NIPPON SUISAN GAKKAISHI

Sparus swinhonis G_ÜNTHER is an important, commercial as well as game fish found in inshore regions all around Japan.
In the present paper description is made about some ecological points of the fish, viz. breeding season, habits of the post-larval and immature fish, age and growth, protandric nature and sex-conversion with age.

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Assuming that the velocity of spoilage of a dead fish muscle is proportional to the population density of bacteria in the fish muscle, the degree of spoilage, a, after t hours from they were killed may be represented by the following formula: -
lna=lna₀+∫^t₀k(θ, w)dt.
where k(θ, w) is a constant depending upon the temperature, θ, and moisture content, w, and a₀ the initial value of a. For w>0.6, k(θ, w) is presumed as k(θ, w)=k(θ)λ(n), where k(θ) is the value of k for undried fish and depends upon the temperature θ, i. e. k(?)=k(θ, w₀) and λ depends upon w only. The relation between λ and w were calculated numerically from the experimental data as shown in Fig. 1.
The influence of air-heating on the spoilage in the course of drying may be divided into two parts, viz. (1) the good influence-shortening of the time of drying, and (2) the bad influence-increasing of the velocity of putrefaction. In order to obtain such condition as the heated-air-drying would lead to good results, the author assumed that the temperature coefficient of spoilage, Q_l0, is constant, and calculated the time of drying by Prof. TAUTI'S law⁽¹⁾ of similitude. Thus, we get the following relation: -
E(θ+Δθ)-e/E(θ)-e 18W₀^1/3+0.22W₀^2/3{E(θ)-e}/18W₀^1/3+0.22W₀^2/3{E(θ+Δθ)-e}>Q₁₀^{Δθ/ ?? 0}
where E(θ) is the maximum vapour tension (in mmHg) of water at the temperature θ°C, e, the vapour tension exist in the air, Δθ the temperature rise by the heater of dryer, and W₀ the initial weight (ing.) of sprited fish for drying.

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The protein in fish-meals is extracted by weak alkali-solution under pressure and treated with formaldehyde. The condensations-product, thus prepared, is more plasticizable and more water-absorbable.

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