This study was aimed at investigating the demineralizing conditions of milk casein hydrolysates prepared enzymatically by electrodialysis (ED). The changes in ash, protein, free amino acid content and so on before and after ED treatment were investigated. All ED treatments were carried out after Low Rejection Reverse Osmosis Membrane (LRO) treatment.
(1) The demineralization of casein hydrolysates proceeded effectively as the operating temperature rose.
(2) The relationship between ash content and electric conductivity was expressed as a linear line.
(3) The amount of ash and free amino acid decreased with ED treatment. In treatment with recovery rates of 87.8, 78.4, and 81.4%, casein hydrolysates with deashing rates of 72.5, 75.7 and 78.6% were obtained, respectively.
(4) It was found that calcium was demineralized more easily than the other minerals in casein hydrolysates. On the other hand, it was difficult to deash sodium.
(5) Both glutamic acid and aspartic acid showed remarkable decreases. Arginine also showed a tendency to decrease. The other amino acids, however, didn't decrease and, on the contrary, showed a tendency to become more concentrated.
(6) ED treatment was proved to be as effective as LRO treatment in improving the taste of casein hydrolysates caused by free amino acids.

View full abstract

To make clear the effect of calcium hydroxide and calcium lactate on hardness and tissue structure of brined small type ume fruit (Prunus mume Sieb. et Zucc), small type ume fruit were brined with a NaC1 solution, a NaC1 solution containing either calcium hydroxide or calcium lactate. After that, controlled amounts of NaC1 were added to each group once a day for 20 days until NaCl in the ume fruit reached 18% concentration. Two weeks after the final addition of NaC1 the hardness, calcium content and pectin content in each group were measured with a rheometer, high performance liquid chromatography and the m-hydroxydiphenyl method, respectively. In addition, tissue prepared from fresh fruit and the brined ume fruit were observed with a scanning electron microscope. The results obtained were as follows: (1) The ume fruit brined with a normal NaC1 solution softened in texture. Those ume showed a remarkably smaller ratio of 0.05 N HC1 soluble pectin (HSP) against total pectin than fresh fruit, and a significantly larger ratio of water soluble pectin (WSP). (2) The brined ume fruits, to which calcium compounds were added, was'nt soft. Those ume fruits had a remarkably larger ratio of HSP and the 0.4% hexametaphosphate soluble pectin (HXSP) against total pectin than the fruit brined with the normal solution, and a markedly smaller ratio of WSP. (3) The hardness of the brined fruit increased with added amounts of calcium compounds. (4) The hardness of the brined ume fruit with calcium hydroxide was almost similar to that of the brined fruit with calcium lactate. (5) The brined fruit with calcium hydroxide increased in 0.05N NaOH soluble pectin (SSP) and decreased in WSP relative to the amounts of calcium hydroxide added, but the ume fruit with calcium lactate increased in HSP and decreased in WSP. (6) In the observtion with a scanning electron microscope, the cell wall of the brined ume fruit looked thinner than fresh ume fruit, and the cell had changed to a flat shape a little. But the cell of brined fruit with calcium compounds were almost similar to that of fresh fruit. As a result of those experiments, it was concluded that the softening of the brined ume fruit is the destruction of the tissue structure arising from the change of HSP into WSP, and the hardness of the brined fruit with calcium hydroxide or calcium lactate is kept up with a maintenance of the tissue structure occuring with an obstruction of change of HSP into WSP, which is caused by cross-linkage between pectin and Caion.

View full abstract

A continuous fermentation system producing soy sauce from unsterilized soy saucemoromi mash (very viscous suspension) was investigated. The system was composed of two laboratory scale air-lift type reactors in which Zygosaccharomyces rouxii and Candida versatilis were immobilized, respectively. MI ceramics (MIC) and honeycomb ceramics (HC) treated with both acid and alkaline were good supports for immobilizing soy sauce yeasts. Efficiency of alcohol fermentation on a reactor of Z. rouxii immobilized on MIC was higher than that on HC. Unsterilized soy sauce-moromi mash was continuously fed for 35 days into the bioreactors on which were immobilized Z. rouxii and C. versatilis, respectively, and both reactors stably run without any problems. A blend of the fermentation products obtained from both reactors was heated, and evaluated good concerning flavor and taste by a sensory test.

View full abstract

We have reported that peptides in enzymatic hydrolyzates of sardine meat can inhibit the activity of angiotensin I converting enzyme (ACE). In a next step, we set out to establish techniques to separate and purify the peptides with high activity and to remove odor and color which hinder the practical use. On the laboratory scale, after enzymatic hydrolyzation of sardine meat, the odor resulting from amines and the peptides which contributes to color were removed by treatment with activated carbon and aluminum silicate. Fatty acids, another odorous component, were removed by ODS fractionation. Thus, peptide fractions that strongly inhibited ACE were obtained. We set up an apparatus that gave reproducible separation by ODS fractionation. The apparatus was suitable for industrial use. We constructed a plant that could process about 30 times the volume handled on the laboratory scale. The pilot plant gave the same satisfactory results, showing the possibility of further scaling up. We then designed a system that could be used for industrial production at processing rate of 1000l/h. The physiologically active peptides obtained by us would be useful in a wide range of application as a food ingredient.

