Extraction process, physicochemical properties, and digestive performance of red yeast rice starch

Area of Science:

• Food Science
• Biotechnology
• Nutritional Science

Background:

• Red yeast rice (RYR) is a traditional ingredient with potential health benefits.
• Starch properties influence its nutritional value and digestibility.
• Understanding RYR starch modification is crucial for its food applications.

Purpose of the Study:

• To optimize the extraction process for RYR starch.
• To investigate the impact of solid-state fermentation on RYR starch physicochemical properties and glycemic index (GI).

Main Methods:

• Single-factor experiments and Box-Behnken design for optimizing RYR starch extraction.
• Analysis of physicochemical properties (particle size, light transmittance, solubility, swelling power, amylose/amylopectin content) at different fermentation stages.
• Determination of digestible starch fractions, resistant starch, hydrolysis index, and GI values.

Main Results:

• Optimized extraction yielded 90.077% RYR starch under specific conditions (5 mL/g, 0.075 mol/L NaOH, 3.1 h).
• Solid-state fermentation increased starch particle size, decreased light transmittance, and enhanced solubility and swelling power.
• Fermentation led to increased amylose and resistant starch content, while decreasing amylopectin, fast and slow digestible starch.
• Hydrolysis index and GI values significantly decreased post-fermentation.

Conclusions:

• Solid-state fermentation effectively reduces the digestibility of red yeast rice starch.
• The process enhances beneficial starch fractions like resistant starch.
• Findings provide a basis for RYR starch applications and development.