Nutritive Parameters and Antioxidant Quality of Minimally Processed "Cime di Rapa" (Brassica rapa subsp. sylvestris) Vary as Influenced by Genotype and Storage Time

Abstract

In order to assess the quality and performance of bagged broccoli-raab, a recently marketed product, several nutritive parameters were determined in novel hybrid and conventional cultivars at pre- and post-packaging stages in the industrial environment. The characterization of shoots and composing organs at post-cut stage included contents of dietary fibre (DF), glycaemic carbohydrates (GC), antioxidant compounds (ACC) and capacity (AOC), which were determined by chromatographic methods and spectrophotometric assays. ACC and AOC were analysed during shelf life of bagged products. Genotype and storage effects were addressed as variability factors at fixed packaging conditions. Contents of DF and GC (39.64-34.57; 7.56-2.21 g/100 g), glucosinolates (37.47-24.63 mg/g SIN), and ACC (total phenolics: 18.64-14.92 mg GAE/g; flavonoids: 34.74-30.96 mg/g CE; flavonols: 14.62-14.08 mg QE/g), and AOC (Oxygen Radical Absorbance Capacity: 354.62-293.25 µmol/g TE; DPPH• scavenging activity: 59.35-46.14) were lower in shoots of the hybrid than marketed cultivar. In both genotypes, AOC was maximal in leaves, followed by florets and stems. The integrated analyses suggested that the hybrid genotype was better suited for fresh consumption and that increased ratio of florets/leaves vs. stem is expected to raise product antioxidant properties. The comparison of unprocessed and bagged products pointed at a value decay of most parameters except for glucosinolates and correlation analyses supported the necessity of performing multiple antioxidant assays to enhance product quality evaluation. As for shelf life, storage time was the major factor affecting antioxidant properties, while genotype and interaction effects were minimal