Rice is “carbs,” we are often told, but there’s a lot more to even just those carbs than we commonly realize. Here are the working notes which we used to help understand the how-and-why of common rice practices in India, and which we need to effectively answer the anti-carb brigades and to know how to reintroduce wide varieties of native rice into our everyday diets. Pair this with “How to Cook Rice” and you may never think of nutrition the same way again.
Starch is Plant Food First! | Rice “Carbs” & Starch Behavior | What happens to starch on cooking? | Is there such a thing as a “Low GI” rice? | Deciding what you need | Sources & Further Reading
There is a Tamil pazhamozhi or saying: “she who begs for rice water is seeking sugar to sweeten her cow’s milk” [neercchu-thannirukku kenjinaval, pasumpaalukku charkkarai thedukiraal]. Although such sayings have famously abstract (and sometimes obscure) meanings, at times literal readings may be useful in discerning traditional views on rice. Rice-water is usually thought of as being less rich and less valuable than cooked rice itself, a sign that there is rice being cooked in the household—but it, too, has a sweetness which complements that of cow’s milk.
Words for cooked rice all across India stand in for “food”: choru, sappaadu, anna or annam, bhaat, and more. And not just for humans: rice may be fed to crows (thought of ancestors), rice flour in kolams was equally thought of as feeding ants. The rice water of the Tamil saying may have been left to sour (and later used to cook more rice)—the “souring” itself a kind of eating by microbes and yeasts.
Underlying all these ideas and practices is an understanding of மாச்சத்து/maacchatthu, ‘the strength or energy of the [rice] flour,’ which refers to starch and the sweetness it contains. More commonly we speak of “kanji” or rice-water, as being easily digestible and providing quick energy for those who may need it: at breakfast, during convalescence and so on. Kanji is also what is used to stiffen cotton clothing, especially saris. Kanji is what has maacchatthu, we could say, the strength and sweetness of rice.
The nutrition contained in rice is not only its starch, of course, but the starchy endosperm is the bulk of a rice grain—nearly ¾ in volume. This article therefore takes a closer look at what we know about rice starch, how this corresponds with traditional Indian cooking practices, and tries to answer some basic questions: why do different rice varieties cook so differently? Why wash rice before cooking it—or roast it to preserve aromas? Why did last night’s leftover rice make a better fried rice? What cooking method is best for table rice? And: what does starch have to do with any of it in the first place?
Rather than demonizing rice for its “carbs,” we’d like to improve our working relationship with this precious grain—even or especially as a basic energy and nutrition source on which so much of the world so heavily depends. This is a working guide.
Starch is Plant Food First!
Plants store food as starch; starch is the most common of carbohydrates found in the plant world. Plants and algae synthesize starch via photosynthesis to store energy in dense, inert, and water-insoluble form. Plants have two types of starch: transitory starch and storage starch. Transitory starch is synthesized in leaves during the daytimes and degraded at night to sustain metabolism (plants need energy to make it through the nights!). The starch that plants send to stems, seeds, roots and tubers is storage starch—it remains for longer, like a reserve store. This storage starch is remobilized during germination or sprouting, so that new leaves can be produced to make more starch for later storage. And so the cycle continues.
Rice grains contain “storage starch” that is really intended for the rice embryo to metabolize during germination, but we humans intervene and have made these millions and billions of tiny grains our primary source of food. But they are all not the same in starch (and nutritional) composition.
Cultivated rice [Oryza sativa] has two major sub-species: japonica and indica.
- Japonica rice is what we know generally as “sushi” rice in Japan, arborio and carnaroli in Italy (both risotto rices), and bomba rice in Spain (a paella rice)—all short-grained, all noted for their stickiness or creaminess in cooking, which is itself indicative of high amylopectin starch content.
- Indica rices are what we mostly know in India, with basmati being the clearest example and posterchild for what distinguishes indica rices: generally longer grains which remain distinct upon cooking, indicating a much higher amylose starch content.
Amylopectin is more easily metabolized (“digested”) by plants, but amylose is particularly important in plant starch storage, because it physically takes up less room and can be packed in tightly into the tiniest of seeds. When you see the differences between amylopectin and amylose below, you’ll understand what is probably more in rice-washing water–and why we always say that’s really good for plants, so don’t throw it away, use it to feed them instead!
