RT Journal Article SR Electronic T1 Variability Among Wines to Protein Clouding JF American Journal of Enology and Viticulture JO Am J Enol Vitic. FD American Society for Enology and Viticulture SP 69 OP 78 DO 10.5344/ajev.1965.16.2.69 VO 16 IS 2 A1 Moretti, R. H. A1 Berg, H. W. YR 1965 UL http://www.ajevonline.org/content/16/2/69.abstract AB There are four major protein fractions in wines. One of these fractions is more heat-labile than the others and has a lower isoelectric point. Protein stability in wines is apparently a function of the ratio of the amount of this fraction to the combined amount of the other fractions.pH is an important factor (but not the only one) in fixing the relative proportions of the protein fractions.More work is needed to discover the other factors involved.