Cooking Research on Deliciousness and Healthiness: Texture analysis on cooked rice using SEM images and Anti-oxidant capacity of roasted vegetables

摘要

We are providing not only gas, but also cooking appliances to residential users and to the commercial customers such as restaurants or hotels. Having scientific information on cooking and assisting the customers in their lives and businesses is crucial to building good relationships with them and/or to increasing customer retention rate. We have started a cooking research project for developing methods aiming at evaluating deliciousness and healthiness and elucidating the mechanisms how they are created. This paper describes part of the project activities such as "Texture analysis on cooked rice using Scanning Electron Microscope (SEM) images" and "Anti-oxidant capacity of roasted vegetables." 1. Texture Analysis on cooked rice using SEM images The purpose of the research is to clarify how the microstructure changes depending on the soaking conditions and to investigate the relationships between the microstructure and human senses such as stickiness and stiffness of cooked rice, which eventually lead to understanding deliciousness of rice. Cooking experiments are conducted under several different soaking temperature and time conditions such as 10 degree C x 60 min or 40 degree C x 20 min. Based on the SEM images, we found that there are at least five stages for the degree of gelatinization shown below. 1st stage: Partially gelatinized inside the amyloplast, 2nd stage: Completely gelatinized inside the amyloplast, but the cell membranes are not gelatinized, 3rd stage: Completely gelatinized, but the honeycomb structure is not well developed, 4th stage: Completely gelatinized, and the honeycomb structure is well developed, 5th stage: Completely gelatinized, and the honeycomb structure is fully developed. The stickiness and the hardness from the texture analyzer, which are well correlated to the human senses, were strongly dependent on the microstructures. It is suggested that the human senses about stickiness and hardness of cooked rice can be predicted by observing its microstructure. 2. Anti-oxidant capacity of roasted vegetables The purpose of the research is to clarify the relationships between anti-oxidant capacity which indicates health benefits of some vegetables and roasting time or temperature, which eventually lead to understanding an optimal roasting condition that can maximize the deliciousness and healthiness. Cooking experiments are conducted under three different roasting time conditions, 180 degree C x 5 min, 10 min and 15 min. Eggplant was used as a food material. In the case of eggplant, the anti-oxidant capacity increased with the roasting time and the color of it was changed to brown by the Maillard reaction. The promotion of the Maillard reaction was confirmed by the increase in quantity of 3-DG, which is an intermediate substance of the Maillard reaction. Both the anti-oxidant capacity and the quantity of 3-DG increased with the roasting time. Therefore, it is thought that antioxidant capacity increased by the Maillard reaction. On the other hand, the deliciousness was good at 10 min and bad at 5min and 15 min. It is considered that the anti-oxidant capacity increases with the roasting time, but that the the deliciousness peaks at around 10 min and decreases if the roasting time exceeds 10 min.