Evaluation of bioactive compounds in by-products of industrial processing of broccoli

This work was aimed at the recovery of bioactive compounds from by-products resulting from various industrial processing steps of broccoli (Brassica oleracea L. var. Parthenon), namely container-leaves, container-stalks, air separation, bleach, vitreous and calibrator. Aqueous phenolic-enriched extracts were prepared for different temperatures in the range 20 °C to 90 °C and the corresponding total phenolic compounds content and antioxidant capacity were evaluated [1 – 2]. The results obtained for the by-products were compared with those of the fresh broccoli not subjected to processing, including leaves and inflorescences. The highest content in total phenolic compounds (expressed as equivalents of gallic acid on dry basis of by-product, mg GAE/g) were 12.4, 6.0, 13.6, 11.8, 9.2 and 6.5, for the container-leaves, container-stalks, air separation, bleach, vitreous and calibrator, respectively. For the inflorescences and leaves of fresh broccoli the content in total phenolic compounds accounted for 9.5 mg GAE/g and 21.0 mg GAE/g, respectively. The maximum antioxidant capacity estimated by free radical scavenging activity of DPPH^· was observed for the extract from the leaves of the unprocessed broccoli, with an IC50 value of 0.20 mg/mL. On the other hand, the extracts from container-leaves by-product exhibited a significantly lower antioxidant activity, with an IC50 of 0.34 mg/mL. This value is similar to that determined for the extracts of unprocessed broccoli inflorescences. The data obtained allow us to suggest that the industrial by-products derived from the processing of broccoli, are a source of bioactive compounds. Work is in progress in order to study other bioactive compounds such as polysaccharides and glucosinolates.

Acknowledgements: Thanks to FEDER, COMPETE and Fundação para a Ciência e Tecnologia (FCT) for providing financial support to CI&DETS (PEst-OE/CED/UI4016/2014) and to CERNAS (PEst-OE/AGR/UI0681/2014).

Keywords: Broccoli, industrial by-product, antioxidant activity, phenolic compounds.

References:

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