Learn the science behind:
Brown rice, Basmati rice, par-boiled rice, whole grain rice, there are a lot of different types of rice. Some are actually different types of rice, others are simply processed in a different way, causing them to behave and be different.
How rice is made and eaten is so different around the world. Some cook it into creamy risottos, others make a spicy fried rice or cook it in stew. But no matter how you transform the rice, it all starts out as a rice plant, that needs to be prepared to be ready for whatever delicious meal it is that you are making.
Rice is a grain
Long before rice enters our kitchens or processing facilities it has undergone a variety of processing steps already. Rice, just like wheat, is a grain and a very important one for nutrition all around the world. Millions of people rely on rice as their main staple food.
The rice grain grows on a rice plant, which is actually a grass. There are two species: Oryza glaberrima or Oryza sativa. The latter is the most commonly grown and known one, being grown all over the world. Within these two species, there are a lot of different rice varieties, different colors, lengths, flavors and shapes. Which specific variety is grown depends on the region, climate and cultural preferences for their preferred rice variety.
Harvesting, threshing and drying rice
The rice kernels grow on the ends of the grass plant and make up only a small portion of the entire plant, as is the case for most grains. During harvest, the grass stalks are cut off. The grains are then removed from these stalks by ‘threshing’ them. At a small scale, you can thresh rice by hand, by slinging the stalks against a hard surface. The force causes the grains to loosen up from the plants and fall out. Nowadays, most threshing is done mechanically, whether at a small scale using a small mobile thresher, on or near the fields, or at a larger scale in processing facilities.
As with any legume or grain, rice kernels then need to be dried to a moisture content of about 14%. Too much moisture causes the kernels to spoil. The high ‘water activity’ makes it a perfect place for microorganisms to grow. Once the rice is dried though, microorganisms won’t be able to grow as easily due to the lack of available water enabling rice storage of months, if not years.
Up to this point, the rice doesn’t yet look like the rice we eat and use. Producers call rice at this stage, that’s been harvested and dried, but not yet milled, paddy rice. Paddy rice grains are still surrounded by a strong husk or hull which protects the rice kernel during growing. You could also call rice at this stage: unhusked rice.
The husk, which makes up about 20% of paddy rice, protects the grain but contains a lot of fibers such as lignin. As a result, the hull is challenging to eat and pretty much indigestible for humans.
It’s why rice is milled. The first step of rice milling removes this firm outer hull from the kernel. The resulting product is what we call brown rice. Brown rice consists of three ‘layers’. The center of brown rice is the endosperm, it makes up the core component of the rice. Attached to the endosperm is the embryo, from which a new rice plant would have grown had you replanted the rice.
Surrounding the endosperm and the embryo is the bran layer which is another protective layer. The bran is less fibrous than the hull and can be eaten. It also contains a lot of valuable nutrients such as fibers, vitamins B1, B3, and B6, and minerals such as phosphorus and iron. Since the bran has a light brown color to it, rice at this point literally is brown rice.
The structure of brown rice may remind you of that of a wheat kernel!
Brown rice is a commercially available product, however, in most regions across the world, the majority of the rice sold is white rice. White rice does not contain the bran and endosperm of the rice kernel anymore. These are removed during additional milling or ‘whitening’ steps. This results in a beautiful white rice kernel, but does remove some of those valued nutrients as well.
When making white rice, you’re removing vitamins and minerals, valuable nutrients for us humans. In order to compensate for this, various countries around the world mandate that manufacturers enrich their rice. In other words, they have to put back these nutrients in. A common and the simplest way to do so is to spray these nutrients on the outside of the rice kernel.
Par boiled rice
Just like par-baked bread, you might expect par-boiled rice to simply be cooked partially, just before it is done. However, whereas par-boiled rice has been cooked already, this wasn’t done on the milled rice. Instead, par boiled rice is cooked before it is milled!
When parboiling rice manufacturers partially cook the rice with the husk and bran still on. This has a lot of effects, including making milling easier and more efficient and, importantly, redistributing the vitamins throughout the whole grain. Some of those valuable nutrients travel from the husk and bran into the actual white rice kernel. As a result, parboiled white rice contains more vitamins and minerals than non-fortified white rice! Also, par-boiled rice takes shorter to cook!
vs. ready-to-heat rice
Parboiled rice might look similar to ‘regular’ rice. This is because par-boiled rice doesn’t feel or look softer. It is a dry rice kernel, just like any other rice variety. As such, you can also store it for months or years. It is very different from ready-to-heat rice which is sold in special pouches to ensure the rice doesn’t go bad.
Sign up to our weekly newsletter to be updated on new food science articles.
The different types of rice
There are a lot of rice varieties out there. And to list the favorite or most common ones would be simply impossible since it so much depends on what you’re making and where you’re from. Though there are a few basic factors to consider:
- Colour: black, dark brown, light brown, red, there are a lot of color varieties out there
- Kernel length: a common distinction between rice types is whether they’re a long or short grain variety, easily seen by looking at the length of the kernel.
- Aromatics: rice can either be aromatic or not, having that extra scent and flavor to them which comes naturally (it’s not added in). Common examples of aromatic rices are Basmati and Jasmine rice.
Gariboldi, F.. Rice Parboiling. Italy, Food and Agriculture Organization of the United Nations, 1984, link
International Rice Research Institute (IRR), link
Oli, Prakash & Ward, Rachelle & Adhikari, Benu & Torley, Peter. (2014). Parboiled rice: Understanding from a materials science approach. Journal of Food Engineering. 124. 173-183. 10.1016/j.jfoodeng.2013.09.010. link
Rice knowledge bank, Threshing, link
Rice knowledge bank, Milling by-products, link
Rice knowledge bank, Parboiling, link
Chatchaporn Uraipong, Investigation into the Biological Functions of Rice Bran Protein Hydrolysates, 2016, p. 6-8, link