Abstract
The physical and chemical composition of grape juice can vary depending on the type of cultivar, variety, climate, soil and other factors. Due these variations, a mixture of species (blend) is used for the preparation of juices as an alternative to maintain the balance between soluble solids and acidity, as well as visual aspects (color). Grape juice has a high concentration of phenolic compounds that are responsible for different biological activities, including the antioxidant activity. The objective of this study was to quantifying the total polyphenol and resveratrol content in the juices produced from the mixture of varieties of organic grapes and conventional grapes, as well as with respect to the expiration date. Quantification of phenolic compounds and resveratrol was carried out by spectrophotometry and highperformance liquid chromatography (HPLC), respectively. The content of phenolic compounds in juices produced from the blend were twice as large compared to the polyphenol content in the juice produced only with Isabel grape. Resveratrol content resulted in a decrease with increasing storage time, indicating a possible degradation over these one. However, the content of resveratrol may be a delay control indicative of validity grape juices. The mix of species for organic grape juice production is very interesting to obtain a differentiated product content of phenolic compounds, which considered as sources of compounds with biological activity.