Physical properties of whipped egg white foams were studied by using the multi-biting test. Comparison of the parameters of mechanical work loads of the plunger (positive and negative) in the multi-biting test of egg white foams was useful to elucidate the effects of whipping time, added sugar content and pH of egg white on the physical properties of whipped egg white foams. The stability of egg white foams was also estimated by comparing the parameters of multi-biting test of egg white foams measured just after whipping with those measured after standing for an hour. Figures of the parameters of mechanical work loads of the plunger in the multi-biting test of egg white foams decreased with standing time. Stability of whipped whole egg (egg white and yolk) foams was lower than that of the egg white foams. Textural changes of egg white in the process of whipping and the physical properties of egg white foams could be also investigated by analysing the profile curves of multi-biting test. Textural changes of egg white foams induced by heating could be effectively compared by the "multi-point mensuration" multi-biting test.

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In order to make clear the inactivation mechanism of soybean lipoxygenase by homogenization, solubility of the precipitate prepared during homogenization, reaction behavior of SH residues, stabilities for SH reagents and effects of foaming on the inactivation, were investigated. The precipitate resulted from homogenization was presumed to be aggregated lipoxygenase which was polymerized by intermolecular S-S and the other bindings from the results of solubility test with several solvents. A partial exposure of SH group in lipoxygenase was also recognized during homogenization. Lipoxygenase was stable on the treatments with oxidative reagents such like KBrO3 or blocking reagents such like N-Ethylmaleimide, whereas unstable to reductive reagents such like 2-Mercaptoethanol. Inactivation of lipoxygenase was highly accelerated by foaming and the inactivation was prevented by the addition of surfactants such like Triton X-100. Conclusively, it was suggested that lipoxygenase was inactivated by homogenization and resulted in the precipitate through unfolding of the enzyme molecule and succesive intermolecular S-S binding and additional polymerization by the other forces. Foaming during homogenization seemed to be the most dominant factor for the inactivation of soybean lipoxygenase by denaturation caused by surface tension.

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The effect of fermentation on skins, a usual method for red wine-making, on the sulfite binding efficiency of three SO₂-acceptors, i.e. acetaldehyde, pyruvate and α-ketoglutarate, were examined with special reference to the effects of free-SO₂ content, pH value and temperature of the wines. The following results were obtained. (1) Sulfite binding efficiency of three SO₂-acceptors was decreased obviously in the wines fermented on skins. (2) The sulfite-binding efficiency increased remarkably in wines containing higher level of free-SO₂ and of lower temperature, while it was not significantly affected by a change in pH range. (3) The level of bound-SO₂ in the wines obtained by fermentation on skins (EL) estimated on the basis of the amounts of three SO₂-acceptors found in wines, were always lower than the actual level of bound-SO₂ (AL) determined. Consequently, the EL was able to account for 73 to 87% of AL in terms of three SO₂-acceptors. (4) The EL of the wines obtained by fermentation on skins was very higher than the AL in the previous papers, the difference between the EL and the AL probably results from the over-estimation of the sulfite binding efficiency of three SO₂-acceptors.

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The distribution of carotenoids in the peel and the flesh of Japanese persimmon (Diospyros kaki Thunb. var. Yotsumizo) was studied using thin-layer chromatography. (1) Total carotenoid contents in the peel and the flesh increased during maturation, it was especially so just before the fully matured stage. At that stage β-carotene (24%) and cryptoxanthin (18%) in the peel, and cryptoxanthin (37%) in the flesh were predominant. The carotenoid level in the flesh was only 1/9 of that in the peel at the fully matured stage. (2) There was high correlation between carotenoid content and HUNTER'S chromatic "a" value. (3) Increase of carotenoids in the peel during the storage was due to the accumulation of β-carotene, whereas lutein, antheraxanthin, cryptoxanthin, zeaxanthin, violaxanthin and cisantheraxanthin decreased or disappeared. Total carotenoids in the flesh slightly increased by the increment of β-carotene. (4) After the drying process all of the 5, 6-expoxicarotenoid were isomerized to the 5, 8-epoxides. Lycopene and hydroxy-α-carotene newly appeared. (5) Chlorophyll content in the peel decreased during the maturation, but not completely disappeared. Its content in the flesh was constantly about 1/3 of that in the fully matured peel throughout all the stage. The chlorophyll level did not change either in the peel or the flesh during the storage.

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A spectrophotometric system was designed and constructed to measure nondestructively visible reflectance spectra, as well as fluorescence spectra, of unevenly colored food such as fruits and vegetables. It is in principle a single-beam spectrophotometer equipped with a large integrating sphere and operated with a microcomputer which controls wavelength scanning and data acquisition. The microcomputer provides also means of examining in detail relationship between color of reflected light or fluorescence of food and various quality factors, such as maturity, constituents, damage, deterioration and so on. For this purpose, several data processing subroutines are involved in the program; reflectance spectra, absorbance spectra, running-average, SAVITZKY-GOLAY'S smoothing, differential spectra, difference spectra, areas of spectral peaks, summation of spectra, parameters of several colorimetric systems, multiple regression analysis and so on. As examples of measurement, visible reflectance spectra of several fruits and vegetables and fluorescence spectra of mandarin orange whose peel oil has been out of oil cell ruptured with a needle are shown. The visible reflectance spectra demonstrate the effectiveness of the differential processing of the second order. The fluorescence spectra show the examples of difference spectra processing. The performance and drawbacks of the present system are discussed.

