Production of methyl ketone mixture from lipolyzed milk fat by fungi was investigated in order to use the mixture as flavorant. Of many Penicillium species isolated from commercially available blue cheese, strain TK-2068 was selected as the most suitable one for methyl ketone production. Methyl ketones produced by this strain were distillated and analyzed by gas chromatography. C₃, C₅, C₇, C₉, C₁₁, and C₁₃ n-2-alkanones were detected in the distillate. Methyl ketone profiles obtained from lipolyzed cream and butter were somewhat different from that obtained from lipolyzed whole milk. A great difference in the formation of methyl ketones between from natural substrates (lipolyzed milk fat) and from a synthetic fatty acid mixture was observed. A two-step method was recommended; sufficient cultivation of the fungi on growth media and subsequent addition of lipolyzed milk fat (substrate) to start methyl ketone-producing reaction. By this method effective production of methyl ketones was achieved.

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A marked difference was observed in the rate of individual methyl ketone formation from lipolyzed milk fat by Penicillium sp. TK-2068. C₇ and C₉ methyl ketones were produced rapidly at first, but gradually decreased after the maximum. On the other hand, C₃ and C₁₁ methyl ketones continue to increase during incubation. Desirable flavor profile was obtained after around 24 hour incubation. In the case of natural substrates (lipolyzed whole milk powder, cream and butter) C₃, C₇ and C₉ methyl ketones continuously increased until the substrate concentration reached to 15-40 mM FFA/100ml culture, while the formation of C₁₁ methyl ketone was not much affected by substrate concentration. When synthetic fatty acid mixture was used as the substrate, methyl ketone formation was low even at relatively low substrate concentration (about 12mM FFA/100ml culture). This may be due to the toxicity of fatty acids to the fungi. High oxygen supply was required for effective methyl ketone production. It was attained to produce a high level of methyl ketones under aerating conditions by the use of jar fermenter. Thus, a method for producing the methyl ketone mixture which can be used as flavorant has been established by applying submerged culture of Penicillium sp. TK-2068.

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Mine-machi, Utsunomiya-shi, Tochigi 320 Aliquots of the alcohol insoluble substance (AIS) prepared from various vegetables, chinese cabbage, cabbage, radish root, carrot root and cucumber were suspended in 5% NaCl solution and then desalted by dialysis for analysis of the composition of pectic substances and the content of Ca, Mg, K and Na. Samples treated with water in the same way were analyzed as controls. The composition of pectic substances in the AIS was estimated by the successive fractionation with different extractants according to the solubility, expressing as the water soluble (W-P), the hot-water soluble (HW-P), the sodium-hexametaphosphate soluble (HX-P) and the hot 0.05N HCl soluble (H-P), respectively. On the other hand, after the extraction with hot water, the residual pectic substances in the AIS were also treated with NaCl and analyzed as stated above. And also, the cation contents in W-P and HW-P fractionated from the AIS treated with the NaCl solution and dialyzed were measured. The result were obtained as follows: (1) The amount of total pectic substance in the AIS did not changed during the treatment with the NaCl solution, whereas the HX-P and the H-P showed a remarkable decrease while the W-P and the HW-P increased so much inversely. (2) After extraction with hot water, the further extraction of the AIS residue with the NaCl solution gave much soluble pectic substances, decreasing the content of the HX-P and the H-P. (3) The treatment of the AIS with the NaCl solution and desalting by dialysing gave a remarkable decrease of the content of Ca, Mg and K in the AIS residue, while increasing Na. (4) The content of Ca, Mg and K in the W-P and the HW-P prepared from the NaCl-treated AIS as mentioned above decreased markedly, while Na increased so much. As the results of this study, it was assumed that the treatment of the AIS with the NaCl sotution, as well as salting of various vegetables previously reported1), might cause the elimination of a considerable amount of the cross-linking cations, Ca and Mg, from the pectic substances by the ion-exchange reaction probably occuring between the cations and Naions of NaCl used, and consequently caused the change of the solubilities of pectic substances, especially decreasing the HX-P and increasing the W-P and the HW-P.

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Electrostatic discussion was given on the reason why the elastic fish flesh gel, kamaboko, contained more abundant bound water than the brittle one. Within the gel, we supposed a straight axis along which a number of ionic amino acid residues were arranged. The combined electric potentials along the axis varied with the position and the number of the residues on the axis. The region of bound water was calculated by assuming that water molecule would bind to the ionic residues in the region where potential energy of water molecule overcomes its kinetic energy. This region was proved to increase as the dispersion and the number of the residues increased. On the other hand, the reflection spectra of the electronograph of the fish flesh gels showed that the protein network structure dispersed more finely and more homogenously in the elastic gel than in the brittle one. From the above results, we concluded that the homogeneously dispersed ionic amino acid residues in the elastic fish flesh gel resulted in an increase in the amount of bound water.

