Optimization of a Small-scale Fermentation Test to Predict the Premature Yeast Flocculation Potential of Malts

Abstract

J. Inst. Brew. 116(4), 413-420, 2010Rapid and early detection of malts likely to cause premature yeast flocculation (PYF) is of major importance both to the brewer and the maltster. To date, the most reliable and widely applied diagnostic tests for predicting the PYF status of malts involve conducting a small scale fermentation test, which usually takes several days to be completed. This study investigated the impact of selected factors on the ability of such a test to distinguish between PYF positive and PYF negative malts and the fermentation time after which the test results, and therefore the PYF status of the malts, could be confirmed. The results obtained suggest that the PYF potential of malts could be predicted 40 hours post pitching by adding 6 mg.L -1 linoleic acid and using a highly flocculent PYF sensitive yeast strain.

The role of ferulic acid and arabinoxylan in inducing premature yeast flocculation

“…Yeast cells were pre‐cultured in 1 mL and then 9 mL of sterile wort broth at 25°C for 24 h without shaking, and finally in 90 mL of sterile wort broth at 25°C for 36 h at 150 rpm. The yeast cells were counted as described by Panteloglou et al for testing PYF using a haemocytometer counting chamber according to the American Society of Brewing Chemists' method . The malt wort was pitched at a rate of 10 × 10 6 cells mL −1 .…”

Malt-induced premature yeast flocculation: current perspectives

“…yeast strain, pitching rate and fermentation temperature) take several days to be completed. However, Panteloglou et al [43] suggested that monitoring suspended yeast cells, using either the absorbance at 600 nm or microscopic cell counting after a number of serial dilutions, is a more accurate predictor than residual gravity for predicting the PYF potential of malts.…”

“…PYF is a sporadic, but serious problem in the brewing and malting industries [19,23,29,43,44]. It has been defined as the phenomenon whereby flocculation competent yeast settle out of the fermentation medium abnormally early and/or heavily during primary fermentation leaving a residual extract [27].…”

“…Selection of yeast strain is just one significant aspect which should be standardised. The lager yeast SMA is one strain which has been proposed as suitable, based upon its susceptibility to PYF [43,44,58]. Variability in the performance of malt samples in PYF tests can also arise because of a lack of homogeneity in samples submitted.…”

Estudio De Los Espectros Dielectricos en Alimentos Con Estructura Coloidal

“…There exist numerous analytical methods for detecting these components. The High Performance Liquid Chromatography (HPLC) makes possible the evaluation of carbohydrates and alcohol content (Panteloglou et al, 2010;Piddocke et al, 2009;Zengran et al, 2008). Other authors optimized and validated an HPLC method with an Evaporative Light Scattering Detector (ELSD) for the quantification of carbohydrates in the beer (Nogueira et al, 2005).…”