Six kinds of jelly samples were prepared by adding 1.0% of Japanese soup stock “Dashi” and 0.5%–3.0% of jelling agent. Viscoelastic measurement and sensory evaluation were conducted to evaluate the interactions between viscoelastic properties and sensory evaluated texture, aroma, and taste. Hardness [Pa], cohesiveness [-], and adhesiveness [J/m³] were determined using texture test. Sensory evaluation was conducted using 42 evaluators, and the sensory scores for preference, hardness of jelly, aroma intensity of Dashi, taste intensity of Dashi, elasticity, ease of swallowing, and the preference of texture were obtained. The results of applying principal component analysis to the sensory evaluation scores indicated that the term related to the strength of the jelly texture was the primary axis of evaluation, followed by the terms related to the strength of the jelly taste and aroma. The interactions between the viscoelastic property and the sensory score were successfully confirmed by a good coefficient of determination obtained from an artificial neural network which applied between the viscoelastic property and the sensory score. Thus, it was clarified that the sensory evaluation results, such as preference, were influenced not only by the aroma or taste components but also by the texture constructed from the viscoelastic properties.

In this study, we investigated the growth risk of Thermoanaerobacterium sp. in tomato products which has not been clarified in previous study excepted for tomato juice. As a result, the growth of Thermoanaerobacterium sp. was not observed in various tomato products with refractive index (RI, index for soluble solid content concentration) 8.0 or more, and pH 4.2 - 4.6. On the other hand, the growth of Thermoanaerobacterium sp. in modified TGC media of pH 4.2 - 4.6 was observed in the range of RI 8.0 but was not observed in the range of RI 19.5 or more. These results suggested that there were other growth inhibitors of Thermoanaerobacterium sp. in tomato products besides RI. Therefore, we investigated the growth risk of Thermoanaerobacterium sp. by adding organic acids contained in tomato products, citric acid, malic acid, and pyroglutamic acid, to a modified TGC medium. As a result, when citric acid alone contained more than 0.52％, no growth was observed, and the coexistence effect of organic acids was not confirmed. These results suggested that citric acid contributes to the growth inhibition of Thermoanaerobacterium sp. in tomato products.

A flow-type reactor was constructed to mass-produce maltulose from maltose dissolved in 10 mmol/L phosphate buffer, pH 7, which was maintained in a liquid state under subcritical water conditions. The reactor was then used to examine the effects of reaction temperature, average residence time, and maltose concentration on the production of maltulose. The optimal conditions were a temperature of 115℃ (the highest temperature in the range tested), with an average residence time of 10 min. Considering both substrate utilization efficiency and maltulose concentration, it was concluded that a maltose concentration of 10% (w/v) was optimal.