Study of polyamines and their precursor amino acids in Grenache noir and Syrah grapes and wine of the Rhone Valley

Polyamines and their amino acid precursors were determined in Grenache and Syrah grapes and in wines made from these grapes. The compounds analysed were the polyamines putrescine, spermidine, and spermine, in addition to their precursors, ornithine, agmatine and arginine. The analytes were determined by reversed-phase high performance liquid chromatography (HPLC) with fluorescence detection using FMOC (fluorenylmethylchloroformate) as a pre-column derivatising agent Grape clusters were sampled from flowering to full maturity at different developmental stages. In addition, different berry parts were analysed separately from half veraison onwards. It appears that at berryset there is a decrease in the concentration of arginine, whereas polyamine concentrations remain constant at this stage. Concentrations of polyamines increased from must to alcoholic to malolactic fermentation; putrescine was the most abundant in wine (mean concentration after malolactic fermentation, MLF was 4.93 mg/l) followed by spermidine and then spermine (mean concentrations after MLF were 1.84 and 0.17 mg/l, respectively). In three of the four fermentation sites concentrations of all three compounds were greater in Syrah than in Grenache wines. In both varieties, it appears that polyamine biosynthesis occurs preferentially from arginine via agmatine. In all cases, concentrations of polyamines found in these grapes and wines were significantly below the levels typically found in other fermented foods.