Emulsifier HLB

Fig. 1. Effect of system components on emulsifier HLB. (------), fat—caseiaate-salts-water—emulsifier (—), fat—water—emulsifier (4).

An optimization of the procedure requires a thorough investigation of the numerous parameters (temperature, nature and number of conqx>nents, emulsifier HLB, pH, ionic strength and stirrer speed) involved in the formulation. Because of... 

A lipophilic emulsifier (HLB about 4). Forms an L2 phase with water... 

A hydrophilic emulsifier (HLB typically about 12-16). Forms micellar solutions An intermediate emulsifier (HLB estimated as about 8)... 

This dimensionless scale ranges from 0 to 20 a low HLB (<9) refers to a lipophilic smfactant (oil soluble) and a high HLB (> 11) to a hydrophilic (water soluble) surfactant. In general, W/O emulsifiers exhibit HLB values in the range 3-8 while O/W emulsifiers have HLB values of about 8-18. There exist empirical tables of HLB values required to make emulsions out of various materials [44] and tables and equations to determine emulsifier HLB values [10,44,46]. If the value is not known, then a series of lab emulsification tests are required, using a series of emulsifying agents of known HLB values. 

Given that most of antioxidants bear -OH groups in their chemical structures, the distribution of antioxidants is expected to depend on a number of parameters including its chemical structure, HLB, the acidity of the solution, temperature, etc. The effects of these and other parameters such as oil polarity, emulsifier HLB, etc. on antioxidant distributions are being investigated and will be part of future communications. 

Edible oils and fats, flavor oils (orange, cinnamon, lemon, etc.) Edible emulsifiers (HLB = 13-16) Ethylene glycol, propylene glycol, glycerol, sugar alcohols, etc. 29... 

The phase-inversion temperature (PIT) is defined as the temperature where, on heating, an oil—water—emulsifier mixture inverts from O/W to a W/O emulsion [23]. The PIT correlates very well with the HLB as illustrated in Fig. XIV-10 [72, 73]. The PIT can thus be used as a guide in emulsifier selection. 

Emulsifiers are classified by the hydrophilic—lipophilic balance (HLB) system. This system indicates whether an emulsifier is more soluble in water or oil, and for which type of emulsion (water-in-oil or oil-in-water) it is best suited. Emulsifiers having alow HLB value are more oil soluble, and are better suited for water-in-oil appHcations such as margarine. Conversely, emulsifiers having a high HLB value are more water soluble, and function more effectively in oil-in-water emulsions such as ice cream (34). The use of this system is somewhat limited because the properties of emulsifiers are modified by the presence of other ingredients and different combinations of emulsifiers are needed to achieve a desired effect. The HLB values of some common emulsifiers are given (35). 

The hydrophile—hpophile balance (HLB) is an empirical system based on the fact that oil—water (o/w) emulsions are best stabilized by water-soluble-emulsifiers and water—oil (w/o) emulsions are best stabilized by oil-soluble ones (3). The HLB scale mns from 0—20 and is based on the ratio of the saponification number of ester, A, to the acid number of recovered acid, where HLB = 20 1-Sj A). The dispersibiUty of an emulsifier in water is related to HLB value. 

Table 3 gives HLB values of some of the important emulsifiers. The HLB optimum for a given emulsifier varies with the components of the food system. A coconut oil—water emulsion that shows optimum stabiUty with an HLB of 7—9 shows a shift ia requirements for stabiUty upon addition of caseia and electrolytes to an optimum stabiUty usiag an emulsifier having an HLB of 3—5. In addition, the stabiUty of an emulsion can be affected by the chemical nature of the emulsifier. The optimum HLB for an emulsifier ia a given system is iafluenced by the other iagredients as is illustrated for a model synthetic milk system ia Figures 1 and 2. 

At low temperature, nonionic surfactants are water-soluble but at high temperatures the surfactant s solubUity in water is extremely smaU. At some intermediate temperature, the hydrophile—Hpophile balance (HLB) temperature (24) or the phase inversion temperature (PIT) (22), a third isotropic Hquid phase (25), appears between the oil and the water (Fig. 11). The emulsification is done at this temperature and the emulsifier is selected in the foUowing manner. Equal amounts of the oil and the aqueous phases with aU the components of the formulation pre-added are mixed with 4% of the emulsifiers to be tested in a series of samples. For the case of an o/w emulsion, the samples are left thermostated at 55°C to separate. The emulsifiers giving separation into three layers are then used for emulsification in order to find which one gives the most stable emulsion. 

The polymeric latex obtained in a hydrophobic organic solvent is poorly dispersed in water because of the presence of an emulsifier with a low HLB value. For this reason, a wetting agent is added to water or emulsion prior to the dissolution. The wetting agent (a surface active substance with a high HLB value) facilitates the inversion of latex phases to produce a direct type emulsion. Usually, it belongs to oxyethylated alkylphenols, fatty alcohols, or fatty acids. 

One of the most important characteristics of the emulsifier is its CMC, which is defined as the critical concentration value below which no micelle formation occurs. The critical micelle concentration of an emulsifier is determined by the structure and the number of hydrophilic and hydrophobic groups included in the emulsifier molecule. The hydrophile-lipophile balance (HLB) number is a good criterion for the selection of proper emulsifier. The HLB scale was developed by W. C. Griffin [46,47]. Based on his approach, the HLB number of an emulsifier can be calculated by dividing... 

Oily surfaces can be deoiled by using a high HLB value emulsifier such as dioctylsulfosuccinate, together with antifoam, applied either as a hot-water soak or pressure washed. 

The performance of secondary alkanesulfonates in applications as emulsifiers in the widespread emulsion polymerization of vinyl monomers can be assessed by their hydrophilic-lipophilic balance (HLB) numbers. The HLB numbers can... 

Formation of emulsions of the oil-in-water or water-in-oil type depends mainly on the hydrophilic-lipophilic balance (HLB) of the emulsifier. Phosphate esters with their various molecular structures can be adjusted to nearly every HLB value desired. Therefore they are able to meet nearly all of demands in this field. 

Griffin studied primarily ethylene oxide (EO) adducts and routinely substituted % EO for % hydrophile. Since that time, the HLB system has become very popular, especially to characterize emulsifying agents. (The reader is referred to sec. V.B. for a more detailed discussion of the use of the HLB system for the identification of adequate emulsifiers and combinations thereof.)... 

HLB value of the oil phase. Further tests can then be carried out with different chemical types of agents around this effective HLB value in order to find the optimum emulsifying system. 

The HLB system - a time-saving guide to emulsifier selection, Publication 103-3 10M (Wilmington ICI Americas,... 

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