Evaluation of two gas chromatography-olfactometry methods: the detection frequency and perceived intensity method.

Two gas chromatography-olfactometry methods were evaluated in terms of repeatability, range of sensitivity and discriminating properties. Six volatile flavour compounds at various concentration levels were analysed by a panel of eight assessors using the detection frequency method and the perceived intensity method. The coefficient of variance, averaged over the individual compounds for three replicate samples, was 16% for the detection frequency method and 28% for the intensity method. The average correlation coefficient of the individual compounds with concentration was 0.93 (range 0.88-0.99) for the intensities. They were slightly higher than those for the detection frequencies (0.91, range 0.81-0.97). The detection frequency method was more accurate in terms of repeatability, and the intensity method was more accurate with regard to discrimination between concentration levels. The range of sensitivity was similar for both methods.