Emulsifiers: Going to the next level.

Atomic force microscopy (AFM) is taking emulsifier research to the molecular level. Molecular-level images of protein globules and polysaccharide chains and their reaction products are revealing detailed information about these compounds.

Working with the Canterbury University Engineering Department and Industrial Research Ltd., scientists at New Zealand's Crop and Food Research have used AFM to examine the cross-linking of carbohydrates and proteins. The researchers hope AFM will help them understand the mode of linkage between proteins and polysaccharides. This knowledge can help in developing emulsifiers with improved emulsification activity and stability. Because of their unique molecular structure, emulsifiers have many diverse functions that can improve the quality of a variety of food products. Starch complexing is possibly the most widespread application of emulsifiers. They also can be used in stabilizing foams, for aeration applications and as release agents.

The atomic force microscope is one of about two dozen types of scanned-proximity probe microscopes. All of these microscopes work by measuring a local property, such as height, optical absorption, or magnetism, with a probe or "tip" placed very close to the sample. The small separation between the probe and the sample, on the order of the instrument's resolution, makes it possible to take measurements over a small area. To acquire an image, the microscope raster-scans the probe over the sample while measuring the property it is targeting. The resulting image resembles an image on a television screen, consisting of many rows or lines of information placed one above the other. Unlike traditional microscopes, scanned-probe systems do not use lenses, so the size of the probe, rather than diffraction effects, generally limits their resolution.

With information from AFM, researchers are aiming to develop emulsifiers with enhanced functionality and which are more appealing to consumers. Many emulsifiers on the market are fatty acid derivatives. But they also can be made from proteins and carbohydrates. Researchers want to develop a novel emulsifier by crosslinking polysaccharides and proteins. Emulsifiers are in use in many products such as ice cream, mayonnaise and yogurt, where fine particles of one substance are dispersed within another.

Further information. Jafar al-Hakkak, Crop and Food Research, Food and Biomaterials Innovation, Private Bag 4704, Christchurch, New Zealand; phone: [phone]; fax: [phone]; email: [e-mail].