Japanese traditional fermented food “natto” is rich in vegetable protein and is consumed on a daily basis. Japan’s older population is rapidly increasing and therefore, it is important to develop a new natto preferred in the elderly people from a nutritional standpoint. For the development of a new natto, following four aspects are essentially required : (1) soybeans and natto strains, its combination, (2) new manufacturing methods, (3) sauce for natto, (4) types of package. However so far, the studies for improving natto have been mainly focused on the characteristics of natto strains. In the present study, by carefully watching the dietary habits of the elderly people, we have developed the new natto that is consumed conveniently and is popular with them. In addition, we explained the sauce and types of package, for natto. It is hoped that “natto” will be consumed not only in Japan but also in wider areas in the near future.

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Potato starch(PS), guar gum(GG), xanthan gum(XG), and water(W)-added cooked rice were used to examine their effect on rice grain digestibility by blood sugar and glucose release values. Blood sugar level did not differ significantly between a sample of rice alone and sol-added samples after rice intake but was significantly lower with an XG-added sample than with PS- and W-added samples in 15 and 30minutes. The XG-added sample yielded significantly lower glycemic index values than samples of rice alone and with PS and W added did. Samples with XG added at 25 and 50w/w% yielded significantly lower glucose release values than samples of rice alone and with PS, W and GG added did. In a sensory evaluation, the XG- and GG-added samples scored significantly higher than the PS- and W-added samples in the ease of swallowing as one piece and coherence of food mass. The above data indicate that GG addition is useful for chewing and swallowing safety and digestibility.

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We have investigated the relationship between phase separated structure and fracture property of multi component gel. In this study, the research aims at the relationship between phase separated structures and fracture properties on three-component gel in the base of three-type of two-component gels. We focus on the difference in gelling mechanism, so the mixed gels were prepared with egg white protein (EWP), agar and curdlan. The fracture properties of multi-component gels were analyzed by a large deformation test. And the gels were treated with boiling water and proteinase in order to clarify the local structure of each component. The gel structures were observed by confocal laser scanning microscopy and scanning electron microscopy. As a result, three-component gel showed a novel fracture property which didn’t show fracture point. And the results suggested that three-component gel had phase separated structure, in which polysaccharides were continuous phases and protein was dispersed phase. Moreover, it had heterogeneous structure that the structure of each two-component gel presented locally. The results of this study reveal that we can describe the correlation between structure and fracture property on three-component gel, which is complex, in the base of each of two-component gels.

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Benifuuki contains unique methylated catechins such as epigallocatechin- 3- O-(3 -O-methyl) gallate (EGCG Me). The hot-water extract of Benifuuki (BE) is an ingredient useful for food industrial applications. In this study, we evaluated the suppressive effect of BE on postprandial hypertriglyceridemia in rats. Rats were fed CE-2 diet for 1 week and deprived of food overnight. A solution containing corn oil (1mL/head) and BE (50 or 100mg/head) was given orally. Corn oil (1mL/head) was given in the control group. Blood was withdrawn via the jugular vein after administration. After the separation of plasma, triglyceride was measured. Increase of plasma triacylglycerol after the administration of corn oil in rats was delayed by BE. The area under the curve (AUC) of plasma triglycerides was significantly decreased (by 43%) in the 100mg per head BE group, as compared with the control group. BE suppressed postprandial hypertriglyceridemia, which is a risk factor for coronary heart disease. These results suggest that BE may help to prevent postprandial hypertriglyceridemia.

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In this study, we focus on durum starch properties that contribute to changes in pasta texture during high-temperature drying. We analyzed the effect of high-moisture heat-treatment, which models the pasta drying process, on the gelatinization and pasting properties of durum starch. Starch treated with high-moisture heating showed decreases in enthalpy of gelatinization, crystallinity and viscosity, while exhibiting increased gelatinization temperature. These results correspond with the properties of a modified starch following heat-moisture treatment. Therefore, we view the changes induced by high-moisture heat-treatment in this study as being similar to changes induced by heat-moisture treatment. In addition, we infer from the increase in starch damage and the disappearance of starch surface roughness following high-moisture heat-treatment that these observations are due to partial gelatinization. Furthermore, we discuss the effect of high-moisture heat-treatment on the physical properties and sensory evaluation of starch gels as a model of cooked pasta. Gels made from starches treated with high-moisture heating showed increased hardness and breakability and decreased adhesiveness. These results correspond with trends in sensory evaluation of different pastas under different drying conditions, as previously shown. Therefore, this study suggests that both the polymerization of protein and the inhibition of starch swelling contribute to changes in pasta texture during high-temperature drying.

