Amino Acids in Must and Wines, Proline, Serine and Threonine

¹ Department of Viticulture and Enology University of California, Davis

Changes in the amounts of proline, serine and threonine found in fresh French Colombard must were followed during fermentation of the must to wine. Proline was the most abundant of the 17 amino acids measured in must, by a factor of 3 to 4. The amount of proline was not significantly changed during fermentation, and it remained the most abundant amino acid in the young wine. Serine was found to be the third and threonine the fifth most abundant amino acids in the must. About twenty-six per cent of serine and seventysix per cent of the threonine were lost during fermentation. The data of this and earlier work indicate that serine was the second and threonine the fourth most abundant amino acid in the young wine.

An attempt was made to separate the amino acids from factors in the must which inhibited the acid production of assay organisms by a chromatographic technique. One effluent fraction from a Dowex 50 column assay was found to strongly inhibit the proline assay. The nature of the factor is unknown. The sugar, tartaric acid and color of the must appeared in early fractions of the column effluent. Serine did not appear in any fraction of the collected effluent.