Experimental Studies on Cooked Rice in a Mass Feeding (Part 1) : On the Decision of the Rate of Water to Rice and the Temperature Control in the Cooking Process

摘要

In order to standardize the cookery methods of rice in a mass feeding, experiments were made using a gas cooker in four different quantities of rice, 5kg, 6kg, 8kg, and 10kg. The moisture content of the rice used in the experiments was 14.97%. The conditions in cooking should be compared with the result, that is, the qualitative evaluation of cooked rice. (1) The rate of water to rice (weight percentage) was found to be 136%. This rate is closely similar to the theoretical rate (136.6%) which was calculated, taking into accounts a moisture content in rice, the amount of water contained in cooked rice and the amount of water evaporated in the cooking process. (2) The gas rice cooker was kept warm from 130°C to 170°C, even 15 minutes after the turning off of the gas. So the medium heat treatment usually followed by that of the weak heat to finish the rice cooking can be omitted. (3) Temperature control was very simplified. The cooking was started and finished always by the strong heat, only that the regulation of the time of heating was necessary in proportion to the quantity of rice. Namely the heating time was 18 minutes for 5kg of rice, 19 minutes for 6kg and 23 minutes for 8kg. Each figure of time shows the time necessary for the middle layer of rice of respective amount to reach the temperature of 100°C and to continue the temperature for 2 minutes. After the turning off of the gas it was appropriate in all cases to allow the cooked rice to settle by its own heat for 15 minutes. This temperature control satisfied the conditions of keeping 98°C for 20 minutes which is necessary to gelatinize the rice.