Abstract The analysis of fermentability, or real degree of fermentation (RDF), involves the determination of real extract (RE) in a fermented sample. Considering that RDF analysis is expensive and time consuming, some researchers instead, report the apparent degree of fermentation (ADF). However, since the ADF calculation considers initial and final specific gravities of the fermented sample, variation in alcohol content could have an effect on ADF. This is especially true when samples with widely different backgrounds are tested, as is often the case during malting barley breeding. The objective of this research was to define the feasibility of using ADF for selecting and discriminating different samples in terms of fermentability. Additionally, different equations for calculating RE and original extract (OE) were compared and discussed. Results showed that ADF values change at different alcohol contents in samples with similar RDF, which could lead to the determination of false differences in relation to this trait. Our findings suggest that ADF is not a reliable indicator of fermentability for the discrimination of barley breeding samples. In addition, it was observed that OE and RE values, as calculated by the Balling Equation, can be over- or under-estimated depending upon the alcohol content of fermented samples.

中文翻译：

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表观发酵度是发酵性的可靠估计吗？

摘要 发酵能力或真实发酵度 (RDF) 的分析涉及对发酵样品中真实提取物 (RE) 的测定。考虑到 RDF 分析既昂贵又耗时，一些研究人员反而报告了表观发酵度 (ADF)。但是，由于 ADF 计算考虑了发酵样品的初始和最终比重，因此酒精含量的变化可能会对 ADF 产生影响。当测试具有广泛不同背景的样品时尤其如此，这在麦芽大麦育种过程中经常发生。本研究的目的是确定使用 ADF 在发酵能力方面选择和区分不同样品的可行性。此外，还比较和讨论了用于计算 RE 和原始提取物 (OE) 的不同方程。结果表明，在具有相似 RDF 的样品中，不同酒精含量下的 ADF 值会发生变化，这可能导致确定与该性状相关的错误差异。我们的研究结果表明，ADF 不是区分大麦育种样品的发酵能力的可靠指标。此外，据观察，根据发酵样品的酒精含量，通过鲍林方程计算的 OE 和 RE 值可能被高估或低估。