Investigate the interfacial behavior of proteins.

In many food processing plants, liquid and semi-liquid foods are pumped through heat exchangers to undergo pasteurization and sterilization, or they move through various piping systems and are eventually filled into cartons, cans or bottles. This type of processing creates deposits or fouling at various critical points in equipment, such as in pumps, valves and bends.

Monitoring hygiene at critical points in food processing equipment and cleaning these systems at the appropriate time reduces the chance that loose pieces of fouling film would drop into the product and impair its quality. Bacteria can cause a product's color, texture, flavor and shelf life to deteriorate. It also can prove hazardous for the consumer. Canadian researchers at Acadia University (Department of Chemistry, Wolfville, Nova Scotia B0P 1X0, Canada) are performing an electrochemical investigation of the surface charge on proteins, which involves protein behavior at interfaces. This research should provide the practical knowledge needed for an improved understanding of the processes involved in the formation of milk stone on the metal surfaces of dairy processing equipment.

Investigators have developed a way to monitor surface adsorption. They've also optimized conditions for removing adsorbed protein, suggesting a possible treatment for the fouling of the surfaces of heat exchangers and ultrafiltration membranes. This is important when you consider that sintered stainless steel membranes are used to process juice.

Studies of the metal-liquid interface are important when trying to understand surface fouling by proteins. This research also might be applied to understanding the behavior of proteins in the formation and stabilization of emulsions and foams in different food systems.

Initial investigations of the electrochemical adsorption properties of bovine b-lactoglobulin, k-casein, hen egg white lysozyme and bovine pancreatic ribonuclease have shown the materials to be very sensitive to changes in pH and temperature. This may be caused by structural changes of the proteins during denaturation. Research has been extended to cover surface fouling by measuring milk proteins, as well as unpasteurized milk. Scientists also are examining protein-phospholipid and protein-polysaccharide interactions important in emulsion stabilization.

To combat the fouling problem in another way, researchers in Europe have been developing sensors capable of detecting fouling films on the internal, and therefore hidden, surfaces of food processing equipment. The sensor techniques under investigation include ultrasonics, optical image analysis and vibrational analysis. They appear suitable for measuring fouling. Using these sensors, scientists have been able to measure fouling film thickness to a maximum of 2 mm.

The ultrasonic sensor is being used for measurements in pipelines, the vibration sensor for inside plate heat exchangers, and the optical sensor for transmitting images from points in equipment that are difficult to assess. Scientists are producing bacterial and gross soils on equipment surfaces in order to evaluate the sensors. They are investigating the production of prototype sensors and cleaning devices. Further information. On protein behavior: Sharon Roscoe; phone: [phone]; fax: [phone]. On sensors: H.O. Mikkelsen, Biotechnological Institute, Holbergsvej 10, PO Box 818, DK-6000 Kolding, Denmark; phone: [phone]; fax: [phone].