Effects of the microwave (MW, 2.45GHz) on stored-product insects at different developmental stages; Sitophilus zeamais (Sz), Sitophilus oryzae (So), Rhyzopertha dominica (Rd), Oryzaephilus surinamensis (Os), Tribolium castaneum (Tc) and Plodia interpunctella (Pi) and on the rice qualities were studied. The temperature in the host media (foods), husked rice for Sz, So, Rd and Pi, wheat for Os and wheat flour for Tc, during the MW treatments were recorded with a floroptic thermometer. The MW treatment could hardly kill the insects without heating the host media. The insects were killed effectively when the temperature of the host media increased more than 60°C, although the susceptibilities of the insects varied depending on species and developmental stages. The adults of So and Os and mature larvae of Pi were most tolerant followed by Rd adult>Pi pupa>Sz adult, Tc adult and Pi egg>Tc pupa, egg and mature larva in decreasing order. The increased moisture content of husked rice resulted in the higher mortality of Sz adult. All species and developmental stages of insects examined were killed by MW with 2.5kW output within 55s. The taste and qualities of husked rice treated with MW for 60s, when the average temperature of rice was ca. 75°C, were unaffected significantly during storage of 4 months at 15, 25 and 30°C. However, after 6 months, the tates of the treated rice stored at 15 and 25°C were more deteriorated than those of their untreated controls.

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Effects of the radio-frequency (RF) electric field (13.56MHz) on stored-product insects at several stages, Sitophilus zeamais (Sz), Stophilus oryzae (So), Rhyzopertha domi nica (Rd) and Plodia interpunctella (Pi) in husked rice, Oryzaephilus surinamensis (Os)in wheat and Tribolium castaneum (Tc)in wheat nour, were studied. Adults of Sz and adults, pu pae and larvae of Tc were completely killed by the irradiation for 60-80s, when the tem perature of the rice was as low as below 40°C. The adults of Sz were most susceptible to RF followed by adults, pupae and mature larvae of Tc, Pi mature larva, Os adult, So adult, S z mature of RF had little effect for increasing the mortalities of Rd adult. The shapes o f exposure time-mortality lines suggested an unknown action of RF on the insects other than the dielectric heating. A feasibility of RF application for pest insect control in f ood processing factories was discussed.

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Flavor-related components were analyzed for pork sausages. Comminuted pork was prepared under a conventional and an aseptic conditions and subsequently cured with and without added nitrite at 5, 10, and 15°C for the period of up to 240 h, respecti vely. Threonine, serine, glutamic acid and glutamine, glycine, and alanine were the predominant free aminoacids in the sausage. Curing with and without added nitrite increased the propotion of the free amino acids having hydrophobic side-chains to those with hydrophilic side-chains. Curing decreased the 5'-inosine monophosphate level while increasing the inosine and hypoxanthine levels. During the course of curing, the sausage prepared under con ventionalee amino acids and n-butyric, iso-butyric, and lactic acids. The raise in curing temperature accelerated these changes. Nitrite addition decreased the rate of appearance of free amino acids and organic acids as well as the rate of disappearance of peptides in the respective sausages prepared under conventional and aseptic conditions. Curing without added nitrite resulted in an accumulation of formic acid and an increase in acetic acid level under conventional conditions, while producing little change in the level of lactic acid, which is the predominant organic acid present in pork, and no detectable build-up of formic acid with added nitrite.

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Changes in free fatty acids (FFA) in comminuted pork and its sausage (comminutedpork after cooking) were investigated in the course of curing under conventiona ied with the curingtime and temperature. Conventional curing resulted in higherFFA levels in comminutedpork than aseptic curing did. The FFA contents in comminuted pork cured without nitriteunder conventional condition were higher than those cured with nitrite, suggesting that anincrease in the FFA contents was affectntly with curing time. Heat treatment increased theFFA contents, particularly linoleic acid, in comminuted pork cured under conventaseptic conditions

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Dried Shiitake mushrooms rehydrated under various conditions were cooked and erences between the cases of Donko and Koshin varieties, the cooked mushrooms which soak ed at 5°C for 5h or more and at 25°C for 5 to 15h were preferable. On the whole, the mushr ooms soaked at 40°C were evaluated to be not preferable, however, some of them soaked for a short time were relatively preferable. The impression for taste of the cooked Shiitake was correlated with the intensities of umami and bitterness. The increase of umami h eightened the impression score for taste. On the other hand, bitterness provided bad effec t on its score. The score for intensity of umami in cooked dried Shiitake was correlated with the concentrations of 5'-GMP and glutamic acid. The content of hydrophobic amino ac ids in dried Shiitake cooked after long time soaking at high temperature were enough to cause bitter taste. Since the mushrooms, which generated much 5'-GMP and contained le ss hydrophobic amino acids, were scored highly for taste and consequently gained a good overall estimate, it was suggested that the soaking for a shorter time at lower temperature was desirable. However, the one soaked for too short time was not thoroughly reh ydrated, so scored lower points for texture and consequently not prefered. (Received Jul. 7, 1988)

