In this study, we have developed a heat storage system, which is able to store waste heat and release it to an appropriate heating equipment elsewhere, in order to improve utility of waste heat and thus reduce environmental pollutants. The heat of solution of a solid-liquid reaction was adopted for the heat storage system. In this system, the reactant was also used as heat transfer medium and being sent to heating parts. Therefore, the evaporator that has been used in conventional chemical heat storage can be omitted to reduce the device size and for motive use. The heat value, heat release rate and cyclic performance of CaCl₂/H₂O system were measured. The results indicated that the heat of solution was proportional to the mass concentration as far as the reaction reached its saturation solubility under ambient temperature. In addition, the heat value per unit mass was higher at lower concentration than that at higher concentration. During the first 1 minute, the heat output of 5.06kW/L- H₂O was obtained for CaCl₂ (s) /H₂O (l) when the reaction reached its saturated solubility. It was found no degradation in chemical composition after 50 times of cyclic operation.

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The author has proposed a hybrid air-conditioner employing both heat and microwave irradiation for achieving greater compactness and higher output of a desiccant air-conditioner. In this research, the effectiveness of this system has been evaluated for promoting desorption of adsorbed water using microwave irradiation and heating under two conditions: air with the same humidity as that in the adsorption process (Case-1) and air with humidity lower than that in the adsorption process (Case-2). This evaluation was done using the desorbability and desorption rate as indicators. In the experiment, measurements were taken of hot air temperature due to the zeolite-filled layer (50–100ºC), microwave intensity (30–100 W), and temperature in the filled layer and humidity at the intake and outlet of the layer, in the desorption process under three types of initial conditions for adsorbed amount. The results are given below. 1) The heat balances for Case-1 and Case-2 can be evaluated using the same technique. 2) The desorption time and thermal efficiency of the system with combined use of microwaves, taking the hot air system desorbability in Case-2 as a reference standard, are respectively a minimum of 0.3 times and a maximum of 1.3 times the values in the hot air system. This suggests that, compared to conventional hot air heating type desiccant air conditioners, it is possible to increase the amount of treated air by 1.25 times, and reduce the adsorption rotor cross-sectional area by 0.8 times. 3) Adoption of microwaves will contribute to efficient, high-level desorption.

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Freeze denaturation of myosin and actin when stored in a form of meat and in myofibrils (Mf) (0.1 M NaCl, pH 7.5) was compared at -20˚C. Frozen storage of Mf inactivated its Ca²⁺-ATPase activity almost completely in 8 days. Decrease of monomeric myosin content occurred similarly to Ca²⁺-ATPase inactivation, while myosin kept its solubility in 0.5 M NaCl during the frozen storage period. Chymotryptic digestion of the frozen stored Mf showed a slight damage at rod portion. The chymotryptic digestion of the Mf also demonstrated a severe actin denaturation as detected by a drastic decrease of actin content in the digest. Denaturation profile of actin was similar to Ca²⁺-ATPase inactivation. On the other hand, such myosin and actin denaturation was not observed when flounder muscle was frozen stored at -20˚C. To study myosin and actin denaturation in frozen stored meat, muscle was converted into muscle homogenate quantitatively. Frozen storage of meat up to 60 days denatured myosin very slightly exhibiting roughly 75 % of Ca²⁺-ATPase activity. Practically no detectable actin denaturation was found with the same frozen stored meat. It was thus demonstrated that actin denaturation in Mf caused quick myosin denaturation in it. Thus, Mf is not a suitable model for studying freeze denaturation of myosin and actin in fish meat.

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The qualities of Japanese frozen chub mackerel Scomber japonicus and imported frozen Atlantic mackerel Scomber scombrus were evaluated several freshness indices (K-value, muscle pH), lipid content and sensory test. From the model experiment, increasing ratios of K-value in both mackerels were almost the same during storage at 0 °C. In addition, when the storage temperature was lower, the increasing ratio was lower. These results suggested that storage time and condition after catch were closely related to the freshness. The K-values of domestic and imported frozen mackerels were 3-36 % and 9-21 %, respectively. The pH value, lipid content, sensory evaluation also showed different qualities among each mackerels. The principal component in this study showed that first component was lipid content and second one was freshness. Namely, if the mackerel have the same lipid content, their qualities greatly depend on the freshness.

