Abstract
The postharvest dehydration process is a technique which can help to increase polyphenols concentration as well as to modify the VOCs (volatile organic compounds) panorama of berry. Cesanese wine grape was dehydrated off-vine at 10°C, 45% relative humidity (RH), and an air flow of 1.5 m/sec. Sampling was performed every week for 6 weeks, until it reached 37% of mass loss (M.L.). PAs (proanthocyanidins) in seeds increased progressively on both fresh and dry weight basis during dehydration until 30% M.L.. Total polyphenols extracted from the epicarp measured on a f.w. basis increased during dehydration. A similar pattern was shown by anthocyanins. As regards VOCs, a high prevalence of benzenoids followed by nor-isoprenoids, terpenols, and C6 compounds was observed. Benzenoids were more localized in the mesocarp than in the epicarp [7352 μg/kg d.w. (dry weight) vs. 3312 μg/kg d.w.] as were nor-isoprenoids. In contrast, as expected, terpenols were concentrated in the epicarp (1787 μg/kg d.w. vs. 1370 in the mesocarp). During dehydration, a significant decrease was observed in these compounds in the mesocarp and a parallel increase in the epicarp, especially concerning benzyl alcohol and 2-phenylethanol among the benzenoids, and vomifoliol and 3-OH-β-damascone among the nor-isoprenoids. Diendiol1, geraniol, and trans-8-OH linalol in the mesocarp decreased progressively during dehydration, while the same compounds, present in the epicarp, increased. C6 increased significantly in the epicarp. Beside an epicarp biosynthesis of VOCs during postharvest dehydration, a mass transfer of VOCs from the mesocarp to the epicarp might occur.
- ©2014 by the American Society for Enology and Viticulture
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