In order to elucidate the deterioration mechanism of lemon flavor, we investigated the time course changes of the flavor components in lemon-shu or lemon oil in the aqueous citric acid solution by GC, GC-MS and mass chromatography. Further, we examined whether off-odor substances were formed in the aqueous citric acid solution from d-limonene, β-pinene or γ-terpinene which were the major components in lemon oil. p-Mentha-1, 5-dien-8-ol and p-mentha-1 (7), 2-dien-8-ol, which are significant intermediates, were formed from citral in lemon oil under the acidic condition and subsequently converted to p-cymen-8-ol. After that, the more stable p-cymene and α, p-dimethylstyrene, which are responsible for the off-odor of deteriorated lemons, were produced. The deterioration rate of citral was much slower in lemon-shu than in lemon oil. β-Pinene was unstable compound under the acidic condtion, resulting in transformation to a-terpineol, fenchyl alcohol and others. d-Limonene and γ-terpinene were relatively stable compounds under the same condition, but incubation of them for a long time gives rise to formation of α-terpineol and p-cymene, respectively.

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Free sugars and free sugaralcohols in the ethanolic extracts of nineteen species of mushrooms were investigated by gas-liquid chromatography and GC-MS analysis. The results obtained were as follows: The amounts of total free sugars and total free sugaralcohols obtained from these mushrooms were found in the range of 0.2-16.3% (the mean value; 5.8%) and 0.1-15.0% (the mean value; 4.2%) in dry materials respectively. In these mushrooms, three kinds of free sugars (trehalose, glucose and fructose) and four kinds of free sugaralcohols (mannitol, arabitol, meso-erythritol and glycerol) were identified. Trehalose and mannitol were found to be predominant in samples, and glucose was also found in all the samples, and meso-erythritol was found in two species of mushrooms, Naratake mushroom (Armillariella mellea) and Naratakemodeki mushroom (Armillariella tabescens). The distribution patterns and contents of free sugars and free sugaralcohols had low similarities among different species of mushroom. Chirality of arabitol and mannitol obtained from seven species mushrooms, Enokitake mushroom (F. velutipes), Hiratake mushroom (P. ostreatus), Shirotamogitake mushroom (L. ulmarius), Tamogitake mushroom (P. cornucopiae), Matsutake mushroom (T. matsutake), Naratake mushroom (A. mellea) and Naratakemodoki mushroom (A. tabescens), were investigated by specific rotatory power. Chirality of arabitol and mannitol in these mushrooms were found D-configuration.

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The inhibitory activity of acetic acid on food spoilage yeasts was investigated. The results obtained were as follows: (1) The growth of ordinary yeasts were logarithmically retarded in broth at pH 5.0 containing above 1.0% of acetic acid, and the growth were inhibited completely with 3.5-4.0% of acetic acid. (2) The concentration of undissociated acetic acid necessary for the complete inhibition of ordinary yeasts was estimated 1272-1456mg/100ml. (3) Combined effect (additive effect) of acetic acid and sodium chloride or ethanol on inhibition of ordinary yeasts were recognized. The minimum inhibitory concentration of acetic acid for ordinary yeasts in the presence of sodium chloride or ethanol was indicated formula 1 and 2, respectively.
(5-% of sodium chloride)×0.7-+0.5……1
(6-% of ethanol)×0.58-+0.5……2
(4) The concentration of acetic acid neccessary for the complete inhibition of salt-tolerant yeasts in broth containing 18% of sodium chloride and combined 18% of sodium chloride with 1% ethanol were estimated 1.3-1.4% and 0.4%, respectively.

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The effect of pH on the dynamic Young's modulus E' of the mixed gels of acylated gelatin and agarose was investigated. Two samples of acylated gelatin showed isoionic point 5.5 and 8.8, respectively. The values of the intrinsic viscosity of the two samples were 2.0 and 5.5 at 35°C in 0. 01 N-KSCN. The concentration of acylated gelatin was varied from 2 to 18% (w/w) in the mixed gels with low molecular weight agarase, and was varied from 3 to 12% (w/w) in the mixed gels with high molecular weight agarose. The concentration of agarose was fixed as 1% (w/w) in all the cases. The values of pH of the mixed gels were 4.0 and 9.2, respectively. When the pH of the mixed gel was far different from the isoionic point, the value of E' of the mixed gel of 3% (w/w) acylated gelatin and 1% (w/w) agarose showed the maximum below 30°C. When the concentration of the acylated gelatin was higher than 10% (w/w), E' decreased rapidly for the mixed gel containing gelatin of isoionic point 5.5 and gradually for the mixed gel containing gelatin of isoionic point 8.8, with increasing the concentratian of gelatin. For the mixed gel containing 3% (w/w) acylated gelatin, the observed values of E' of mixed gels were larger than the estimated ones by a theory on dispersed systems when the pH of the mixed gels was far different from the isoionic point. The situation was opposite for the mixed gel whose pH was near to the isoionic point.

