RESUMO
Carotenoid compounds in wine grapes (Chardonnay, Merlot, Primitivo, Negroamaro) grown in Apulian region were investigated by chromatographic and spectrometric analyses. Cis-isomers of lutein and beta-carotene (9Z, 9'Z-lutein and 9Z-beta-carotene) and 5,6-epoxyxanthophylls were detected: 9'Z-neoxanthin, violaxanthin, and 5,6-epoxylutein. Moreover, zeaxanthin was efficiently resolved from lutein by a selective factor > 1 (alpha= 1.06) and was found in high amounts (50 to 300 microg/kg) in the grape extracts analyzed in 3 y of study (2006 to 2008). At grape maturity, beta-carotene had concentration approximately 2-to 4-fold higher than (all-E)-lutein in all varieties. Because carotenoids are potential precursors of aroma compounds, it was determined carotenoids change DeltaC (microg/kg), from the difference of total carotenoids concentration between veraison and maturity. Chardonnay and Merlot had the highest DeltaC values and principal component analysis showed that they were characterized by 5,6-epoxyxanthophylls derivatives and zeaxanthin, lutein, and beta-carotene derivatives, respectively. An important effect of vintage on DeltaC values in the analyzed grapes was also observed. A strong positive correlation was determined between DeltaC and temperature data that seem to be responsible for the difference of DeltaC in the Chardonnay and Merlot compared to the Primitivo and Negroamaro varieties.