Food Technology Department, Lleida University, XaRTA-TPV, Rovira Roure 191, 25198 Lleida, Spain.
Food Microbiol. 2010 Oct;27(7):909-17. doi: 10.1016/j.fm.2010.05.015. Epub 2010 Jun 15.
Predictive models can be a tool to develop strategies to prevent mould development and consequently mycotoxin production. The aims of this work were to assess the impact of a) high/low levels of inoculum and b) optimal/suboptimal environmental conditions on fungal responses based on both kinetic and probabilistic models. Different levels of spore suspensions of Aspergillus carbonarius and Penicillium expansum were prepared and inoculated centrally with a needlepoint load on malt extract agar (MEA) with 50 replicates. While optimum conditions led to a colony diameter increase which followed Baranyi's function, suboptimal conditions led to different grow functions. In general, growth rate (mu) and lag phase (lambda) were normally distributed. Specifically, the growth rate (mu) showed similar distributions under optimal growth conditions, regardless of the inoculum level, while suboptimal a(w) and temperature conditions led to higher kurtosis distributions, mainly when the inoculum levels were low. Regarding lambda, more skewed distributions were observed, mainly when the inoculum levels were low. Probability models were not much affected by the inoculum size. Lower probabilities of growth were in general predicted under marginal conditions at a given time for both strains. The slopes of the probability curves were smaller under suboptimal growth conditions due to wider distributions. Results showed that a low inoculum level and suboptimal conditions lead to high variability of the estimated growth parameters and growth probability.
预测模型可以用来制定策略，以防止霉菌的生长和随后真菌毒素的产生。本研究的目的是评估以下因素对真菌反应的影响：a）高/低接种量和 b）最佳/次佳环境条件，其依据是动力学和概率模型。将不同浓度的青霉碳曲霉和扩展青霉孢子悬浮液制备并接种到麦芽提取物琼脂（MEA）中央，使用针尖加载，每个条件有 50 个重复。在最佳条件下，菌落直径的增加遵循巴兰尼的函数，而在次佳条件下，生长函数则不同。通常，生长速率（μ）和滞后期（λ）呈正态分布。具体来说，在最佳生长条件下，生长速率（μ）无论接种量如何，分布都相似，而次佳的水活度和温度条件导致更高的峰度分布，主要是在接种量较低时。关于 λ，观察到更偏斜的分布，主要是在接种量较低时。概率模型受接种量大小的影响不大。对于两种菌株，在给定时间下，在边缘条件下，生长的概率通常较低。由于分布较宽，次佳生长条件下的概率曲线斜率较小。结果表明，低接种量和次佳条件会导致估计的生长参数和生长概率的高度变异性。
