Modelling the growth/no growth boundary of Zygosaccharomyces bailii in acidic conditions: a contribution to the alternative method to preserve foods without using chemical preservatives

International Journal of Food Microbiology
T D T DangF Devlieghere

Abstract

The aim of the study was to develop mathematical models describing growth/no growth (G/NG) boundaries of the highly resistant food spoilage yeast-Zygosaccharomyces bailii-in different environmental conditions, taking acidified sauces as the target product. By applying these models, the stability of products with characteristics within the investigated pH, a(w) and acetic acid ranges can be evaluated. Besides, the well-defined no growth regions can be used in the development of guidelines regarding formulation of new shelf-stable foods without using chemical preservatives, which would facilitate the innovation of additive-free products. Experiments were performed at different temperatures and periods (22 degrees C for 45 and 60days, 30 degrees C for 45days) in 150 modified Sabouraud media characterized by high amount of sugars (glucose and fructose, 15% (w/v)), acetic acid (0.0-2.5% (v/v), 6 levels), pH (3.0-5.0, 5 levels) and a(w) (0.93-0.97, 5 levels). These time and temperature combinations were chosen as they are commonly applied for shelf-stable foods. The media were inoculated with ca. 4.5 log CFU/ml and yeast growth was monitored daily using optical density measurements. Every condition was examined in 20 replicates in or...Continue Reading

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