Emulsification properties

Y. Sela, S. Magdassi, and N. Garti Newly Designed Polysiloxane-Graft-Poly (Oxyethylene) Copolymeric Surfactants Preparation, Surface Activity and Emulsification Properties. Colloid Polym. Sci. 272, 684 (1994). 

Emulsification properties. Caseins and caseinates are commonly selected for food product applications that require surfactant properties, e.g., emulsification and foam stabilization, since they contain high protein contents of > 90 %, are highly soluble, and are resistant to heat-induced denaturatlon in products to be subjected to high temperature processing conditions (15). 

Emulsification properties in model food systems. Pearson et al. (25) investigated the emulsification properties of caseinate and NFDM in model emulsion systems produced by blending soybean oil into an aqueous buffer system as a function of pH and ionic strength (Figures 7 and 8). They found that caseinate exhibited good emulsification properties under all pH and ionic strength conditions studied, but was particularly effective at pH 10.4. 

The emulsification properties of NFDM were slightly better than for caseinate at all protein levels. However. NFDM exhibited lowest emulsification properties at pH 10.4 and highest emulsification at pH 5.6, which was directly opposite the results with caseinate. Thus, the molecular state of caseins, whether in the. micellar or soluble complex form is important in determining their functionality as an emulsifier. 

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. 

Figure 9. Emulsification properties of sodium caseinate in the absence of chemical emulsifiers (26)...

It is essential to consider the physico-chemical properties of each WPC and casein product in order to effectively evaluate their emulsification properties. Otherwise, results merely indicate the previous processing conditions rather than the inherent functional properties for these various products. Those processing treatments that promote protein denaturatlon, protein-protein Interaction via disulfide interchange, enzymatic modification and other basic alterations in the physico-chemical properties of the proteins will often result in protein products with unsatisfactory emulsification properties, since they would lack the ability to unfold at the emulsion interface and thus would be unable to function. It is recommended that those factors normally considered for production of protein products to be used in foam formation and foam stabilization be considered also, since both phenomena possess similar physico-chemical and functionality requirements (30,31). 

Peanut Seed. Ramanatham et al. (21) studied the influence of such variables as protein concentration, particle size, speed of mixing, pH, and presence of sodium chloride on emulsification properties of peanut flour (50% protein) and peanut protein isolate (90% protein). Emulsions were prepared by the blender... 

Sunflower Seed. Emulsion capacity of defatted sunflower meal was investigated by Huffman et al. (45) at three pH levels (5.2, 7.0, 10.8), blender speeds (4500, 6500, 9000 rpm), and oil addition rates (30, 45, 60 ml/min). With low mixing speeds and rapid rates of oil addition, optimum emulsion capacity occurred at pH 7.0. These authors related the observed emulsification properties to protein solubility, surface area and size of oil droplets, and rate of protein film formation. 

Table X. Emulsification properties of safflower protein isolates as influenced by pH and drying method.

Another area of interest is in the emulsification properties of gum acacia. The protein-rich fractions which are amphiphillic in nature are responsible for stabilization of oil-in-water emulsions by gum arabic. Immunoassays developed against these protein-rich fractions can be used to measure emulsification capability. This was tested out (148) using heated and unheated gum samples. The heated samples exhibit poor emulsification properties versus the unheated and ELISA was able to distinguish these two gums, indicating the viability of using IA for testing the emulsification properties of gum acacia. 

J. Al-Hakkak and S. Kavale, Improvement of emulsification properties of sodium caseinate by conjugating to pectin through the Maillard reaction, in G, 2002, 491—499. 

Since good solubility and emulsification properties at acidic pHs are required for some food applications such as acid soft drinks and acid foods,... 

McCrae, C.H., Law, A.J.R., and Leaver, J. 1999. Emulsification properties of whey proteins in their natural environment effect of whey protein concentration at 4 and 18% milk fat. Food Hydrocoil. 13, 389-399. 

Span surfactants are lipophilic and are generally soluble or dispersible in oil, forming water in oil emulsions. They are used for their excellent emulsification properties in personal care, industrial cleaning, fibre finish, crop protection, water treatment, paints and coatings, lubricant and other industrial applications. 

Little and Singleterry (7) have published an interesting study on micellization of surfactants in a variety of solvents. Their data show that the better the solvent is for the surfactant, the less tendency there is for the surfactant to form aggregates or micelles. Yet to be determined is the effect of this micellization on emulsification properties. 

Bnulsion Capacity. The most viscous emulsions of peanut meal with mayonnaise consistencies were produced from suspensions at pH 1.5 in water and 0.1 M NaCl, and by the water suspension adjusted from pH 6.7 to 4.0 to 8.2 (Figure 6). At pH 4.0, poor emulsifying properties were noted for all suspensions. The two-step pH adjustment from 6.7 to 4.0 to 6.7 improved emulsification properties of only the water suspension over those of samples where the pH was not adjusted or was minor. 

Encapsulant material Solubility Viscosity Stability to pH, salts, temperature, shear, enzyme degradation Film forming and emulsification properties Regulatory status for food application... 

Emulsification Properties of Crude Oils. Although impossible to predict with certainty which crude oil systems will easily emulsify to form stable 0/W emulsions, some general rules were observed to apply ... 

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