Rice “Carbs” & Starch Behavior
The major carbohydrate of rice is starch, about 75%. Rice also contains some free sugars (glucose, sucrose and dextrin), and can have other non-starch polysaccharides—which is why some rice readily tastes sweet.
Both Amylopectin and Amylose are both starches present in rice, but to varying degrees. Amylopectin is in general the larger proportion, ~80% of the starch. Amylose is the remaining ~20%. Rice and rice flours are can be separated according to amylose concentration: waxy 0-5%, very low 5.1-12.0%, low 12.1-20.0%, intermediate 20.125.0%, high >25.0% [Juliano 1993]. So when we speak of “high-amylose rice,” as for some basmati types, it’s still in the 1/3 range, not more [and how Nik Sharma over at Foood52 claims that basmati has 73% amylose is a mystery].
Each starch has a distinct structure. Amylopectin is a much larger molecule and a branched polymer of α-D-glucose units; Amylose is a smaller molecule and a linear polymer of α-D-glucose units. The basic Amylose chain is helical, twisted or coiled into a tight spiral. Now imagine that coil with multiple branches and more sprawling—that is amylopectin. Waxy rice tends to have more short branches and few long chains. Generally, rice high in amylose will have many more long chains than low-amylose rice. But because of amylose’s compact structure, at times the tiniest of grains can pack a good amount of amylose. Jeeraga Samba and many kaima (small grained Wayanadan) are good examples of tiny grains with high(er) amylose content.
| Amylose | Amylopectin |
| linear polymer of α-D-glucose units, much smaller molecule | branched polymer of α-D-glucose units, much larger molecule |
| about 20% of starch | about 80% of starch |
| less water soluble | more water soluble |
| does not form a gel in hot water | forms a gel in hot water |
| does not swell when cooked | swells when cooked |
Both starches are insoluble in cold water. In hot water, amylopectin is more readily soluble and therefore forms a gel (i.e., starches “spill out,” creating stickiness along with some swelling of the grain). The grains continue to gelatinize while cooking. By contrast, amylose is less readily water-soluble even in hot water, and does not readily gel (i.e., grains remain still discreet and without obvious swelling). The tight coiled structure of amylose needs more extreme heat treatment to hydrate—but then once amylose does hydrate, it becomes more soluble than amylopectin. In other words, it gelatinizes faster but at higher cooking temperatures (and then becomes more digestible). This is the reason why high amylopectin rice grains tend to “ooze” or “leach” rather quickly in the cooking process, while grains higher in amylose take some time to fully soften.
The cooking quality of rice depends largely (but not wholly, as we shall see) on these characteristics and the quantum of each starch present in the rice endosperm. Very generally speaking, japonica rices are higher in amylopectin, while indica rices are higher in amylose. So-called “glutinous rices” (like Thai sticky rice and sushi rices) are almost wholly amylopectin with almost no amylose, in starch composition. So-called “waxy rices” (like the short-grained japonicas and some indicas) have a little more amylose. Long-grained rices like basmati are generally prized for their higher amylose and low amylopectin composition—though there can be a great deal of variation among the 30-odd varieties of basmati and other similar aromatic long-grained rices. Grain shape and size can thus be some indication of (1) starch composition and (2) cooking behavior—but only roughly. For example, the medicinal rice njavara is famously slimy in texture, even though its amylose content is high. Gopinath et al. (2007) postulate that this property could be due the presence of non-starch polysaccharides (NSP). So starch composition is only a partial indication of cooking textures. There’s a lot else in those little grains that can change things around completely!
What happens to starch on cooking?
Let’s look now at what is happening to these starches at each stage of the cooking process.
Washing: In the case of whole grain or “brown rice,” washing is mostly cleaning because the starches are well-encased in the bran layers. In the case of semi-polished and polished rice, however, washing rice removes the “loose” powdered starch residue that invariably accumulates during milling. It’s probably a good idea to wash rice to clean it, but
- If you want a stickier rice texture, less washing may be quite ok
- For a fluffier rice texture, washing rice “until the liquid runs clear” is necessary
- To wash or not to wash? Nik Sharma over at Food52 says you must always. Aaron Hutcherson at WaPo says it depends on what dish you’re making.
Soaking: This is the start of grain hydration. We tend to think of soaking as a step that saves on cooking time, but it plays a role in improving nutrition. Certain aromatic rice varieties (like Iluppaipoo samba and Randhunipagal) release their scents only when they are hydrated; in these cases soaking can have the double benefit of bringing out the aroma and then reducing cooking time so these fragrances are retained.
