HYDROPHOBIC POLYPEPTIDE EXTRACTION DURING HIGH GRAVITY MASHING - EXPERIMENTAL APPROACHES FOR ITS IMPROVEMENT

The aim was to establish if a substantial increase in hydrophobic poly peptides could be achieved during high gravity mashing. When worts wit h gravities ranging from 5-20 degrees P were analysed for hydrophobic polypeptide content it was found that there was no appreciable increas e in hydrophobic polypeptide levels. Remashing of the spent grains fro m low and high gravity mashes demonstrated that this resulted from ine fficient extraction of hydrophobic polypeptide levels during the mashi ng process. For example, wort produced from remashed high gravity spen t grains contained 150 mg/L hydrophobic polypeptides compared to only 10 mg/L in the low gravity remashed spent grains. Experiments were con ducted, employing standard mashing techniques, in an attempt to increa se the extraction of hydrophobic polypeptides during high gravity mash ing. Thus the use of gypsum, proteolytic stands, varying liquor to gri st ratios and wheat malt addition were all investigated for their effe ct on hydrophobic polypeptide extraction during high and low gravity m ashing. Wort analysis demonstrated that none of the techniques employe d had a significant effect on hydrophobic polypeptide extraction. When wort from remashed spent grains was used as mashing in liquor for a f resh mash and the resultant worts analysed for hydrophobic polypeptide s it was observed that no increase in hydrophobic polypeptide extracti on was achieved. For example, wort from the remashed high gravity spen t grains, containing 140 mg/L, hydrophobic polypeptides, when used as mashing-in liquor, produced no increase in hydrophobic polypeptide lev els in the resultant high gravity wort (230 mg/L) when compared to a h igh gravity wort produced using distilled water as mashing-in liquor ( 255 mg/L). It is therefore concluded that a saturation point has been reached and no more hydrophobic polypeptides can be extracted during m ashing regardless of the procedures employed.