Microwave-assisted aqueous enzymatic extraction of oil from Isatis indigotica seeds and its evaluation of physicochemical properties, fatty acid compositions and antioxidant activities

A novel and green microwave-assisted aqueous enzymatic extraction (MAAEE) of oil from Isatis indigotica seeds was investigated in the present study. Enzyme cocktail (cellulase/proteinase/pectinase = 1/1/1, w/w/w) was found to be the most effective in releasing the oil. Under the optimal conditions as enzyme concentration 1.82% (w/w), temperature 43 °C, time 83 min and irradiation power 375 W, the highest oil recovery of 59.27% was obtained using the emerging technique. As compared to conventional Soxhlet extraction-derived oil (SEO), MAAEE-derived oil (MAAEEO) revealed the similar physicochemical properties but exhibited better oxidation stability. In addition, MAAEEO had higher contents of valuable polyunsaturated fatty acids, tocopherols and phenolics as against SEO, and it exhibited considerable antioxidant activities with IC50 values 9.58 and 15.03 mg/mL, according to DPPH radical scavenging assay and β-carotene/linoleic acid bleaching test, respectively. Scanning electron micrographs illustrated the severely structural disruptions of sample cell walls and membranes by MAAEE.

► A novel green MAAEE technique is developed for the I. indigotica seed oil extraction.
► MAAEE process with enzyme cocktail is optimized by response contour methodology.
► MAAEE-oil reveals better oxidation stability as against Soxhlet extraction-oil.
► MAAEE-oil has more PUFA, tocopherols and phenolics than Soxhlet extraction-oil.
► MAAEE-oil exhibits stronger antioxidant activity than Soxhlet extraction-oil.