COLD STERILE FILTRATION - A SMALL-SCALE FILTRATION TEST AND INVESTIGATION OF MEMBRANE PLUGGING

Beer brewed from 24 commercially and bag malted samples by a small sca le brewing method was assessed by a micro-filtration efficiency (MFE) test designed to emulate the cold-sterile (membrane or micro-) filtrat ion process. The level of malt derived beer components with the potent ial to reduce MFE, such as beta-glucan, arabinoxylan, protein and poly phenol. were consistent over duplicate beer batches suggesting that be er quality was reproducible using the small scale method. The small sc ale MFE test was able to differentiate (P<0.001) between beer brewed f rom distinct malt samples in a reproducible fashion, suggesting that t he test is effective in assessing beer MFE in the laboratory. Subseque ntly, the effects of various malt derived beer components on micro-fil tration were investigated. MFE (measured as V-max) was negatively corr elated with beer arabinoxylan content (r=-0.62. P<0.01). suggesting th at the arabinoxylan content of malt, and subsequently beer, may influe nce MFE. Total beer beta-glucan was not significantly related to beer MFE (r=-0.36). However, it was likely that beta-glucan molecules of hi gh molecular weight influenced MFE more so than the total beta-glucan content. Beer viscosity, which was correlated to both beer beta-glucan and arabinoxylan content (r=0.86. P<0.001 and r=0.68, P<0.05. respect ively), correlated with V-max (r=-0.81. P<0.001).