Physicochemical and Morphological Changes in Long-Grain Brown Rice Milling: A Study Using Image Visualization...

Area of Science:

• Food Science and Technology
• Agricultural Engineering
• Materials Science

Background:

• The milling process is crucial for transforming brown rice into edible white rice.
• Understanding the impact of milling on rice quality is essential for optimizing processing and consumer satisfaction.

Purpose of the Study:

• To evaluate the physicochemical and appearance changes in long-grain rice during milling.
• To investigate the effects of grinding on rice quality using advanced imaging and analytical techniques.

Main Methods:

• Employed flatbed scanning, scanning electron microscopy (SEM), X-ray micro-computed tomography (micro-CT), low-field nuclear magnetic resonance (LF-NMR), and headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS).
• Analyzed changes in milling degree, broken rice rate, whiteness, nutrient content (dietary fiber, vitamin B1), surface morphology, and volatile compounds.

Main Results:

• Milling increased broken rice rate (50.84%) and whiteness (21.13%), while reducing dietary fiber (54.41%) and vitamin B1 (66.67%).
• Visualizations showed cortex removal, reduced thickness, and a smoother, shinier surface.
• LF-NMR revealed shifts in T2 relaxation times.
• Identified 31 flavor compounds, with volatile concentrations changing based on milling stage and bran layer reduction.

Conclusions:

• Milling significantly alters the physicochemical properties and appearance of long-grain brown rice.
• Image processing techniques provide valuable insights for optimizing milling parameters to enhance rice quality and flavor.