Ten samples of Bunashimeji [Hypsizigus marmoreus (Peck) Bigelow], fourteen samples of Nameko [Pholiota nameko (T. Ito) S. Ito et Imai in Imai] and eight samples of Enokitake [Flammulina velutipes (Curt.: Fr.) Sing.] mushroom cultivated on sawdust substrate beds were obtained together with their substrate beds, which were all of distinct origins. By analyzing proximate compositions and mineral contents in both these mushrooms and their substrate beds, effects of the sawdust substrate composition on the mushroom composition were examined. In Bunashimeji, Nameko and Enokitake mushrooms, the nitrogen content in their fruit body was not significantly related to that in the substrate. In Bunashimeji mushroom, concentration of minerals to the fruit body from the substrate was found in K (11.6 times), Na (9.73 times), Zn (1.81 times), Cd (4.30 times) and Hg (1.80 times), but a significant correlation between them was found only in Na. Fe from the substrate was not concentrated in the fruit body, however, a significant correlation between the fruit body and its substrate was observed. In Nameko mushroom, concentration of minerals to the fruit body from the substrate was found in K (5.9 times), Na (2.31 times), Mg (1.52 times), P (4.52 times), Cu (1.69 times), Zn (4.02 times) and Cd (3.23 times). Ca from substrate was not concentrated in the fruit body, however, a significant correlation between the fruit body and its substrate was observed. In Enokitake mushroom, concentration of minerals from the substrate to the fruit body was found in K (3.13 times), Zn (1.76 times), Cd (1.89 times) and Hg (1.88 times). Cu was not concentrated in the fruit body from the substrate, however a significant correlation between the fruit body and its substrate was observed.

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Cooked rice grains were subjected to amylography programmed to hold at 50°C after reaching this temperature. The cooked rice grains stored at 4°C for 3 days were also subjected to the amylography. The rice samples adopted were high grade (Koshihikari-excellent, Koshihikari-good and Koshihikari-Niigata), middle grade (Yukihikari, Mitikogane and Tomohikari) and low grade (Koshihikari-inferior and third-class). Each rice species showed characteristic amylogram. The viscosity of all Koshihikari species increased significantly after the holding temperature period, but that of third-class did not, and these of the other species were between the range. Similar tendency was observed in the case of cooked rice sample stored in a refrigerator, although their patterns at initial stage were different. Among Koshihikari species, an oscillation width of initial stage was different, namely, the excellent was small, the good and the Niigata were medium and the inferior was large. Hence, the two indexes (final viscosity and initial oscillation width) obtained from the amylogram will be useful for quality evaluation of cooked rice. Because, an oscillation width and viscosity of initial stage indicated hardness of grain surface, and viscosity of final stage indicated a molecular shape properties of starch. X-ray diffraction analysis of cooked rice showed V-type pattern. and the peak (2θ=13.5°) in the pattern suggested existence of lipid-starch complex and the peak was more clearly observed in the case of low-grade rice than the high grade. This observation and amylographic results of Koshihikari species suggest that lipid-starch complex which acts to harden grain surface may be richly formed in low-grade species more than high grade and this complex may cause a decrease in texture, but there may be little significant difference in starch structure among Koshihikari species.

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Physical properties of cold-gel prepared from heated soy protein isolate were investigated compared with heat-gel and freeze-gel. Based on the results of breaking and creep tests, strain and retardation time (λ) of cold-gel were higher than those of heat-gel and freeze-gel. Both elasticity and smoothness of cold-gel on sensory evaluation were significantly higher than those of heat-gel and freeze-gel. The water-holding capacity of cold-gel was increased with time during cold storage, and was in well agreement with changes of gel strength. Line-width value of NMR spectra on cold-gel decreased with the elapse of time during cold storage. The gels heated or frozen after treatment of cold storage had higher strain than gels heated or frozen without cold storage. Based on a SEM observation, the unit of mass on microstructure of cold-gel was bigger than that of heat-gel or freeze-gel. It was suggested that the unit size of microstructure of cold-gel was responsible for elasticity of the gel.

