Miniature Fermentation Method

摘要

Using a commercial malt and a malt that showed premature yeast flocculation (PYF), the change in apparent extract (AE) during fermentation could be modeled by a nonlinear logistic equation using commercial software. The method is suitable to provide estimates of original extract (OE) and AE and to calculate the apparent degree of fermentation (ADF). The ADF within-lab error, or repeatability values, averaged 0.011 for both the control and PYF malts. The ADF between-lab error, or reproducibility values, was 0.030 and 0.016 for the control and PYF malts, respectively. The highest coefficient of variation encountered was approx. 3.5%. The parabolic behavior of the yeast in suspension can be modeled with a variant of a Gaussian curve, termed a "tilted Gaussian" model. Examination of paired data from control and PYF malts indicated there were significant differences (P ＜ 0.05) between the curves.