Non-protein-stabilized emulsions

Some products, such as butter and margarine, are stabilized by fat crystals. Salad dressings and beverage emulsions are stabilized by other emulsifiers. 

The stability of non-protein-stabilized food emulsions, involving lower molar mass-type molecules tends to be better described by the DLVO theory than are protein-stabilized emulsions. An example of an O/W emulsifier whose emulsions are fairly well described by DLVO theory is sodium stearoyl lactylate [12]. 

The added emulsifiers not only influence stability but also reduce interfacial tension and influence drop-size distribution, hence influencing the creaminess of the product [29]. They can also modify the extent and type of fat crystallization [50]. Mixed gels have also been used [50]. fl-Carotene is often added to produce a yellow colour and provide vitamin A. By varying the amounts of components such as vegetable oils, animal fats and milk fat, a wide range of variations have come into use. Some examples of these spreadable fats include butter, margarine, low-fat spread, vegetable-fat spread, butterfat spread, low-calorie spread, yellow-fat spread, water-continuous spread and so on [50]. The reduced-fat and low-fat spreads tend to have fat contents of 10-79%. Flack [50] provides an illustration of a process plant layout for the manufacture of spreadable fats. 

Flavour microemulsions are used in clear products such as clear mouthwashes and clear beverages [54]. 

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It should be noted that the composition of milk protein-stabilized emulsions can change substantially after homogenization due to exchange of adsorbed emulsifiers with non-adsorbed emulsifiers. For this reason, a number of workers have studied preferential adsorption and competitive displacement of milk proteins with each other and with other types of emulsifiers [27,32,52-58]. 

Demetriades, K. and McClements, D.J. (1998) Influence of pH and heating on the physicochemical properties of whey protein stabilized emulsions containing a non-ioific surfactant. /. Agria Food Chem., 46, 3936-3942. 

Incorporation of non-meat ingredients, such as gums or proteins, into processed meats has been shown to stabilize emulsions and increase fat and... 

Radford, S.J., Dickinson, E. (2004). Depletion flocculation of caseinate-stabilized emulsions what is the optimum size of the non-adsorbed protein nano-particles Colloids and Surfaces A Physicochemical and Engineering Aspects, 238, 71-81. ... 

Das, K.P. and Kinsella, J.E. 1990. Stability of food emulsions physicochemical role of protein and non-protein emulsions. Adv. Food Nutr. Res. 34, 81-201. 

Thickeners, high molecular weight molecules soluble in the continuous phase, enhance its viscosity. They stabilize emulsions by slowing the droplet mobility. Flocculation, sedimentation or creaming and coalescence are either slowed or completely inhibited. Typical thickeners are (modified) starches and proteins for foods or glycerine or polyethylene oxides in non-food products. 

Kerstens S, Murray BS, Dickinson E. 2006. Microstructure of P-lactoglobulin-stabilized emulsions containing non-ionic surfactant and excess free protein Infiuence of heating. J Colloid Interface Sci 296 332-341. 

Non-sulfonated lignins find utility as emulsifiers and stabilizers in water-based asphalt emulsions, as coreactants in phenolic binder applications, as negative plate expanders in lead acid storage batteries, as protein coagulants in fat rendering, and as flocculants in waste water systems. 

Non-dairy creams (cream alternatives) are O/W emulsions stabilized by milk proteins. A relatively thick adsorption layer provides stability, mostly by steric stabilization and partly by electrostatic stabilization [829]. Figure 13.3 shows an example of a soybean-oil and milk-protein emulsion stabilized by fat globules and protein membranes. Stabilizers, such as hydrocolloid polysaccharides, are added to increase the continuous phase viscosity and reduce the extent of creaming. They must be stable enough to have a useful shelf-life but de-stabilize in a specific way when they are... 

The adsorption of proteins at interfaces is a key step in the stabilization of numerous food and non-food foams and emulsions. Our goal is to improve our understanding of the relationships between the sequence of proteins and their surface properties. A theoretical approach has been developed to model the structure and properties of protein adsorption layers using the analogy between proteins and multiblock copolymers. This model seems to be particularly well suited to /5-casein. However, the exponent relating surface pressure to surface concentration is indicative of a polymer structure intermediate between that of a two-dimensional excluded volume chain and a partially collapsed chain. For the protein structure, this would correspond to attractive interactions between some amino acids (hydrogen bonds, for instance). To test this possibility, guanidine hydrochloride was added to the buffer. A transition in the structure and properties of the layer is noticed for a 1.5 molar concentration of the denaturant. Beyond the transition, the properties of the layer are those of a two-dimensional excluded volume chain, a situation expected when there are no attractive interac-... 

The adsorption of proteins at fluid interfaces is a key step in the stabilization of numerous food and non-food foams and emulsions.1 Our general goal is to relate the amino acid sequence of proteins to their surface properties, e. g. to the equation of state or other structural and thermodynamic properties. To improve this understanding, the effect of guanidine hydrochloride (Gu HC1) on /1-casein adsorption is evaluated in the framework of the block-copolymer model for the adsorption of this protein. At first the main features of the model are presented, and then the effect of Gu HC1 is interpreted using the previously introduced concepts. 

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