Roasting: Very lightly roasting rice in a touch of oil or ghee is a method of helping the volatiles from the rice bran or outer layers to dissolve and remain even after the next steps of cooking. The rice grains turn opaque, some gelatinization takes place. This is a quick technique used with special, aromatic rices especially when they are to be cooked in water [and not milk which will have its own fats to dissolve aromas].
Heating/Cooking: Heat application induces both physical and chemical changes. Starch gelatinization can begin even in the soaking period, but it is accelerated in cooking.
- As the grains absorb water, they swell (starch granules swell up—sooner for amylopectin, later for amylose). The temperature at which rice starch begins to gelatinize is about 70C, the highest of all cereals.
- Then there is the “melting” of the helical structures of starch. At ambient temperatures, water cannot penetrate the tightly wound starch structures, but when temperatures are raised, these areas become increasingly diffuse, amylose chains separate and dissolve into amorphous forms, and the size of crystalline regions decreases.
- In the case of amylopectin, water penetration increases the randomness in the starch granule structure. Swelling leads to leaching and eventually to the granules’ disintegration.
- At some point, starch “thickens” or becomes “viscous”—this is evidence of starch becoming solubilized—but when and how this happens depends on many variables: grain processing, ph, salt, fat, proteins present, even water used.
In the image above: Sevai or rice noodles need rice that holds shape and remains firm, i.e. with higher amylose. Black rice like karuppu kavuni won’t work at all because of the way the starch spills in cooking.
Cooling: Setting rice out to “dry” before mixing in spices or making mixed/variety rices, refrigerating rice and using day-old rice to make fried rice—these methods re-harden the rice grains somewhat, produce a “bite” that is enjoyable for such dishes. What is happening here is that the gelatinized starch is retrograding. The solubilized starch chains once again become insoluble, and starch chains (especially amylose) re-crystallize somewhat. But they don’t return to their original form. This is why boiled-and-cooled cereal grains are harder than raw grains, and with glassy surfaces.
Amylose retrogrades much more than amylopectin: a “firmer” rice has a tendency to regain its shape, but some rices never do and those likely will have more amylopectin. Retrogradation is most in high amylose rice, during prolonged storage, and in starches heated beyond gelatinization. These starches are less digestible by small intestine enzymes, which is why we call them RS/Resistant Starch. RS acts like dietary fibre in our guts. It passes into the large intestine where it becomes food for the microbes there—which is all good until you have too much of it too fast, and then it produces gas! In general, however, more RS is considered to be helpful in many ways, so finding ways to engineer it in rice cooking would be beneficial.
Is there such a thing as a “Low GI” rice?
We think of starch as being the primary culprit behind the body’s glycemic responses to food, but it’s not about starch alone or starch in isolation. There is of course no single GI value that is always “right” for everyone—at times, we need a fast infusion of energy from starch and sugars, at other times and in other conditions, the point may be to reduce that load. And then some rices may be much more valuable for their bran than their starch, others are enjoyable precisely because of their starch composition. Living in attunement with the natural world means learning these characteristics of individual varieties and not generalizing them overly.
Here is a synthesis from our readings of the various factors that can drive GI responses up or down.
- Amylose content of the rice grain: the higher the amylose (or high amylose to amylopectin ratios), the lower the GI—but this can be altered by the degree of gelatinization, or the extent to which the starch is broken down in cooking. The more you cook, the more starch you make available to the body for faster absorption, engineering a higher GI response.
- Dietary fibre: bran and the quantum of resistant starch in the rice which acts like fibre in the gut can significantly alter how and how fast the body responds.
- Particle size: polished grain, broken grain, and flour—have decreasing degrees of GI response. Generally, the higher the surface area available more quickly to α-amylase enzymatic attack, the higher the GI response.
- Milling: There are three ways in which rice milling affects GI response. The presence of bran slows digestion and reduces GI response in all three.
- As with particle size, the bran acts as a physical barrier to water entry, impeding the starch granules from swelling during cooking.
- The bran fraction is also a barrier to enzymatic action.
- Finally, phytic acid and polyphenols etc. in the bran fraction also inhibit digestion and slow starch digestion, both physically and chemically.
