Changes in the taste and texture of the surf clam foot due to cold storage (5°C) and cooking were analysed. During cold storage, the weight of the surf clam foot gradually decreased by up to 90% after 10 days. The changes in the total content of free amino acids in raw surf clam foot during cold storage were not statistically significant. However, the concentration of ornithine increased significantly after 10 days, which indicates decomposition. The ATP content of raw samples started decreasing after 3 days in cold storage, and their K' value, which is a freshness indicator, was 48% after 5 days.

Cooking the surf clam foot for 30 min reduced the weight by up to 65% of the original weight. The levels of free amino acids, as well as ATP and related compounds, were higher in the cooked samples than the raw samples. Shear force, piercing force, and thickness measurements of the cooked samples were higher than those of the raw samples; these parameters were the highest in samples cooked for 30 min. The sensory evaluation of three surf clam foot samples, namely, raw, cooked for 15 s, and cooked for 10 min, revealed a stronger fishy odor in raw samples than the cooked ones. The samples cooked for 10 min were harder to bite and had greater elasticity (chewiness) compared with those cooked for 15 s. Raw samples were inferior to those cooked for 15 s in overall preference.

Mechanical and sensory evaluations were conducted to assess the intraoral sensations produced by carrot puree prepared under five different pulverization conditions. Particle size, particle shape, and physical properties of the carrot puree were found to be affected by pulverization conditions. The results showed that the resistance force in the horizontal direction reflected the heterogeneity and liquidity of the samples. Average scores from the sensory evaluation showed a significant increase in perceived sweetness and smoothness, as well as a significant decrease in the intensity of granular sensation with increasing pulverization. No significant differences were found in acceptability of the granular sensation, or in overall acceptability of the samples. To identify trends in individual preferences, sensory scores of intensity of granular sensation were plotted against acceptability for each panelist. All the panelists were classified into different cohorts having preference for smooth texture, rough texture, and others. The results showed that individual preference trends had no correlation with evaluation of smoothness or intensity of granular sensation. Acceptability of samples was found to conform to different preference trends. This study showed the usefulness of considering individual preference trends when analyzing the acceptability of samples.

Previously, we presented a novel method for evaluating the early staling of cooked white rice using spectrophotometric and image analyses of squashed cooked rice grains to a certain thickness. Here, we used this new method to evaluate seasoned cooked rice. Concerning the physical properties, salt-seasoned cooked rice was staler than unseasoned rice, and vinegar-seasoned cooked rice was less stale. Seasoning cooked rice with mixed vinegar (a mixture of sugar, salt, and vinegar) caused staling similar to that observed upon vinegar-seasoning, suggesting that even when salt and sugar coexist, vinegar strongly influences the staling of cooked rice. In the measurement of squashed cooked rice grains, Ratio of White Area_α130 , which was calculated from the ratio of the area of gray value 130 or less in a gray-scale image, and L* for salt-seasoned cooked rice were higher after refrigeration for 14 h, and vinegar- and mixed vinegar-seasoned cooked rice exhibited lower values than unseasoned cooked rice. High correlation coefficients were observed between L* and Ratio of White Area_α130 and sensory evaluation results. Thus, we demonstrate that the L* value and Ratio of white Area_α130 of squashed cooked rice grains can indicate early staling of seasoned and unseasoned cooked rice.

Rice cooked in pH 3 and pH 9 buffers showed a significant increase in adhesiveness, which demonstrates a staling control effect under refrigeration. However, cooking rice in a pH 5 buffer showed an accelerated staling. Samples cooked at pH 3 and pH 9 showed the highest abundance of solid components and proteins that cover the rice grain surface. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of eluted rice proteins indicated protein degradation by aspartic proteinase under acidic conditions, and protein solubilization by disulphide bond reduction under alkaline conditions. These results suggest that such property changes promote water absorption and starch swelling under acidic and alkaline conditions, contributing to an increased solid content adhering to the grain surface. However, protein solubilization is limited, and both starch swelling and gelatinization are obstructed at pH 5, suggesting that this condition can accelerate staling.

This study compared the cooking characteristics of raw soy sauce, in which various enzymes are active, with those of heat-treated soy sauce in the preparation of cooked rice takikomi gohan.

There was no significant difference in the gelatinization ratio between the rice cooked with both soy sauces. As for the colour tone of the cooked rice, the use of raw soy sauce made it possible to prepare light rice with a bright and subtle redness. In the case of high salinity (2.0% (w/w) added salt concentration against rice), the results of the breaking and brittleness forces showed that cooked rice is softer and less brittle when prepared with raw soy sauce than when prepared with heat-treated soy sauce. In addition, the amount of reducing sugar was significantly higher in cooked rice prepared with raw soy sauce compared to that prepared with heat-treated soy sauce, which was consistent with the sensory test results, suggesting that a cooked rice with a sweeter flavour can be better prepared with raw soy sauce than with heat-treated soy sauce.

As a result, the use of raw soy sauce provided different food textures and tastes compared to the heat-treated soy sauce owing to the function of starch-degrading enzymes, such as α-amylase, and other enzymes.