How Dehydration Temperature and Weight Loss Affect the Biosynthesis of Nutritional Compounds in Irrigated 'Aleatico' Grape

This work studied the effect of three postharvest drying temperatures on the content of nutritional polyphenols in 'Aleatico' (Vitis vinifera L.) grape. The results show that different temperatures can modulate the synthesis of these compounds in grapes and the consequent concentration in wine. A temperature of 20°C was the most effective to induce the formation of nutrtional polyphenols such as catechin, quercetin, and trans-resveratrol up to a weight loss between 10 and 30% depending on the compounds. A temperature of 10°C induced less increments. 30°C stimulated the synthesis of quercetin only. Polyphenols oxidase (PPO) increased in parallel with the increase of catechin at 20°C but not in the other samples. These results open a good perspective for the production of wine or grape juice with high levels of nutritional compounds.