Effect of Cooking Conditions on the Properties of shimetamago

Abstract

Shimetamago is a type of cooked egg that is served as one of the ingredients of Japanese clear soup. It is made by holding a half-coagulated egg in a suitable container covered by cloth after heating in boiling water.
The cooking conditions for shimetamago were analyzed by measuring the toughness with a Rheometer, by SDS-polyacrylamide gel electrophoresis and by a sensory panel test.
When the egg was slid into boiling water (100°C), more proteins coagulated than when slid into simmering water (90°C). The addition of salt to the egg or to both the water and egg accelerated the coagulation of egg proteins. The toughness of shimetamago increased with increasing heating time and final temperature.
The volume of boiling water used for preparation affected the toughness of shimetamago, and 4 to 6 times (V/W) of the egg was needed to achieve best results.
A sensory comparison of shimetamago with or without salt indicates that the taste of one prepared with the addition of salt to both the egg and water was significantly preferred (P<0.01), but that the appearance of one prepared without any salt was significantly preferred (P<0.01). Shimetamago seems to have satisfactory appearance and taste, when salt is added to the egg and not to the water.