Spanish researchers uncover common signs of potential grape and peach juice adulteration.
Because of its high price and short harvest season, pomegranate is occasionally adulterated at the supply level. Actually, it’s often adulterated at the supply level. According to domestic supplier POM Wonderful (Los Angeles), pomegranate juice imports were so often adulterated last year that FDA placed an “Import Alert” on several suppliers.
In order to help concerned juice manufacturers, Spanish researchers are analyzing the nutrient changes that occur when pure pomegranate juice is mixed with commonpomegranate juice adulterants, namely peach juice and grape juice. Peach juice and grape juice are relatively cheap ingredients in Spain and presumably other countries, but researchers at the Miguel Hernandez University of Elche say these juices are used to adulterate pomegranate for different reasons. Peach juice can make pomegranate juice taste sweeter and less astringent, and grape juice can mimic pomegranate juice’s deep red color.
Hoping to improve everyone’s ability to detect potential adulteration, the Spanish researchers analyzed pomegranate juice from two popular cultivars-a 4:1 ratio of “Mollar de Elche” and “Wonderful”-and compared resulting nutrient levels to those of the same juice mixed with peach juice or grape juice. By quantifying a broad range of minerals, organic acids, sugars, and other compounds present, the researchers settled on a few observations that could, in many cases, signal potential adulteration.
Minerals: Potassium is the most abundant mineral in pomegranate juice, so low levels of potassium (and high levels of less abundant minerals such as iron and copper) may indicate adulteration. But while juice with potassium content lower than 2000 mg L-1 is “highly suspicious” of being adulterated, the researchers acknowledge that a low potassium content alone is not enough to confirm adulteration.
Organic acids: Citric and malic acids are the predominant organic acids in pomegranate juice, whereas tartaric acid makes up more than 50% of acids in grape juice. Any detection of tartaric acid in pomegranate juice beyond trace levels may indicate adulteration.
Sugars: Even though pomegranate and grape share similar sugar profiles (primarily fructose and glucose) peach juice has a completely different sugar makeup. With peach, sucrose is the predominant sugar. But high sucrose content may also suggest presence of another common adulteration, which is sugar cane.
Proline: Addition of grape or peach juice will likely result in important increases of proline content.
The researchers used an AIJN Reference Guide for pomegranate juice to corroborate their findings.
POM Wonderful, which creates pomegranate products from the Wonderful cultivar used in the study, is pleased to see this kind of research taking place in support of an honest marketplace.