Fac-simile Scheda Linee di Ricerca - Federalimentare

Parole chiave- essiccamento uva- water stress- polifenoli, antocianine- composti volatili del vinoDati pubblicati inerenti il tema di ricerca:1. Costantini, V., Bellincontro, A., De Santis, D., Botondi, R., Mencarelli, F. (2006) Metabolicchanges of Malvasia grapes for wine production during postharvest drying. Journal of Agriculturaland Food Chemistry 54: 3334-3340.Malvasia (Vitis vinifera L.) grapes were harvested at 17.8% of soluble solids content (SSC) and placed inside aninnovative dehydration room where temperature, relative humidity, and air flow were maintained, respectively, at15 °C, 40%, and 1-1.5 m s-1. Weight loss of bunches reached _33% in 29 days. SSC increased inversely proportionallywith the weight decrease, reaching at the end of experiment 23%. Abscisic acid (ABA) increased rapidlyfrom around 29 to 80 íg g-1 of dry weight at 11.7% of bunch weight loss and then declined gradually. Lipoxygenase(LOX) showed the same behavior as ABA, whereas alcohol dehydrogenase (ADH), read in the way ofethanol oxidation, increased continuously when the weight loss reached _19.5%. In parallel with the activity ofLOX, C6 compound [hexanal, hex-1-enol, (E)-hex-2-enal] concentrations reached a peak at 11.7% of weightloss, whereas ethanol and acetaldehyde increased with the increase of ADH and successivelydecrease and ethylacetate increased. Proline increased initially as ABA and successively with the increase of ADH, 5.3-fold increaseversus 4.2-fold increase of proteins. Postharvest dehydration of Malvasia grapes shows a biphasic pattern:a first metabolic stress response up to 11.7% of bunch weight loss and a second stress response beyond 19.5% ofweight loss. The metabolic mechanism of these postharvest water stress responses is discussed.2. Bellincontro A. Fardelli, D. De Santis, , R. Botondi and F. Mencarelli (2006) Postharvest Ethyleneand 1-MCP Treatment both Affect Phenols, Anthocyanins, and Aromatic Quality ofAleatico Grapes and Wine. Australian Journal of Grape and Wine Research 12: 141-149.Aleatico grapes (Vitis vinifera L. cv. Aleatico) picked at 20.4–20.6°Brix were treated with air containing 500mg/L ethylene for 15 h, or 1 mg/L 1-MCP (1-methylcyclopropene) for 15 h, or 1 mg/L 1-MCP for 15 h + 500mg/L ethylene for further 15 h, or air (control). All treatments were imposed at 20°C and 95–100% relative humidity.Samples undergoing treatment were then held in air at 20°C and 85% relative humidity for 13 days. Ethyleneproduction from ethylene-treated grapes was very high (25 µL/kg.h) immediately after treatment, and declinedprogressively until day 6; 1-MCP-ethylene-treated grapes showed lower ethylene production (10 µL/kg.h).This high ethylene production was mainly due to in-out diffusion of ethylene absorbed during the treatment, but apotential effect of 1-MCP is postulated, since 1-MCP-treated grapes did not show ethylene production for 2 daysafter treatment, whereas control grapes produced constant amounts (3–4 µL/kg.h) of ethylene. After day 6, nosignificant difference was observed among samples. No difference in respiration was revealed. Total phenolswere increased significantly by ethylene treatment from 520 mg/L up to 710, while total anthocyanins were lostin air-treated samples (from 175 mg/L to 120) and remained constant in ethylene and 1-MCP-treated grapes.HPLC analyses of anthocyanins confirmed this result: air-treated samples lost anthocyanins rapidly while thisloss was delayed in gas-treated samples. Terpenols, esters, alcohols, and C6 compounds were increased by ethylenetreatment. Conversely, 1-MCP-treated grapes showed a significant loss of terpenols and esters, althoughmaintaining alcohols, especially hexan-1-ol. Berry pathology was also affected, with 1-MCP and 1-MCPethylenetreated grapes hosting a diffuse attack of grey mould. Wine analyses revealed higher concentrations of phenolsand anthocyanins in wine from ethylene-treated grapes, although aromatic compounds were lost, and thus thearoma profile of those wines was diminished.SISTAL - SOCIETA’ ITALIANA DI SCIENZE E TECNOLOGIE ALIMENTARIDipartimento di Scienze e Tecnologie Agroalimentari, Università degli Studi della TusciaVia San Camillo de Lellis, 01100 ViterboTel.: 0761- 35 74 94/7 , Fax: 0761- 35 74 98, e-mail: mmoresi@unitus.it481