SGMS Meeting 2001: Plenary Lecture

APCI-MS for rapid and dynamic measurement of flavour release

Andy Taylor
Division of Food Sciences, University of Nottingham, Sutton Bonington Campus, Loughborough LE12 5RD, UK

Flavour analysis has been conventionally achieved by extraction of flavours from foods followed by GC-MS using EI and/or CI sources. These techniques have led to the identification of many of the flavour components in food, especially when coupled with GC-Odour Port Analysis. However, it has proved difficult to relate the flavour composition of a food with the perceived flavour characteristics. One reason is that flavour release during eating of food affects the relative amounts of flavour (and their rate of delivery) to the olfactory and gustatory receptors. What is needed is a method for sampling air from the noses of people eating food to measure the release profile under in vivo conditions.

Of the methods available, Atmospheric Pressure Ionisation methods are particularly suitable as they tolerate water and make interfacing between humans and the MS simple. However, API needs close control to achieve quantitative, reproducible ionisation. In our lab we developed an API interface where the sample flow rate, water content and ionisation parameters were optimised to achieve reproducible results over a fairly wide range. Potential problems like ion suppression have been studied and some solutions found. Sensitivity is around 10ppbv (nL volatile/L air) which allows many aroma compounds to be measured below, or close to their odour threshold. The limitations seem to be the ionisation efficiency of individual compounds and the amount of chemical noise in the system.

The MS issues will be presented and discussed along with examples of applications which show the potential of this technique for measuring flavour release in a variety of situations.