Response surface modeling for optimization of formulation variables and physical stability assessment of walnut oil-in-water beverage emulsions

The effect of Arabic gum content (5-10% w/w) and walnut-oil concentration (3-6% w/w) on properties of prepared walnut oil/water emulsion, including turbidity loss rate, density, size index, particle size and stability, was investigated using response surface methodology (RSM). For each response, a second-order polynomial model with high coefficient of determination (R²) values ranging from 0.907 to 0.989 was developed using multiple linear regression analysis. The lack of significant difference between the experimental and predicted values proved the adequacy of response surface equations for describing the physical changes of emulsions. An increase of Arabic gum content in range and initial concentration of walnut oil were associated with high emulsion stability and minimum droplet size. It can be concluded that RSM can determine the most suitable formulation (3% w/w walnut oil and 9.62% w/w Arabic gum) to achieve the highest stability in a developed beverage emulsion based on walnut oil.     

Influence of molecular character of chitosan on the adsorption of chitosan to oil droplet interfaces in an in vitro digestion model

The relationship between the adsorption of chitosan to oil droplet interfaces (surface adsorption) and the molecular characteristics of the chitosan (molecular weight and charge density) was examined using an in vitro digestion model. This model involved adding different concentrations (3–10 wt%) of oil droplets to a 0.1 wt% chitosan solution at pH 3 to simulate consumption of an oil-containing meal after ingestion of chitosan. The pH was then incrementally raised to investigate pH variations that occur when a food material passes through the human digestive tract at an oil concentration of 3%. The amount of chitosan adsorbed to the oil droplet interface decreased with decreasing molecular weight (MW) and with increasing degree of deacetylation (DDA): ≈132, 85, and 78 g of oil per g of chitosan for MWs of 200, 500 and 750 kDa (all 90% DDA), respectively; and, 47, 65, and 78 g of oil per g of chitosan for DDAs of 40%, 70% and 90% (all 750 kDa), respectively at pH 3. In addition, the extent of droplet aggregation and the nature of the aggregates formed (strong versus weak; large versus small) also depended on chitosan characteristics. The pH dependence of the interaction between anionic oil droplets and cationic chitosan molecules depended on both MW and DDA. Microscope images showed formation of large flocculated structures at pH > 7 except for low DDA chitosan which remained soluble at all pH levels. Our results may have important consequences for understanding the bioactivity of chitosan, and for designing functional food ingredients to reduce lipid digestion and absorption.     

有机硅阴离子氨基乳液稳定性探讨

用乳液聚合的方法合成了有机硅阴离子氨基乳液,对影响乳液稳定性的诸多因素如反应时间、温度、中和剂及乳液非挥发物含量在不同存放条例下随时间的变化值等进行了探讨。结果表明,在80℃下反应6h可获得稳定的阴离子乳液;在酸性条件下存放,该乳液的非挥发物含量随时间逐渐递增,约30天后稳定;用20%三乙醇胺溶液中和后存放,乳液的非挥发物含量在前10天内逐渐增加,然后趋于稳定。     

水基环氧树脂乳液及其胶粘剂

概述了环氧树脂乳液的发展及制造方法;介绍了以环氧树脂乳液为基础的胶粘剂配方及基本性能;重点讨论了单组分环氧乳液作为胶粘剂在建筑领域的应用。     

有机硅乳液的剖析

采用柱层析,红外光谱法,核磁,质谱和化学分析法,分离分析了有机硅乳液的几种主要成分,为有机硅乳液的剖析提供了一般程序和一些独特的方法。     

乳化剂对核／壳型丙烯酸酯乳液性能的影响

选用阴离子乳化剂和非离子乳化剂复合使用,研究了乳化剂的用量、乳化剂的配比以及加入方式对核／壳型丙烯酸酯乳液性能的影响。     

Production and Emulsifying Effect of Polyglycerol and Fatty Acid Esters with Varying Degrees of Esterification

Esters with acyl groups can be formed by the esterification of polyglycerol. The purpose of the present study was to produce fatty acid esters [hexanoic (caproic), octanoic (caprylic), decanoic (capric), dodecanoic (lauric), tetradecanoic (myristic), hexadecanoic (palmitic), octadecanoic (stearic)] and polyglycerol (average number‐of degrees of polymerization of 5) with varying degrees of esterification and to examine their emulsifying properties. A number of fundamental catalysts of polyglycerol acylation reactions by methyl esters of carboxylic acid were studied, and sodium methoxide was found to be the best choice. The temperature rate of transesterification increased from 180 to 220 °C with the fatty acid chain alkyl residue. Synthesized mono‐, di‐, tri‐, tetra‐, and heptaesters of various fatty acids and polyglycerol provided the highest hydroxyl values from 15 to 815 mg KOH g^?1 and saponification values from 82 to 321 mg KOH g^?1. The emulsifying properties were assessed for all polyglycerol and fatty acid esters, with results showing maximum emulsifying effect for tri‐ and tetraesters of capric, lauric, and caprylic acids. Regardless of the hydrophilic–lipophilic balance value (HLB) of polyglycerol esters and carboxylic acid, a 4:1 ratio of sunflower oil to water formed a water‐in‐oil type emulsion. When mixing oil and water in a 1:1 ratio, mono‐ and diesters of polyglycerol formed an oil‐in‐water type emulsion, heptaesters formed a water‐in‐oil type emulsion, and tri‐ and tetraesters formed both of types of emulsions, depending on the length of the acid hydrocarbon radicals.     

Coalescence Behavior of Pure and Natural Fat Droplets Characterized via Micromanipulation

For two approaching oil droplets, a region of arrested coalescence lies between full coalescence and total stability. Here the fusion of two droplets begins, but they are stopped from fully relaxing into one spherical droplet. The internal rigidity of the solid fat network within each droplet can provide the resistance necessary to arrest the shape change driven by Laplace pressure. These intermediate doublet structures lead to the partially‐coalesced fat networks important for the desired physical properties of ice cream and whipped topping. The use of micromanipulation techniques allows coalescence events between two oil droplets to be microscopically observed. In this study, oil droplets composed of different fats were manipulated at varying elastic moduli, interfacial tension, and radii. It was seen that increasing the elastic moduli of the droplets or increasing droplet radii resulted in coalescence being arrested earlier. Under these experimental conditions, different interfacial tensions did not change the coalescence behavior between two oil droplets.     

A novel approach to prepare large-scale and narrow-dispersed latex particles by emulsion polymerization based on particle coagulation mechanism

In order to understand the mechanism of narrow particle size distribution of the final latex during particle coagulation, a series of experiments were performed to investigate the effect of polymer nature on particle coagulation capability. In particular, thermodynamics and kinetics in aqueous phase were considered to illustrate the detail process of particle coagulation. The final particle size decreased with the increasing side chain length of alkyl methacrylate from 181.5 nm in MMA to 131.6 nm in EMA, 119.3 nm in PMA, and 115.1 nm in BMA, indicating that the particle coagulation capability was proportional to the hydrophilicity of polymer. With increasing polymer hydrophilicity, the affinity between surfactant molecules and particle surface decreased, thus enhancing the particle coagulation capability. Moreover, the critical length of oligomer radical also increased with increasing hydrophilicity and the efficiency of radical capture decreased, thus increasing the saturation of monomer concentration in the inner part of particle, promoting particle coagulation. Combining these results and the La Mer Diagram, a novel approach was developed to prepare large-scale, narrow-dispersed, and high solid content polymer latex based on particle coagulation mechanism. Three criteria, namely, rapid nucleation, fast coagulation, and a long growth period, should be met to produce latex with a narrow particle size distribution.