Evaluation of Herb and Fruit Juice Adulteration and Authenticity by Coulometric Array detection and Pattern Recognition Analysis

Although the adulteration of herbs and fruit juice is a frequent phenomenon, there are few simple methods available for the screening of large numbers of commercial batches of product. The challenge arises from the complexity and variability of genuine material combined with the unrelenting conduct of adulteration. Herb and fruit variety, growing region, season, ripeness, and processing methods all contribute to the variability of the authentic product, making unambiguous characterization difficult.

Currently, the most reliable and applicable authentication methods are based on analytical chemical fingerprinting (metabolomic) techniques. HPLC with coulometric detection is particularly suitable for generating chemical fingerprint for herb and fruit juices that contains endogenous electroacitive components essential to their flavor, stability, color and aroma. An extension of phytochemical fingerprinting utilize statistical program such as principal-component analysis and pattern recognition to evaluate the authenticity of a given sample by comparing its chromatogram with a compiled population of authenticated reference sample.

We investigated the approach of using HPLC-Coulometric Array detection with pattern recognition software to identify potential oregano herb and fruit juice adulteration. Oregano adulteration by blending with adulterants such as thyme and marjoram, were readily detected. In a second study, fruit juice adulteration using dilutions with another juice, or the inclusion of orange peel/pulp-wash could readily be evaluated using this technique. The specificity of this approach even allows the classification of orange juice samples by varietal and geographical region.