The bottle of pomegranate juice may not be as pure as you think, cautions a scientist.
Cynthia Larive, a professor of chemistry, is applying chemical tests to juice products sold as pomegranate juice or pomegranate juice blends, in order to authenticate their contents.
"We are measuring levels of unique compounds in pomegranate juice and are able to use this 'molecular fingerprint' to discriminate against adulterated juice products," said Larive.
Larive and her Daniel Orr are measuring levels of different biochemicals, called small-molecule metabolites, present in juices.
To make their measurements, the researchers are using nuclear magnetic resonance spectroscopy, liquid chromatography-mass spectroscopy, and gas chromatography-mass spectroscopy - three methods that together allow them to measure amino acids, organic acids, sugars, pomegranate pigment compounds, as well as health-producing antioxidant molecules that are unique to pomegranate juice.
"We have received a collection of pomegranate samples from around the world, as well as commercial juices such as beet, grape, apple and pear - to name just a few.
"We're looking at whether or not our molecular fingerprint method can be used to identify products claiming to contain pomegranate juice when they don't, and products claiming to be pomegranate juice when they are not," said Larive.ccording to Larive, the three methods her lab used on pomegranate juices can be used to authenticate other products such as wine and olive oil by checking whether their metabolite profiles match what the products are claimed by their manufacturers to be.
Larive explained that by examining the levels of different compounds in, say, pomegranate juice, a statistical picture - or chemical profile - emerges that describes the juice.
Then, depending on how much an unknown product's profile differs from the pomegranate juice profile, her lab can determine whether that unknown product is pomegranate juice or contains only some or none of it.