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Changes of molecular structure of heated soy protein in gelation process during cold storage were investigated. It was considered that disulfide and hydrogen bonds contributed to cold-gel formation, judging from changes in protein solubility against mercaptoethanol, urea and SDS. However, contribution of disulfide bond to cold-gel was small compared with that to heat-gel or freeze-gel, as judged by the reduction of SH contents in gelation process. Hydrophobic bond was regarded as a significant foctor in cold-gel on the basis of a remarkable decrease in fluorescent intensity in gelation process. Furthermore, reduction of one basic subunit band (I) and one acidic subunit band (VI) in cold-gel was shown by SDS-PAGE. These results suggested that contribution of hydrophobic and hydrogen bonds to cold-gel was big as compared with those to heat-gel and freeze-gel, and that gelation during cold storage is accompanied by the reduction of one basic subunit band (I) and one acidic subunit band (VI).

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This study was conducted to determine the effect of two modified atmosphere packaging systems with and without vacuum treatment on storage quality characteristic of thin sliced beef stored at 5°C. Thin sliced beef was packaged in atmospheres of: (A) air without gas flush treatment (control), (B) 20% CO₂+80%O₂ after vacuum treatment and (C) 20% CO2+80% O2 without vacuum treatment. After 0, 2, 4, 6 and 8 days of storage, each sample was evaluated for pH value, microbial growth, metmyoglobin (MetMb) formation, lipid oxidation (TBA number). The pH value of the control was significantly higher than those of (B) and (C) samples after 8 days of storage. The viable and psychrotrophic bacterial counts and the number of coliforms of (B) and (C) samples were less than those of the control during storage. The control, (B) and (C) samples attained a MetMb level of 20% after 3, 5 and 6 days of storage, respectively. At 6 days of storage, MetMb formation of (C) sample was significantly lower than that of the control, but the difference in the results of the control and (B) sample could not be regarded as significant. Although the TBA numbers of (B) and (C) samples were higher than those of the control, both samples maintained a TBA number of 3.0 even after 6 days of storage. These results suggested that the differences in pH value, microbial growth, lipid oxidation of vacuum between samples with and without vacuum treatment were not recognized significantly, but the rate of MetMb formation may be different between them during storage.

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The objective of our study was to investigate the effect of modified atmosphere packaging on myofibrillar fragmentation, extractability of muscle protein and LDH activity of thin sliced beef. The sample was packaged in atmospheres of: (a) air without gas flush treatment (control), (b) 20% CO₂+80% O₂ after vacuum treatment, (c) 20% CO₂+80% O₂ after being flushed with the gas of the same composition and then was stored at 5°C for 2, 4, 6, and 8 days. The degree of myofibrillar fragmentation of all samples gradually increased during storage. The rate of myofibrillar fragmentation increased in order of control >(b)>(c). The extractability of water-and salt-soluble muscle proteins of all samples decreased during storage. SDS-PAGE patterns of proteins extracted with GS-solution from thin sliced beef stored under different conditions exhibited a decrease in salt-soluble protein due primarily to the decrease in the extractability of myosin molecules. LDH activity of the control decreased during storage, but the samples packaged in modified atmospheres maintained their LDH activity, particularly the (c) sample did. These results suggest that samples packaged in modified atmospheres retain biological activity even after 8 days of storage.

