The carbohydrate components associated with sweetness of heat-cooked sweet potato are free sugars and starch. The free sugars are glucose, fructose, sucrose and maltose, and they are mainly generated from starch. Maltose is generated after hydrolysis of gelatinized starch by beta-amylase, and the amount of generated maltose is significantly correlated with starch gelatinization temperature rather than beta-amylase activity in normal roots. The sweet potato cultivated under cooler condition increases maltose generation by heat-cooking because of its lower starch gelatinization temperature induced by change in molecular structure of amylopectin. These results suggest that the starch gelatinization plays an important role in maltose generation in sweet potato during heat-cooking. Sucrose is secondary abundant sugar in heat-cooked roots, and however it makes contribution to the sweetness as equally as maltose because its sweetness is stronger than maltose. Sucrose accumulation is observed in fresh root during storage, and it can be facilitated by lower temperature condition. The texture of heat-cooked storage root, which could affect the sensory evaluation of sweetness, is practically correlated with content of carbohydrate components such as starch. The beta-amylase is also concerned with the texture of cooked sweet potato root via enzymatic starch digestion during heating.

Flavor is one of the important factors for udon, white salted Japanese noodles. Using gas chromatography/mass spectrometry, we analyzed the volatile compounds from the flour, dough, and boiled noodles to clarify the mechanism of udon flavor formation. Hydrocarbons were the main compounds from the flour, while aldehydes and ketones were the main compounds from the dough and noodles. These aldehydes and ketones are presumed to be generated from the enzymatic oxidation of unsaturated fatty acids by lipoxygenase (LOX) upon the addition of water. LOX activity was significantly higher in the cultivar Norin61 than in Satonosora. In conclusion, the characteristic volatile compound profiles of Norin61 are due to differences in LOX activity. These results have been applied to the development of new value-added noodle products by various companies.

The starch properties of the new potato variety ‘Pearl Starch’ were analyzed and the applicability to beer brewing was examined. ‘Pearl Starch’ starch has a smooth spherical shape with a mean grain size of 23.5 µm, which is larger than that of Ca^2＋-fortified particulate starch and standard potato starch. ‘Pearl starch’ starch gelatinizes at a low temperature of 64.8 °C. During beer brewing, its viscosity is rapidly increased by the addition of water and via the heating processes. However, immediately after the disintegration of starch grains, the viscosity rapidly decreased to a level lower than that of standard potato starch. Moreover, in the presence of malt amylase, ‘Pearl Starch’ starch gelatinized at 62.0 °C, which is 2.8 °Clower than in the absence of the enzyme. Even when the temperature decreased after gelatinization, the viscosity did not increase (no aging). This suggests that most of the starch disintegrated. ‘Pearl Starch’ starch can be sufficiently saccharified by heating at 65 °Cin the presence of malt amylase, even without pre-gelatinization. The ethanol concentration in the wort fermented liquid containing ‘Pearl Starch’ starch was 6.62 %, which was slightly lower than that of fermented liquids containing only wort (7.01 %), but higher than that containing Ca^2＋-fortified particulate starch (5.37 %) and standard potato starch (5.05 %). Therefore, we suggest that starch made from the new potato variety ‘Pearl Starch’ is an effective auxiliary material for beer production (following revisions of the Liquor Tax Law) and potentially simplifies the beer brewing process. This is because ‘Pearl Starch’ starch is sufficiently saccharified by heating at 65 °Cin the presence of malt amylase without pre-gelatinization, unlike cornstarch, which is commonly used in beer brewing.

Currently, consumers expect not only functional value such as ‘cooling’ but also emotional value such as ‘relaxation’ or ‘healing’ when consuming ice cream. In this study, we focused on the effect of blow molded type ice cream on autonomic nervous system activity and mental fatigue. Heart rate variability was employed to assess autonomic nervous system activity. To measure the degree of mental fatigue, the flicker test was performed before and after a simple calculation task, the ‘Uchida Kraepelin Test’, for 30 minutes. Next, the flicker test was performed after eating ice cream samples. Subjective assessment of emotional state was also conducted using the Visual Analog Scale (VAS). The difference between maximum and minimum postprandial palmer skin temperatures was calculated using data collected from thermography. As a result, heart rate decreased and parasympathetic nervous activity increased significantly in volunteers who consumed a smooth textured sample. In addition, only the group who consumed a smooth textured sample showed a reduction in subjective fatigue, as calculated from VAS. The hard textured sample showed larger decreases in thermography-measured palmer skin temperature than the smooth texture sample. These results suggested that the smooth textured sample has the highest relaxation effects, and the coolness and smooth texture interacted with each other for a relaxation effect. Furthermore, the refreshing effect of the smooth textured sample was also supported by the results of autonomic nervous system activity and mood states.

The aim of this study was to evaluate the glycemic response and taste of rice salad made from the high-amylose rice “Koshinokaori”, using Koshihikari as a control. (1) An increase in resistant starch due to heating/cooling treatment was observed only in Koshinokaori. (2) The glycemic response of Koshinokaori rice salad was significantly lower than that of Koshihikari cooked rice. (3) In sensory evaluation, both Koshihikari and Koshinokaori rice salads were highly evaluated, and the texture of Koshinokaori tended to be preferred. These findings indicate that rice salad is a better choice as an intake form of Koshinokaori.