- Note this study which found that “both polishing speed and duration impacted the physicochemical and rheological properties of different rice starches” to differing degrees! [Zekun et al., 2021]
- Parboiling: heat treatment during parboiling debranches amylopectin and creates linear amylose molecules (it can increase amylose content of rice). Amylose-lipid complexes form more efficiently during parboiling and these remain insoluble in water, making parboiled rice more resistant to enzyme hydrolysis. Resistant starch is increased, and this lowers GI load or response. But the degree of parboiling matters, too. Pressure parboiling or “severe” parboiling can have a greater GI-lowering impact than simple home conditioning. [Read more on Parboiling here.]
When you put all these together, there is no one-size-fits-all way in which to claim that one rice type or another is a “Low GI-Rice.” That medical measure has become a marketing gimmick to cash in on the health food fads and get you to buy—we often have no idea of the basis for such assessments. And even after you buy, how you process and consume the rice may alter its effects on your body.
Deciding what you need
What matters to you—the texture of the rice? The way in which the rice releases starch to provide quick energy? Or perhaps you want to slow things down and prevent those sugar spikes? Some amount of “engineering” is possible at home. Ultimately, it’s about finding the right balance of texture and digestibility without the sugar-spikes or a controlled GI response. Here are a few thoughts to help you along in your daily decision-making.
Image above: to the left is pal thondi, used by Wayanadan farmers to prepare breakfasts and kanjis for quick energy infusions. To the right is parboiled kichili samba, which mushes into a sticky mass that we all have used to seal letters in the days before pre-applied glue and email!
Cooking for Texture:
- You’ll want to pick the rice type that gives you the texture you want:
- Stickier rices, generally higher in amylopectin, will be creamier (and will make a good glue). As long as your rice is grown organically and picked clean of stones and other processing debris, having some “loose starch” unwashed will help to achieve a creamier texture, faster.
- Fluffier or flakier texture-producing rices like Basmati or Jeeraga samba will hold their shapes better, longer—higher in amylose, better for pulaos and biriyanis or any dish where you want that firm grain bite. Washing these rices will help—as will spreading them out on a plate after they are cooked to allow them to “dry” and the starches to retrograde. Storing them and using them the next day after a full cooling in the refrigerator may be the best method of all for fluffy texture (and resistant starch) though aromatic rices may not retain their signature fragrances this way.
For Quick Energy:
Amylopectin is more easily digestible by plants and humans. High amylopectin rice is likely to be a quicker energy source than high-amylose rice, simply because the starches “spill” and leach faster with less heat treatment. Beyond the usual sticky rices typically from the East and North East, if you are able to cook rice fast and you see gelatinization as I did once with Vadan Samba, then you’ve probably got a high amylopectin rice on your hands. The amount of amylopectin in a rice generally determines its stickiness.
Polished rice, broken rice grains, and then rice flour—in decreasing order, are going to make starch available more readily, more quickly for the body to metabolise into sugars. Baby foods, for reasons of both texture and digestion, are flours.
Pressure cooking rice tends to produce the greatest amounts of rapidly digestible starch, possibly because of the combination of hydration and degree of gelatinization, facilitated by that pressured environment.
Long cooking (or over-pressure-cooking) has a similar effect of breaking starches down and making them easily digestible. My 79 year-old mother asks always for “kozhanja sadam” which means quite literally rice that has a kozha–kozha or slimy, overcooked texture—precisely because it’s easily digestible.
Some processing techniques (like puffing) improve rice starch digestibility—which is how easily starch is available to the enzyme α-amylase to be broken down. We think of pori or muri as “light”—and that it might well be, because “light” means it’s also giving us a good, quick sugar infusion!
To slow the body’s GI response:
First, Choose the right rice type!
High-amylose starch is more resistant, at least until it degrades, to digestion again because of its compact, linear structure. Choosing high-amylose rices (typically the ones that retain their shape and form even after long cooking) will be the first step in modulating bodily response.
Brown rice (unpolished), or semi-polished rice that retains some or all of its bran layers will help! The bran acts as both a physical and chemical barrier to enzymatic action, slowing things down for longer.
Parboiled rices generally produce lower GI responses because they often have altered amylose content, contain more RS/Resistant Starch, and because their surfaces and kernel densities are less immediately open to enzymatic action. They are great for fermentation both in the gut and in your idli-dosa batters because they sour in somewhat more measured ways. Note here that “idli rice” like Ambai 16/Ambasamudram idli rice is a short-grained cultivar, always sold parboiled for this purpose.
