Detection of addition of apple juice in purple grape juice

•Methods for detection of apple juice in purple grape juice.•Methods of analysis of phlorizin and sorbitol were validated.•The analysis of sorbitol and phlorizin were effective to detect the adulteration of grape juice with apple juice.•Among the 39 samples of commercial grape juice analyzed, four were adulterated.

Due to increasing grape juice consumption, quality control is a reality in all countries which produce and consume this product. The most common form of adulteration is by substituting grape juice with apple juice. The adulterated samples can be identified by specific analysis, since apple juice has some compounds that grape has not. There are many studies about the phlorizin and sorbitol content in wines, but in grape juice they are scarce. Therefore, analytical methods to identify the composition of grape juices and determine their authenticity are needed to ensure quality control. The present study aimed to the validation and application of analytical methods for the determination of phlorizin and sorbitol, to detect the addition of apple juice in purple grape juice, by high-performance liquid chromatography. Initially, the methods were validated and tests were conducted by additions of percentages of apple juices in grape juices. Finally, experimental and commercial grape and apple juices were analyzed. Our study found that both methods are effective in detecting the addition of apple juice in grape juice. Four of the 39 commercial grape juices analyzed showed adulteration by the addition of apple juice in grape juice.