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Three kinds of analytical methods, purge-and-trap, porapak Q column and simultaneous distillation and extraction under reduced pressure (SDE), were used for analysis of volatile compounds in salted Perilla frutescens. Volatile compounds were analysed by a capillary gas chromatograph and a gas chromatograph-mass spectrometer. By the purge-and-trap method, salted Perilla frutescens was found to give 104 peaks, 85 of which were identified. By the porapak Q column or SDE methods, 52 and 78 peaks, respectively, were detected. The peak area percentages of terpene hydrocarbons such as l-limonene and major oxygenated-compounds such as 1-octen-3-ol, linalool and benzaldehyde by the purge-and-trap method were higher than those by the other methods. The percentage of perilla aldehyde, main peak of salted Perilla frutescens, was highest in porapak Q column method. The mean reproducibility (n=6) of major 10 peaks was 8.1% for porapak Q column method and 13.7% and 15.3%, respectively, for the purge-and-trap and SDE methods as a coefficient of variation. Purge-and-trap method was better for analysis of the volatile compounds in salted Perilla frutescens. However, porapak Q column method which is simple and rapid, is applicable for analysis of major volatile compounds except for l-limonene.

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Four varieties of amylopectins isolated from tropical starches, i.e., edible canna, arrowroot, cassava and sago, were used to study their fine structure. Potato and corn amylopectins were used as references. The amylopectins were treated with isoamylase and the slow debranching process was monitored by gel permeation chromatography. The rates of these isoamylase α-1, 6 debranching reactions varied a little among six varieties of amylopectins, however, the respective retention times of peaks produced from each debranched amylopectin became longer as the debranching reaction proceeded, indicating that molecular weight of the isoamylase-treated amylopectin gradually became smaller. Conversely the retention time of the unit chain gradually became very slightly shorter. This shows that the molecular weight of the unit chain increases slightly as the debranching reaction proceeds. If the isoamylase debranching reaction proceeds predominantly at the outermost α-1, 6 linkage, the inside unit chain will be expected to be longer.

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Far-infrared radiation have been attracted interest for the thawing of frozen raw material such as tuna. Since the quality of food is greatly influenced by the thawing rate and the final temperature, investigation of heat transfer in food heated by far-infrared radiation, is important. An apparent specific model was introduced to predict two dimensional heat transfer in tuna. A finite element method was applied to solve the fundamental equation and was used to examine the influences of the air flow rate around the sample, the heater temperature and the sample thickness on heat transfer. Experiments of far-infrared heating were carried out to check the validity of the mathematical model. Temperature distributions in samples were measured by using thermocouples and they agreed well with the theoretical predictions. To prevent tuna from overheating, control of the surface temperature was achieved by irradiation of the energy intermittently.

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An endo-1, 4-β-xylanase (1, 4-β-Xylanohydrolase, EC 3.2.1.8) has been easily purified from culture filtrate of Robillarda sp. Y-20 by combination of specific affinity chromatography on Bio-Gel P-6DG and gel filtration chromatography on Toyopearl HW-55S. The yield of the purified enzyme was about 40% of that in the culture filtrate. The molecular weight of the xylanase determined by SDS-PAGE was 23400Da. The pI value was 9.5. The optimum pH and temperature were pH 4.5-5.5 and 55°C, respectively. The HPLC analysis showed that the main hydrolysate of xylooligosaccharide was xylobiose, and the enzyme had the transxylosidase activity. Km and Vmax values for xylotriose, xylotetraose, xylopentaose and xylohexose were obtained and from these data the enzyme was shown to have 5 subsites. It was found that the enzyme showed a specific affinity toward P-6DG column in the presence of xylooligosaccharides.

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The effects of elevated CO₂ levels in modified atmospheres on the preservation quality of chum salmon fillets were investigated. The fillets of chum salmon (Oncorhynchus keta) were held in the modified atmospheres (30% CO₂: 70% N₂, 50% CO₂: 50% N₂, 70% CO₂: 30% N₂) and 100% CO₂, and stored at 5°C and 10°C up to 6 days. Controls were stored similarly in air.
After 2 to 6 days of storage at both temperatures, the bacterial counts were lower in chum salmon stored in the CO₂-enriched atmospheres compared to samples stored in air. The CO₂ levels of more than 50% at 5°C and 70% at 10°C showed the effective inhibition of microbial growth, respectively. Moreover, a modified atmosphere containing 70% CO₂ was more effective than 100% O₂ on the inhibition of microbial growth of chum salmon fillets in this study.

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