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To make clear the digestion process of soybean proteins during miso fermentation, water-insoluble proteins prepared at various stages of miso fermentation have been investigated by polyacrylamide gel electrophoresis using sodium lauryl sulfate (SDS PAGE) and gel filtration in 6M guanidine hydrochloride (GuHCl). On the gel of SDS PAGE, soybean proteins showed obscure bands during the initial 10 days of fermentation and newly formed bands of lower molecular weight (about 1×104) appeared. The similar tendency was also observed in the elution patterns from 6M GuHCl Sepharose 6B column. Therefore, it was concluded that soybean proteins could undergo the digestion within several days of fermentation and the water-insoluble proteins of miso were resistant to the further hydrolysis by the koji enzymes.

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The properties of lipids in fresh horse mackerels, Trachurus japonicus, and that in salted semidried products were compared immediately after manufacturing. The changes in properties of lipids in products during storage were also studied. Fresh fishes were washed, soaked in NaCl solution (Be 16°) for 35min., and dried using drying oven at 33±3.0°C for 165min. The products were stored in a incubator (25±2.0°C) for 9 days, in a refrigerator (8±0.5°C) for 5 weeks, or in a freezer (-20±3.0°C) for 4 months. Acid value (AV), peroxide value (POV) and carbonyl value (COV) of total lipids (TL) which were extracted according to the procedure of BLIGH and DYER were measured. TL was separated into individual lipid by silicic acid column and thin layer chromatographies. Fatty acid composition of TL, neutral lipid fraction (NL) and compound lipid fraction (CL) were analyzed by gas-liquid chromatography. (1) TL contents in products were lower than those of fresh fish. (2) The ratio of 18:1 acid in TL, NL and CL of products was lower than that of fresh fish. (3) When the products were stored at 25°C or 8°C, AV, POV and COV of TL changed markedly. These values of the products stored at -20°C showed little change. (4) In products stored at 25°C and 8°C, decrease in CL contents and increases in free fatty acids (FFA) contents of TL were observed, but in products stored at -20°C, little changes in CL and FFA contents of TL were observed. (5) In products stored at 25, 8 and -20°C, little change in fatty acid composition of TL and NL were observed. On the other hand, in products stored at 25°C and 8°C, decreases in the ratio of 22:6 acid of fatty acids of CL were observed, but in products stored at -20°C, little changes in fatty acid composition of CL were observed. (6) From the results we concluded that storage at -20°C was effective against rancidity for 4 months and storage at 8°C was effective for one week, but storage at 25°C had no effect.

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The volatiles from Japanese radish processed by fermentation with rice bran after salting (Shinzuke takuan) was separated by a lyophilization system and analyzed by combined gas chromatography and mass spectrometry. Forty compounds, including 10 alcohols, 9 esters, 4 carbonyls, 8 acids, 3 lactones, 3 sulfur containing compounds and 3 other compounds were identified. Thirty two of these compounds were newly identified as volatile flavor components of Takuan. Sensory evaluation indicated that the three sulfur containing compounds, 2-methylthioethanol, methionol and 3-methylthiopropyl acetate contribute to the formation of the characteristic aroma of Takuan.

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The inhibitory activity of organic acids on food spoilage bacteria was investigated to obtain the following results: (1) All organic acids tested inhibited food spoilage bacteria at higher pH value than hydrochloric acid did. (2) Volatile low molecule fatty acid including propionic, acetic and formic acid showed strong inhibitory effect at even above pH 4.5. (3) As a food additive employed at pH 5.0, acetic acid was the most effective, being followed by succinic and lactic acid. Malic, tartaric and citric acid, however, were of weak inhibitory effect. The inhibitory activity of organic acids were in good agreement with the rate of undissociated molecule of the organic acids. (4) Acetic acid completely inhibited all the bacteria tested except lactic acid bacteria with the concentration of 0.5% at pH 5.0.

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The inhibitory activity of ethanol on food spoilage bacteria was investigated. The results obtained were as follows: (1) Ethanol influenced all growth phase of food spoilage bacteria. In paticular, the lag phase of most of gram positive bacteria was prolonged, and the growth rate in logarithemic phase of most of gram negative bacteria was prolonged. (2) The growth of those bacteria was inhibited logarithmically with the increase of ethanol concentration, and in above level of the critical concentration of ethanol, the growth was completely inhibited. (3) The minimum growth inhibitory concentration (MIC) of ethanol against gram positive bacteria was 9 to 11%. In this case, lactic acid bacteria was required highest value of MIC. The MIC of ethanol against gram negative bacteria was less than 9%, in particular against facultative anaerobic bacteria including intestinal bacteria it was lower.

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