Determination of apple juice authenticity using gas chromatography-mass spectrometry, volt-ampere and new conductometric methods.

Background: Organoleptic properties and positive health effect on consumers both justify the importance of determining apple juice authenticity with respect to retail and wholesale trade networks worldwide.

Results: Adulteration of apple juice through dilution with water, as well as with ascorbic acid, has been determined. It has been demonstrated that polarization curves of a platinum electrode in apple juice are useful for undeclared antioxidant determination, as a result of the movement of the polarization curve to the left, by 200 mV, when ascorbic acid was added. A difference between the equivalent electrical conductivity of suspended solids of undiluted and diluted (1:1) juices has been substantiated as a new quantitative criterion for determining adulteration through dilution. The criterion values range from 0.030 to 0.034 S m for juices of different apple varieties. Gas chromatography-mass spectrometry results have shown the presence of (E)-2-hexenal and n-hexanal in all juices tested obtained from different apple varieties.

Conclusion: A new conductometric method for the determination of diluted apple juices has been substantiated. It has been established that the volt-ampere method is useful for the investigation of undeclared ascorbic acid. © 2018 Society of Chemical Industry.