Microwave-assisted aqueous two-phase system based extraction of phenolics from pulses: Antioxidant properties, characterization and encapsulation

In the current study, a microwave-assisted aqueous two-phase system (MA-ATPS) was examined for the extraction of phenolic compounds from green lentils, chickpeas, and dry beans. The recovery of phenolic compounds by MA-ATPS was optimized by response surface methodology (RSM). A comparative study was performed by conventional ATPS (C-ATPS) and classical mono-phase extraction (C). The DPPH scavenging activity, ABTS antioxidant activity, and metal chelating activity of the extracts were determined. The highest extraction yield (6.68, 2.10, and 1.69 mg GAE/ g sample for green lentil, chickpea and dry bean, respectively) and antioxidant properties (70.98, 7.60, and 9.68 μmol TE/g for DPPH scavenging activity for green lentil, chickpea, and dry bean respectively) were observed from the extracts obtained by MA-ATPS. Furthermore, the phenolic extracts were encapsulated by freeze-drying and the structural characterization of microcapsules has been performed by Fourier Transform Infrared (FT-IR) spectrometry and Scanning Electron Microscopy (SEM). The releasing profiles of the encapsulated phenolic compounds were investigated. Additionally, the effects of extracts on oxidative stability on sunflower oil under accelerated storage conditions were assessed. The results of the present study proved that the MA-ATPS might be considered as an efficient environment-friendly method for extraction phenolic compounds from pulses as evidenced by the antioxidant activity of extracts. Moreover, the encapsulated phenolic extracts may serve as an alternative ingredient for the food industry to be used in various functional formulations potentially leading to an increase in the value of green lentil, chickpea, and dry bean and possibly their by-products.