Evaluation of broccoli (Brassica oleracea var. italica) crop by-products as sources of bioactive compounds

Abstract

This study was performed to evaluate different by-products of broccoli (Brassica oleracea var. italica) production (leaf, inflorescence and stem) as sources of valuable bioactive compounds, considering different cultivars and states of maturation. The total phenolic and chlorophyll contents as well as the antioxidant, ACE-inhibitory and antimicrobial activities were quantified from the ethanolic extracts of the different broccoli tissues at two different maturation stages from five cultivars (‘TSX 007′, ‘Monaco’, ‘BRO 2047′, ‘Parthenon’ and ‘Summer purple’). The major compounds in ethanolic extracts were identified by HPLC-UV-ESI-MS/MS, whereas chlorophylls were determined by UV–vis spectrometry. The leaf extracts showed the highest antioxidant activities and were the best sources of chlorophylls and phenolic compounds, constituting mainly kaempferol and quercetin glucosides. These compounds were more abundant in extracts from the ‘Summer Purple’ variety and commercial state. Glucosinolates were more abundant in the inflorescence extracts, principally in the flower bud state. The stem and inflorescence extracts, mainly from the ‘TSX 007′ variety, showed a strong inhibitory effect on the three bacteria studied (Bacillus cereus, Staphylococcus aureus and Listeria innocua), which was related to a higher concentration of fatty acid derivates. The findings suggest that broccoli by-products are useful and value-added products as sources of bioactive compounds, providing a sustainable alternative to reduce residues from this crop.