The synergistic antioxidant effects of organic acids and their derivatives with tocopherol (Toc) on cookies was studied. As a synergist, L-ascorbic acid (AA) and its stearyl ester (AS), erythorbic acid (EA), citric acid (CA) and its isopropyl ester (IPC) were used and one of them was added to cookie dough with or without of α-, δ-Toc and a mixed tocopherols concentrate (m-Toc). Baked cookies were stored at 40°C for 12 months, and periodically analyzed on peroxide value (PV) of extracted oil and residual ratios of Toc and synergists. (1) AS showed a clear antioxidant effect on cookies, strongly suppressed the prooxidant effect of α-Toc, and synergistically enhanced the antioxidant effects of δ-and m-Toc. These effects become stronger with an increase in the added amount of AS. The addition of more than 1000 ppm of AS along with 100ppm of δ-Toc was the most effective, and resulted in the complete inhibition of elevation of PV during the storage for 8 months. On the other hand, AA, EA, CA and IPC hardly showed such antioxidant effect and synergistic effect with Tocs. (2) The residual ratio of Tocs in cookies were improved by the addition of AS. The improvement was remarkable in that of α-Toc. However, no improvement was observed in the addition of AA, EA, CA or IPC. (3) AS in cookies entirely disappeared within the storage for 5 months, but its synergistic antioxidant effect with Toc on cookies was still kept even after its disappearance. In the cookies which had δ-or m-Toc, residual ratio of EA or AA was higher than that of AS, but their effects on the oxidative stability of cookies were small.

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Simultaneous saccharification and fermentation (SSF) of potato waste from starch refinery into L-lactic acid was investigated. In a conventional SSF system, two or more kinds of microorganisms are cultivated in a single reactor, and it is very difficult to monitor the growth of each of the organisms. In this study, a membrane reactor system for SSF was developed. This consists of a reactor for starch hydrolysis and a reactor for lactic acid production. Medium was continuously circulated through the two reactors by means of tubes, while an ultrafiltration system was installed between them to confine each microorganism in one reactor. It was possible to measure the growth of each microorganism by this system. When Aspergillus awamori for starch hydrolysis and Lactococcus lactis for lactic acid production were used, the final lactic acid concentration and yield from 2.5% granular starch mesium were 11.3g/l and 0.72, respectively. This yield value is higher than those reported to date, and shows that this novel SSF system is very efficient for lactic acid production. In the medium containing 3% starch extracted and condensed from potato waste, the final lactic acid concentration was 6.3g/l and the yield was 0.36. In order to improve the yield, it is necessary to determine the optimal culture conditions for agitation speed, dissolved oxygen concentration, time to start the substrate circulation and a ratio of substrate volume in the two reactors.

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Sterilization of E. coli in foods under a high pressure was studied. E. coli cells cultivated at 37°C for 48h were used in this study, because they were more resistant to a high pressure than the younger cells. Samples in a nylon bag containing the 10 7-10 8 cells/ml were treated under 300MPa or 400MPa at 20°C for 10, 15 or 30min. E. coli was sterilized in any solution of water, 10-20% protein or 1-10% sucrose at pH 7.0-8.8 after 10min under 400MPa or at pH4.4-5.0 after 10min under 300 MPa. In the presence of more than 50% of soybean oil sterilization requires 15min under 400MPa, as opposed to the treatment for 10min under 400MPa with lard (solid oil). E. coli in a emulsion made by mixing an oil and a protein was needed to be sterilized under 400MPa for 30min. The most effect method for the sterilization was to treat bacteria solution frozen at -20°C under 200MPa for 10min.

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A laser beam particle analyzer was applied to measurement of soymilk particle size distribution. The distribution of particle size in soymilk was composed of two parts in a range of 1-100μm; a sharp peak below 1μm and a broad peak around 10μm. The total particle counts of soymilk increased linearly with an increase in concentration of soymilk at the concentration level between 0.1 and 5%. Therefore, the to total particle counts of soymilk were applicable to estimate the concentration of soymilk. By comparing the total counts of soymilk with those of denatured protein solutions prepared from defatted soybean meal, about 15% of the total counts of soymilk was attributed to heat-denaturation process of protein and the remaining counts to the emulsifying process with lipid. The up-and-down temperature shift affected the counts and the size of soymilk particles.

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Changes in particle size distribution in coagulation reaction of soymilk were measured by laser beam particle analyzer. When calcium chloride solution was continuously added to soymilk, the peak appeared at around 10μm of particle size and then shifted to at about 100μm. Prolonged stirring had no more effect to get particles with reduced sizes. The simultaneous measurement of stirring torque based on our previous report showed characteristic correspondences to the distribution changes of coagulated soymilk particles. The optimum coagulations condition deduced from the analyses of particle size. distribution of coagulated particles under various conditions were as follows: concentration of soymilk; around 5%, coagulation temperature; 60 to 64°C, stirring speed; around 140 rpm, and final concentration of calcium chloride; around 10mM. These results agreed very closely with those of the previous work by torque methods. The average size of coagulated particles at optimum reaction conditions was around 200μm by means of image analysis. Conclusively the final concentration of calcium chloride and the initial stirring speed were the most important controllable factors in order to get the desirable sizes of coagulated soymilk particles.

