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.