Reducing starch digestibility of white rice by structuring with hydrocolloids

Area of Science:

• Food Science
• Biochemistry
• Materials Science

Background:

• High glycaemic index foods like white rice are linked to obesity and type-2 diabetes.
• Controlling starch digestion is a key strategy for mitigating these health risks.
• Hydrocolloids are explored for their potential to modulate starch hydrolysis and glucose release.

Purpose of the Study:

• To investigate the efficacy of various hydrocolloids in modifying white rice starch digestibility.
• To further explore the potential of low acyl gellan gum (LAG) in controlling starch digestion.
• To elucidate the mechanism by which LAG affects starch digestibility and bolus breakdown.

Main Methods:

• Screening of multiple hydrocolloids for their effect on in-vitro starch digestibility of white rice.
• Detailed investigation of low acyl gellan gum (LAG) at 1% concentration.
• Analysis using Scanning Electron Microscopy (SEM) to observe structural changes.
• Simulated gastric and intestinal digestion studies to assess bolus breakdown and enzymatic hydrolysis.

Main Results:

• Low acyl gellan gum (LAG) significantly reduced the in-vitro estimated Glycaemic Index of white rice by approximately 20%.
• SEM revealed a protective gel-like layer on LAG-treated rice grains.
• LAG-treated rice exhibited slower bolus breakdown in simulated gastric conditions and reduced susceptibility to enzymatic hydrolysis in intestinal conditions.
• LAG strengthened in acidic environments, enhancing its effect on digestion control.

Conclusions:

• Low acyl gellan gum (LAG) demonstrates significant potential for controlling starch digestion kinetics in white rice.
• The mechanism involves the formation of a protective surface layer that hinders bolus breakdown and enzymatic hydrolysis.
• LAG's properties suggest its utility in developing functional foods for managing metabolic health conditions.