This article is a broad overview of rice milling, told from an Indian perspective—that is, with a keen interest in our traditional agricultural practices, native rice varieties, and the consequent production of edible food. It has been prepared by Vijhay Ganesh, with editing, photographic and other inputs by Deepa Reddy and Sheetal Bhatt.
What is rice milling? | Traditional Milling Methods | Traditional Storage Methods |
Grades of Milled Rice | Rice husk and its applications | Sources & Further Reading
WHat is rice milling?
Rice milling is the transformation of paddy into several grades of consumable rice.
After harvest, paddy is allowed to mature for a period, depending on the variety, to allow for hardening. If the rice is milled before maturation, the texture of the cooked rice will be mushy or not suitable for raw rice consumption. Aged paddy produces more head rice post milling, which means less broken grain and more sturdy rice that we buy and cook regularly.
The timing of the paddy harvest has a direct bearing on milling. Harvest too late, and the percentage lost to breakage during milling will be high. Harvest too early, and the grain may not have fully set and would not be suitable to convert into raw rice. [On the other hand, some early-harvested, freshly milled rice is what is typically used to prepare Pongal at Sankranti time. The fresh grain’s softness makes it perfect for such soft, porridge-like preparations]. Quality differences between Tanjore and Ganjam, Guntur and Nellore rice was once considered an indication of differences in harvesting and therefore milling practices (Ramiah 1937).
Varietal differences aside, the region in which a rice is grown appears to have some bearing on its character and therefore milling qualities. Ramiah says that “As a general rule, all the short duration kar varieties [eg. Poongar, Kullakar etc.] of the province are soft and have to be converted into parboiled rice” (96). Rice grown in fields irrigated by wells (“garden lands” or dry lands) generally produces harder grains than can be obtained in rich, wet deltaic soils (“wet lands”). This difference was greatly exploited in the green revolution, which produced rice varieties best suited to controlled, tubewell irrigation.
Paddy may also be parboiled by steaming before the maturation period. This has been found to help infuse nutrients from the husk into the kernel, improving nutritional quality of even the fully polished grains, and also increasing shelf life.
The first stage after the prerequisite ageing time is to clean the harvest using a winnower to remove impurities such as stones, dust and straw. After which the paddy is fed into a machine called a rubber roll husker to remove the inedible outer protective layer (hull) with the aid of friction. Paddy is fed between the abrasive rollers that can be adjusted to provide the desired level of polish and even shape. Both raw and parboiled rice have the same process of milling. The hulled product, known as whole grain rice, retains the bran and germ layers that are made of lipids, vitamins and minerals. After obtaining the whole rice, cleaned again and further processed into polished variants if necessary. Traditionally, each step has an individual machine and is even processed by hand [see the section on “Broken rice” below].
Machine or power milling equipment is in general expensive. Usually, it is a small handful of wealthier farmers per few villages who invest in a mechanized unit that other farmers rely on. For many farmer cooperatives, this has become a means to ensure that at least some more of the profits of rice production return to the producers. Marginal farmers who have limited storage facilities, mill in small quantities on a need-basis to reduce the chances of rancidity. They also report that the aromatic and other qualities of certain rice is best preserved when aged, milled in small quantities, and consumed fresh.
Ramiah’s fascinating 1937 account of rice milling in Madras reports that mills at the time would color the rice grains after milling to enhance their appeal: In the preparation of raw rice according to the requirements of special tracts where a preference is shown for rices with either a yellowish or reddish tinge, the millers add some colouring matter during polishing, turmeric or yellow ochre for the yellow tinge and red ochre for the red tinge.The par-boiled rice before it is bagged is sometimes mixed with a white flour which acts as an absorbing agent of moisture and gives the rice an attractive whitish colour (92). He adds that “Sometimes it is usual to add a small quantity of ordinary blue, as used in laundries, to accentuate the whiteness of the intact”!
Traditional MILLING Methods
In India, traditional methods of rice storage and milling are still prevalent, especially in rural areas though hand-pounding tends to be expensive because it is labor-intensive and difficult to undertake in volumes. Many rural communities still live, however, with a small pit for rice milling in their homes, and many continue to mill only what they require for immediate use—being free in this sense of many other problems of spoilage and shelf-life.
