Michizo Suyama

Free imidazole compounds in white and dark muscles of migratory marine fish

1. Extractive nitrogenous components were analyzed in specimens of white and dark muscles of three tunas and the Pacific saury. 2. Tunas contained high concentrations of histidine, anserine and creatine in white muscle, and of taurine, anserine and creatine in dark muscle. 3. Imidazole compounds were determined in both muscles of 11 migratory marine fish. Histidine was found in great quantities in all species except swordfish, anserine was found in relatively large amounts in tunas and swordfish, but carnosine was only present in small amounts in yellowfin and skipjack tunas. 4. The dark muscle had a lower content of imidazole compounds than white muscle.

Changes in gelatin in hot water extracts of snapping turtle during heating.

The changes in content and molecular weight of gelatin in hot water extracts from snapping turtles during heating were investigated. The amounts of gelatin and total nitrogen increased rapidly and reached a maximal value after 24h of heating. The breakdown of gelatin molecules occurred during heating; the average molecular weights estimated by a gel filtration and an SDS-polyacrylamide gel elect-ophoresis were approximately 50, 000 and 35, 000 after 8h, 28, 000 after 12h, 8, 000 after 24h, and 4, 000 after 48h. It was suggested that the degradation products of gelatin play an important role on the taste of the soup.

Studies on phosphopeptides of fish eggs. V. Chromatographic fractionation of phosphopeptides of rainbow trout eggs.

×A mixture of phosphopeptides, obtained from the mature eggs of rainbow trout Salmo gairdneri by extraction with trichloroacetic acid and by precipitation with ethanol, was separated into 12 fractions by anion exchange chromatography using Dowex 1-2; 9 of them containing typical phosphopeptides were further separated into 2-3 fractions by gel chromatography using Sephadex G-50. Moleculaz weights of 15 phosphopeptides thus obtained ranged from 1, 100 to 2, 100 and from 4, 200 to 5, 500. Serine was the most prominent amino acid in all peptides, and phosphate and serine contents of each peptide were almost equimalar. On the basis of molecular weight, amino acid composition, and phosphate content, the consistution of phosphopeptides were char-acterized.

Decomposition of carnosine and its methyl derivatives in aquatic animal meats during storage

The decomposition of carnosine, anserine, and balenine during storage of the big-eye tuna and the sei whale meats was studied with a view to ascertain the formation of methyl derivatives of histamine and β-alanyl-histamine. A chromatographic deteiination of these amines on a 15cm column of a cation exchange resin (JEOL, LCR-2) was achieved using a borate buffer of pH 10.2 having sodium concentration of 0.32N, at 52°C. When the big-eye tuna meats with and without addition of chopped sardine skin were stored at 5°C for 12 days or 20°C for 5 days, and when the sei whale meats with and without addition of mackerel slime at 25°C or 37°C for 3 days, the meats turned putrid in the late stages of the storage periods. The amounts of anserine in the big-eye tuna, and carnosine and balenine in the sei whale did not decrease. Although a lot of histidine was decarboxylated into hislamine in the big-eye tuna meat at 20°C, the methyl derivatives of histamine and β-alanyl-histamine were not detected.

AMINO ACID COMPOSITION OF THE PROTEIN OF ANCHOVY

Amino acid analyses on the proteins prepared from the whole body, ordinary meat, dark meat and viscera of anchovy, Engraulis jaPonicus, were carried out by chromatography on columns of Amberlite CG-120. An imperceptible but obvious difference between the amino acid composition of ordinary meat and dark meat and characteristic pattern of composition of viscera were observed. We wish to express our sincere thanks to Taiyo Fisheries Co., Ltd. for supply of fresh anchovy.

Changes in Chemical Compositions during the Maturation of Rainbow Trout Eggs

As an approach to the biochemical changes occurring in the maturation of fish-eggs, some chemical properties and pH value of rainbow trout eggs were determined at intervals of a month from August to December, i.e., from unmatured stage to matured. The maturity grades of the eggs were estimated by egg-diameter and weight per cent. per total body. These figures and analytical results obtained are shown in Tables 1 and 2, and summarized as follows: 1) Water and non-protein nitrogen contents tended to decrease, while protein nitrogen and ash contents to increase during the maturation. 2) The amount of ether-extractives decreased, to the contrary, the quantities of lipides (alcohol-chloroform-extractives minus ether-extractives) and phosphorus and nitrogen increased. 3) It is interesting that pH values decrease gradually on the acid side, from 6.13 to 5.90, then, turned back to neutral as the maturation advanced and finally grew up to 6.55.

Studies on the Fish Proteins

The coagulation temperature of the myosin, isolated and purified from the fresh muscle of carp-fish, is usually determined by the method which measuring the lowest temperature that makes the myosin insoluble in most adequate solution as shown in Table 1. This method is not, however, always suitable because the troubles are not few. To determining the coagulation temperature easily, the author applied the viscometrical determination by using, Ostwalds viscometer, and obtained the curve of relative viscosity plotted against the temperature as showin Figure 1. First winding point of the curve is indicating the beginning of flocculation of myosin by heat denaturation, and the second is showing the second is showing the finish og flocculation. This second winding point (45°C) is the coagulation temperature of myosin. The ciscometrical determination was, however, unfited for the salt-free precipitated protein (Figure 2).