Chemical interactions between NaCl and proteins (ovalbumin from agent, ovalubmin from egg white, β lactoglobulin, soy beans globulin) were studied. There was no binding between any proteins used and Na ions except for β lactoglobulin. For the case of β lactoglobulin, there was a slight binding at only pH 9.0 although its amount was under the threshold value of salty taste. The difference NMR and FT-IR spectra between protein solution with NaCl and without NaCl was not observed for all the samples studied. It was suggested that the interactions between proteins to Na ions were very weak. The relationship between rheological properties of isolated soy protein sol and the dissolution of Na ion from the protein sol was studied. The rate of dissolution of Na ion from the mixture of NaCl and various kinds of protein sols was in the order of isolated soy protein>decomposed protein sol with coagulants by protease>protein sol with coagulant. The measurements of viscosity of protein sols showed that the higher the viscosity of the sample, the slower the rate of dissolution of Na ions from the mixtures of protein sols and NaCl. It was suggested that the viscosity of protein sols increased by the addition of NaCl, and the rate of dissolution of Na ion decreased with increasing the viscosity of protein sols, and the destruction of stereo structure of protein caused the decrease of viscosity of the sol together with the increase of dissolution rate of Na ions.

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Salt taste assessment of cocked food containing various food ingredients, such as acids, amino acids, proteins, sugars, and etc, might become very complex. We tried to digitalize salt tasty by measurement of Na⁺ activity in various model food solutions, model gels and cocked food co-existing using two types of ion-selective electrode, ion-selective microelectrode and the other is ion-selective membrane electrode. Na⁺ activity was suppressed by co-existing with acetic acid, glutamic acid, albumin, agar, gellan gum, κ-carrageenan. In tofu gel and egg white gel the Na⁺ activity was also decreased. However, in gel food the effect of syneresis might be considered in the results of Na⁺ activity measurement.

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Tofu is a popular and traditional Japanese food. It is formed by the formation of heat-induced gels of soybean proteins, leading to determine its texture. Salts are used as coagulants on an industrial scale for the preparation of tofu and strongly affect the gel formation of soybean proteins. This article focuses on effects of salts on physical properties and gel structures of tofu. We explain: 1) relationship between physical properties and gel structures of commercial tofu, 2) effect of different coagulants on physical properties and gel structures of tofu, 3) effect of sodium chloride on the gel formation of soybean protein isolate, 4) effect of sodium chloride on physical properties and gel structures of tofu.

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Egg sols diluted with various liquids are easily converted to soft and smooth gels by heating. In this paper, effects of various salts on the properties of the diluted egg and egg white gels were discussed. With univalent NaCl or KCl, the breaking strength of gels were lower than with divalent MgCl₂ or CaCl₂, though increased gradually with added salt concentration. The amounts of liquid released by syneresis from gels with divalent salt were significantly large compared with univalent salt.Moreover, the breaking strength of gels with same charge showed same behavior, by adjusting to the same pH value of the sols.
The results of saltiness sensory evaluation test by Probit method of egg white gels with various concentration salts added were as for lows: The hardness of gels showed little influence on the saltiness. With other salts substituted to 5% of NaCl, the saltiness was weakened with MgCl₂ or CaCl₂ contrasting to little ef fect with KCl.

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The sol-gel transition of agar, κ-carrageenan and gellan gum in the presence of sodium chloride were investigated by thermal and rheological measurements. The G′, G″ and DSC curves for the agar solution during cooling and heating were slightly affected by added sodium chloride. In respect of the κ-carrageenan and gellan gum solutions, G′ and G″ were increased, and DSC curve shifted to a higher temperature in the presence of sodium chloride. The rheological and thermal behavior in the presence of sodium chloride may have been affected not only by the change density of molecules but also by the gelation mechanism, since gelation of the gellan gum sol was much more accelerated than the κ-carrageenan.

