Rice Milling and processing: Step by Step production

Rice milling is a crucial post-production step that transforms raw paddy into the edible, white rice kernels we consume daily. The primary goal of a rice milling system is to efficiently remove the husk and bran layers, ensuring a sufficiently milled product free of impurities. This comprehensive guide will take you through the step-by-step process of rice milling, exploring the techniques, compositions, and guidelines that contribute to producing the highest quality rice.

The Composition of Rice Kernels

Understanding the composition of rice kernels is fundamental to the milling process. Most rice varieties consist of approximately 20% rice hull or husk, 11% bran layers, and 69% starchy endosperm, collectively referred to as the total milled rice. In an ideal milling process, these components result in fractions of 20% husk, 8−12% bran, and 68−72% milled rice or white rice, depending on the variety. The milled rice comprises whole grains (head rice) and brokens, while the by-products include rice hull, rice germ, bran layers, and fine brokens.

The Rice Milling System

The rice milling process can be a simple one or two-step process or a multi-stage process, depending on the desired outcome and market requirements. These processes include:

1. One Step Milling:
   • Husk and bran removal in a single pass.
2. Two Step Process:
   • Separately removing husk and bran.
3. Multistage Milling:
   • Applicable for local consumption or commercial marketing.
   • Involves several processing steps, including pre-cleaning, dehusking, paddy separation, whitening, grading, mixing, mist polishing, and the final weighing of rice.

Guidelines for Good Rice Milling

Ensuring the quality of rice requires attention to paddy quality and milling technology. Follow these guidelines to achieve the best results:

1. Maintain Optimal Moisture Content:
   • Mill at 14% moisture content to avoid excessive grain breakage.
2. Pre-Clean Paddy:
   • Use impurity-free paddy for a cleaner end product.
3. Avoid Mixing Varieties:
   • Different paddy varieties have unique milling characteristics.
4. Utilize Rubber Roll Technology:
   • Rubber roll huskers produce superior quality compared to outdated huller types.
5. Implement Paddy Separation:
   • Separate all paddy from brown rice before whitening for better quality.
6. Consider Two-Stage Whitening:
   • Reduce overheating by incorporating at least two stages in the whitening process.
7. Grade the Milled Rice:
   • Install a screen sifter to remove small brokens and chips, enhancing overall quality.
8. Regular Maintenance:
   • Monitor and replace spare parts regularly to ensure consistent high-quality rice.

Conclusion

Mastering the art of rice milling involves a combination of technological precision and adherence to quality guidelines. From understanding the composition of rice kernels to implementing efficient milling systems, each step contributes to the production of flawless rice. By following these guidelines, rice millers can ensure the best quality, optimize productivity, and meet the demands of a growing market. The journey from paddy fields to perfectly milled rice is a meticulous process, and it is this dedication to quality that makes every grain a culinary delight on our plates.