View full abstract

To make clear the effect of ashed objects on the hardness, chemical components and tissue structure of brined ume fruit, small type ume fruit (Prunus mume Sieb. etZucc.) were brined by NaCl solution containing egg shell dried at 105°C (DES), egg shell ashed at 500°C (AES-500) or 720°C (AES-720) or oyster shell ashed at 1000°C (AOS). After brining of the fruit, a controlled amount of NaCl was added to each group once a day until NaCl concentration in the fruit reached to 18%. Two weeks after the final addition ofNaCl, the hardness, Ca and pectin contents in each group were measured. Tissues prepared from fresh ume fruit and the brined ume fruit were also observed with a scanning electron microscope. Further, X-ray diffraction patterns of DES, AES-500, AES-720 and AOS were analyzed with a X-ray analyzer. The results obtained were as follows: (1) The ume fruit brinedwith DES, AES-500, AES-720 or AOS contained larger amounts of Ca than the fruit brined only by NaCl. (2) Te fruit brined with DES or AES-500 shrank and the hardness value was smaller. Conversely, fruit brined with AES-20 or AOS didn't shrink and the hardness value was larger. (3) The fruit brined only by NaCl was remarkably smaller in the amount of Hot 0.05 N HCl soluble pectin (HSP) than the fresh ume fruit, and the amount of Water soluble pectin (WSP) was significantly larger. (4) The brined fruit to which DESor AES or AES-500 was added, were remarkably smaller in HSP than the fresh ume fruit, and the amounts of WSP and Hexametaphosphate soluble pectin (HXSP) were significantly larger. (5) The fruit brined with AES-720 or AOS was remarkably smaller in the amount of HSP than the ume fruit, and larger in the amounts of HXSP and Cold 0.05 N NaOH soluble pectin. WSP remained mostly unchanged. (6) The X-ray diffraction patterns of both AOS and AES-720 were roughly similar to that of CaO, but those of DES and AES-500 were similar to that of CaCO3. (7) In observation with a scanning electron microscope, the cellsof fruit brined with DES tended to flatten, but the those brined with AOS were similar tothat of fresh fruit. As a result, it is concluded that the hardness of the brined ume fruit with the egg shell ashed at 720°C or the oyster shell ashed at 1000°C is kept with a maintenance of the tissue structure caused by an obstruction of change of HSP into WSP which is formed through cross-linkage between pectin and Ca ion from CaO.

View full abstract

In order to clarify the mode of inhibition by salts, some properties of two enzymes involved in IMP degradation during the cold-storage of fish flesh were studied. Crude 5'-nucleotidase from walleye pollack showed an optimum pH of about 8.0 and an apparent Km value of 0.83mM for IMP, while that from silver whiting showed the pH of above 9.0 and the Km value of 0.18mM. They were uncompetitively inhibited by NaCl with the K; values of 0.38 and 0.36M, respectively. CaCl2 and KCl also inhibited their activity. On the other hand, crude purine nucleoside phosphorylase from walleye pollack showed the Km value of 0.20mM for inosine, while that from silver whiting showed the value of 0.1mM. The former was not inhibited by NaCl and CaCl2, but the latter was noncompetitively inhibited by NaCl with the K; value of 1.0M.

View full abstract

As a factor of dehydration suitability for processing of Japanese persimmon fruits, cavity degree was used in the present study. The surface layer of the furit was removed along concentric circles by an electric peeler. Some chemical components related to dehydration processing of persimmon fruits were measured at some different layers of the edible portion. Center parts of the flesh contained less total sugar, ascorbic acid and soluble tannin, more total pectin and water soluble pectin than the surface layers. The yield of flesh was concerned deeply with depth of fruit cavity, and the following three methods were used to measure depth: the curvi-meter method that is the ratio of a complete circle to circumference obtained a digital curvi-meter, a caliper method, the ratio of minimum diameter to maximum obtained by a caliper and the depth gauge method, direct depth obtained by a depth gauge.
The caliper method was most suitable for cavity depth determination, since the value obtained agreed well with the degree of cavity depth observed visually and poor yield of peeled fruit. The center part (equatorial part) as measuring part of cavity depth was the most excellent. The values obtained by the caliper method were used as depth coefficient.

View full abstract

Since early 18th century, starch syrup "Gyousen" has been manufactured in Kagawa Prefecture, Japan by a unique traditional procedure, that is, boiled glutinous rice is mixed with malt made from wheat cv. Seto. The mixture is then allowed to stand overnight during which starch is converted into maltose. Clarified extracts are evaporated in a stainless steel cauldron. This procedure results in final products with unique flavor. No report is available about the components responsible for the characteristics of "Gyousen". Hence, in this paper free amino acid, organic acid and carbohydrate contents were analyzed by chromatographic techniques. The samples analyzed were glutinous rice extract, residues in a jute bag, extracts immediately at the start of heating, and after 6.5 hours, the final products and starch syrup (manufactured by acid-hydrolysis) from the local market. Aspartic acid and proline were the most predominant free amino acids followed by serine and glutamic acid. Pyroglutamic acid derived from glutamic acid was 21.4mg per 100g, making up 41.2% of the total organic acids. The dextrin and glucose contents of "Gyousen" were lower than those of commercial starch syrup since there were still impurities in the "Gyousen", hence the sweet taste of "Gyousen" appeared mild in comparison with that of the commercial one.

View full abstract

Various proteins prepared from cereals, milk, fish and meats retarded the oxidation of sardine oil emulsion initiated by hemoglobin. Of all proteins examined, zein from corn and gliadin from wheat showed the most remarkable inhibitory effect. The precipitated fraction of an α-lactalbumin hydrolyzate also exhibited good protection. From a comparsion of the antioxidant activities among the different sources of myosins, the most pronounced effect was observed in squid. In addition to myosin itself, coexistent α-tocopherol and phospholipids were also found to protect against oxidation. The protective effect of myosin against the hemoglobin-catalyzed sardine oil oxidation is different than the ferrous ion-catalyzed oxidation.

View full abstract