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The salty taste strength of foods may not necessarily depend on their NaCl contents. The saltiness we feel often varies according to the physical properties of the foods that function in the mouth. However, no clear scientific information has been available up to the present.
With it as a background, we undertook a project research aimed at elucidating the relationship between the NaCl contents of foods and their saltiness. The following foods with different NaCl contents were prepared: egg white gel, 0.4-1.2% NaCl; soy protein isolate gel, 1.0, 2.0% NaCl; soy protein curd (tofu), 0.5, 1.0% NaCl; and agar gel, 0.8, 1.0% NaCl. Sensory tests using well-trained panel members were first carried out with these food preparations to define their saltiness in terms of salty taste efficiency ratio (STER). The tests gave the STER values ranging from 0.58 to 1.10. Physical data were also measured with the foods to obtain several of their parameters involving gelling properties. It was then tried to correlate the physical data with the STER values. We could not find any significant correlation as far as the same food was tested irrespective of its different NaCl content. However, all the foods we prepared were comprehensively submitted to the physical parameter-sensory score analysis, significant relation appeared (R²: 0.83) which were clearly represented by an equation as a function of breaking stress value. It was also suggested that the STER differences were generally larger between foods than within a food having different NaCl contents.
This project research is apparently the first that objectively expresses the saltiness of foods in relation to their physical properties. It would contribute to our scientific aspect on how the proper saltiness for cooking of foods varies depending on the physical properties.

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タピオカゲルをアルカリ金属塩類や糖類の水溶液中に浸漬した場合, タピオカゲルの物性にその共存物質や浸漬温度がどのような影響を及ぼすのかを明らかにすることを目的に研究した. アルカリ金属塩類および糖類の1Mの水溶液中に10, 20, 30℃の3段階の温度条件でタピオカパールを24時間浸漬した場合の物性と体積を測定した. タピオカゲルの水和現象およびその理論的解析については動的水和数の理論を利用して検討した. その結果, 浸漬水溶液の共存物質の動的水和数の値が大きいものほどタピオカゲルは硬くなり, 逆に体積は小さい傾向を示した. 浸漬温度でも異なる傾向を示した. タピオカゲルの物性には塩類や糖類の共存物質および浸漬温度が影響することが認められた.

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遊離型アスタキサンチン (As) とラビリンチュラ (LB) Thraustochytrium sp. CHN-1が、キンギョ (朱文金) の体色改善に及ぼす影響を調べた。Asの経口投与 (1.6または16mg/kg体重/日) は有意な体色改善効果を示さなかった。LBの経口投与 (160mg/kg体重/日: As量に換算して0.05mg/kg体重/日) は、数週間以内に著しい体色改善効果を示した。LBの投与は、体表の赤色部分において赤色素細胞数の増加をもたらした。
以上の結果は、キンギョの体色改善 (赤色部分の鮮明化) にLBの経口投与が極めて有効であることを示すと共に、LBの体色改善効果が、既存の赤色素細胞におけるAs蓄積量を増加させることに加えて、赤色素細胞数の増加を促すことにより生じている可能性を示唆する。

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サンゴ骨格 (あられ石) に存在する硫酸イオンは炭酸イオンとのイオン交換反応により共沈している可能性がある. その平衡定数 (K_so4) は次のように書ける: K_so4=[CaSO₄](s)[CO₃^2-](aq)/[CaCO₃](s)[SO₄^2-](aq). ここで, 平衡定数と海水中の炭酸イオン濃度は温度に対する変数であるが, 平衡定数の変化は小さいと仮定すると, 上式はサンゴ骨格の硫酸塩含量が海水中の炭酸イオン濃度に反比例することを示す.
サンゴ骨格の硫酸塩含量と海水中の炭酸イオン濃度および海水の温度の関係から, 硫酸イオンの共沈の過程を明らかにするため, イオンクロマト法を使って, ポナペ島 (ミクロネシア), カンカオ島 (タイ), セブ島 (フィリピン), 水釜, ルカン礁 (沖縄県), 堺港 (和歌山県) から採取したサンゴ試料中の硫酸塩含量を定量した. 硫酸塩含量はカンカオ島の試料 (0.404±0.050wt%) を除き, 他の試料でほぼ同じ範囲の値 (0.566±0.064wt%) であり, サンゴの硫酸塩含量と海水中の炭酸イオン濃度および海水の温度の間に明確な相関は認められなかった. したがって, 硫酸イオンのサンゴ骨格への共沈は, 炭酸イオン濃度および海水温だけに支配されておらず, 平衡定数の温度依存や他のトレース元素の共沈などからも影響を受けている可能性が考えられる.

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