Ramiah describes a more elaborate piece of equipment and method from the Malabar and South Kanara: “There is an improved type of this to be found in parts of Malabar and South Kanara where the feet are used instead of the hands. This consists of a wooden beam, 6 feet to 8 feet long and works on the see-saw principle fixed to a pivot. To one end of the beam is fixed a short pestle and this drops into a wooden mortar, fixed in the ground. The mortar is filled with the grain and the worker treads on the beam end opposite to the one to which the pestle is fixed and this lifts the pestle to 2 or 3 feet above the mortar. By suddenly releasing the pressure on the beam the pestle drops with force into the mortar and pounds the rice contained in it. This is usually worked by men, and is more arduous than the ordinary pestle and mortar though much more efficient. After a obtain amount of shelling is done the grain is removed from the mortar, the separated husk winnowed away and the unshelled grain put in again into the mortar for pounding” (1937: 89).
Ramiah continues: “When the whole shelling is finished the rice is polished in the same mortar to remove the bran. Such hand-pounded rice can never get the same polish as that of a machine-milled rice” – and this is largely the reason why older communities, even those consuming polished rice, continued to associate rice with producing health and well-being. Even the cooking water from rices milled in these ways was, as we learned in Gujarat, thought of being tasty and “like Bournvita.”
Traditional STORAGE Methods
Storage practices are deeply rooted in the agricultural traditions of the country and are adapted to the local climate and conditions.
- Bamboo Bins: Farmers in the north east (and other areas where bamboo grows) often use bamboo bins for storing paddy. These bins are lined with mud and cow dung to protect and act as pest repellants, and they are elevated from the ground to prevent moisture ingress and rodent attacks.
- Mud Silos: Mud silos or mud pots are another common storage method. These are coated with cow dung and mud to provide insulation and prevent pests.
- Gunny Bags across India: Paddy is also stored in jute or gunny bags, which are then stacked in a well-ventilated storage area. These bags are often treated with neem leaves to repel insects.
- Polythene-lined Pits across India: In humid and wet regions, farmers use underground pits which they have started to line with polythene sheets in more recent times to store paddy. These pits are covered with straw and soil to protect the grain from moisture and pests.
- Granaries: Traditional granaries made of wood and thatch are still used in some areas. These structures are built on stilts to keep the grain safe from floodwaters and pests. Wealthier families or join families may have had entire rooms, sealed off and only accessible at specific points, into which they would pour paddy for storage.
Grades of Milled Rice
What rice one chooses to consume is a factor of region, community and personal preferences. Ramiah makes observations in 1937 that broadly hold true to this day: “In Tamil districts the consumption of raw rice is generally confined to the well-to-do classes while all the labourers and poor classes eat only boiled rice. In the Circars and Ceded districts however, all classes of people irrespective of their status, use mostly raw rice. In Malabar, the consumption is exclusively of par-boiled rice with all classes of people” (1937: 93).
1. Whole-grain or “brown” rice
Brown rice refers to grains which have simply been hulled, and which have the bran layers still intact. This is also referred to as “whole grain” rice. Brown or whole grain rice undoubtedly the best variant for nutritional satisfaction and fulfilment. It takes some time to acquire the taste for these pearls if you are mostly used to polished varieties and the benefits are worth it. Rice with bran and germ is the most nutrient-rich part of the grain, high in fibre content, and therefore useful as roughage and slower for the body to absorb. In Ayurveda, unpolished (and therefore “colored”) shastika rice was used to restore imbalances in the human body. Pigmented rice are generally known to have disease-preventing, metabolism-boosting, blood-sugar-stabilising, hormone-balancing and cholesterol-regulating qualities.
Ray et al. note first the relationship between bran coloration and nutritional content: “About 38% to 60% of the total polyphenol content is present in grains of light brown rice. In contrast, the red and black pericarp of coloured grains contains around 81% of the polyohenols. The natural hues of rice bran colour have a profound effect in determining the nutritional content of grains.” Different grades of milling result in the progressive loss of these free phenolics, which are mostly concentrated in the pericarp. Thus, “the functional dietary potential and the protective effect of the rice grain in the prevention of age-related degenerative diseases become reduced during processing” (2021: 153).
