The free amino acid content in wines is closely related to quality, authent
icity, and the technology of winemaking. Some attempts have been made in th
e past to find an unequivocal relationship between free amino acids and the
authenticity of wines, but the complexity and diversity of the factors inv
olved has made this matter a controversial one. This study investigates the
possibility of using the analysis of 18 free amino acid revels to detect i
mitations of Port Wine by linear discriminant analysis. The 105 samples ana
lyzed were divided into two data sets: the training set, used to build the
model (55 Port Wines and 13 Port imitations) and the test set of unknown sa
mples (37 wines). Fifty-four of the 55 Part Wines and 12 from 13 Port Imita
tions were correctly classified in the training set; the discriminant funct
ion derived enabled the correct classification of 97% of the wines from the
test set. Considerable discriminating power was obtained from only five Va
riables - alanine, arginine, tyrosine, valine, and leucine (error 2.3% for
the test set) - after data reduction by step-wise discriminant analysis. It
is concluded that free amino acid content may be a good indicator in discr
iminating between Port Wine and Port Imitations.