Apple (Malus domestica Borkh.) is one of the most used fruit for beverages in Romania. The goal of the study was to evaluate the antioxidant activity and discrimination of various parts of organic and non-organic apple varieties cultivated in the western region of Romania using the DPPH kinetics-PCA (principal component analysis) approach. Organic and non-organic apples were subjected to solid-liquid ethanol extraction. Core and shell extracts were mixed with DPPH· and spectrophotometrically monitored at 517 nm. Antioxidant activity and mean DPPH· reaction rate at various time ranges reveal significant differences between organic and non-organic samples, as well as apple parts. Organic core and shell extracts had higher antioxidant activities than the corresponding non-organic samples (74.5-96.9% and 61.9-97.2%, respectively, 23.5-94.3% and 59.5-95.5%). Significant differences were observed for the DPPH· reaction rate for the first ½ min, especially in the presence of organic core extracts (3.7-4.8 μM/s). The organic samples were well discriminated by DPPH· kinetics-PCA, the most important variables being the DPPH· reaction rate for the first time range. This is the first DPPH· kinetics-PCA approach applied for discriminating between organic and non-organic fruits and can be useful for evaluating the quality of such type of fruits.
Keywords: DPPH·kinetics; Malus domestica Borkh.; antioxidant activity; apple; mean DPPH· reaction rate; organic and non-organic orchards; principal component analysis discrimination.