Amount of CF, citrovorum factor, in pyloric coeca of skipjack was determined by bioassay with Leuconostoc citrovorum as 5.9γ per one gram of this tissue. However, the presence of a substance which favors the growth of this bacteria but behaves at variance with the known CF was also disclosed as mentioned below, suggesting the share of this unfamiliar substance, “unknown factor” so to speak, in the above value of total CF. In the incubation of pyloric coeca of skipjack or aqueous extracts thereof, maximum liberations of citrovorum factor, including the unknown factor, took place when conjugase obtained from chick pancreas was employed or when this tissue was subjected to autolysis at pH 4.5, while the conjugase from hog kidney and also takadiastase were found less effective, simultaneous use of cysteine or ascorbic acid known as activator of conjugase having no effect on the liberation of CF from conjugated state (see Table 1). The unknown factor was proved by the bioautographic method to be completely separable from the known CF (see Fig. 1). As regards the promotive effect on the growth of Leuc. citrovorum, while the known CF is readily damaged when acidified to pH 2.0, the unknown factor factor can survive such acidification (See Figs. 2 and 3).
1. At variance with the known CF which readily loses the power of promoting the growth of Leuconostoc citrovorum after being kept at a pH lower than 2.0, the unknown factor is not damaged of its activity toward this microorganismus even when exposed to any pH in the range from 1.0 to 14 (Table 1). 2. The unknown factor is comparatively unstable to a strong acid. It loses said promotive power to some extent when boiled in 5% H2SO4 and is completely invalidated by heating with 25% H2SO4 (Fig. 2 and 4). On the other hand, the unknown factor remains comparatively stable against a strong alkali. Its characteristics toward Leuc. citrovorum are not damaged even when kept in contact with 10% KOH (see Fig. 3). In this connection, the response of Leuc. citrovorum to the unknown factor appeared to be more or less strongly suppressed in the presence of salt inevitably ensuing from the neutralization of the agent employed in acidification or alkalization. 3. The unknown factor can be selectively adsorbed on an ion-exchange resin, only when the resin is of strong acid form (see Table 2 and Fig. 5). It can also be desorbed from the exchanger by means of 0.5N NaOH. 4. The unknown factor itself could not be precipitated by the addition of any agent thus far tested. 5. A crude preparation of the unknown factor was positive to diazo reaction, Morlish's reaction and Folin's reaction, but negative to ninhydrin reaction (Table 4).
As a method for evaluating the freshness of fish in transit, the relative merits of measurements of electric resistance, volatile basic nitrogen, pH and organoleptic test were discussed. The species of fish mainly tested was Cyprinus carpio. For information, the distribution of its body temperature was measured at three regions; high, medium, and low. It was revealed that the time change curve obtained by electric resistance method paralleled those by other methods with respect to the degree of freshness; individual difference and that by the side of body were non-existent, but there was a difference by the site of body, pointing to possible relation with the body constituents; also there was a difference discernible depending upon the species.
It is well known that from the observation of the period of torsional oscillation of a wire suspending a weight, we can determine the modulus of rigidity of the wire. This method can not be applied to the case of a netting cord, because a heavy weight hung down by a cord rotates about the axis of the cord gradually untwisting that cord. If a weight attached to a cord is light, it does not rotate, and can be set in torsional oscillation. But this oscillation is damped so rapidly that the measurement of the period is difficult. Now, in the present experiment, the upper end of a cotton cord suspending a light weight is fixed to the lower end of a metal rod which is held vertically, and can be made to oscillate about its axis at a given amplitude. The ratio (m) of the amplitude of the lower end to that of the upper end of the cord, and the phase difference ( ?? ) between the oscillations of the lower end and the upper end were observed. From the analysis of the observed values of m and ?? depending on the frequency of oscillation, it was found that the behaviour of the cotton cord can be understood by the Voigt model. Further, the rheological constants for cotton cords of various diameters were obtained.
1. The idea of the inflection point of water temperature, d2T/dt2 (here, T: temperature and t: time), was applied to an analysis on the correlation between the feeding activity of goldfish and the changes of water temperature, especially taking into consideration both the time factor in the biological clock of the fish and the stimulus of water temperature for fish feeding. The results thus obtained were compared with those obtained by the use of the average water temperature and the coefficient of water temperature variation respectively. 2. The experiments were carried out for five to seven consecutive days a month during the period from March 1957 to February 1958, at the greenhouse of the Faculty of Fisheries, Hokkaido University. Feeding activity of the goldfish was recorded by an automatic feeding apparatus. For measuring the water temperature an automatic recording thermometer was used. 3. Feeding activity of the goldfish almost ceased under the condition of water temperature below 7 or 8°C. A plus correlation between the total daily feeding frequency and the average daily water temperature was clearly found so far as the water temperature ranged from about 9 to 25°C. However, even if in two consecutive days the average daily water temperature was almost the same, it was not rare that the feeding activities for the two days were found to be clearly different from each other; generally, more active feeding was recorded on a day when the coefficient of water temperature variation was larger. So, it is presumable that in such a case changes of the water temperature with high fluctuation accelerated the feeding activity as stimuli for the fish. 4. Throughout the present experiment, almost all of the daily feeding was found to be recorded at the time of the rising phase of water temperature, that is, the temperature showed the plus value in its changing rate (C°/Hr). In both the autumn and spring months, the maximum feeding frequency was often found to occur at just the time of the inflection point of water temperature. Especially, in late autumn as the water temperature fell, the peak of the feeding was found to correspond clearly with the time of the inflection point of water temperature. In the summer months, however, such a tendency was found to be very rare. 5. It seems that when the fishes were acclimatized to a relatively high temperature, the effect of change of the water temperature on fish feeding was rather inconspicuous, but when the fishes have adapted to the condition of low temperature such as in late autumn, they became more sensitive even to a slight change of the water temperature as a strong stimulus. Generally speaking, however, the peak of the fish feeding is found to occur at the time of the inflection point of water temperature. Such an idea of the inflection point may be applied also to any ecological and physiological studies.
