Antioxidant properties of minimally processed endives and escaroles vary as influenced by the cultivation site, cultivar and storage time

The influence of cultivar (CV), growth site (GS) and storage time (ST) on the quality of minimally processed endives was investigated by targeting curly and smooth-leafed cultivars, which were grown in two planting areas (Fiumicino and Fucino) and bagged in modified atmosphere at fixed conditions. The changes of antioxidant properties were examined at one and seven days post-packaging by measuring both contents of total flavonols (Fol), flavonoids (Fid), carotenes (Car) and chlorophylls (Chl) and the antioxidant capacity (AOC) through chemical (ORAC) and erythrocyte-based methods (CAA-RBC and hemolytic assays). Referring to one day of storage, curly types differed from smooth ones due to the total contents of Fid (341.0-891.7 vs 312.3-572.3 mg kg−1 CE), Fol (312.0-452.7 vs 194.3-520.3 mg kg−1 QE), Car (72.4-110.5 vs 7.3-38.8 mg kg−1) and Chl (342.7-824.6 vs 276.5-490.4 mg kg−1). CV and GS majorly affected the content variation, whilst ST did not exert any impact on the amounts of pigments (Chl and Car). As for the AOC at one day post packaging, curly and smooth endives respectively showed ORAC mean values of 5045± 2287 and 4822 ± 573 mmol kg−1 TE, CAA-RBC units of 27.5 ± 5.4 and 21.1 ± 2.6 μmol kg−1 QE, and hemolysis percentage of 62.5 ± 5.9 and 57.9 ± 10.9. The three factors acted on the AOC variation at the single level and CV x GS was the most affecting interaction. The ORAC values showed positive correlations with Fid, Fol and Chl contents as well as those of CAA-RBC vs Fid and pigment amounts, while only the Fol raise agreed with increased anti-hemolytic effects. Positive correlations among the AOC assays were significant just for ORAC vs CAA-RBC units. Finally, the principal component analysis clearly pointed at the curly types from Fiumicino as bearing the highest antioxidant quality.