Modelling the effect of temperature and water activity on growth of Aspergillus niger strains and applications for food spoilage moulds.

摘要

To develop a model for the combined effect of aw and temp. on growth of strains of Aspergillus niger and compare results with data on food spoilage fungi in the literature, an extended combined model describing growth of 2 strains of A. niger, as a function of temp. (25-30癈) and aw (0.90-0.99), was developed. Growth rate (mu) was expressed as the increase in colony radial growth per unit of time. This extended the previous square root model showing the relationship between temp. and bacterial growth rate and the parabolic relationship between the logarithm of the growth rate and aw. A good correlation between experimental data and model predictions was obtained with a regression coeff. of >0.99. In addition, use of this model allowed predictions of cardinal aw levels (aw(min), and aw(opt)). Estimation of min. aw levels (aw(min)) was in accordance with literature data for similar, and a range of other, Aspergillus and related species, regardless of the solutes used for aw modification. Estimation of optimum aw (aw(opt)) and optimum growth rate (muopt) were in good agreement with experimental results and literature data. It is concluded that this approach enables accurate prediction of the combined effects of environmental factors on growth of spoilage fungi for rapid prediction of cardinal limits using surface response curves, and will have applications for improving the shelf life of intermediate moisture foods.