This study was aimed at characterizing changes of starch in kiwifruit (Actinidia chinensis Planch. cv. Monty) during fruit growth (14-170 days after anthesis) and storage for 70days at 5±1°C, using histochemical methods. Sugars were also determined by high performance liquid chromatography. At day 14 after anthesis, starch granules were observed in the pericarp and central core by transmission electron microscopy. By polarization microscopy starch granules in the pericarp and central core were observed at day 28 and 63 after anthesis, respectively. During fruit growth, the starch granules in the pericarp and central core increased both in size and number, and they tended to decrease during storage. The decrease of starch granules in the central core was remarkable. During fruit growth, the content of starch increased to reach 8.3% at day 160 after anthesis, but thereafter it decreased. Starch was hydrolysed into sugars and decreased rapidly during storage. These changes of the starch content in kiwifruit were correlated with the histochemical changes of starch granules during fruit growth and storage.

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The conductance method, the Malthus system, was examined to detect the post-pasteurization contamination of pasteurized milk. The difference of detection time depended on genera of organisms. The shortest detection time was obtained by Enterobacter cloacae (about 4 hours), the longest one was by Pseudomonas sp. (about 13 hours). To determine the optimum conditions, Pseudomonas sp. were selected as model organisms, which gave alittle change in conductance. The optimum parameters were as follows; 1st Difference Threshold was 0.5μS, Base Line Threshold was 0.4μS and sample and medium volume was5ml, respectively. The results obtained by the Malthus system gave good agreement with the standard plate count. It was observed that 97% of positive samples could be detected within l hour, 98% within 4 hours and 99% within 9 hours after 16 hours of pre-incubation. There fore, the post-pasteurization contamination of pasteurized milk could be detected within 25 hours by this system.

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The changes in products found during baking of cookies, especially in use of different materials of cookies, were investigated. When cookies were baked, absorption in the 281-295nm range increased in proportion to heating time. It was considered that the use of sugar, which was one of the materials of cookies, was responsible for the change. Heating products of baked cookies were separated into ten components by high performance liquid chromatography (HPLC). The components of peaks 3, 5and 6 were considerably in higher levels, Peak 5 was formed in the first heating step during baking and moreover, it was developed clearly by heating of fructose with egg white. Peak 6 was abruptly formed at 30 minutes of heating and was tentatively identified as 5-hydroxymethyl-furfural (HMF), comparing with the authentic sample. HMF is the main product formed during heating of sugar.

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The effects of dietary apple and grape pomace on serum cholesterol level were co mpared to those of pectin and cellulose in rats fed cholesterol-enriched diets. Male yo ung rats were fed these dietary fiber sources at 10% level for 30 days. Pomace from these frui ts, particular ly that from grape, exhibited a potent hypocholesterolemic activity compared to cellulose, although the efficacy was lower than that of pectin. Serum glucose level tended to be lower in rats fed the pomace than in those fed cellulose. The results indicate a useful lness of grape pomace as well as apple pomace as a dietary fiber which is capable of regulating serum cholesterol level.

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The rheological properties of agar gels were investigated using five agar samplesdifferent in primary seaweeds and preperation methods. Moreover, the relation between therheological properties of the gels and the sulfur content and intrinsic viscosity of the samplesand the melting point of the gels was investigated. The rupture stress and energy of the gelsincreased with the intrinsic viscosity of the solution and the melting point of the gels. On thecontrary, it was noted that the greater sulfur content of the samples, the smaller dynamicand static modulus of the gels. It was also suggested that the elasticity of agar wasentropic: elastic modulus was slightly increased with increasing temperature.

