Daizo Yonezawa

An attempt at preparing water-in-oil-in-water multiple-phase emulsions

Abstract It has been found that W/O/W-type multiple-phase emulsions can be prepared by a two-step procedure of emulsification using a variety of nonionic emulsifying agents. The first step in emulsification, providing the W O emulsion, was made with an organophilic emulsifying agent such as Span 80, and the second step, providing the W/O/W emulsion, was then carried out by mixing the W O emulsion with an aqueous solution of a polyoxyethylene-type hydrophilic emulsifying agent. Yield of the W/O/W emulsion was measured by the amount of marker (glucose), which migrated from the dispersed globules to the continuous phase, using dialysis for separating the migrated glucose from the newly prepared W/O/W emulsion, and using Nelson-Somogyis technique for analyzing the amount of the glucose. The results of the yield measurement for a series of the samples indicate that the significant factor affecting the W/O/W emulsion formation is the ratio of the organophilic emulsifying agent in the oil phase to the hydrophilic emulsifying agent in the aqueous continuous phase. The correlation between the yield of the W/O/W emulsion and the ratio of emulsifying agents used for the two-step in emulsification shows that when one desires a yield of the W/O/W emulsion higher than 90%, the organophilic emulsifying agent needed is 10 times or more the amount of the hydrophilic emulsifying agent.

Viscometric method for estimating the stability of W/O/W-type multiple-phase emulsions

Abstract An attempt was made to establish the method for estimating the stability of the W/O/W-type multiple-phase emulsions in the light of the correlation between the viscosity and the disperse phase concentration using Mooneys theory, as In η rel = ΦW i + Φ o )/ ≈ 1 − λ(ΦWi + Φ0)∼, where ηrel is the relative viscosity of the W/O/W emulsion,ΦWi and Φ0 are the volume fractions of inner aqueous phase and oil phase, and α and λ are the constants. As a result of the rupture of the oil layer on the surface of the dispersed inner aqueous-phase globules, the volume fraction ΦWi should decrease following the mixing of the inner aqueous-phase component with the outer aqueous phase. This may reduce the viscosity of the W/O/W emulsion according to the relationship ΦWi = α[log ηrel ≈ (2.303/α) − (2.303λΦo/α) − Φo] (α + 2.303λ log ηrel). The experimental results obtained suggest that it is possible to estimate the stability of the W/O/W emulsions by measuring the time dependence of the viscosity in a range of the relatively low disperse phase concentrations, although the presence of ingredients, such as protein, electrolytes, saccharides, in both aqueous phases affects the rheological properties of the W/O/W emulsions.

Wheat flour proteases and their action on gluten proteins in dilute acetic acid.

The presence in wheat flour of several kinds of proteases was shown on the basis of pH-activity profile, substrate specificity, and response to inhibitors. Among them, 14C-hemoglobin and cbz-Phe-Ala hydrolases (14C-Hbase and CPAase) showed optimal activity around pH 4. 14C-Hbase was inhibited almost completely by pepstatin, and CPAase was partially inhibited by DFP. About 85% of 14C-Hbase activity and 40% of CPAase activity in the original flour were retained in gluten fraction. The decrease in viscosity of the gluten solution in dilute acetic acid was effectively prevented by pepstatin. An SDS-PAGE pattern showed that hydrolysis of gluten proteins was prevented effectively by pepstatin, although not completely, and that the simultaneous addition of pepstatin and DFP prevented completely self-digestion of the gluten proteins. Therefore, pepstatin and DFP sensitive proteases were shown to be responsible for the self-digestion of gluten proteins. The mode of action of these enzymes was relatively specific f...

Aggregation behaviors of glutens, glutenins and gliadins from various wheats.

The aggregation behavior was investigated by the method presented in the previous paper, with the glutens separated from ten kinds of wheat flours different in the mixing property. It was shown that the rate constant of aggregation, k, increased in the order of the weak, medium and strong flour. This is an additional evidence for the correlation between the aggregation behavior of the separated gluten and the mixing property of the flour, which was suggested in the previous paper with four kinds of flours. The aggregation behaviors of glutenin and gliadin were also investigated after fractionation of gluten. A good correlation was observed between the τ10/C values of gluten and glutenin separated from it, showing that the difference of the aggregation behavior of gluten is mainly due to the nature of glutenin.

