Most interesting antifungal compounds from sourdough fermentation are acetic acid (AA) and DL-3-phenyllactic acid (PLA). Although the role of pH on the activity of organic acids has been established long time ago, no information is available on the importance of undissociated acid (HA) expressed on the aqueous phase of bread (CHA, mmole/L). Mostly, concentrations (mmole/kg dough or bread, CTOT) and pH are given side by side. The aim of this study was to show the importance of CHA for adequate comparison of in-vitro growth data with bread shelf-life. Growth of Penicillium paneum and Aspergillus niger was recorded using a micro-dilution assay with optical density measurements. Parameters such as aw (0.94-0.98), pH (4.6-6.0), temperature (10-30 °C), time (0-8 days) and CTOT (0-300 mM) were varied. Growth/no-growth models were developed and shelf-life tests of par-baked breads of 45 days at 20 °C were conducted. The modelled inhibitory concentrations of undissociated acid were comparable with the shelf-life test of bread: (PLA) 50 versus 39-84 mmol/L; (AA) 110 versus 110-169 mmol/L. This study showed the applicability of G/NG models for bread shelf-life prediction and highlighted the importance of CHA. Moreover, it was found that naturally present PLA in sourdough bread is insufficient to increase bread shelf-life.

中文翻译：

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DL-3-苯基乳酸和乙酸对面包变质模具的抗真菌活性的建模和验证。

酵母发酵中最有趣的抗真菌化合物是乙酸（AA）和DL-3-苯基乳酸（PLA）。尽管很早以前就已经确定了pH对有机酸活性的作用，但尚无关于在面包水相上表达的未离解酸（HA）的重要性的信息（CHA，mmole / L）。通常，并排给出浓度（毫摩尔/千克面团或面包，CTOT）和pH值。这项研究的目的是显示CHA的重要性，以充分比较体外生长数据和面包的保质期。使用具有光密度测量的微稀释测定法记录了青霉和黑曲霉的生长。改变了诸如aw（0.94-0.98），pH（4.6-6.0），温度（10-30°C），时间（0-8天）和CTOT（0-300 mM）之类的参数。建立了生长/无生长模型，并在20°C下对45天的半熟面包进行了保质期测试。未解离酸的模型抑制浓度与面包的货架期测试相当：（PLA）50对39-84 mmol / L；（AA）110对110-169 mmol / L。这项研究表明了G / NG模型在面包保质期预测中的适用性，并强调了CHA的重要性。此外，已经发现，发面面包中天然存在的PLA不足以增加面包的保质期。这项研究表明了G / NG模型在面包保质期预测中的适用性，并强调了CHA的重要性。此外，已经发现，发面面包中天然存在的PLA不足以增加面包的保质期。这项研究表明了G / NG模型在面包保质期预测中的适用性，并强调了CHA的重要性。此外，已经发现，发面面包中天然存在的PLA不足以增加面包的保质期。