Research Unit Food Microbiology and Food Preservation, Department of Food Technology, Safety and Health, Member of Food2Know, Faculty of Bioscience Engineering, Ghent University, Belgium.
Research Unit Food Microbiology and Food Preservation, Department of Food Technology, Safety and Health, Member of Food2Know, Faculty of Bioscience Engineering, Ghent University, Belgium.
Food Microbiol. 2020 Jun;88:103406. doi: 10.1016/j.fm.2019.103406. Epub 2019 Dec 19.
This study aims to assess, by means of a full factorial design, the effect of storage temperature (10-30 °C), water activity (a, 0.87-0.89), headspace oxygen (O) level (0.15-0.80%) and pasteurization intensity (95 °C-105 °C/15sec) on the time to visible growth (t, days) of Aspergillus fischerianus on acidified Potato Dextrose Agar (aPDA, pH 3.6) for up to 90 days. Moreover, in order to validate the results obtained on aPDA, 12 conditions were selected and assessed in concentrate strawberry-puree based medium. Overall, storage temperature had the greatest effect on the t of A. fischerianus on the evaluated conditions. At 10 °C, no visible growth was observed over the 90 day incubation period, whilst visible mycelia (diameter ≥ 2 mm) were present in 37% and 89% of the conditions at 22 °C and 30 °C, respectively. Pasteurization intensity had only a minor effect on the outgrowth of A. fischerianus. Growth inhibition was observed when a was reduced to 0.870 ± 0.005 in combination with very low headspace O levels (0.15% ± 0.10) in both, aPDA and concentrate strawberry-based media, regardless of the incubation temperature and heat pasteurization intensity. Overall, longer t's were required when incubation was done at 22 °C compared to 30 °C. Ultimately, the effect of O (0.05 and 1%) and pasteurization intensity (95 °C and 105 °C/15sec) were evaluated on totally 22 fruit purees (un-concentrates and concentrates) over a 60 day storage period. None of the concentrates purees (a ≤0.860) evaluated in this study supported the growth of A. fischerianus. On the other hand, A. fischerianus growth inhibition was only observed when the O levels were ≤0.05% on un-concentrates fruit purees (a ≥ 0.980) stored at ambient temperature (22 °C). Combination of multiple stress factors effectively inhibited growth of A. fischerianus. In general, storage of fruit purees at low temperatures (<10 °C) or distribution in the form of concentrates can be considered as important strategies to prevent the growth of spoilage associated heat-resistant moulds.
本研究采用完全因子设计，评估了储存温度（10-30°C）、水活度（a，0.87-0.89）、顶空氧气（O）水平（0.15-0.80%）和巴氏杀菌强度（95°C-105°C/15sec）对酸化马铃薯葡萄糖琼脂（aPDA，pH 3.6）上产黄青霉（A. fischerianus）可见生长时间（t，天）的影响，时间长达 90 天。此外，为了验证在 aPDA 上获得的结果，在浓缩草莓纯基培养基中选择并评估了 12 种条件。总的来说，储存温度对评估条件下产黄青霉 t 的影响最大。在 10°C 下，在 90 天的孵育期内未观察到可见生长，而在 22°C 和 30°C 下，分别有 37%和 89%的条件下出现了可见菌丝（直径≥2mm）。巴氏杀菌强度对产黄青霉的生长抑制作用较小。当 a 降低至 0.870±0.005 并与顶空 O 水平非常低（0.15%±0.10）结合时，无论是在 aPDA 还是浓缩草莓基培养基中，均观察到生长抑制，而与孵育温度和热巴氏杀菌强度无关。总的来说，在 22°C 下孵育时需要更长的 t 值，而在 30°C 下孵育时则需要更短的 t 值。最终，在 60 天的储存期内，总共对 22 种水果果泥（未浓缩和浓缩）评估了 O（0.05%和 1%）和巴氏杀菌强度（95°C 和 105°C/15sec）的影响。本研究中评估的所有浓缩果泥（a≤0.860）均不支持产黄青霉的生长。另一方面，当未浓缩水果果泥（a≥0.980）在环境温度（22°C）下 O 水平≤0.05%时，仅观察到产黄青霉的生长抑制。多种胁迫因素的组合可有效抑制产黄青霉的生长。总的来说，将果泥储存在低温（<10°C）下或浓缩形式进行分配可被视为防止耐热腐败霉菌生长的重要策略。
