Optimization of paddy parboiling process for higher starch crystallinity by response surface methodology

Area of Science:

• Food Science
• Materials Science
• Agricultural Science

Background:

• Paddy parboiling improves nutritional value, milling quality, head rice yield, and insect resistance.
• Lower starch crystallinity in parboiled rice leads to fungal infestation and suboptimal resistant starch content.
• Improving starch crystallinity is crucial for creating slow-digestible parboiled rice with reduced enzyme accessibility.

Purpose of the Study:

• To investigate the impact of controlled cooling on starch crystallinity in parboiled rice.
• To optimize parboiling processing conditions for enhanced starch properties.
• To evaluate the effect of processing on rice's water absorption and digestibility.

Main Methods:

• Experimental data were fitted to quadratic second-order polynomial models.
• Independent factors included pH, steaming time, cooling temperature, and cooling time.
• Starch crystallinity and reorganization were evaluated using X-ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FTIR), and Visible spectroscopy.

Main Results:

• Controlled cooling of parboiled paddy significantly increased crystallinity percentage.
• Optimal processing conditions led to better starch reorganization, as evidenced by XRD, FTIR, and Visible spectrum analysis.
• Optimally processed parboiled paddy exhibited reduced water absorption and lower sediment values, indicating enhanced crystallinity.

Conclusions:

• Controlled cooling is an effective method for improving starch crystallinity in parboiled rice.
• Enhanced starch crystallinity imparts desirable properties such as slow digestibility and improved storage stability.
• Optimized parboiling techniques offer a pathway to higher-quality parboiled rice with increased resistant starch content.