The Meticulous Process of Rice Harvesting and Processing

Rice harvesting and processing is a meticulous process aimed at ensuring quality and usability. Initially harvested at 18-25% moisture, rice undergoes mechanical drying to reduce moisture content to less than 15%. This drying process can take place on the farm, at a commercial dryer, or at the mill, and is critical for safe storage and further processing. Prior to drying, rough cleaning is conducted to remove sticks, stones, dust, and other foreign materials. The drying typically occurs in upright continuous flow dryers with a concurrent flow of heated air, followed by cooling.

Once dried, the rice undergoes additional cleaning through various separation methods to yield rough rice or "paddy." Some paddy rice is subjected to parboiling, which involves soaking in water, draining, steaming to gelatinize the starch, and then drying again. This traditional process enhances the rice’s nutritional value by redistributing soluble B vitamins from the bran into the endosperm, and stabilizes it against insects and lipolytic rancidity, though it does not reduce cooking time for consumers.

The majority of paddy rice is hulled using rubber rolls rotating in opposite directions. This process separates the hulls from the rice, which are then removed through aspiration. The unhulled or rough rice is separated using a paddy machine or gravity table to produce brown rice. Parboiled rice often starts from brown rice and follows the outlined steps for parboiling.

A critical step in rice milling is the removal of some or all bran layers, a process known as “pearling,” which involves abrasion. The bran layers, known as pearlings, are then removed through aspiration. The resulting milled or white rice is sorted by size into different grades: heads (unbroken kernels), second heads (larger broken kernels), brewers’ rice (smallest broken kernels), and screenings. While each grade has various important uses, head rice is often used for puffed rice products, and second heads for rice flakes. When rice is intended for inclusion in formulated flaked, shredded, or extruded cereals, rice flour made from grinding second heads or brewers’ rice is utilized.

The rice processing industry continuously innovates to improve efficiency and quality. Recent advancements include more precise moisture control during drying and enhanced cleaning technologies, ensuring higher quality and safer rice products for consumers. Moreover, sustainability efforts are increasingly integrated, such as using husk waste for bioenergy, reducing the carbon footprint of rice production and processing.
The Meticulous Process of Rice Harvesting and Processing

Rice Processing: Milling

Rice Processing: Milling
Harvested at 18 – 25% moisture, rice is mechanically dried to less than 15% moisture on the farm, at a commercial dryer, or at the mill before storage or processing. Rough cleaning (removal of sticks, stones, dust, and other foreign material) may precede drying, which is usually done in upright continuous flow dryers with a concurrent flow of heated air. After cooling, the dried rice is cleaned by various separation methods to give rough rice or “paddy”.

Some paddy is parboiled or converted by being soaked in water, then drained, steamed to gelatinize the starch, and dried again. This traditional process may increase the nutritive value by distributing soluble B vitamins from the bran into the endosperm, and it may stabilize against insects and lipolytic rancidity, but it does not decrease consumer cooking time.

Most paddy is hulled between rubber rolls turning in opposite directions, aspirated to remove hulls, and separated from the unhulled or rough rice in a paddy machine or gravity table to give brown rice. Most parboiled rice is prepared from brown rice by the steps already outlined for parboiling.

Finally comes the most important rice milling operation, removal of some or all of the bran layers by abrasion, or “pearling”, as it is called. After removal of the pearlings by aspiration, the milled or white rice is separated by size into heads (unbroken kernels), second heads (larger broken kernels), brewers’ rice (smallest broken kernels), and screenings. Although this grades have other even more important uses, head rice is used for puffing and second heads for rice flakes. If rice is desired as a component of a formulated flaked, shredded, or extruded cereal, rice flour made from grinding second heads or brewers’ rice is used.
Rice Processing: Milling