Drying kinetics, physico-chemical properties, antioxidant activity and phenolic composition of foam-mat dried germinated rice bean ( Vigna umbellata) hydrolysate.

This research was aimed to study physico-chemical properties and antioxidant activities of foam-mat dried germinated rice bean ( Vigna umbellata) hydrolysate. Germination led to an increase in released phenolic content and antioxidant activity ( DPPH radical scavenging activity and FRAP) of rice bean hydrolysate. The hydrolysate obtained from germinated rice bean ( GRB) and non-germinated rice beans ( NGRBs) was foam-mat dried at 60 and 70 °C. Semi-theoretical and empirical model could suitably describe the drying characteristic of foamed bean hydrolysate. Total phenolic content and antioxidant activities of foam-mat dried samples decreased with increasing air-drying temperature ( P ≤ 0.05). Gallic acid, catechol and epicatechin were major phenolic compounds in foam-mat dried samples prepared from both GRB and NGRB. The higher phenolic content and antioxidant activities were found in foam-mat dried hydrolysate of GRB. Electron spin resonance spectrometry revealed that foam-mat dried rice bean hydrolysate showed a strong ability to scavenge free radicals, especially carbon-centred radicals. [ABSTRACT FROM AUTHOR]