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By alteration of pH values and addition of salts and sugar during the process of ham preparation, the denaturation temperatures of whey protein concentrates (WPC) and their constituents, α-lactalbumin (α-La) and β-lactoglobulin (β-Lg) were investigated by differential scanning calorimetry (DSC). The denaturation temperatures of WPC, α-La, and β-Lg shifted to the higher temperature by alteration of pH values to an isoelectric value for each protein, and addition of sodium chloride. These results may due to alteration of the balance of forces (such as charge-charge interactions, hydrophobic bonding, and hydrogen bonds etc.) which have been implicated in the stabilization of the secondary-tertiary structure of a globular protein according to the change of pH values or addition of sodium chloride. Secondly, effects of the addition of WPC on model hams preparation were studied. The DSC curves of the model ham paste added WPC showed another endothermic peak besides the endothermic peaks that were found in the model ham paste without WPC. From these results, it became evident that WPC, a-La, and β-Lg denaturated at the heating temperature (ca.75°C) in ham preparation process. The ability of water-retention was improved and some properties, such as strength, cohesiveness, elasticity and chewyness, became higher in the ham added WPC.

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I inquired the keeping way of frying oils, and examined thermal changes of oils obtained from 202 household of college students by measuring AV, POV, CV, TBA and color darkening. There were no differences in their values of oils among the frying and keeping ways. However, AVs, CVs, and TBA values of darkening oil (more than the mean) were higher than those of less-darkening oil. When the AVs, POVs, and CVs of oils used were compared with the guideline values of the Ministry of Health and Welfare, AVs and POVs of the samples were lower than those of the guideline, but CVs of 44 samples were higher than the limited guideline.

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Two kinds of conjugate were made from globin (G) and succinylated globin (SG); the one (CMHT) was prepared by β-mercaptoethanol-hydrogen peroxide treatment of these proteins, the other (CUT) by urea treatment of them, and the gelling properties of these conjugates were investigated. In the case of CMHT, the pH range of gel formation became wider as the compounding ratio of G was high. For example, though the gel-forming pH was only 2.0 when the ratio of G and SG was 3:7, the gel was formed in the pH 2.0 to 3.5 region when G and SG were 9:1. On the other hand, CUT formed gel at limited pH when the ratio of G and SG were 7:3 or 9:1 respectively. The gel of the conjugates was transparent in strong acidic pH region. In addition, the transparence of the gel increased with increasing the compounding ratio of G. In the equal ratio of G and SG, CMHT formed the strongest gel at pH 2.0. However, the gel strength of CMHT gel showed the maximum value at pH 3.0 in 9:1 ratio of G and SG. Although strong gel was formed at pH 2.0 when G and SG was 3:7 ratio, the values of the gel strength of CUT gel were low as a whole.

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The texturization of defatted soy flour was observed by using a twin screw extruder with windows on barrel and cooling die. In addition to the in-situ observation, the material in the barrel was examined after removing the screw. The findings in this study were: (1) The soy flour exhibited a the rmoplastic behavior similar to that of ordinary thermoplastic polymers, and the melt contained a number of bubbles. (2) The melt flow in the cooling die changed largely with barrel temperature, resulting from a difference in viscosity. (3) The flow must be laminar from the screw head to th edieentrance in order to achieve a proper texture.

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Kamaboko-folding tester was designed to evaluate elasticity of kamaboko gel by an objective folding test. In the folding tester developed here, a sample of disk type (3cm diameter, 3mm thickness) was first once-folded to 6-7mm thickness, and after a prescribed time (1, 5 or 10s), twice-folded to 6.5-8.5mm thickness. The tester was reliable and sufficiently utilizable for quality control of kamaboko manufacturing. The force required to fold a sample, however, was remarkably influenced by the thickness of the sample, therefore, it should be needed to make its thickness accurate to obtain good correlation between quality of the sample and time-force curve during folding.

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An improved database system was established to apply for wholesomeness evaluation and trouble-shooting of food. Each document or reference concerning food-born diseases or claim was classified and registered as a casecard file of the database. It was easy to operate this system and to search the files. This system made mistakes and overlooks less to search the files, and speeded up to evaluate the wholesomeness or investigate the cause of troubles. It was also useful for training to learn how to deal with trouble-shooting of food.

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The conditions for measuring viscosity of spices to detect radiation treatment and the applicability of the method to various spices were investigated. Viscosities of black and white peppers, ginger and turmeric decreased depending upon dose, when they were measured after heat gelatinization at pH 12. However, the viscosities of cinnamon and nutmeg did not show a dose dependent relation. The viscosity of irradiated onion powder was lower than that of unirradiated sample, when determined at pH 5 without any heat treatment. A normalized viscosity parameter, viscosity/starch content (mPa. s/g of starch), resulted in almost constant values for unirradiated black and white peppers, irrespective of the harvesting locality. The results in this study suggest that irradiated black and white peppers can be detected by viscosity measurement without any information about the harvesting locality.

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