DETECTION OF ADULTERATION IN ORANGE JUICES BY A NEW SCREENING METHOD USING PROTON NMR-SPECTROSCOPY IN COMBINATION WITH PATTERN-RECOGNITION TECHNIQUES

This paper describes the application of proton NMR spectroscopy as a s creening tool for the determination of the authenticity of orange juic es. Principal component and discriminant analyses were used to discrim inate between authentic and nonauthentic (suspect) samples. In one set of profiles, additions of sucrose, beet medium invert sugar, sodium b enzoate could easily be detected. In another set of data, K-nearest ne ighbor classification based on the principal component scores was used to correctly classify at least 94% of samples known to deviate from a uthentic samples when measured with analytical techniques such as high pressure liquid chromatography and atomic absorption spectroscopy. Pr incipal component loading plots and factor spectra were an effective t ool in the interpretation of the differences between the profiles.