A History of Producers Rice Mill

Producers Rice Mill was born in 1943 as an idea in the minds of a group of distinguished farmers dedicated to the cause of improving the marketing returns of the members it served.

Utilizing a mill built by the Standard Rice Company in 1916, Producers milled just 143,500 barrels the first year, and had assets of only $125,000. Today Producers’ annual milling rate has increased to over 50 million bushels, and sales have topped the $305 million mark in recent years.

Service was expanded in 1946 when Producers Dryer, Inc. was organized to handle members rice drying in a co-op manner. The first year, the dryer only handled 126,488 bushels of rice for the entire season. Receipts during the 2004 peak harvest period exceeded over 550,000 bushels per day at the Stuttgart facility alone. In 2004, the Stuttgart facility handled just under 14,000,000 bushels of green rice in single season, a new record. | To the left is Producers’ truck parking lot with the milling complex in the background during the record 2004 harvest. | With the purchase of Gibbs Harris Rice Dryer at Wynne, Arkansas, and the Pioneer Food facilities, Producers added locations in DeWitt, Eudora, Fair Oaks(shown at right), Marianna, Pine Bluff, Wilmot, Wilson and Yellow Bend, Arkansas–increasing our size many times over. | In October 2001, Producers further expanded its milling and storage capacity by purchasing the A. C. Humko plant at Greenville, Mississippi.

This plant had a white rice mill, a parboil mill, a rice flour mill and a barge loading facility on the Mississippi River. As well as adding the ability to better serve our Mississippi members, the extra milling capacity and the ability to load barges directly on the Mississippi River greatly enhanced Producers’ export capabilities. | In October 2003, Producers purchased the Monsanto plant (more commonly known as Hartz Seed Company) in Stuttgart. This facility, located on a main industrial thoroughfare in Stuttgart and adjacent to property already owned by Producers, added 26 acres of land, two warehouses, an office, and 1,640,000 bushels of sorely needed storage for the Stuttgart operation. Today Producers is a full-line supplier of the finest quality rice available. From our central location in the heart of the Southern Rice Belt, Producers ships products across the country and around the world.

Producers serves all major divisions of the rice industry–foodservice, retail, private label, export and industrial. As one of the largest private label packers in the country, Producers packs over 100 brands for major food chains and food distributors in the United States and abroad. |

Importance of millingMilling is a crucial step in post-production of rice. The basic objective of a rice milling system is to remove the husk and the bran layers, and produce an edible, white rice kernel that is sufficiently milled and free of impurities. Depending on the requirements of the customer, the rice should have a minimum of broken kernels.|

The rice kernel composition
Most rice varieties are composed of roughly 20% rice hull or husk, 11% bran layers, and 69-% starchy endosperm, also referred to as the total milled rice. In an ideal milling process this will result in the following fractions: 20% husk, 8-12% bran depending on the milling degree and 68-72% milled rice or white rice depending on the variety. Total milled rice contains whole grains or head rice, and brokens. The by-products in rice milling are rice hull, rice germ and bran layers, and fine brokens. See also: diagram with the different rice fractions.

Milling systems
A rice milling system can be a simple one or two step process, or a multi stage process. In a one step milling process, husk and bran removal are done in one pass and milled or white rice is produced directly out of paddy. In a two step process, removing husk and removing bran are done separately, and brown rice is produced as an intermediate product. In multistage milling, rice will undergo a number of different processing steps. Depending on whether the the paddy is milled in the village for local consumption or for the marketing rice milling systems can be classified into the categories village rice mills and commercial mills.

Village milling
Traditional hand pounding| Single pass, single stage rice mill for home use| Single pass, two stage rice mill

Commercial rice mills
Small commercial multi-stage mill| State of the art modern multi-stage rice mill

Objective of commercial milling
A commercial rice miller will have following objectives:
* produce edible rice that appeals to the customer- i.e. rice that is sufficiently milled and free of husks, stones, and other non-grain materials * maximize the total milled rice recovery out of paddy minimize grain breakage

Terminology
To understand the different objectives of rice milling, please review the following terminology. Back to top

Rough rice
Also called paddy rice. Rice as it comes from the field. Rice kernels are still encased in their inedible, protective hull.

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Brown rice, husked rice or cargo rice
the least processed form of rice. It has the outer hull removed, but still retains the bran layers that give it a characteristic tan color and nut-like flavor. Brown rice is edible but chewier texture than white rice. Cooking time of brown rice is longer than milled rice

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Milled rice
Also called white rice, or rice after milling which includes removing all or part of the bran and germ from the rough rice.

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Milling recovery
total milled rice obtained out of paddy; expressed as weight percentage of milled rice (including brokens) obtained from a sample of paddy. The maximum milling recovery is 69-70% depending on rice variety, but because of grain imperfections and the presence of unfilled grains, commercial millers are happy when they achieve 65% milling recovery. Some village type rice mills have 55% or lower milling recovery. Back to top

Milling degree
a measure of the amount of bran removed from the brown rice

Head rice
milled rice with length greater or equal to three quarters of the average length of the whole kernel. It is often expressed on a % paddy or rough rice basis (on 14% Moisture content basis).