1. Pareuchaeta russelli is one of the common species in the warm waters of Japan. 2. The eggs are carried in the egg-sac attached to the genital pore until they are hatched. 3. The subspherical egg of P. russelli is measured 0.29mm. in diameter. The number of eggs in one sac is usually about 20. The sac is thrown off after spawning and within 8 days the next batch may appear. 4. The eggs in sac and in ovary are bright bluish green in colour, but the red oil-globules give the embryo a reddish tinge at time they emerge. 5. It appears that P. russelli passes through its nauplius stages without feeding, because it has the plentiful supply of yolk to pass through its nauplius, stages. 6. There are six nauplius stages. The total durration of the nauplius stage was usually about 4 days. 7. 24-30 hours elapse before the final nauplius moults and develops into the Copepodite I, and this period appears to be most critical in the development.
In Japan, 13 kinds of food preservatives are approved for use by Food Sanitation Law, of which nitrofurazone (NFS), nitrofuryl acrylic amide (NFA), sorbic acid and sodium sorbate are permitted for such fish products as “kamaboko” (fish cake), fish sausage and whale meat products. Recently, chlortetracycline (CTC)-ice was permitted as an aid in keeping the freshness of fish hauls by trawlers. The purpose of this study was to investigate the effect of incubation temperature, pH value of the medium or the addition of glucose upon the inhibitory action of all of the 13 food preservatives, as well as CTC and oxytetracyline (OTC) upon some species of cocci and bacilliincluding spore bearing organisms. In addition, a possibility of preventing allergy-like food poisoning due to consumption of some kind of fish products was studied by the aid of such preservatives as nitrofurazone, CTC or OTC. Results obtained may be summarized as follows: 1. NFA and NFS were found to have the highest antibacterial action among the legally approved food preservatives and methyl-naphthoquinone (MNQ) and p-hydroxy benzoic acidbutyl-ester (POBB) were the next. At pH 7.0 and 20°C, growth of Pseudomonas fluorescens was not inhibited by almost all of the preservatives. At the optimum growth condition, Proteus morganii, the causative organism of allergy-like food poisoning, was inhibited only by NFA within the legally permissibleconcentration. 2. Minimum growth inhibitory concentrations of some agents in a medium of pH 7.0 were determined at 24, 48, and 72 hours of incubation. As for NFS and NFA, the values did not change markedly in 72 hours. On the other hand, with CTC or OTC, the values tended to become larger as incubation period proceeded, indicating the decomposition of the antibiotics. 3. The antibiotic activity of CTC or OTC in nutrient broth at pH 7.0 markedly decreased during incubation at 37°C, the tendency was more conspicuous with CTC. 4. No marked difference was observed in the minimal growth inhibitory concentration of the food preservatives in the broth by changing hydrogen ion concentration within a range of pH from 6.0 to 7.5, or by the addition of 1 per cent of glucose. However, in the case of CTC, the value varied markedly in response to pH of the growth medium.
The protein composition of fresh fish muscles has been investigated of eight species of teleosts and one species of elasmobranchs. The procedures for extraction and fractionation used are given in Fig. 1 and the results obtained are summarized as follows: (1) Values for sarcoplasmic, fibrilar and stroma fractions for different species within teleosts are quite similar: sarcoplasmic fraction comprises some 20-30 per cent of total proteins, fibrilar proteins some 60-70 per cent and stroma about 3 per cent. (2) Values for the stroma of teleosts are of interest, since they are considerably lower than those observed for elasmobranchs and rabbit. This suggests that the difference between these muscles in the stiffness may depend upon the amount of stroma. (3) Accompanying the post-mortem aging of the fish muscles, the fibrilar protein (myosins soluble in salt) readily become insoluble and move into the residual intracellular fraction, while the sarcoplasmic proteins (non-myosins) suffer no change in their solubilization properties. Thus, lowered values for the total extractable proteins observed in aged muscles are mainly attributable to decreased levels of the myosins. (4) The rate of denaturation of myosins in muscle during the cold storage seems to vary to a great extent with the fish species.
