Olfative Sensor Systems for the Wine-Producing Industry

The quality of wine is influenced by different sensory characteristics. The most important is aroma. This attribute has a 70% weight in sensory panels with respect to texture and taste. Usually, the determination of volatile compounds is carried out through expensive techniques such as gas chromatography-mass spectrometry (GC-MS) which require complicated extraction methods and in addition are very expensive. The most important drawback, however is that these techniques are not able to measure in real time and in an on-line process. Olfative sensor systems (electronic noses) technology has emerged as a possibility for aroma profile analysis. The electronic nose consists of an array of gas sensors with different selectivity, a signal collecting unit, and a pattern recognition software (PCA, ANNs, etc). Different types of sensors have been used to detect wine aroma, such as electrochemical sensors, resistive sensors (mainly type MOS), and gravimetric sensors (type SAW) allowing for the distinguishing of wines elaborated with diverse grape varieties and ageing processes. It has also been possible to determine the detection and recognition threshold values of typical compounds of the wine and to compare them with the values obtained by a sensory panel, as well as to discriminate defects in order to detect adulterations or to identify ageing times and barrel type in order to avoid frauds. Portable systems are being developed for measuring in situ the wine evolution process, which is of great interest to the wine-producing industry.