Antioxidant activity of fermented broccoli and spinach by Kombucha culture

Broccoli (Brassica oleracea L.) and spinach (Amaranthus spp.) are vegetables that known to have many benefit for health. Previous studies on the fermentation of those vegetables using kombucha cultured showed increase in bioactive components such as total polyphenol content. The current studies was performed to evaluate the antioxidant activity of fermented spinach and broccoli before (feed) and after treatment with filtration (retentate and permeate). Filtration was conducted using Stirred Ultrafiltration Cell (SUFC) with UF membrane 100,000 MWCO mode at fixed condition (stirred rotation 300 rpm, room temperature, pressure 40 psia). Antioxidant evaluation was conducted using 2,2-diphenyl-1-picril hydrazyl (DPPH) free radical scavenging activity assay. The results showed that all samples from fermented broccoli showed antioxidant activity (feed 15.82% inhibition and retentate 15.29% inhibition), with the best antioxidant activity was obtained from permeate (75.98% inhibition). Whereas from fermented spinach only permeate showed antioxidant activity (21.84% inhibition) and it significantly lower than broccoli permeate. The mass spectrum of LCMS analysis on broccoli samples showed the present of several mass spectrum with (M+H) range from 148.1 to 442.5 in feed, retentate and permeate. In those samples (M+H) 360.4 always has the highest relative intensity. These results suggest that fermented broccoli has potential for development as functional drink for the source of antioxidant and the permeate obtained from filtration treatment significantly increased the antioxidant activity.