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 ( NGRB s) 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.