Correlation coefficients between polyphenols and protein have been established for 130 samples of barley and malt varying from 8 to 17% in protein content. Three analytical methods were tested on several extracts, and the effect of solvent extraction of polyphenols was studied. A true extraction was obtained with 75% acetone, while the extraction with water was governed by a protein and polyphenol equilibrium. Dimethyl formamide (75%) tended to give higher values than acetone, but did not show true extraction properties. Statistical evaluation shows that barley polyphenol data may be used for predicting the content of the same compounds in the malt. One of the tested methods, the analysis of vanillin reactive polyphenols, is easy to peform and shown to give substantial information about the different polyphenol fractions of the malt. The polyphenol content of the barley and consequently malt is influenced more by the growth conditions than by the variety.
Keywords: barley malt polyphenol protein statistical analysis