(1) The amino acid composition of the two components of salmon Hb was determined by the column chromatographic method. (2) Difference was found between both components in many of amino acids, especialy remarkable in glutamic acid, basic amino acids. and cystine and/or cysteine. (3) The presence of isoleucine, the high content of tryptophan and the low content of histidine seem to be characteristic of these components in comparison with mammalian Hb's. (4) The distributions of groups in both components differ in some respects from each other and further from those in mammalian Hb's.
Forty-three kinds of volatile hydrocarbons, alcohols, and esters were submitted to chromatostrip and their Rf values were determined. By the use of such Rf values and size of spot, essence added to fish ham and fish sausage could be learned in a short time by a simple apparatus and simple procedures, as well as revealing the main component. When n-hexane is used as developing solvents, oxygen-containing substances appear below Rf 0.3 and hydrocarbons above Rf 0.3, while the use of 15% ethyl acetate in n-hexane as the solvent gives the spot of hydrocarbons at above Rf 0.6, those of esters between Rf 0.50 and 0.60, and those of alcohols below Rf 0.5. Carbonyl compounds can be detected by spraying sulfuric acid solution of 2, 4-dinitrophenylhydrazine to derive them to hydrazones on the strip.
The contents of the volatile components of Laminaria sp. differ according to habitat and quality. This Laminaria from Hidaka district contains larger amount of volatile components than that from Kushiro district, while the content is lager in better quality products. The fatty acid fraction saponified with 3% potassium hydroxide contained myristic acid, and there was no presence of carbonyl compounds possessing a phenol radical. Neutral fraction from the volatile components of Laminaria sp. contained uneicosane and also substances which showed silvery white and yellow fluorescence. These substances were purified through column chromatography and their elemental analyses gave the molecular formulae of C14H15O2 and C11H20O.
The authors studied about the oil contained in gamma-irradiated fish meat. The results obtained were as follows: (1) The grade of oxidation of oil in irradiated meat was influenced by source. When the source of irradiation was weak or far from sample meat, the oil was oxidized to a greater extent than in using of strong source (Table 1). (2) Oils in irradiated fish meat was fairly prevented from oxidation by subjecting the samples, before irradiation, to vacuum packing, instilment of CO2, or immersion in ascorbic acid solution (Table 2). (3) The grade of oxidation of oils in irradiated fish meat was different by kinds of packing film. Films made from polyvinyliden chloride, Polycello (polyethylen laminated with cellophane) or rubber hydrochloride showed better results than polyethylen film (Table 3).
(1) Effects of pH, salt concentration, and temperature on the oxygen dissociation curve of the two components of chum salmon Hb were investigated. (2) The effects of pH, phosphate concentration and temperature were much more remarkable on component F than on component S. The mode of effect of the other salts such as NaCl, KCl and Na2SO4 was also different between both components. (3) Physiological significances of the existence of the two components were discussed.
As already reported, for the manufacture of fish oil into a chlorination product an oil after polymerization is rather suited, insofar as it remaines soluble in organic solvents, as compared with an oil before polymerization. In this point of view, the conditions that favor the polymerization were studied through experiments wherein a few kinds of fish oil were heated at 150-1700°C under reflux in the application of di-t-butyl peroxide as polymerizing agent. From the results obtained it was inferred that some volatile matters usually present in raw fish oil, including a small amount of water, are possible to obstruct the rise of reaction temperature and hence the advance of polymerization. This inference made a good hit when polymerization was actually carried out with success by using samples of fish oil previously well aerated with air and/or nitrogen gas. Since aeration with air gave rise to increases of acid value and peroxide value, which also proved in this study to do no good to the polymerization, aeration with nitrogen is considered as a recommendable method of removing the volatile matters from the fish oil to be chlorinated.
The influences of natural spices and their powdered essences on the quality of fish sausage were compared with each other. It was found that a large number of bacteria observed in fish sausage may be attributed to bacteria contained in a large amount in natural spices. The natural spices make color of sausage dark owing to their own pigments. It was hard to notice the difference in quality between sausages mixed with natural spices and their essences. But it seemed that the spice essence is rather preferred to natural spice. The appropriate amount of powdered essence spices was found to be one-tenth or one-seventh of natural spices.
Inhibitory action of some food preservatives and antibiotics, nitroflazone (NFS), nitro-furylacrylic amide (NFA), chlortetracycline (CTC) and oxytetracycline (OTC), on the growth and histamine formation of Proteus morganii, the causative organism of allergy-like food poisoning, has been studied. Results obtained may be summarized as follows: 1. The growth of seven strains of the organisms occurred with essentially the same concentration of eiter NFS, NFA or CTC in nutrient broth. A single strain showed a fairy high sistance in respect to OTC. 2. The minimal growth inhibitory concentration tested in the flat-fish infusion and in the mackerel infusion were approximately the same. 3. Effect of NFS, NFA, CTC or OTC in the broth upon the formation of histamine by Proteus morganii was in parallel with that upon the growth. 4. The formation of histamine in the raw mackerel flesh suspension was inhibited by CTC, OTC or NFA in much low concentration as compared with the minimal growth inhibitory concentration of each drug. The possible replacement in microbial flora in raw flesh suspension with resistant organisms has been discussed.