Rice Grading: How a Rice Sizer Gets You a Better Price
By Bajrang Khaitan · Published
The problem as you see it
Your rice is clean, white and well polished. You know the paddy was good. Yet the buyer offers a lower rate, or points to a sample and says there is too much broken, or that the grain size is mixed. Another mill with similar paddy gets a better price.
In many such cases the problem is not the quality of the rice. It is the grading. Buyers pay for what they see in the bag: how uniform the grains are and how much broken is mixed in. A good lot that is poorly graded sells like an average lot.
Why grading decides the price
Every rice mill produces a mix of whole grains and brokens of different sizes. Buyers and markets have their own grade specifications, mainly the share of broken allowed and the uniformity of grain length. If whole grains and brokens are not separated properly, the head rice carries too much broken and drops to a lower grade.
A rice sizer, also called a length grader, separates rice by grain length. In common designs, indented cylinders lift the shorter brokens into a trough while the longer whole grains stay in the cylinder and move on. Sieve-type graders separate by size through screens. Either way, the result is cleaner head rice and separate broken fractions that can be sold or blended as needed.
Brokens are not waste either. Large brokens, small brokens and fine brewers each have their own buyers and their own price. A mill that grades well can sell each fraction where it fetches the most, instead of selling one mixed broken stream at the lowest rate. That is money that stays in the mill without any change to the paddy or the polish.
Grading can also go wrong in the other direction. If the sizer is set too hard, whole grains are pushed into the broken stream and you lose head rice yield.
What to check, step by step
- Know the buyer's specification. Ask each buyer exactly what grade, broken limit and grain uniformity they expect. Grade your rice to that standard, not to a general idea of good quality.
- Measure broken properly. Take a fixed sample from the final rice and separate the brokens by hand. Do this regularly, so you know your real broken content before the buyer tells you.
- Sizer capacity. Compare the rated capacity of the sizer with the actual TPH passing through it. An overloaded sizer cannot separate properly.
- Cylinder or sieve size. Check that the indent size or sieve opening matches the variety you are running. Long grain, medium grain and parboiled rice may each need different settings.
- Trough adjustment. On indented cylinder graders, the trough position decides how sharply whole and broken are separated. Small changes make a large difference.
- Check the broken stream. Look at the broken outlet. If you find many whole grains there, the sizer is set too hard and you are losing head rice.
- Wear and cleanliness. Worn indents and dirty or blocked sieves reduce separation. Inspect and clean on a schedule.
- Breakage before grading. The sizer separates broken rice; it does not prevent it. If breakage is high, look upstream at paddy moisture, parboiling and drying, the rubber roll gap in the husker, and whitener pressure.
- Sortex position. Make sure the colour sorter and the sizer are in a sensible sequence for your line, so each machine is doing the job it is meant for.
- Blending. Where your buyers allow a fixed share of broken, controlled blending after grading gives a consistent product, rather than whatever share happens to come through.
Consistency is what buyers remember
A buyer who receives the same grade lot after lot starts to trust the mill and stops checking every bag at the gate. A buyer who finds one good lot and then one mixed lot will keep pressing the rate down to cover the risk. Good grading is how a mill delivers the same rice every time, even when paddy and conditions change through the season.
When to call a consultant
If buyers still mark your rice down after these checks, the cause may be a mix of grading and breakage earlier in the line. Sorting that out needs someone to see the sizer, the husker and the whitener working together, which I can do on a mill visit. If you want to talk it through first, book a free intro call and share your current grading setup and the buyer's specification.