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Total level of bound-SO₂ (EL) estimated theoretically from the amounts of three SO₂-acceptors, acetaldehyde, pyruvate and a-ketoglutarate, was compared with the actual level of bound-SO₂ (AL) determined experimentally in the different wines. It was found that years of vintage, grape varieties, young and stored of wines were not correlated with sulfite binding capacity. The sulfite binding efficiency of three SO₂-acceptors in whites was notably higher than that in red wines. The ratio of EL to AL of the white wines was greatly higher than that of the red wines. And also, EL was always lower than AL and able to account for 51.0 to 85.3% of the AL in terms of three SO₂-acceptors.

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The effects of microwave irradiation at 2450MHz on dehydrated sweet potato flour were studied. Freezedried sweet potato flour at various moisture levels (moisture content: 10, 15, 20 and 25%) was irradiated at 180W for up to 480sec. at intervals of 60sec. It was demonstrated that microwave heating was effective in decreasing enzyme activities (α-amylase, β-amylase). The rate of amylolytic enzyme inactivation was influenced by the initial moisture content of flour. Amylolytic enzyme in the flour with higher moisture content was inactivated by shorter irradiation. Most notable physicochemical changes after irradiation of flour (initial moist.content: 15%, irradiation time: 420sec.) compared with non-irradiated one were as follows (1) increase of water capacity, (2) increase of Amylograph viscosity, (3) decrease of reducing sugar content together with increase of starch content in cooked dough, (4) increase of starch retrogradation rate, and (5) decrease of polyphenol oxidase activity. From irradiated sweet potato flour, foods with high expansivity and good texture.

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A method is described for the hydrochloric acid extraction of total potassium, magnesium calcium, zinc, manganese, copper and iron in soybean, green soybean and roasted soybean flour. Homogenized sample was weighed in a polypropylene bottle and 1 or 3% hydrochloric acid was added. After extraction for 1 hour with occasionally shaking at room temperature or 70-80°C, filtrate or supernatant was analyzed by atomic absorption spectroscopy. The values obtained using this procedure were compared with those obtained after dry ashing method with platinum dish. The results are as follows: (1) K, Mg, Ca, Zn, and Mn in these samples were completely extracted with 1% hydrochloric acid at room temperature. (2) Cu was completely extracted with 1% hydrochloric acid at 70-80°C. (3) Above mentioned 6 elements were completely extracted with 3% hydrochloric acid at 70-80°C, but extraction rate of iron was 90-95%. Hydrochloric acid extraction procedure was considered to be a rapid and simple method for preparing sample solution.

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A process for preparing spun protein fibers from Antarctic krill (Euphauia superba) muscle was described. Na-alginate, NaOH solution and deionized water were mixed to make spinning dopes which were extruded into a calcium coagulation solution to produce the fibers. The relationships between the composition of dopes and their spinnability were studied. Spinnability of dopes were classified into five grades and dopes with good spinnability were those which could be taken up at avelocity of 35m/min when extruded into a calcium coagulation solution (pH 5 or 7.6). The nature, pH and temperature of the coagulation solution also affected the spinnability of the dopes. The optimum conditions for obtaining the most adequate fibers were 3.8% (w/v) of CaCl₂ and 15-25°C of temperature of the coagulation solution. At 45°C of temperature of the coagulation solution, there was a decrease in the fiber strength. Protein recovery fiber-making from the antarctic krill muscle was about 70%. Fibers with adequate strength could also be obtained by extrusion of the dopes into sea water containing 3.8% (w/v) of CaCl₂.

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Denaturation and hydrolysis of proteins occur easily during the preparation of dope from antarctic krill (Euphausia superba) muscle proteins thus it is hard to obtain the homogenous spun fiber products. Heat generated during the mixing process of spinning dope enhances the denaturation and hydrolysis. In order to find out the most adequate approach to prepare spinning dope, the relationships between the spinnability and the major subunit contents of antarctic krill muscle proteins in various spinning dopes were studied with SDS-polyacrylamide gel electrophoresis and gel filtration. Dope which showed good spinnabilily was prepared optimum at 48°C during the mixing process and the most adequate concentration of NaOH was found to be 0.4% (w/w). The elution pattern of raw antarctic krill muscle proteins showed 3 peaks, but it was apparently altered by Na-alginate or k-carrageenan. Results showed that there was a complex formation between antarctic krill muscle proteins and anionic polysaccharides as they were homogenized during the mixing process.

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