Head rice recovery
weight percentage of head rice (excluding brokens) obtained from a sample of paddy. Under controlled conditions head rice recovery can be as high as 84% of the total milled rice or 58% of the paddy weight. Commercial rice mills turn out 55% head rice on average, whereas head rice recovery of village type rice mills is in the order of 30%.

Whole kernel
a milled rice grain without any broken parts

Broken kernel
or brokens. Depending on the rice mill this can be only one fraction or it can contain several fractions of different size: * Large broken kernel: 50-75% of the whole kernel size
* Medium broken kernel: 25-50% of the whole kernel size
* Small broken kernel: less than 25% of the kernel size, can not pass through a sieve with 1.4mm diameter holes * Chips: fragments of a kernel which pass through a sieve with 1.4mm diameter holes

Impurities materials in the rice that are not part of the milled rice kernel. May include stones, husk, chaff, weed seeds, etc.

What is commercial milling?
Commercial milling systems mill the paddy in stages, and hence are called multi-stage or multi-pass rice mills. The objective of commercial rice milling is to reduce mechanical stresses and heat buildup in the grain, thereby minimizing grain breakage and producing uniformly polished grain. Compared to village-level systems, the commercial milling system is a more sophisticated system configured to maximize the process of producing well-milled, whole grains. The rice milling facility comes in various configurations, and the milling components vary in design and performance. “Configuration” refers to how the components are sequenced. The flow diagram below shows a modern commercial mill catering to the higher end market. It has three basic stages, * the husking stage,

* the whitening-polishing stage, and
* the grading, blending, and packaging stage.
In modern rice mills, many adjustments (e.g. rubber roll clearance, separator bed inclination, feed rates) are automated for maximum efficiency and ease of operation. The whitener-polishers are provided with gauges that sense the current load on the motor drives which gives an indication of the operating pressure on the grain. This provides a more objective means of setting milling pressures on the grain.

The modern rice milling process
Modern rice milling processes consist of:
Stage| Function|
Pre-cleaning| removing all impurities and unfilled grains from the paddy| Husking| removing the husk from the paddy|
Husk aspiration| separating the husk from the brown rice/unhusked paddy| Paddy separation| separating the unhusked paddy from the brown rice| De-stoning| separating small stones from the brown rice|

Whitening| removing all or part of the branlayer and germ from the brown rice| Polishing| improving the appearance of milled rice by removing remaining ran particles and by polishing the exterior of the milled kernel| Sifting| separating small impurities or chips from the milled rice| Length grading| separating small and large brokens from the head rice| Blending| mix head rice with predetermined amount of brokens, as required by the customer| Weighing and bagging| preparing milled rice for transport to the customer|

Flow diagram of a modern rice mill
The flow diagram below represents the configuration and flow in a typical modern rice mill.

1- paddy is dumped in the intake pit feeding the pre-cleaner 2 – pre-cleaned paddy moves to the rubber roll husker:
3 – mixture of brown rice and unhusked paddy moves to the separator 4 – unhusked paddy is separated and returned to the rubber roll husker 5 – brown rice moves to the destoner
6 – de-stoned, brown rice moves to the 1st stage (abrasive) whitener 7 – partially milled rice moves to the 2nd stage (friction) whitener 8 – milled rice moves to the sifter
9a – (for simple rice mill) ungraded, milled rice moves to bagging station 9b – (for more sophisticated mill) milled rice moves to the polisher1 10 – Polished rice, will move to length grader
11 – Head rice moves to head rice bin
12 – Brokens moves to brokens bin
13 – Pre-selected amount of head rice and brokens move to blending station 14 – Custom-made blend of head rice and brokens moves to bagging station 15 – Bagged Rice moves to the market
A – straw, chaff and empty grains are removed
B – husk removed by the aspirator
C – small stones, mudd balls etc. removed by de-stoner
D – Coarse (from 1st whitener) and fine (from 2nd whitener) bran removed from the rice grainduring the whitening process E – Small brokens/brewer’s rice removed by the sifter

Examples for outputs from the different stages
Clean paddy after pre-cleaning
Paddy grain after precleaning. Poor quality grain is evident from its darker color. These are immature kernels or half filled grains that are not removed in the precleaner. The presence of poor quality grain lowers the total milling recovery. | |

Brown rice at the rubber roller husker
Mixture of paddy grain and brown rice coming out of the rubber roll husker. With uniform size paddy, about 90% of the paddy should be husked after the first pass. This mixture goes through a paddy separator, after which the paddy is returned to the husker,and the brown rice goes to a de-stoner.

Milled rice after polisher
Milled rice after the 2nd stage friction polisher. Small broken grains are still evident. This product goes to a sifter to remove the small broken grains. Note: Most mills have several polishing stages for gentle milling. In those mills there is undermilled rice after the 1st stage friction whitener. Not all the bran layers are fully stripped. In times of rice shortage, production of undermilled rice is promoted because of the higher milling recovery.

Brewers rice from the sifter
Brewer’s rice or small broken grains removed by the screen sifter.
http://www.knowledgebank.irri.org/rkb/index.php/rice-milling