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Effects of a freezing period and frozen storage temperature on lipid oxidation of frozen Atlantic mackerel (Scomber scombrus Linnaeus) and frozen Chub mackerel (Scomber japonicus Houttuyn) during frozen storage were investigated. The lipids contents of frozen Atlantic mackerel captured from Norway and frozen Chub mackerel captured from low latitude of the sea near Japan in winter were higher than the other mackerel. Peroxide value and aldehyde contents increased by higher frozen temperature and storage period. In addition, 4-hydroxy-2-hexenal, one of the aldehyde generated by oxidation of n-3 unsaturated fatty acid, increased with the reduction of the vitamin E level during frozen storage. In this summary, the lipid oxidation of the frozen Atlantic and Chub mackerel in Japanese market were shown various levels. In order to improve these qualities from the point of view lipid oxidation, we needs to pay attention to temperature and period during the frozen storage.

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In order to clarify the minimum temperature made a fillet, maintaining the quality of frozen round mackerel, we studied on temperature and fat content that effected on the physical quality of frozen mackerel. We showed that the penetration stress to frozen mackerel increased with decline in temperature, the changing point of penetration stress existed between -30℃ and -40℃, and fat content controlled penetration stress.

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Regarding the quality of frozen spotted mackerel Scomber australasius, it was examined how the freshness of the fish before freezing temperature i.e. the freezing speed influenced on the state of ice crystals formed in the muscle tissue of fish when frozen. And the amount of the drip oozes out when the frozen-stored fish was thawed. First of all, in order to prepare the fish samples differing in freshness, the fish just caught were kept at a temperature of 4 ℃ for different lengths of time: 3, 27, 51 and 123 hours. The freshness of the fish was assessed by the K value. These fish samples (fillets) with different freshness were frozen at three different temperatures: -20 ℃ -30 ℃ and -60 ℃, and frozen-stored at the respective temperature for one month. As to the size of ice crystals formed in the muscle tissue, the lower the freshness, larger crystals were observed, and the lower the freezing temperature, the smaller crystals. Between the size of ice crystal and the production of the drip, a positive correlation was seen. In case of fish with low freshness, relatively large sized ice crystals were observed and a relatively large amount of drip was measured, although the fish were frozen at lower temperature such as -60 ℃, namely, these factors indicate that the quality of the fish was less desirable.

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When the tuna meat is frozen sequentially from outside of body by air blast freezer, the duration for freeze is different in each part. Though it was suggested that the meat quality is different in each part, the distribution of that is almost unknown. In this study, the relationship between chemical components and meat color through whole body was analyzed. The ratio of ATP around vertebra was lower than that of the skin. The content of lactic acid was higher at the point of low ATP. The red meat color was negative correlated with the ration of ATP and total sugar amount, and positive correlated with lactic acid content and myoglobin content. Therefore, it could be shown that the distribution of chemical components in tuna muscle had been individually different.

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Recently, frozen raw oysters for consumption have come to be appeared in a market. We investigated the effect of freezing conditions on the extractive components in the frozen raw oysters. Oyster with shell or shucked oyster was frozen individually in liquid nitrogen or ethanol brine below -40°C within 3 min for shucked oyster and 23 min for oyster with shell. Also oyster was frozen at -20, -10 and -5°C in a freezer. The frozen oysters were directly deproteinized with perchloric acid for analysis. After neutralization with a KOH solution, free amino acids, organic acids, and nucleotides in the extracts were analyzed. There was no significant difference in free amino acid contents and organic acids contents in the shucked oysters among different freezing conditions. On the other hand, contents of free amino acids and organic acids in oysters with shell frozen at -5 and -10 °C were significantly lower than the shucked oysters frozen in liquid nitrogen.

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In order to control damage to the food cell by freeze, it is necessary to make an ice crystal nucleation uniform．One of the solutions is to freeze the food using a supercooling phenomenon．On the other hand, supercooling is an unstable probability phenomenon, and obtaining the high degree of supercooling is difficult．In this report, numerical computation model is proposed to calculate the probability of freezing and the distribution of the degree of supercooling at the time of freezing of an arbitrary shape．Influence of specimen geometry and cooling rate on temperature distribution of tuna sample at the instance of freezing is evaluated and verified with the experimental results．It was found that suppression of freezing from the surface of specimen and increasing of the degree of supercooling at the center of the specimen can be possible by controlling the cooling technique to minimize the temperature distribution at the time of freezing.

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