B-complex levels are generally higher in traditional landraces than in the green revolution introduced varieties used for comparison in one research study–confirming native understandings of native grains as being better for health and well-being than any HYV rices (Roy et al., 2020).
Whole grain, unpolished rice has a notoriously short shelf life, however, as its nutraceuticals do attract pests and there are higher chances of lipids becoming rancid. Effective ways to store are – to buy short quantities, store it in air-tight containers and shake it every five days. Another method is to add dried red chilli, neem leaves, or nochi/nirgundi/Vitex Negundo as a natural pest repellent.
2. Semi-polished rice
Semi-polished rice is abraded about 30 to 50 % of the bran. The result is a smooth grain with shaved bran and germ. This grade of rice has a moderate shelf life compared to refined, due to the lipids in bran and germ that can become rancid when exposed to air. Semi-polished rice takes a little longer to cook than white rice and carries some earthy taste from the bran and germ, along with its color. Many shift to the whole grain food lifestyle with the help of these variants to train and strengthen the digestive system slowly. The germ weighs about 1% of the total rice and yet it is packed with about 30% of vital nutrients. The rice germ, which contains the embryo from which new life will spring, is of particular interest from a nutritional point of view due to its phytochemical characteristics and antioxidative properties
3. White rice or polished rice
When we remove the bran and germ completely, we are left with the starchy white rice, with small quantities of protein, oils and mineral matter. The better the polish and appearance, the less nutritious a rice is. The success story of polished white rice is due to the ease of storing, cooking and digesting. Most importantly, the milling process removes lipids which can get rancid if exposed to air for a longer duration. Polished rice thus has the longest shelf life of all milled grades. Many traditional aromatic rices used for kheer and other ceremonial offerings are ironically all polished—when we learn from farming communities that such varieties are best milled in very small quantities to preserve their fragrant qualities. The benefit of longer shelf-life is thus to be weighed against the loss of the true and full properties of the grain. What whiffs we get in the end are just the last of a long trailing scent!
It is best to wash the white rice to get a fluffy texture as it has a residue of free starch from the milling process that clumps up when cooked. Depending on the starch profile of the rice, particle size, age and milling quality as well as cooking method, some native rices may still have low-GI effects—they cannot simply be blackmarked because of milling. Parboiled white rice also has a lower GI when compared to raw rice of the same variant due to the starch retrogradation, or the “reconstitution” of starch that happens after steaming-and-cooling. These varieties are better alternatives to good health and it is best to experiment with a few varieties to find a suitable balance between taste, health and availability.
4. Hand-pounded and broken rice
Before we had machinery, hand-pounding rice in a mortar and pestle was common. Hand pounding renders a similar appearance to semi-polished and when observed closer, you can notice a coarser texture with slightly better nutrition content due to uneven and thicker layers of bran and germ depending on how hard it is pounded. This method is followed by marginal farmers who cannot afford milling and they pound rice as and when they need to sell or eat. Unlike machine-milled rice, the hand-pounding process generates significantly less heat resulting in better taste.
In addition to these milling grades, rice can also be classified based on the percentage of broken grains. The broken rice is separated from the head rice and is often used for different culinary purposes or as animal feed. A good rice mill will produce about 10% large broken and about 15% small broken kernels depending on the country’s standards.
Indian native rice varietals tend to be tall grasses, prone to lodging or falling over. Lodging during the ripening stages contributes to a high percentage of breakage in milling. This is why unseasonal rains have always been a farmer’s bane, and why there has been a hunt for “dwarf” rice varieties from the 1950s and through the green revolution.
Warding against too breakage has been the preoccupation of Indian agriculturalists: early domestication of rice was in large measure a process of selecting non-shattering grains, harvest as we have seen is timed to control breakage, and grains of similar sizes must be milled together to reduce breakage (there is no mixing of varieties during milling).
