Abstract
We studied for rice gruel mixtures containing several different ratios of rice (3 bu kayu, 5 bu kayu, 7 bu kayu, Zenkayu) * with regard to their physical properties and digestibility, and we also conducted sensory tests. We compared two brands, i.e. Thai rice and Japanese “Koshihikari.” The following is a summary of the results :
1) After cooking, Thai rice grains gained more weight than “Koshihikari” and had a higher degree of swelling.
Rice gruel with a low ratio of rice had a bigger weight increase and a higher degree of swelling.
All of the rice gruels absorbed some degree of water and swelled when left for some period of time after cooking.
2) The hardness and adhesiveness of cooked rice were higher in the rice gruel with a high ratio of rice.
A remarkable difference between Thai rice and “Koshihikari” was seen in adhesiveness. In the case of “Zenkayu, ” Thai rice had a higher adhesiveness, and in the case of the other ratios of rice gruel, “Koshihikari” had a higher adhesiveness.
3) Changes in the degree of swelling, hardness, and adhesiveness were seen when the temperature fell to 60°C after cooking.
4) α-Amylase produced more reducing sugar in Thai rice and gruels with a high ratio of rice.
5) In sensory tests on appearance and ease of swallowing, “5 bu kayu” showed fewer difference with Thai rice and “Koshihikari” than “Zenkayu.”
Concerning the smoothness and adhesiveness, when both “Zenkayu” and “5 bu kayu” showed distinct difference between Thai rice and “Koshihikari.”
The panellists preferred “Koshihikari” on the whole.
6) Observing the surface of the cooked rice, it was noticed that Thai rice was rough, while “Koshihikari” was smooth, which corresponds with the result of the sensory tests.
(* 3 bu kayu : rice gruel made of water and 5% rice; 5 bu kayu : rice gruel made of water and 10 % rice; 7 bu kayu : rice gruel made of water and 15 % rice; Zenkayu : rice gruel made of water and 20 % rice.)
