Quality assessment of fruit juices by NIR spectroscopy

In the article there is described the detection of substances used for adulteration of fruit juices. They were investigated in juice products distributed within the network of retail markets. This detection was performed using the method of near-infrared spectroscopy (NIR). There were analysed samples of orange juices, apple juices, and grapefruit juices. At the beginning, there were assessed quality parameters (soluble dry matter, total acids, formol number, malic acid, citric acid, ascorbic acid, lactic acid, specific density, and ethanol content) and their compatibility with the limit values specified by the Association of the Industries of Juices and Nectars. The research covered 45 kinds of fruit juices and there was found 10 cases when at least one parameter was out of the approved limits. After that there was used the discrimination analysis and it enabled to separate pure juices from those containing at least 1 % of admixtures. This method also helped to distinguish between the group of fresh squeezed juices and the juices made of fruit concentrates. Using the diagnostics "Principal Component Scores 3D Display", there were arranged various numbers of similar groups of juice samples with similar compound profiles.