Effects of carboxymethylation, hydroxypropylation and dual enzyme hydrolysis combination with heating on physicochemical and functional properties and antioxidant activity of coconut cake dietary fibre

The effects of carboxymethylation, hydroxypropylation and dual enzyme hydrolysis combined with heating on some physicochemical and functional properties, and antioxidant activity of coconut cake dietary fibre (CCDF) were studied. Results showed that both the hydroxypropylation and carboxymethylation could effectively improve (p < 0.05) the water retention capacity (WRC), oil retention capacity (ORC), viscosity, alpha-amylase inhibition activity (alpha-AAIR), glucose dialysis retardation index (GDRI), cation-exchange capacity, emulsifying capacity index (ECI) and bile adsorption capacity (BAC) of CCDF. Moreover, the cellulase and hemicellulase hydrolysis combination with heating significantly enhanced (p < 0.05) the soluble dietary fibre content, WRC, emulsion stability, GDRI, alpha-AAIR and BAC of CCDF; but caused decrease in ORC and browning of color. In addition, improvement of total phenol content, Fe2+ chelating ability, ABTS(+)center dot and O-2(-)center dot scavenging activity were obtained in carboxymethylaticted CCDF. These effects were mainly attributed to the composition and structural modifications as evident from SEM, FT-IR and XRD analysis.

Automated summary

Hydroxypropylation and carboxymethylation can improve various properties of CCDF, while cellulase and hemicellulase hydrolysis combined with heating can increase soluble dietary fiber content but decrease oil retention capacity. Carboxymethylated CCDF also shows improved total phenol content and antioxidant activity.