White must and wine fatty acids are present mainly in the free form, o
r esterified as ethyl esters, and both contribute to flavor and foam p
roperties of wine. A reliable and sensitive analytical procedure for a
nalyzing the free fatty acids (C6-C18) and their ethyl eaters has been
developed. Sulfuric acid (3%) in methanol was selected as a derivativ
e reagent, and optimal derivatization conditions were established (3 h
at room temperature). This reagent gives total methylation of fatty a
cids and partial transesterification of ethyl eaters to methyl esters
and, through the study of this transesterification, free and bound fra
ctions were determined satisfactory. (C) 1997 Elsevier Science B.V.