A novel approach to quality and authenticity control of fruit products using fractionation and characterisation of cell wall polysaccharides

Cell wall polysaccharides were investigated for their suitability as markers for quality and authenticity control of fruit products. For this purpose, the alcohol-insoluble residue (AIR) was fractionated into water-, oxalate-, acid-, and alkali-soluble pectins, hemicellulose and cellulose. Neutral sugars of each fraction were determined by capillary zone electrophoresis. Particular attention was given to strawberries and cherries of different cultivars, proveniences, and stages of ripening, whereas preliminary investigations were also conducted on apples. Within the respective fruit species, characteristic neutral sugar profiles of the AIR fractions were found, which may be used for the differentiation of fruit products devoid of carbohydrate-based hydrocolloids, e.g. purees. Furthermore, the isolated hemicellulose fraction not only allowed the detection of admixtures of non-declared fruits on the basis of the monosaccharide composition. Even more important, since the content of the hemicellulose fraction proved to be constant in the AIR, its determination provided promising perspectives for calculating the fruit content of complex products such as fruit preparations, jams and spreads.