Some native rice varieties naturally contain a fraction of resistant starch! Basmati is said to be one such (Kaur et al, 2024), Jeeraga Samba/ Seeragasamba/ Jeerakashala is perhaps another, along with some black and red rices.
Next, cook rice the right way
To cook high-amylose rice, we may want to find methods that regulate or interrupt the full breaking-down of starch, or that produce more RS/resistant starch. See our article on “How to Cook Rice” for more on this.
The 2-step traditional boiling and draining or the “pasta” method, precisely because it withdraws hydration during draining, effectively allowing the rice grains to cool and swell slightly, can limit digestibility and reduce the body’s glucose response—though we are not sure by how much.
Allowing rice that is fully cooked even in pressure cookers to cool and harden slightly may also help—though it may compromise texture. Drying cooked rice in this way allows some time for starch retrogradation, producing grains that are then perfect for fried rice and other such mixed rice preparations.
The steaming method of cooking rice, as it turns out, is the least common but produced the lower rapidly digestible starch and higher slowly digestible starch in all the rice varieties investigated in one study (Rashmi and Urooj 2003). If you have rice that can be soaked and steamed, this may be a method to try. Here, it is interesting to note that many glutinous rices (i.e. higher amylopectin) are cooked by steaming to achieve the right texture. Since steaming generally produces less rapidly digestible starch and more slowly digestible starch, it’s possible that the traditional practices of steaming glutinous rices are not just about getting the right texture, but may also be the best from a starch release point of view.
Then there’s the method proposed by researchers at the College of Chemical Sciences in Sri Lanka, designed to enhance the RS/resistant starch in cooked rice (James et al. 2015):
Start with a native or folk rice. You can use a parboiled rice which already will have a quotient of RS. Wash thoroughly and soak for an hour (optional). Then cook the rice using the boiling method with coconut oil: one teaspoon of coconut oil to one half-cup of rice. The oil enters the starch granules, adding a layer that is resistant to digestive enzymes—less starch is available to the body. After cooking the rice on the stovetop, set it out to dry and cool. Now refrigerate the rice overnight, for use the next day. The chilling period allows for the formation of starch the body cannot digest, which makes for less calorie absorption.
Sources & Further Reading
- Alandi Ashram, “Resistant Starch and Ayurveda.” Accessed August 28, 2024.
- Chang, Un Jae, Yang Hee Hong, Eun Young Jung, Hyung Joo Suh. “Rice and the Glycemic Index.” In Wheat and Rice in Disease Prevention and Health. London: Academic Press, 2014. Pp. 357-364.
- Casiraghi, M.C., F. Brighenti, N. Pellegrini, E. Leopardi, G. Testolin. “Effect of Processing on Rice Starch Digestibility Evaluated by in Vivo and in Vitro Methods.” Journal of Cereal Science, Volume 17, Issue 2, 1993, Pages 147-156
- Gopinath, Deepa & Singh, Vasudeva & Naidu, Akhilender. (2008). Nutrient composition and physiochemical properties of Indian medicinal rice – Njavara. Food Chemistry. 106. 165-171. 10.1016/j.foodchem.2007.05.062.
- James, Sudhair A., Pushparaj, T., Thavarajh.D, Premakumara.S, Abeysekera, K and Sotheeswaran, S. (2015). Rice (Oryza sativa L.) resistant starch and novel processing methods to increase resistant starch concentration. ACS publications. USA
- Juliano, Bienvenido O. 1993. Rice in human nutrition. Rome: International Rice Research Institute Food And Agriculture Organization of the United Nations
- Kaur, Prabhjot, Harpreet Kaur, Renuka Aggarwal, Kiran Bains, Amrit Kaur Mahal, Lachhman Das Singla, and Kuldeep Gupta. 2024. “Analysing the Impact of Resistant Starch Formation in Basmati Rice Products: Exploring Associations with Blood Glucose and Lipid Profiles across Various Cooking and Storage Conditions In Vivo” Foods 13, no. 11: 1669. https://doi.org/10.3390/foods13111669
- Sharma, Nik. “Do you really need to wash rice?” Food52, September 20, 2020
- Zekun Xu, Yijuan Xu, Xiaojing Chen, Lin Zhang, Haitao Li, Zhongquan Sui, Harold Corke. “Polishing conditions in rice milling differentially affect the physicochemical properties of waxy, low- and high-amylose rice starch.” Journal of Cereal Science vol.99, 2021.