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A vegetable gel was made of thermostable gelling agent and vegetable puree. The objective of this research was to investigate the preparation and cooking applicability of vegetable gel. The vegetable gel formulation was 1-2% gellan gum, 0.6% calcium lactate in 10% RO water, 50% carrot puree and carrot juice. The vegetable gel collapsed in boiling water with 0.5% NaCl, whereas a high salt concentration prevented gel collapse. At 90°C, the vegetable gel did not collapse even after heating in a salt solution for 90min. Vegetable gel with seasoning simmered for 20min showed slight collapse; however, panelists considered it “not collapsed” . These results demonstrate the applicability of thermostable vegetable gel as a consistent quality foodstuff in vegetable cooking.

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With the aim of expanding the use of rice paste, we attempted to create a powder from rice paste by drying at 40°C and 60°C. Average particle size of the dried powder was larger than the pre-dried rice paste, but became similar to rice paste when restored in water. The ratio of damaged starch in the dried powder was similar to that of rice paste, while lower than that of rice powder made from jet-milling under dry conditions. The rate of water absorption of the dried powder was higher than for rice paste, with a lower syneresis rate. The gelatinization characteristic values of dried powder at 60°C and rice paste were measured using RVA, but no differences were identified. The swelling rate, specific loaf volume, hardness and cohesiveness of bread crumbs made with 30% substitutes of 40°C and 60°C dried powders were equivalent to those for bread made with 30% rice paste. In addition, bread made with a substitute of 60°C dried powder was improved with the sensory properties of rice cake. These results indicate that powder made from thermally-dried rice paste at 60°C maintains the gelatinization properties of rice paste, and improves upon the deficiencies associated with powder made from jet-milling under dry conditions.

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Yacon (Smallanthus sonchifolius) root is known as a functional food material because it contains antioxidants high in polyphenols and fructooligosaccharides. However, yacon root is astringent. We reported that while the astringency was removed by exposure to ethanol (EtOH) vapor, as previously observed in persimmons, the antioxidative activity and fructooligosaccharides were retained. In this study, we investigated the mechanism of astringency removal in yacon root. Levels of proanthocyanidin (PA), which contains the gallate ester structure responsible for astringency, in yacon were decreased during EtOH treatment. The decrease in PA was proposed to originate from changes in its water solubility. About 57.7% of PA was insoluble in water after the treatment. This change in solubility might be caused by the reaction with acetaldehyde, which is generated by the action of alcohol dehydrogenase (ADH). ADH activity increased during the treatment period, as previously observed in the case of persimmons. These results suggest that the removal of astringency in yacon root is a result of the increase in insoluble PA.

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Volatile fractions obtained by simultaneous distillation extraction (SDE) methods were analyzed in order to clarify the undesirable aroma components of cooked barley. The volatile compounds were subjected to gas chromatography, gas chromatography-mass spectrometry and gas chromatography-olfactometry (GC-O). Eleven aldehydes, eleven alcohols, nine ketones, one carboxylic acid and two furans were identified in cooked barley. The contribution of each component to cooked barley was estimated on the basis of the flavor dilution (FD) factors determined by GC-O/AEDA (aroma extract dilution analysis). Hexanal, (E,E)-2,4-nonadienal, (E)-2-nonenal and (E,E)-2,4-decadienal exhibited especially high FD factors in volatiles of cooked barley. The results suggested that these aldehydes contribute to the undesirable odor of cooked barley.

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Molecular-level understanding of ice crystal surfaces holds the key to unlocking the secrets of various fields. To observe ice crystal surfaces at the molecular level, we developed an advanced optical microscope, and succeeded in visualizing individual elementary steps of 0.37nm in height on ice basal faces. Utilizing this microscope, we also attempted to visualize the surface melting processes of ice crystals. We found the presence of two types of surface liquid phases (quasi-liquid layer phases) that exhibit different morphologies and dynamics on ice basal faces.

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Recrystallization of ice crystals is a physical cause of deterioration in frozen foods during both storage and distribution, and therefore needs to be controlled and predicted for optimal storage and distribution of frozen foods. However, a systematic understanding of recrystallization is lacking and the accumulation of sufficient recrystallization experiments remains difficult due to the time-consuming storage experiments necessary to investigate recrystallization behavior. In response to this challenge, we showed that the concept of water mobility in a freeze-concentrated matrix is useful for predicting the recrystallization rate of ice crystals in model frozen foods. Thus, knowing the water diffusion coefficient, an index of water mobility, in a freeze-concentrated matrix would enable us to predict the recrystallization rate of ice crystals and limit the need for time-consuming storage experiments.

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