engleski

HPLC UV-DAD determination of (+)-catechins and (-)-epicatechins in grape seeds of the Babić and Plavac mali varieties

Flavan-3-ols, members of the large family of plant polyphenols, are an ingredient of grapes, in which they can be found as monomers or serving as precusor units for polymer molecules. The most significant flavan-3-ols in grapes are the diastereoisomeric pair: (+)-catechin (3 S) and (-)-epicatechin (3 R)  1 . During maceration of black grapes, only a part of polyphenols from solid sections of grapes  2 is selectively extracted into wine. This paper concerns the performed extraction of flavan-3-ols, under conditions simulating the maceration process, from grape seeds of the autochthonous Croatian varieties of Babić and Plavac mali from two variety-growing areas.  3 . The (+)-catechin and (-)-epicatechin were separated by means of the HPLC method of direct injection, with no prior preparation of the sample, using a reverse-phase column. Identification of the chromatogram was made by means of retention times and confirmed with characteristic UV-Diode Array specters. Spatial chromatograms (218.55-400.26 nm) and UV specters were analyzed, and peak purity was identified. Quantitative identification was carried out by means of calibration curves. It was identified that the mass contents of (+)-catechins (29.95-37.41 mg/kg) and (-)-epicatechins (33.51-44.59 mg/kg) from different positions within the same variety differ significantly in grape seeds of the Plavac mali variety (p<0.01), while the p-value (0.078) of catechin (16.30-36.40 mg/kg) indicates a possible variance in the Babić variety. There are no indications of a possible variance (p=0.639) for epicatechin (35.04-37.35 mg/kg).

(+)-catechin; (-)-epicatechin; grape seed; HPLC-UV-DAD; Babić; Plavac mali

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