P36 Use of n‐butanol as an odourant to standardize the organoleptic scale of breath odour judges

Abstract

The alcohol n‐butanol has been recommended for use as a standard odorant by various groups for the training or standardization of breath odor judges and sensory evaluation panels.Objective To assess the use of n‐butanol as a suitable odorant for use in organoleptic training of breath judges.Methods One judge with full smell acuity was trained in the method of organoleptic assessment using odorant solutions of all chemical classes (acids, amines, indole, sulphides) with the exception of alcohols. The subject was proficient in scoring odorant solutions, standard gas mixtures and human breath using the Rosenberg 0–5 organoleptic scale. The judge had gained over 5 years experience of assessment and for the purposes of this work was considered to be the gold standard. A wide range of n‐butanol solutions were prepared from 0 up to 90 000 ppm and dispensed as replicate 12 ml volumes in Universal bottles (24 ml) leaving a headspace of 12 ml. Sets of odorants were prepared, labelled by code, randomised and presented to the judge in a completely blind fashion. The judge scored each concentration. This process was repeated on 32 occasions over a period of 12 weeks. Means of data for each determination for each concentration series were plotted against the log concentrations of odorant. Linear regression slope analysis was used to measure slope, the 95% CI of slope and the scatter of points (R2 value). Head space concentrations of odorant were determined using GC analysis.Results The n‐butanol regression slope gave a high R2 value (0.971) and low scatter. However, the data did not correspond to that of other workers using an ASTM method where the range of recommended butanol concentrations was insufficient at the high end to determine the top of the organoleptic scale and insufficient at the low end to determine threshold. Moreover, headspace analysis using GC confirmed the published gas concentrations to be in error by a factor of 10. It was also observed that high concentrations of odourants were irritant causing desensitization if used for prolonged periods.Conclusion A previously described method had erroneous headspace calculations listed and n‐butanol could not be recommended as a training odorant because of its irritancy.