Abstract 093
Study of colloidal instability of millet wine
J. Amer. Soc. Brew. Chem. 64 (2): 86-93, 2006
J.I. Yang, Y.C. Lee, and K.J. Siebert
Millet wine, xiao-mi-jiu, is a traditional fermented beverage consumed in some regions of Eastern Asia. This study presents information on post-bottling instability of millet wine during 20-week refrigerated storage at 4°C. The pH and ethanol content of millet wine were stable but the color turned from brown to darker brown during 20-weeks of storage. Development of haze and sediment were observed. The levels of nitrogen, proteins, polyphenols, and carbohydrates in solution in the millet wine exhibited quantitative changes. Decreases in the amounts of polyphenols and proteins presumably resulted from polyphenol-protein association, which plays a key role in haze formation. The SDS-PAGE pattern of millet wine proteins showed that there were polypeptides with molecular weight ranges of 10-18 kDa and 25-60 kDa. The 14 kDa and 18 kDa millet wine proteins gradually decreased during storage. These proteins were proline-rich (16-17% of total amino acids), prolamin-derived proteins that produced haze upon addition of tannic acid. The 14 kDa or 18 kDa millet wine proteins could be useful indicators for judging the colloidal stability state of millet wines.
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