Abstract The impact of processing conditions on the microbial quality of par-baked wheat and sourdough bread was investigated. Processing conditions included par-baking time (8 and 13 min), temperature (150 and 200 °C), amount of steam (200 and 600 mL), and packaging (air and modified atmosphere (MA)). Total anaerobic mesophilic plate counts, moulds and yeasts and spore-forming bacteria, together with pH and aw of the par-baked breads were evaluated. Data were used to make predictive models showing the impact of the main effects and their interactions. Sourdough addition could extend the time of acceptable bread quality based on the anaerobic counts from 8 to more than 13 days. Visual growth of moulds and yeasts (presence/absence of single spots) was most efficiently suppressed by the combination of MA-packaging and the highest baking temperature and time. Microbiological analysis of moulds and yeasts however, showed that again sourdough had the best preservation potential, followed by MA-packaging. This study showed that adjusting the par-baking conditions, bread composition and packaging can increase the shelf-life of par-baked bread in a natural way.

中文翻译：

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标准烘焙和包装对标准烘焙小麦和酸面包微生物品质的影响

摘要 研究了加工条件对半烤小麦和酸面包微生物品质的影响。加工条件包括标准烘烤时间（8 和 13 分钟）、温度（150 和 200 °C）、蒸汽量（200 和 600 毫升）和包装（空气和气调 (MA)）。评估了总厌氧嗜温菌落总数、霉菌和酵母菌以及孢子形成细菌，以及标准烘焙面包的 pH 值和 aw。数据用于制作预测模型，显示主效应及其相互作用的影响。添加酸面团可以将基于厌氧计数的可接受面包质量的时间从 8 天延长到 13 天以上。MA 包装与最高烘烤温度和时间相结合，可以最有效地抑制霉菌和酵母菌的视觉生长（存在/不存在单个斑点）。然而，对霉菌和酵母菌的微生物分析表明，酸面团再次具有最佳的保存潜力，其次是 MA 包装。这项研究表明，调整标准烘焙条件、面包成分和包装可以自然地延长标准烘焙面包的保质期。