Phlorizin and sorbitol in Vitis labrusca grape juices

Abstract

In Brazil, grape juice is a not fermented beverage, made from Vitis labrusca varieties and their hybrids. The most common form of adulteration is by the addition of apple juice. The adulterated samples can be identified by specific analysis, since apple juice has some compounds that grape has not. A more simplified and assessible way to determine this kind of adulteration is the phlorizin analysis by high performance liquid chromatography (HPLC). Phlorizin is a phenolic compound that has been used to identify adulterations in juices. Besides phlorizin, it can be seen that adulteration by quantifying the levels of sorbitol, present in apples, but absent in healthy grapes. The content of this compounds in grape juices can vary due to the variety of grape and harvest.This study aimed to analyze phlorizin and sorbitol, in 141 experimental samples of Vitis labrusca grape juices, harvest 2016, of 9 varieties and 43 commercial samples (different vintages). The experimental juices from red grapes showed higher sorbitol content than the white grapes. For sorbitol analysis, the juices of Ives differed statistically of the juices of: Isabella, Concord, Niagara Branca and White Muscat. It was detected the presence of apple juice in 5 commercial grape juices.