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Systematic mathematical model was featured for designing the installations and operational conditions in multi-stage feed and breed reverse osmosis (RO) in order to economize the cost for concentration of cheese whey under limiting stable volume flux (Jvlim)without fouling. The total RO cost for removing one m3 of permeate was divided into twoterms; a changeable cost (C_θ) which varies depending upon flux level, and the othercost. Formulae to calculate the costs for RO operation were derived. Relationships among factors in RO operation were studied by introducing equations for membrane transport, concentration polarization and Jvlim. The systematic mathematical model, which was also introduced in the present study, was applied to calculate C_θ from the values of concentration factor and the recirculation flow rate, and consequently this enabled to conceive the optimumplant design and operation mode which minimize the cost for RO by monitoring concentration factors and recirculation flow rates on every stage in RO operation. The minimum cost for RO was estimated regarding four typical experimental cases, in which the values of Jvlim had been determined, on concentation of cheese whey of 100m³ by three fold in 20h by means of the three-stage feed and breed RO plant equipped with plate-and-frame Arlamo-26 modules and a FL-190 membrane of 0.90 in salt rejection rate. The RO cost was minimized when the whey of pH5.8 was concentrated at 40°C after standing for one hour at 50°C. The total cost for RO, to remove 1m3 of the permeate, was estimated to be 1140yen which was allotted to itemized costs of 4% for energy for high-pressure feed pump, 7% for energy for recirculation pump, 11% for membrane replacement, 13% for solids loss, 1% for waste water treatment, 2% for cleaning, 8% for the pretreatment of whey to adjust pH with CO₂, 16% for labour and 38% for depreciation and interest for investment. Changeable costs for the every stage were capable to be expressed as a function of recirculation flow rate, and then the values for recirculation flow rate and concentration factor, which were to minimize the total RO cost, were estimated by simplified computation.

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"Namashibori" on Tofu processing is a squeezing and separating step into soymilk and the residue at mild temperature after crushing soybeans swelled with water, and today, this step is eliminated from modern Tofuo processing in Japan. But the Tofu prepared by the process including the "Namashibori" step was more preferable than the ordinary Tofu. Therefore, it was suggested that the effect of squeezing temperature on quality of soymilk and Tofu has been important. In order to make optimum temperature clear, the effects of squeezing temperature on yield, viscosity, glycoside content, lipoxygenase activity and n-hexanal level of soymilk from the cotyledon and the whole bean were examined. A yield as solid was maximum in soymilk squeezed over 30°C from the cotyledon and at 60°C from the whole bean. Viscosity of soymilk significantly decreased with increasing temperature and showed a minimum value at 60°C. A glycoside content as solid increased in soymilk, squeezed above 50°C and was approximately 2.6 times higher in soymilk at 95°C than at 20°C. The lipoxygenase activity, which is the major cause of undesirable flavor of soymilk, decreased in soymilk squeezed with increasing temperature, and it was not detected in soymilk squeezed over 70°C. n-Hexanal, which was produced by lipoxygenase, was about half in soymilk squeezed at 60°C as compared with 20°C. Accordingly, optimum squeezing temperature on soymilk and Tofu processing was recommended in range of 50-60°C.

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4'-Galactosyllactose (4'-GL) as a major product was produced from lactose by intact and immobilized cells of Cryptococcus laurentii OKN-4. The maximum yield of 4'-GL was about 30% against added lactose. By-products such as glucose and disaccharides were produced. Tetrasaccharides were detected at the late stage of the reaction. The pH range of the reaction was 3.0 to 7.0. The optimum temperature was 65 to 70°C. The formati on of 4'-GL was independent of the lactose concentration in the reaction mixture. The immobilized cells were stable after more than forty times repeated batch reaction.

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The changes in the color and the contents of free amino acids, organic acids, free fatty acids and volatile components in canned cooked curry during storage at room temperature were investigated. (1) Amounts of free amino acids, organic acids and free fatty acids decreased during the storage. It was shown that the main components decreased more rapidly than the minor components. (2) The lightness and saturation of the color of cooked curry decreased during the storage. It became darker slightly. (3) The amount of volatile components were found to decrease during storage. Low boiling point volatile components (LVC) and medium boiling point volatile components (MVC) decreased remarkably. (4) Although the color and some volatile components changed during the storage, good balance was obtained between the each component. It may be the reason why the stored cooked curry shows more delicious taste.

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This paper describes the seasonal changes in starch content, and α-and β-amylase activities of two cultivars of kiwifruit, 'Koryoku' and 'Hayward'. The main purpose of the study was to investigate the seasonal changes in starch content in relation to α-and β-amylase activities and also to examine the properties of these two enzymes in both cultivars. The highest activity of α-amylase in the insoluble fraction was observed in September for 'Koryoku'and in October for 'Hayward', whereas that of β-amylase in the same fraction was observed in October for both cultivars. Both enzyme activities were higher in the insoluble than in the soluble fraction. The highest starch content in 'Koryoku'was observed in the middle of October, while in 'Hayward' it was observed in the later part of October or early November. In both cultivars, α-amylase activity peaked one month earlier than starch content.

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