Fruit juice concentrate authenticity

Establishing Criteria for Determining the Authenticity of Fruit Juice Concentrates... 

For fruits and their products, HPLC techniques for phenolics have been used to study the effect of processing, concentration, and storage on the phenolic composition of juices as well as a potential precursor for an off-flavor compound in juices. Phenolic analysis has been further applied to the detection of economic adulteration and especially to verify the authenticity of fruit juices. This is especially important when cheaper fruits can be added to more expensive ones in a fraudulent manner. In most fruits, the nonanthocyanin flavonoids consist mainly of flavonols and flavanols, with trace amounts of flavones. Glycosides are the predominant forms present. These most often are separated by reversed-phase HPLC on Cl8 columns with gradients consisting of acidified H20 and ACN, MeOH, or EtOH. 

Fruit juices, whether of natural strength or concentrated, are materials of commerce, to be sold direct or for use in a variety of food and drink applications. It is essential that they conform to legislative requirements for authenticity and purity, whether for labelling purposes (in avoidance of misleading statements), nutritional standards or in respect of food safety in the final product. 

However, it is not just the presence or absence of an element that is useful (as most elements will be present at some concentration), but it is the relative variation in the trace element profile that is the parameter that provides the major discriminatory power. McHard et al. [16] were possibly some of the first researchers to apply a normalization procedure to multielement data in order to maximize the differences between two sets of samples. Their approach, which is now accepted as being a standard tool for use in chemometric investigations, was to identify an element whose concentration was constant, irrespective of the geographical origin of the samples, and then to normalize all other elemental data against it. In McHard s study on fruit juice, they used Zn. The authors of this chapter used Ca in an egg authenticity study, where eggshells were used as the sample matrix (unpublished data) and Mg was used in a study of Welsh onions [14]. 

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