Nodogoshi is the Japanese term for the sensation of swallowing, which can be determined by subjective assessment. In this study, we examined the effect of viscosity of liquids on Nodogoshi using sensory characteristics and electromyographic activity. The effects of participant age and head position during swallowing were also taken into consideration. We used vitamin water with viscosities of 1, 40, 60, and 90 mPa s (denoted by η₁, η₄₀, η₆₀, and η₉₀, respectively) at a shear rate of 50 s⁻¹. In the sensory evaluation of Nodogoshi, the young participants found that η₉₀ was less palatable than η₄₀ (p<0.05) and there was no difference between the η₁, η₄₀, and η₆₀ samples. In contrast, the elderly participants found η₆₀ to be more palatable. Both young and elderly participants found that the η₉₀ drink had the most unpalatable aftertaste. The results of this study suggested that Nodogoshi may be affected by the viscosity of a drink; however, it is difficult to determine the optimum viscosity that makes a drink palatable because it depends on the tastes and preferences of individual drinkers.

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Green tea contains catechins, which are beneficial to human health. The retention of catechins and caffeine was measured in various dishes prepared with powdered green tea, among other ingredients. Catechins were detected in all the dishes tested, although the detected levels were lower than those of caffeine. One of the dishes tested for catechins and caffeine was pancakes containing powdered green tea. The level of catechins decreased just by mixing the tea powder with dough, and decreased further after baking, while the quantity of caffeine measured in the baked pancake was almost the same as that in the unmixed tea powder. Catechins in tea powder interact readily with various food materials and are unstable at cooking temperatures. It is important to give due consideration to this and other chemical properties of catechins while developing recipes of dishes containing tea leaves, if the objective is to increase the intake of catechins, and prevent the overwhelming of catechins by caffeine.

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