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A personal computer was interfaced with a compressing-tensiling digital rheometer so that stress relaxation analysis could be performed and analyzed automatically. This equipment eliminated time consuming measurements and analysis of viscoelasticity of hydrogels of food stuffs. In addition, simulation results of stress relaxation phenomenon according to a cooperative flow theory could be shown on either a system display or on a printer. The rheometrical system was suitable for gels with a lower limit of 0.3s for the relaxation time. The rheological properties of hydrogels of agar (1%), low methoxyl pectin (LMP, 2%), κ-carrageenan (1%) and gelatin (3%) were analyzed by a cooperative flow theory. The data for the time dependence of the relaxation function suggested the existence of two separate flow processes for gels of agar, LMP and κ-carrageenan. One process occurred at early times (10-1-10s) and the other occurred at late times (10-103 or 10-104s). For gelatin gel, a flow process only at late times (<104s) was found. Typically the observed half relaxation time was longer for the gels which had a more dense by packed microstructure than that of the gels which had a three-dimensional network structure. But a cooperative flow theory may not be adaptable for agar gels in stress relaxation analysis.

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Effect of major constituents of milk solids on the conductivity of cow's milk-strong electrolyte system was investigated by employing pure or semi-pure systems. All of the major solid consituents of cow's milk, namely lactose, casein and fats, decreased linearly the condutivity of strong electrolyte (NaCl) solution with increasing their contents. The depression rates of conductivity, however, were different for every constituents. For lactose, the rate was 1.47% per w/w% (anhydrous, initial concentration), independent on the electrolyte concentration. For casein, the rate was 1.25% per w/w% (initial), estimating from the investigation with sodium caseinate. Fats had the different rates with their states. It was 0.56% per w/w% (initial) and 0.53% per w/w% (initial) in the cases of solid (suspension) and liquid (emulsion), respectively.

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Akaborishinmachi, Yokkaichi-shi, 510 A new method for measuring total solids content in cow's milk was proposed, which was based on conductivity measurement of NaCl added milk (final concentration: 1.125M NaCl). The total solids content estimated from our method agreed with that obtained from gravimetric method (the method of A.O.A.C.) with an error of 0.07%. No undesirable effect was observed when kitchen salt (>99% NaCl) and tap water was used insted of NaCl (GR) and deionized water. Their use will reduce the running costs of the measurements, so the methad will be useful for a field analysis.

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The caffein content of 157 varieties of commercial foods containing tea or coffee were determined. The method was based on chloroform extractian and quantitative analysis of caffein by gas liquid chromatography with a flame-ionization detector and a column of 2% silicon OV-17 on chromosorb W (AWDCMS, 60-80 mesh). The detection limit of this method was 1 μg. The recoveries of caffein added to green tea, coffee, cola beverage, "usucha arare" and buckwheat dry form containing green tea were in the range of 75-107%. The caffein contents of foods containing coffee were 37.1-76.2mg% in coffee infusion, 0-518.1mg% in canned coffee, 3.8 -18.1mg% in milk beverages, 0-23.3mg% in soy milk, 0-424.9mg% in confectioneries and 0-612.6mg% in candies. The caffein contents of foods containing tea were 0-359.0mg% in herb teas, 37.9mg% in soy milk, 0-89.9mg% in confectioneries, 0-46.1mg% in candies and 0-44.5mg% in instant "chazuke".

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Effect of temperature of a headspace trapping apparatus on the aroma components of a coffee brew was investigated. When the coffee brew was incubated at 75°C, and the enviromental temperature of the trapping column was 40°C, the enviromental temperature above a water bath significantly influenced the amounts of the trapped aroma components and internal standard substance (panisaldehyde). Theenviromental temperature had to be kept at 40±0.3°C in order to maintain the variation of internal standard peak area below 5%.

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Acid precipitation was examined in the recovery of pectin from acidic- and alkaline waste fluids from satsuma mandarin (Citrus Unshiu Marc.) cannery. In the alkaline waste fluid, the most desirable precipitation was obtained at pH 1.8, and the recovery yield was about 90%. The higher the pectin concentration in alkaline waste fluid, the higher the recovery yield was. The acidic waste fluid was demethylated with sodium hydroxide prior to acid precipitation, and the most successful recovery yield was obtained at the same pH level. It was found that acid precipitation is much more suitable than ethanol- or calcium precipitation.

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