Real in-mouth analysis of flavor.

Analysis techniques have been developed that model in-mouth flavor release. In addition, scientists have been able to directly analyze volatiles in the air expired through the nose and the mouth. They've confirmed that the volatile profile changes over time. Despite a significant increase in understanding, we still don't know how various flavor compounds combine to produce a specific flavor that a consumer experiences. Thus, it's difficult to predict product flavors accurately.

Because it is difficult to determine flavors in the mouth, researchers have attempted to simulate some of the mouth processes in model systems that control temperature, shear rate or hydration. Research groups have developed such systems as a retronasal aroma simulator that shears food to simulate eating as well as a plunger system that imparts shear to food by screw action and adds artificial saliva to food to simulate hydration.

These systems provide data on the effects of hydration on volatile release, but they don't always accurately reflect what happens in the mouth. Some research teams have trapped volatiles from breath samples to concentrate them before further analysis. Trapping methods have entailed using low temperatures or adsorbing polymers. Scientists found that volatiles are released at different rates during eating. It is possible to draw time-release curves for specific compounds. This may make it possible to compare volatile time-release curves with sensory time-intensity curves.

But trapping methods are time-consuming, and it may take several weeks to gather enough data to plot a single volatile-release profile. Scientists at the University of Nottingham (Department of Applied Biochemistry and Food Science, Sutton Bonington Campus, Loughborough LE12 5RD, England, U.K.) have used atmospheric pressure ionization to track the real-time release of volatiles from consumers as they eat.

It is possible to follow the release of several compounds simultaneously. The response time is quick enough to analyze breath-by-breath release from the nose. The ability to measure the volatile profile in the nose during eating and compare it with time-intensity data is a powerful technique that's still under development. But eventually this approach should enable investigators to better their understanding of the relationships between specific compounds and the overall sensory perception of food flavor.

Further information. A.J. Taylor; fax: [phone]; email: [e-mail].