Effects of lecithins and proteins on the stability of emulsions

Abstract

Food consists of three components, carbohydrates, proteins and fats, which are linked by various types of chemical and physical bonds. The interactions at the interface of dispersions and emulsions are influenced by surface‐active emulsifiers such as lecithins. Synergistic effects on the emulsion stability can be obtained by selected protein‐lecithin combinations. Hydrocolloids enhance the stability by viscosity increase and gel formation. Lecithins are modified physically and enzymatically, giving a range of food grade emulsifiers with different hydrophilic‐lipophilic‐balance (HLB) values. The influence of phospholipid fractions in the homogenization process can be measured by the particle size distribution technique (PSD) and emulsifying tests, which assess the emulsion stability. Basic studies on the interactions of surface‐active proteins and lecithins in emulsions are reviewed. The principles of combined use of proteins and lecithins are presented for processed foods such as mayonnaise, margarine, instant milk powders, fat reduced cookies, and chocolate coatings for ice cream dipping. A new challenge for the food industry is the liposome encapsulation technique. Liposomes are produced with phosphatidylcholine fractions to encapsulate water and oil soluble components, such as flavours, in one capsule.

Influence of soybean protein isolates‐phosphatidycholine interaction on the stability on oil‐in‐water emulsions

“…When the amount of PC increased, the BS% evolved in the same way. A diminution of D [3,2] of the particles with the addition of PC in the initial emulsion could not be observed ( Table 1). The effect of PC on creaming kinetics and particle density of the creamed phase could be related to an increase in the interfacial charge, which would protect the emulsion against the flocculation process (11).…”

“…The effect of PC on creaming kinetics and particle density of the creamed phase could be related to an increase in the interfacial charge, which would protect the emulsion against the flocculation process (11). Nevertheless, an increase was observed in oil droplet size in the creamed phase, compared to the initial stage, for the NSI control and NSI/PC systems: D [3,2] = 23.5 and 17-19 µm, respectively. These results suggest that the presence of the phospholipid can bring about a partial control of coalescence.…”

“…Oil droplet size distribution was determined by volume. Sauter mean diameter, D [3,2], was calculated as follows: [1] where V i = relative volume in class i, d i = mean class diameter, m = 3, and n = 2. Figure 1A shows the ∆BS profiles corresponding to the PC control system of an O/W emulsion obtained by the addition of only PC corresponding to a 25:1 buffer/PC ratio.…”

“…D [3,2] (µm) Sample D [3,2] to the evolution of the creaming process and the creamed phase (Fig. 5B).…”

“…Also, they have interesting surface properties that enable them to achieve emulsion stability in different products (1). Interactions between proteins and phospholipids may lead to changes in surface activity, modifications of protein structure, and incorporation of protein into surfactant micelles and vesicles (2).…”