Postharvest induction modeling method using UV irradiation pulses for obtaining resveratrol-enriched table grapes: a new "functional" fruit?
A modeling method for the induction of resveratrol synthesis by UV irradiation pulses in Napoleon table grapes is proposed. The method is based on the combination of four main parameters: irradiation power (IW), irradiation time (IT), irradiation distance (ID), and number of elapsed days to achieve the highest resveratrol accumulation (D(m)). Maximum resveratrol content (11-fold higher than untreated grapes) was achieved using the combination: IW = 510 W, IT = 30 s, ID = 40 cm, and D(m) = 3 days. Sensory characteristics and main features of irradiated grapes (color, weight, firmness, flavor, size, ripening index and vitamin C content) remained unaltered after 1 week of storage. UV induction signal migrated to the hidden side of the grape skin with a delay of 3 days as compared to the directly irradiated side. Phenolic compounds were not detected in Napoleon grape flesh. Resveratrol content per standard serving (200 g) of irradiated grape was about 3 mg, an amount more than 10-fold higher than that of untreated Napoleon grapes. This means that a serving of irradiated grape (unpeeled) could supply the resveratrol content equivalent to 3 glasses of a red wine with high resveratrol content ( approximately 1 mg/glass). Therefore, controlled UV irradiation pulses are useful as a simple postharvest treatment (and alternative to genetic engineering) to obtain possible "functional" grapes (with enhanced health-promoting properties) as a dietary source of high resveratrol content.
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Laboratorio de Fitoquímica, Departamento Ciencia y Tecnología de Alimentos, CEBAS-CSIC, P. O. Box 4195, 30080 Murcia, Spain.
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Tomás-Barberán
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D000872:Anthocyanins / Q000032:analysis; D001205:Ascorbic Acid / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D005524:Food Technology; D006293:Health Promotion; D007700:Kinetics; D008962:Models, Theoretical; D010636:Phenols / Q000302:isolation & purification; D000077185:Resveratrol; D012677:Sensation; D013267:Stilbenes / Q000032:analysis / Q000378:metabolism*; D014466:Ultraviolet Rays; D027843:Vitis / Q000737:chemistry / Q000378:metabolism* / Q000528:radiation effects*
D000872:Anthocyanins; D010636:Phenols; D013267:Stilbenes; D001205:Ascorbic Acid; D000077185:Resveratrol