Effects of honey types and heating treatment on the textural, thermal, microstructural, and chemical properties of glutinous rice flour gels

Hardening issue in starch-based products that arises during storage, is ascribed to the long-term starch retrogradation which involves the recrystallisation of amylopectin. Present study aimed to delay storage hardening with the addition of high diastase honey bee honey (HBH) and low diastase kelulut bee honey (KBH) into glutinous rice flour (GRF) gels. As compared to KBH, retardation of texture deterioration by HBH was more prominent as evidenced by the significantly (p < .05) lowest hardness and rate of hardening of GRF gel added with HBH (honeygel) throughout the 7-day storage. Heated honey and sugar solution did not reduce gel hardness that gel weakening was associated to the naturally occurring diastase in raw honey. Hence, only conventional GRF gel (congel), GRF gel added with KBH (kelugel) and honeygel were assessed for intrinsic viscosity, thermal, microstructural and chemical properties. The results were substantiated by the significantly (p < .05) lowest intrinsic viscosity (62.93 mL/g) and thermal enthalpy (333.7 J/g) of honeygel. A weak gel network structure was illustrated in honeygel with the significantly (p < .05) highest pore diameter (125.27 μm). In conclusion, the GRF gel has successfully demonstrated the potential of honey diastase in inhibiting the long-term retrogradation which could solve the industrial real problem.

Keywords: anti-staling; diastase; glutinous rice flour; kelulut bee honey; raw honey.