Emulsifier milk proteins

Ice-cream is a product which has been developed since mechanical refrigeration became available. Ice-cream mixes comprise fats (not always dairy), milk protein, sugar and additives such as emulsifiers, stabilizers, colourings, together with extra items such as fruit, nuts, pieces of chocolate, etc., according to the particular type and flavour. The presence of this mixture of constituents means that the freezing... 

Polysorbate 80 is an emulsifying agent that is often used in ice cream to prevent milk proteins from completely coating the fat droplets. This allows them to join together in chains and nets, to hold air in the mixture, and to provide a firmer texture that holds its shape as the ice cream melts. 

Reconstituted milks with natural milk fat globules (CREAM) or emulsified milk fat droplets stabilized by jS-casein (BCAS), /i-lactoglobulin 5g/L (BLG5), skim milk proteins (MP). 

Leman, I, Kinsella, J.E. (1989). Surface activity, film formation, and emulsifying properties of milk proteins. Critical Reviews in Food Science and Nutrition, 28, 115-138. 

Cornec, M., Wilde, P.J., Gunning, P.A., Mackie, A.R., Husband, F.A., Parker, M.L., Clark, D.C. (1998). Emulsion stability as affected by competitive adsorption between an oil-soluble emulsifier and milk proteins at the interface. Journal of Food Science, 63, 39 13. 

Milk protein products. As indicated in Table 1, the food industry is placing major emphasis on the production and utilization of milk protein products in a wide variety of formulated food products (20,21,22). Although nonfat dry milk (NFDM) and whey powder are major milk protein ingredients in formulated foods, casein and whey protein concentrates, which contain their proteins in a more highly concentrated and functional form, are essential for certain food product applications, such as those products that require the proteins as an emulsifier agent. Additional details on the processing methods and conditions used to produce the various milk protein products are available (23). 

Whey protein concentrates (WPC), which are relatively new forms of milk protein products available for emulsification uses, have also been studied (4,28,29). WPC products prepared by gel filtration, ultrafiltration, metaphosphate precipitation and carboxymethyl cellulose precipitation all exhibited inferior emulsification properties compared to caseinate, both in model systems and in a simulated whipped topping formulation (2. However, additional work is proceeding on this topic and it is expected that WPC will be found to be capable of providing reasonable functionality in the emulsification area, especially if proper processing conditions are followed to minimize protein denaturation during their production. Such adverse effects on the functionality of WPC are undoubtedly due to their Irreversible interaction during heating processes which impair their ability to dissociate and unfold at the emulsion interface in order to function as an emulsifier (22). 

The following factors appear to control the emulsification properties of milk proteins in food product applications 1) the physico-chemical state of the proteins as influenced by pH, Ca and other polyvalent ions, denaturation, aggregation, enzyme modification, and conditions used to produce the emulsion 2) composition and processing conditions with respect to lipid-protein ratio, chemical emulsifiers, physical state of the fat phase, ionic activities, pH, and viscosity of the dispersion phase surrounding the fat globules and 3) the sequence and process for incorporating the respective components of the emulsion and for forming the emulsion. 

Interfacial tension analysis may be used to study the interaction of emulsifiers and milk protein at the oil-water interface of whippable emulsions. The interfacial activity of proteins is affected only slightly by temperature changes. In general, emulsifiers can reduce interfacial tension much more than protein, and this effect is especially pronounced at low temperatures. 

Interfacial tension studies in relation to ice cream were also carried out using model two-phase systems similar to those mentioned above in connection with whipped toppings9. These studies were carried out to analyze the interplay of emulsifiers and milk proteins at the oil-water interface. 

When both skimmed milk proteins and emulsifiers are present, a mixed film of both types of surface active species forms at 40°C (Figure 18). When cooled, the emulsifier... 

Increased fat and increased protein content in the mix delay adsorption of emulsifiers to air. Low temperature also has an inhibiting effect on this phenomenon. Surface tension analysis may be used to measure dosage effect in low-fat ice cream mixes. Such studies show that on a weight basis emulsifier is bound 10 times more strongly to fat than to milk protein in the mix49. 

EMULSIFYING ACTIVITY AND STABILITY OF NATIVE AND ESTERIFIED MILK PROTEINS MEASURED BY OIL DROPLET DIAMETER, DIRECTLY AFTER EMULSIFICATION OR AFTER A TWO-WEEK STORAGE AT 4 °C USING 4 MG/ML PROTEIN CONTENT AND 15% SUNFLOWER OIL... 

Sitohy, M., Chobert, J.-M., and Haertle, T. 2001c. Improvement of solubility and of emulsifying properties of milk proteins at acid pHs by esterification. Nahmng 45, 87-93. 

The sugar confectionery system that most commonly relies on emulsifiers is toffee. A typical toffee has a continuous phase of a high solids sugar syrup with milk proteins present. The disperse phase may be all milk fat, a mixture of vegetable fat and milk fat, or purely vegetable fat. The interface between the two phases is likely to be formed of some of the milk protein and any added emulsifier. 

Milk protein acts as an oU-in-water emulsifier. Consequently, the use of milk, casein, or caseinates can result in a phase reversion. Therefore, most spread formulations are mdk and milk-protein free. 

Mellorine is similar to ice cream, but contains at least 6% of fat other than milk fat (usually vegetable oil). Milk protein is, again, the major emulsifier, but 0.1% of polysorbates 65 and/or 80 may also be used. 

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