Characterisation and classification of pineapple (Ananas comosus [L.] Merr.) juice from pulp and peel

Large quantities of by-products, such as peels and trimmings, emerge during industrial pineapple (Ananas comosus [L.] Merr.) processing. The latter are further exploited by juice extraction. However, the low-quality juices obtained may be marketed as genuine pineapple juice from pulp or be admixed to the latter, thus adulterating the final product. To identify chemical markers, juice was extracted from edible pulp, from flesh adhered to the peel, and from milled peel. The metabolite pattern in the juices was elucidated by HPLC-DAD-(HR)-ESI-MSn. Unsupervised principal component analysis (PCA) and hierarchical cluster analysis (HCA) as well as supervised partial least squares discriminant analysis (PLS-DA) and PLS regression calculated on the basis of physico-chemical parameters and metabolite profiles enabled the distinction between juices from pulp and those from peel, irrespective of the fruit maturity degree. In addition, selected marker compounds were deduced from the multivariate statistics, permitting the unambiguous distinction between pulp and peel juices as well as the three maturity stages assessed.