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In order to identify the taste-active components of scallop Patinopecten yessoensis, freeIn order to identify the taste-active components of scallop Patinopecten yessoensis, free and combined amino acids, nucleotides and related compounds, quaternary ammonium bases, organic acids, glycogen, inorganic ions, etc. in the muscle extract were analyzed. High content of glycine and taurine, and a high but somewhat lower content of arginine, alanine and glutamic acid were shown. These five amino acids occupied 97% of the total free amino acids. Besides, considerable amounts of AMP, glycinebetaine, homarine, trigonel- line, trimethylamine oxide and trimethylamine were observed. More than 95% of the total extractive nitrogen was accounted for by these nitrogenous constituents. The succinic acid content was very low, while a large amount of glycogen was detected. As for inorganic ions, Na⁺, Kt⁺, Cl^- and PO4^3- were major components. After confirming sensorially that the synthetic extract prepared with pure chemicals in accordance with the analytical data except glycogen and combined amino acids could reproduce the taste of the scallop extract fairly well, we carried out omission tests and found that glycine, glutamic acid, alanine, arginine, AMP, Na⁺, K⁺ and Cl^- were taste-active.

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Stabilities and antioxidant effects of α and δ-tocopherol (Toc) in cookies were investigated. (1) Both α and δ-Toc were decomposed by ca 20% during the baking process of cookies. The loss of α-Toc in cookies during the storage at 25-60°C was consid erably greater than that of δ-Toc, but the losses ofα-or δ-Toc were reduced with an increase in amounts of added whole milk powder or egg. (2) In the case of the cookies added α-Toc, peroxide value (PV) of lipid fraction was relatively high just after the baking. However that value decreased with an increase in added amounts of whole milk powder or egg. Then, the addition of whole milk powder or egg protected against oxidative degradation of lipids in cookies. (3) δ-Toc showed a remarkable effect on the cookies toward oxidation. PV of lipid fraction in the cookies was 0 just after baking, and only about 1.0 even after the storage at 40°C for 5 months.

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A study on the effect of pH (4.5-6.8) was conducted to clarify the characteristics of the orientation behavior of rennet casein. As a result, the orientation of rennet casein was observed at pH5.3-5.4 after squeezing out the casein from a syringe by shear stress. A maximum pellet volume of rennet casein at 10°C was given at about pH5.4. On the other hand, calcium and phosphate in rennet casein tended to transfer to the serum at low pH, but the degree of their transfers decreased gradually above pH5.4. From the relation between the change of pellet volume and the shift of protein fraction to the serum, the maximum degree of hydration of rennet casein was observed at about pH5.3-5.4. The phenomena of the orientation of rennet casein could be explained from the behavior of hydration of rennet casein and of the transfer of calcium and phosphate to the serum.

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Changes in chemical and functional properties of gelatin were investigated on reaction with vaporized hexanal to reveal the reaction mechanism between oxidized lipids and proteins. Among the amino acid residues of gelatin, only lysine and hydroxylysine residues decreased on the reaction. The analysis of UV spectrum suggested that almost all of theε-amino groups in the decreased amino acid residues were modifed to alkyl-substituted pyridinium rings, i. e, , 1-(5-carboxy-5-aminopentyl)-2-pentyl-3, 5-dibutylpyridinium betaine.Gelatin was not assumed to polymerize on the reaction with hexanal. These results suggested that the hexanal-induced polymerization of proteins did not always require the cross-linking involving lysine residues. The solubility of gelatin decreased as the modified lysine and hydroxylysine residues increased. When the extent of such modifcation reached to 57%, a remarkable decrease in solubility occurred. On the other hand, the emulsifying activity of the modified gelatin increased as compared with that of the unmodified gelatin when the extent of the modification was 4 or 27%, but decreased at a 57 or 71% modification.

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The quality characteristics of natto starter affects the quality of natto such as flavor, taste and the production of sticky materials. In order to get good natto starter, Bacillus natto isolated from commerical natto starters was transferred from nutrient agar slant and incubated on three solid media; soybean extracts agar, phytone agar and nutrient agar. Natto manufactured with the starters of soybean extracts agar and phytone agar contained high amounts of organic acids and amino acids, but natto manufactured with the starter of nutrient agar contained low amounts of those components. The quality of the former two natto were of high grade, while that of the latter natto was of low grade. It was proved that transferring B. natto from nutrient agar slant to soybean extracts agar slant or phytone agar slant was effective to get good quality of natto starter.

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