Differentiation of Fresh Greek Orange Juice of the Merlin Cultivar According to Geographical Origin Based on the Combination of Organic Acid and Sugar Content as well as Physicochemical Parameters Using Chemometrics

Abstract

The aim of the present study was to differentiate fresh Greek orange juice prepared from the Merlin cultivar according to geographical origin, based on organic acid/sugar content, and physicochemical parameter analysis, using chemometrics. For this purpose, oranges were collected during the harvesting period 2013–2014 from four different regions in Greece where Merlin oranges are produced. The analysis of organic acids and sugars was performed using a modified high pressure liquid chromatographic (HPLC–DAD/RI) method. Applying MANOVA and LDA analysis to the collected data, orange juices were successfully classified according to geographical origin (correct classification rate 83.3%). For validation purposes of the applied model, oranges from the harvesting period 2014–2015 were also collected and new instrumental and chemometric analysis carried out involving orange juice from both harvesting periods. Cumulative results showed that the classification rate remained practically constant, recording a correct classification rate of 80.4%, confirming the discriminatory power of the applied model. In order to further improve the overall classification rate, physicochemical parameter data were subjected to chemometric analysis along with organic acid and sugar content data. Results showed that the combination of organic acids, sugars, and physicochemical parameters somewhat increased the overall correct prediction rate to 82.0%. Present results enhance the potential of multi-parameter analysis for the correct geographical differentiation of Greek fresh orange juice, aiding to product quality and authenticity control.