Congee and Porridge.
A cup of rice and ten cups of water become, after an hour and a half, a pot of silky congee. The thickness is arithmetic; the silk is time.
Congee (粥, jook) is rice cooked far past done. In a large amount of water, the grains absorb what they can, gelatinise (VII.1), swell until they split, and release their starch into the liquid, which thickens into a smooth, flowing gruel. Stirring breaks the grains further and stops them catching on the bottom. Cantonese congee uses about 1 part rice to 10–12 of water and simmers for an hour or more until the grains have nearly dissolved; northern and everyday Chinese 稀饭 is thinner and shorter-cooked, the grains still whole; Japanese okayu and Korean juk sit between. Oat porridge is the same idea with oats' gummy beta-glucans doing much of the thickening.
Thickness is a mass balance: the dry rice solids divided by everything left in the pot after evaporation. An open pot at a steady simmer loses a lot of water over an hour, so the same ratio gives a thicker congee open than with the lid ajar; a congee too thick is thinned with boiling water at the end, never the other way. Soaking or freezing the washed rice first, or breaking the grains, speeds the release. The workshop makes a pot.
Below: the solids in a pot of congee from 100 g of rice with the ratio of water you choose, simmered for the minutes you choose with the lid open or ajar (mass balance with evaporation), against the bands for thin 稀饭, Cantonese congee and thick porridge.
- Explain how congee thickens.
- Choose a ratio of water to rice.
- Account for evaporation.
- Make smooth Cantonese congee.
Ratio, evaporation, time
With 1 part rice to 11 of water simmered 90 minutes, the pot holds about 8.3 % solids with the lid ajar but 11.7 % with it off — a thick porridge, which would need about 228 g of boiling water stirred in to come back to a flowing 9 %. Cooks who simmer uncovered start with more water; cooks with a heavy pot and a lid ajar use less. Taste and texture tell you more than the clock: a spoonful should flow slowly off the spoon.
Method for Cantonese congee: rinse 100 g of rice, toss it with a teaspoon of oil and a pinch of salt (or freeze the wet rice overnight, which cracks the grains); bring 1.1 litres of water to the boil, add the rice, return to the boil, then simmer with the lid ajar for 90 minutes, stirring every 10–15 minutes and scraping the bottom. Thin with boiling water to taste. Add pork, fish or century egg in the last minutes (皮蛋瘦肉粥), and serve with ginger, scallion, white pepper, 油条 and soy. Congee keeps the rice's Bacillus cereus risk (XXI.4): keep it hot or cool it fast.
Make congee with 100 g rice and 1.1 kg water. Weigh the pot before and after 90 minutes (subtract the pot) and work out how much water evaporated.
Terms
- Congee (粥)
- Rice simmered in much water until it breaks into a smooth gruel.
- 稀饭
- Thin everyday rice porridge with grains still whole.
- Solids
- The dry matter in a dish as a share of its weight.
- Beta-glucan
- The gummy fibre that thickens oat porridge.
Sources
- USDA FoodData Central, SR Legacy (April 2018), public domain.
- A teaching value chosen for the course: the right order of magnitude and shape, not a measurement of a particular food.
- H. McGee, On Food and Cooking: The Science and Lore of the Kitchen, 2nd ed., Scribner, 2004.