Broken rice is something of a lesser product. “Kanki” finds place in Gujarati cuisine, which makes much room for grain-bits in handvo, khichdis and the like. Broken rice is also used to make flour, and is the base starch for local brews and rice beers. Boliya, a Kodava rice Anjali Ganapathy writes about, was likely so suitable for brewing because it was a varietal prone to lodging, and therefore breakage during milling.
Rice husk and its applications
Rice husk constitutes the largest by-product of rice milling. It is about 20% of the weight of rice and is composed of cellulose (50%), lignin (25%–30%), silica (15%–20%), and moisture (10%–15%). The siliceous nature of rice husk composition resists natural degradation. Rice husk therefore cannot be disposed of easily because of its high silica-cellulose content, the highest of all plant offal. Rice husk therefore presents a significant disposal problem, especially since traditional uses are usually local, and small-scale.
Some of these traditional uses include:
- Burning the husk to produce umikari (biochar) or sambal (ash), in Tamil Nadu and Kerala. This is is an ingredient in rustic village tooth powders.
- This husk biochar can be converted into activated charcoal, and has been shown to be useful in the “manufacture of good cream coloured jaggery” because it can remove impurities (Ramiah 1937: 93).
- The pulverized husk is mixed with other mill fractions as cattle feed although it has a low protein content and feed value.
- Paddy husk was also used in combination with specific grades of clayey soil of the Thanjavur Delta region in the outer coverings of wax sculptures before firing, as part of the famous lost-wax method of bronze sculpting. There may have been many such local uses.
Rice husk has considerable value for a variety of possible industrial uses. The major use of husk at the moment is as fire briquettes as fuel for steam boilers, wherever parboiling is practiced. Perhaps the best use is to make biofuels but there are not many farmers investing in these machines as it is not economically viable yet.There are not enough systems to maximise the benefits and it is mostly sold to industries extracting rice bran oil or simply fed to livestock.
Some other potential industrial uses:
- There is considerable interest in investigating the use of rice husk as additives to traditional clay bricks, to reduce cost and shrinkage during drying. Beyond a point, however, the addition compromises the brick strength.
- Rice husk ash or RHA (obtained by burning the rice husk at 600-700°C for 2 hours) has pozzolanic or cementitious qualities, which means it can act as a binder and can hasten the hardening process of cement. There is much interest in exploring its uses as an additive or alternative to cement manufacturing [See this article by Phatak and Kishor 2024]
- Some modern entrepreneurs are using the husk waste to produce new forms of “plywood.”
Sources and Suggested Readings
- Bhat, F. M., and Riar C. S. “Health benefits of traditional rice varieties of temperate regions.” Med. Aromat. Plants 4.198 (2015)
- Directorate of Rice Development. “Post harvesting operations” Rice in India: A Status Paper, (2002). https://drdpat.bih.nic.in/Status Paper – 05.htm
- Gauthaman L.K. “Traditional rice processing challenges.” presented at the Desi rice webinar (2021): https://www.youtube.com/watch?v=zbFz-hJ-s14
- Kowsalya, P., Sharanyakanth P. S., and Mahendran R. “Traditional rice varieties: A comprehensive review on its nutritional, medicinal, therapeutic and health benefit potential.” Journal of Food Composition and Analysis 114 (2022).
- Phatak, Omkar Abhay and Roop Kishor. 2024. “A Systematic Review on Utilization of Rice Husk Ash in Manufacturing of Concrete” IOP Conf. Ser.: Earth Environ. Sci. 1326 012063
- Ramaih, K. 1937. Rice in Madras: A popular Handbook. Madras: Government Press.
- Ray, Sandipan, Debal Deb, and Mousumi Poddar Sarkar. “Colour based nutraceutical potential of some traditional rice (Oryza sativa L. ssp. indica) varieties of India.” Indian Journal of Natural Products and Resources (IJNPR)[Formerly Natural Product Radiance (NPR)] 12.1 (2021): 153-157.
- Roy, P., Deb, D., Poddar Sarkar, M., Roy, B. and Saha, T., An analysis of B vitamins in selected Indian rice landraces. Basudha Data Paper #4, Basudha Laboratory for Conservation, Kolkata, 2020.
