Theanine, a major amino acid in green tea, exhibits a stress-reducing effect in mice and humans. Matcha, which is essentially theanine-rich powdered green tea, is abundant in caffeine. Caffeine has a strong antagonistic effect against theanine. The stress-reducing effect of matcha was examined with an animal experiment and a clinical trial. The stress-reducing effect of matcha marketed in Japan and abroad was assessed based on its composition. The stress-reducing effect of matcha in mice was evaluated as suppressed adrenal hypertrophy using territorially-based loaded stress. High contents of theanine and arginine in matcha exhibited a high stress-reducing effect. However, an effective stress-reducing outcome was only possible when the molar ratio of caffeine and epigallocatechin gallate (EGCG) to theanine and arginine was less than two. Participants (n = 39) consumed test-matcha, which was expected to have a stress-reducing effect, or placebo-matcha, where no effect was expected. Anxiety, a reaction to stress, was significantly lower in the test-matcha group than in the placebo group. To predict mental function of each matcha, both the quantity of theanine and the ratios of caffeine, EGCG, and arginine against theanine need to be verified.
Fruit crispness is of great importance in cucumber as well as in other fruit vegetables, because it relates directly to the commercial value of the product. In breeding projects and pre-or postharvest studies of fruit texture, an effective quantification method has been desired to replace rough, qualitative evaluations of fruit texture based solely on human perceptions. We applied several analytical methods to the force-deformation curve to quantify cucumber fruit crispness and assessed the efficacy of these methods as candidate cucumber fruit crispness indicators for use in breeding or research. Texture parameters for the flesh and placenta of 12 cucumber cultivars, based on the crispness index, apparent fractal dimension, and power spectrum and peak analyses, were calculated from mechanical measurement results. There was a significant large genotypic (cultivar) effect on the texture parameter values and a lesser, but still significant, contribution from the environment. Furthermore, we found strong relationships between these texture parameters and sensory crispness. These results indicate that these methods for analyzing the force-deformation curve provide effective, quantitative indicators of fruit crispness, with considerable promise for application in scientific research and breeding programs.
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