greatly influenced it. Some useful combinations of hurdles were found which assured non mold growth during a critical period of product storage at room temperature. This study contributed to optimize operation conditions in order to obtain a safer product when fails occur during the hot filling process or when the product is stored for a long period of time.
Session 14C, Food Microbiology: Food mycology
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