Broken Rice Going Into Bran? How a Bran Sizer Helps
By Bajrang Khaitan · Published
The problem as you see it
Pick up a handful of bran from the outlet of your whitener or polisher and rub it between your fingers. If you feel hard particles, or see small white pieces when you spread it on a dark surface, that is rice. Brokens and fine pieces are leaving the mill with the bran and being sold at bran price.
Most mills do not notice this because the loss is spread across every hour of every shift. The bran buyer may also complain that your bran is not uniform from one lot to the next. Both are signs that rice and bran are not being separated properly.
Why rice ends up in the bran
During whitening and polishing, the bran layer is removed from the grain and pushed out through the screens of the whitener and polisher, then carried away by aspiration. Some rice always escapes with it. How much depends on the condition of the machines:
- Screens. Worn screens, damaged slots or screens with the wrong opening for your rice let small brokens pass through with the bran.
- Whitening pressure. Too much pressure in the whitener breaks more grain. The extra brokens and fine pieces then find their way into the bran stream.
- Aspiration. Air set too strong in the bran collection system pulls light brokens and fine pieces out along with the bran.
- Brittle grain. Paddy that was dried badly, or parboiled rice that was not dried evenly, breaks more easily in the whitener and adds to the loss.
A bran sizer is a sifting machine that takes the bran stream and separates rice particles from the bran. The recovered pieces go back to the broken rice stream, where they have a better value than bran. The bran that comes out is cleaner and more uniform.
A bran sizer does not work well on its own, though. Screen selection, consistent feeding and regular maintenance decide whether the separation is good or poor.
What to check, step by step
- Sample every outlet. Collect bran from each whitener and polisher separately. Sieve a known amount by hand and look at what stays on the sieve. This shows which machine is the main source.
- Whitener and polisher screens. Check the screens for wear, damage and the correct opening. Replace worn screens on a schedule, not only when they tear.
- Whitening pressure. Review the pressure and load settings on each whitener. If one machine is set much harder than the others to achieve the same whiteness, look at why.
- Aspiration settings. Check the air on the bran collection system. It should remove bran and dust without pulling rice pieces with it.
- Paddy and drying. If breakage in the whitener is high, look further back at paddy moisture, drying and, for parboiled rice, the soaking, steaming and drying steps. The rubber roll husker also matters, because grain cracked at hulling breaks again at whitening.
- Bran sizer screen selection. If you already have a bran sizer, confirm that the screen mesh suits your rice and your bran. The wrong mesh either lets rice through or sends good bran to the rice side.
- Even feeding. Feed the bran sizer at a steady rate across its full width. Overloading it reduces separation sharply.
- Screen cleaning. Bran is oily and blinds the sieve over time. Clean the screens on a fixed schedule so they stay open.
- Where the recovered pieces go. Check that the rice recovered from the bran actually reaches the broken rice bin and is not mixed back into the bran further down the line.
- Record and compare. Keep simple daily records of bran samples. When the amount of rice in the bran rises, compare with recent changes in screens, pressure or paddy.
Clean bran has its own value
Separating rice from bran is not only about recovering brokens. Bran buyers, especially those supplying oil extraction or feed units, prefer bran that is consistent from lot to lot. Cleaner bran with fewer rice pieces is easier to sell and leaves less room for dispute over quality. When the separation is done well, both streams improve: the broken rice bin gets back what belongs to it, and the bran is closer to what the buyer actually wants to pay for.
When to call a consultant
A bran sizer is worth considering when you have already corrected the whitener screens, pressure and aspiration and still find rice in the bran. Choosing the right machine and screens for your rice, and placing it correctly in the line, is something I help with in an online consultation. Keeping screens, whitener settings and the bran sizer in good condition through the season is also part of my annual maintenance support.