What can nature offer from an emulsifier point of view: trends and progress?

The most complex emulsions are those of foods and, therefore, are difficult to stabilize. An infinite number of microstructures of combinations of pro teins, carbohydrates, fats and lipids are present in food systems. There is an increasing awareness of many investigators to the relevance of the prin ciples of colloid and surface science to many of the technological problems related to advanced foods. Amphiphilic molecules play a key role in the st abilization of many of the food colloids. It is, therefore, very important to understand the interfacial behaviour of these molecules and to select th e proper ones for the proper activity. Synthetic surfactants and emulsifier s are widely used in many of our foods, but, it becomes very important to r eplace them by natural molecules with good health records. The following re view discusses the main natural ocurring molecules that are in use today an d the future trends in this area. Monomeric emulsifiers such as mono and mo no-diglycerides, lecithins and lysolecithins are still key players. Glycoli pids are present only in very minor concentrations in plants and animals an d therefore are not commercially available. Saponins are a very interesting group of materials with increasing potential. The polymeric amphiphilic co mpounds are "native" and enzymatically modified proteins. However, in situ products chemically modified by a Maillard reaction can also be used as emu lsifiers. The most interesting new emulsifiers are some selected hydrocolloids that e xhibit surface properties and emulsification capabilities. Enzymatically mo dified hydrocolloids show significant promise. Biosurfactants have also bee n studied and considered as emulsifiers, but are not food grade products. N ew trends and progress will also be discussed. (C) 1999 Elsevier Science B. V. All rights reserved.