HIGH-RESOLUTION GAS-CHROMATOGRAPHY SELECTIVE ODORANT MEASUREMENT BY MULTISENSOR ARRAY (HRGC SOMSA) - A USEFUL APPROACH TO STANDARDIZE MULTISENSOR ARRAYS FOR USE IN THE DETECTION OF KEY FOOD ODORANTS/

The typical odour of foods can be represented by a small part of its v olatile ingredients. In order to control food quality the monitoring o f these key food odorants is indispensable. In the case of butter the odour can be simulated by composing diacetyl, butanoic acid and delta- decalactone in appropriate composition. A sensory panel consisting of five persons evaluated a strong similarity of the recombinant to natur al butter. The off-odour of aged (rancid) butter is caused by an incre ased concentration of butanoic acid. In the experimental setup differe nt kinds of sensors were attached besides a flame ionisation detector (FID) at the port of a gas chromatograph (GC). The involved sensors we re different types of metal oxide semiconductors and a surface acousti c wave (SAW) device coated with poly(isobutylene). In different GC run s recombinants of fresh and rancid butter were analysed recording the FID signal and the signals of the different sensors. The quantities we re 0.35 ng diacetyl, 3.7 ng butanoic acid (rancid: 37 ng) and 4.9 ng d elta-decalactone in each GC run. The SAW sensor and a ZnO sensor at th e port of the GC respond with high signals to butanoic acid and delta- decalactone. Both sensors are insensitive to diacetyl. The differing r elative sensitivities allow discrimination of butanoic acid and delta- decalactone without GC-separation. The palladium doped ZnO sensor was sensitive to diacetyl. In contrast, the diacetyl peak of the FID was d ifficult to distinguish from the base-line. Using the HRGC/SOMSA, the characterisation of sensors can be done by replacing natural foodstuff samples with the described recombinants. (C) 1997 Elsevier Science S. A.