Boiling and/or steaming
Rice is normally prepared by boiling or steaming (or some combination of these) and it absorbs water during this process. Long-grain rice tends to remain separate or ‘fluffy’ after cooking while short- and medium-grain rice will tend to stick together more. After standard boiling or steaming, rice can be eaten directly with side dishes, added to soup, combined with other ingredients in a wok to make ‘fried rice’, used to stuff vegetables or vine leaves, or used for forming various types of sushi (using medium- or short-grain rice). Reportedly, the digestibility of cooked milled rice is approximately 88% in adults and children (Hopkins cited at www.fao.org).
Boiling in excess water: Rice can be boiled in excess water. When the rice is almost fully cooked, the excess water is drained off and the rice then steamed until it is fully cooked. As with pre-rinsing and pre-soaking, this cooking method results in the loss of water-soluble nutrients including starch and protein (fao.org). “Boil-in-the-bag parboiled rice in perforated plastic bags makes cooking in excess water simple and convenient” (www.fao.org).
Optimum-water-level method: In a covered pot or rice cooker, the right amount of water can be measured and added to the raw rice before cooking and this water will be completely absorbed into the rice. The recommended ratio of raw rice to water varies from about 1:1.5 (firmer result) to about 1:2 (softer result), depending on preference. After coming to the boil, the heat should be reduced to simmering until the rice is cooked (and all water absorbed). Generally the bottom layer will be softer than the top layer of rice after cooking.
Rice porridge or gruel: This can be made by adding extra water when boiling the rice, so that the cooked rice is saturated and disintegrates and the result is very soft. Rice porridge is commonly eaten as a breakfast food, and is also a traditional food for the sick. This can be made with glutinous or non-glutinous rice. Internationally, this is known as congee, fawrclaab, okayu, Xifan, jook, bubur, etc.
Stir-frying in oil or fat before boiling: This method is used when making dishes like risotto, paella, saffron rice, spanish/mexican rice, pilaf or biryani. Generally for these dishes, the raw rice is stir-fried with selected spices and/or other ingredients for the dish (meat, seafood, vegetables), before adding the right amount of water and covering the pot.
Germinated brown rice: Prior to standard boiling, brown rice can be soaked, drained and sprouted or germinated over a period of a few days, to enhance the nutritive value. This is known as sprouted brown rice, germinated brown rice (GBR) or GABA rice (as it contains increased levels of GABA – gamma-aminobutyric acid).
Compressed rice: This is another method that involves boiling or steaming rice. Compressed rice is popular in Indonesia (known as ketupat or lontong) and Malaysia (nasi himpit). Traditionally, the raw or partially-cooked rice is placed inside a woven or rolled coconut leaf or banana leaf pouch or cylinder, and then boiled or steamed. When cooked, the rice will have formed a solid mass, having been compressed by the pouch containing it. While still hot or after cooling, it is then cut open, sliced and served with side dishes, sauces and soups. Compressed rice packets can also be cooked with vegetable or meat fillings as a snack. Often muslin bags or plastic pouches are used instead of hand-made leaf pouches, but there may be health risks associated with cooking in plastic bags.
Washing prior to cooking
This is common practice in places where rice packaging and storage methods leave rice exposed to dust and other contaminants. Rinsing rice, sometimes multiple times, results in the loss of water-soluble nutrients, including starch, protein, vitamins, minerals and fats. Use of clean packaged rice reduces or removes the need for washing and thus prevents the loss of nutrients (fao.org).
Pre-soaking rice is a fairly common practice, which can save fuel by decreasing cooking time (the grains begin the process of expanding as they absorb water during soaking). Opinions vary on the effects on taste, texture and nutritive value. If the water used for soaking is drained off, this would result in the loss of water-soluble nutrients, as with washing/rinsing.
Parboiling rough rice before milling, as is common in India and Bangladesh, allows a portion of the vitamins and minerals in the bran to permeate the endosperm and be retained in the polished rice. This treatment also lowers protein loss during milling and increases whole-grain recovery.
Cooking with rice flour
Rice flour is made from ground raw rice (glutinous or non-glutinous). It can be used as a gluten-free alternative to wheat flour. Rice flour is commonly used in countries where rice is the staple food to make other food products, including certain types of bread, cakes, biscuits, pancakes and dumplings. It is also used to thicken soups and sauces and to make batter for deep frying crispy snacks (such as for Japanese tempura or fried bananas). Flat rice noodles and extruded round noodles are made from wet-milled rice flour. These are eaten with side dishes or in soups. Glutinous rice flour is commonly used to make many types of sweet and savoury cakes in Asia, including Japanese mochi and Indonesian layered rice cakes (kue lapis).
Rice cooking time: minutes mean millennia
The cooking time of rice is determined by the temperature at which the crystalline structures of the starch begin to melt. This is called gelatinization temperature (GT) and it ranges from 55 to 85 °C in rice. Rice with high GT takes a long time to cook and the cooked rice has an unacceptable texture; low-GT rice takes a shorter time to cook and the cooked rice is more palatable. Recently, a key gene affecting GT has been discovered: starch synthase IIa (SSlla). This discovery allows us to breed rice varieties with lower GT, which could decrease average cooking time by up to 4 minutes. Although this might initially seem insignificant, computing the number of times rice is cooked in any one day by the millions of households around the world, a decrease of just 4 minutes for each cooking event could save more than 10,000 years of cooking time each day. This represents massive potential for global energy savings.