Studies on the Contribution of Sugars to the Change of Proteins in the Manufacture of Tenobe-somen

(1) 各種糖のグルテンに対する作用を比較するために糖を小麦粉に添加して50°C,RH 82%に貯蔵した後,湿グルテンをとり出してその状態を調べた結果,ペントースは作用力が強く,その強さはリボース>キシロ-ス>アラビノース>ラムノ-スの順であったが,ヘキソースはほとんど作用が認められなかった. (2) 糖をグルテンに添加して40°C,BH 83%に貯蔵し,グルテンの溶解性に対する影響を調べた結果でも,アラビノースはかなりの影響を示すのに対し,グルコースの影響はほとんど認められなかった,なおこの実験において,糖の添加による吸湿促進のためにグルテンの溶解性が低下する現象が観察された. (3) グルテンのアミノ酸分析を行なった結果では,グルコース添加のものもアラビノース添加のものもともに,貯蔵後にリジンがかなり減少していることが認められた. (4) 手延素麺の還元糖含量は製麺時に増加し,厄中にも幾分増加を示したが,厄後には減少していた. (5) 素麺水抽出液中の糖組成はグルコース,キシロース,アラビノース,ガラクトース,マンノースと未知の物質少量からなり,グルコースが80%を占めている.(フルクトースは定量しなかった)単糖は水可溶性糖の約1/10を占め,その80～90%がグルコースであり,マンノースとガラクトースがこれにつぐ.ペントースは微量で素麺100g中にアラビノースが3mg前後,キシロースが1mg前後であった.グルコースは厄中に増加し,厄後に減少した.マンノース,ガラクトースは貯蔵中に増加した.ペントースは厄中に幾分増加しているようであるが,その変化量はわずかであった. (6) 小麦粉および厄後の素麺粉末に水を加えてincubateし,小麦粉中に含まれる多糖を分解する酵素作用の有無を検索した.incubationにより主としてグルコース(あるいはマルトース)による還元力の増加が見られ,ガラクトース,マンノースの増加も観察された,ペントースは小麦粉では増加を認めなかったが,素麺粉末ではアラビノースが幾分増加した.ただし,量的には微量である. (7) 厄中の素麺水抽出液中に含まれる糖を,素麺に含まれるのと同じ割合でグルテンに添加貯蔵してグルテンの溶解性に与える影響を調べたが,その影響は小さかった.またその影響は,全抽出糖のうちアラビノースだけを添加したものと同程度であった.

Effect of pH on Bovine Casein Micelles

(1) 脱脂乳を緩衝液または乳清で100倍に希釈して, pH6.8からpH5.5付近までの各種のpHを与えてその濁度を測定すると, pHの低下とともに濁度が減少し, pH5.7付近で濁度は最低となった.さらにpHを低下させると,ミセルの集合が起こりはじめ,濁度は上昇する. (2) 同様の現象は,脱脂乳そのものでも観察された.ただし脱脂乳の場合は, pH6.3付近まではpHの低下による濁度の上昇が見られ, pH6.3に濁度の極大があらわれた. (3) pHの低下による濁度の減少は,溶媒のイオン強度を高めると促進せられ,カルシウム濃度を高めると抑止された. (4) pH5.8へのpHの低下によって,ミセルの容積が3/4前後に収縮することがペレット容積,粘度,沈降の測定を通じて明らかにされた.なお,このときミセルタンパク質の乳清への溶け出しは認められなかった. (5) 乳清のカルシウム濃度を測定して, pHの低下とともに,ミセルから乳清にカルシウムが移行する状況を観察した. (6) 以上の実験結果に基づき, pHの低下による濁度の低下は,カゼインミセルからのカルシウムの離脱によるものであることを結論した. (7) ミセルの集合により濁度の上昇がおこるpHは,カルシウム濃度に依存し,カルシウム濃度が高くなるほど低下する事実を認めた,このことから,ミセルの集合が起こるためには,これに先立ってカルシウムの離脱によるミセルの構造の破壊が,まず起こらなければならないと考えた.

The Creep Behaviour of Synthetic Flour Doughs

The complexity of rheological properties of wheat flour dough has prompted the present study of the viscoelasticity with synthetic flour dough, which was prepared by mixing three major components of wheat flour dough, i. e. the gluten protein, wheat starch, and water.The results obtained can be summarized as follows:(1) The source of the gluten protein fractionated from the commercially available wheat flours plays an important role in knowing the creep behaviour of synthetic flour Boughs of the same composition.(2) The values of the creep parameters derived from the creep data decrease with increasing measure of shear stresses, so that the synthetic system exhibits non-linear viscoelastic behaviour.(3) The introduction of a small amount of cystein into the system is pronouncedly effective to the softening, which may be due to the introduction of thiol-disulfide interchange reactions in the protein network.(4) The glutenin fraction of the gluten protein is a major component in the network structure of protein in the dough system.