Convenience and a rise in health awareness has increased the demand for ready-to-eat vegetables and fruits; however, along with this increase in demand has been an increase in the number of food poisonings associated with the low-temperature storage and distribution of foods. To maintain the quality and safety of vegetables, we have conducted basic research on the freezing tolerance of plants by using chlorella and yeast. First, two low-temperature inducible genes from Chlorella were investigated by genetic modification techniques. Next, the availability of taurine and trehalose to plants stored at freezing temperatures was investigated. Finally, a rapid detection method for Listeria monocytogenes, a psychrophilic bacterium and a pathogen in foods stored and transported at low temperature, was developed based on subtyping clinical isolates and isolates from food and the environment.

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To characterize the koshi, or physical texture of cooked noodles, the distribution of viscoelasticity between the surface and center of cooked noodles was investigated using a modified compression creep test. Typical creep curves were described at 4 different points between the surface and center of the cooked noodles, and individual points of sample A (shortly after cooking) and sample B (24 hours after cooking) were analyzed for 6 or 8 viscoelastic elements. The measured η₁, η₂ and η₃ were 1/10∼1/100 smaller than η_N; therefore, we ignored the effects of these 3 viscous elements and simplified the noodle viscoelasticity into 2 elements. The calculated relaxation time at the measured points of the cooked noodles ranged from 10 seconds to about 1 minute, which was much longer than the less than 1 second noted for chewy cooked noodles. As a result, it was proposed that the elastic elements significantly affected the chewiness of the cooked noodles. The elasticity of sample A increased gradually from the surface to the center of the noodle, which showed elevated chewiness, i.e., strong koshi. The elasticity of sample B increased shortly after chewing and then leveled out or decreased, indicating that the noodle had lost springiness. These results agreed with those from sensory evaluation.

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The basic physical properties of raw and roasted flours from 12 different cereals (wheat, rice and millets, including some whole grain), which are easily obtained in Japan, were determined. (1) The maximum viscosity and breakdown of polished rice flours showed approximately twice as large as those of wheat flour. Millets flours showed various RVA (Rapid Visco Analyzer) viscosity. RVA viscosity decreased sharply by roasting. (2) Four kinds of rice, which showed higher maximum viscosity, showed higher swelling capacity. Three kinds of wheat, job’s tears, foxtail millet and roasted flours, which showed lower viscosity, showed higher soluble sugars. (3) Although the moisture sorption curves were not different between raw flours, curves from roasted flours showed changes of sorption behavior, indicating starch degradation to lower molecular size. (4) All flours showed A-type of X-ray diffraction patterns, and there was a little crystalline change by roasting. (5) Degradation by roasting was not observed by microscopic observation of these cereal starches.

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The purpose of this research is to develop a manufacturing method for high-amylose rice noodle using mechanical mixing of gelatinized rice and extrusion. We investigated the relationship between processing conditions and physical properties of rice gel and noodles. Polished high-amylose rice was gelatinized using a rice cooker at two levels of water addition : 100% and 120%, and then mixed at 1500rpm for 1, 2 and 3 min using a cutting mixer. During mixing, the internal pressure of the mixer bowl was set to 0.01, 0.04, 0.07MPa and standard pressure. Formation of rice gel into noodles was performed using a noodle extruder. Dynamic viscoelasticity of rice gel and rupture stress of rice gel noodles were measured. As a result, storage modulus (G’) and loss modulus (G’’) of rice gel, and rupture stress of rice gel noodles were greater with less added water, longer mixing times and lower pressure during mixing. The hardness of rice gel noodles cooked with 100% water addition and mixed for 3 min was similar to that of Udon noodles (Japanese wheat flour noodles). This proposed method enables the production of rice noodles from high-amylose rice without milling.

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We determined stable carbon and nitrogen isotopic compositions (δ¹³C and δ¹⁵N) and nine trace element abundances (Mg, P, Ca, V, Mn, Zn, Rb, Sr, and Ba) of boiled and salted wakame (Undaria pinnatifida) from South Korea, China, and two areas in Japan, Sanriku and Naruto, to evaluate the utility of the combination of isotope and trace element analyses in the discrimination of the geographical origin of wakame. Wakame from Naruto was characterized by relatively higher δ¹⁵N values than those from other areas, whereas the wakame from China had relatively higher abundances of Mg, V, Mn, Zn, and Ba. Based on δ¹³C and δ¹⁵N values and trace element abundances (Mg, V, Mn, Zn, and Ba), the wakame investigated was divided into the following three groups with respect to geographical origin : Naruto, China, and other areas (Sanriku and South Korea), with 100 % and 96 % discrimination being achieved for Naruto and China, respectively. No significant difference was found between wakame samples from Sanriku and South Korea. Thus, combination analysis of stable isotope composition and trace element abundance can be employed as a tool with great potential for the discrimination of the geographical origin of wakame.

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Monthly changes in the fatty acid composition of ayu (Plecoglossus altivelis) hatched and cultivated in the Yufunezawa River of Gifu Prefecture were investigated. Results of monthly sampling and GC-MS analysis showed that the fatty acid composition of ayu stabilized after two months of river cultivation. Moreover, it was found that the fatty acid composition of both cultivated and stocked ayu was related to the fatty acids of the feed.

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The impact of dietary steamed and cured sweet potato slices (100g/day for 2 weeks) on bowel movement was examined in 84 Japanese female students, comprising a constipation group (n = 15) and a non-constipation group (n = 69). During the test period, the subjects recorded their bowel movement themselves status daily. Subjects completed a food-frequency questionnaire and were given a physical examination once a week. In all subjects, it was observed that the intake of the test food significantly increased the number of days of stool frequency, amount of stool, flatus, and the proportion of subjects who had soft stools.

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