Influence of the skin hardness on the wine-grape dehydration kinetics.

BACKGROUND: Knowledge of the influence of initial mechanical properties on the evolution of the weight loss of berries through the drying process is scarce. Therefore, themain purpose of this work was to investigate the effect of skin hardness at two different physiological stages of off-vine drying kinetics of grapes. Skin hardness was evaluated as the berry skin-break force parameter,measured by the texture analysis test. RESULTS: The decrease of berry weight as a function of the drying time was linear, indicating that the drying rateswere constant within each cultivar studied (Moscato bianco and Erbaluce), and for each ripening stage and berry skin hardness. The drying rates decreased as berry skin hardness increased for the ripest grapes in the cultivars studied. CONCLUSION: The study allowed the assessment of the correlation between the skin hardness of fresh berries and the weight loss determined for different drying days.