モノグリセリドとソルビタンエステルを含む乳脂肪-水エマルションの安定性 (第3報)
O/Wエマルションの安定性に及ぼす油-水界面膜の粘弾性の影響
1981 年 30 巻 3 号 p. 166-172
詳細
1981 年 30 巻 3 号 p. 166-172
The rheological characteristics for oil-water interfacial films prepared from oil phase consisting of milk fat (MF), monoglycerides (MG), and sorbitan esters (SE) and aqueous phase consisting of caseinate (CA) and water (W), as model protective films, were studied.
All the interfacial films exhibited viscoelastic behavior. From the creep compliance-time curves for the oil-water interfacial films a mechanical model can be derived consisting of a unit of Maxwell Model in series with two units of Kelvin-Voigt Model (6 element model). Instantaneous elasticity (E0) and Newtonian viscosity (ηN) of the said films increased as the hydrocarbon chain length of the sorbitan esters (HCL) increased.
From comparison of electrophoretic mobility vs HCL curves for O/W emulsions with the rheological characteristics vs HCL curves for the oil-water interfacial films, instantaneous elastic behavior, Newtonian viscous behavior and retarded viscoelastic behavior of the films might be related to HCL under coexistence of (MG+SE+CA), (MG+SE), (SE) respectively at the oil-water interface.
Since the rate of oil globule coalescence for the O/W emulsions prepared from oil phase consisting of MF, MG, and SE, and aqueous phase consisting of CA and W decreased linearly as E0 increased, and the rate decreased drastically at the region where ηN was higher than ca. 25 104 surface P, the mechanical strength of those protective films covering oil droplets in O/W emulsions was suggested as being responsible for the stability of the O/W emulsions.
