Taste And Freshness Of Cooked Rice Using A Superheated Steam Rice Cooking Machine

We investigated the physicochemical and sensory properties of cooked rice prepared with a newly developed superheated steam rice cooking machine. Rice prepared with an ordinary electric rice cooker was used as a reference. We also stored the two types of rice at 5 degrees C and compared them, obtaining the following results. 1) The steamed rice was whiter than the ordinary cooked rice. 2) The steamed rice did not harden or decrease in stickiness after storage as much as the ordinary cooked rice did. 3) The steamed rice maintained a higher degree of gelatinization during storage than ordinary cooked rice did. 4) After slicing and staining grains of rice with aqueous iodine solution, the steamed rice grains were purplish red, while the ordinary cooked rice grains appeared bluish purple. Steamed rice grains kept their shape for the most part, while ordinary cooked rice grains were more deformed. 5) The run-off from the steaming process was analyzed with gel permeation chromatography and it consisted almost entirely of amylose. 6) Steamed rice that had been stored at 5 degrees C for one day was preferred in overall sensory evaluation, and it was also less retrograded. This study confirms that some amount of amylose escapes during the process of steaming rice, and as a result steamed rice shows slower retrogradation than ordinary cooked rice.