A b s t r a c t. The potential of electronic nose to distinguish of wheat seeds was studied. The reproducibility and practicability of electronic nose data was evaluated by repeating the analysis of samples with a time difference of two months. The principle components analysis and linear discriminant analysis were applied to the generated patterns to distinguish the varieties of wheat seeds. The results showed that they could distinguish the wheat varieties properly. The stepwise discriminant analysis and a three-layer backpropagation neural network were developed for pattern prediction models. The results showed that both models could identify the wheat varieties, the back-propagation neural network presented the higher percent of correct classifications in comparison to stepwise discriminant analysis. Moreover, gas chromatography mass spectrometry analysis of the headspaces of same samples confirmed that electronic nose as a powerful tool is able to identify the wheat seeds.K e y w o r d s: electronic nose, wheat seeds, identification, gas chromatography mass spectrometry
INTRODUCTIONThe usual methods for identification of wheat seeds are seed protein electrophoresis, DNA molecular markers techniques, morphological identification and field evaluation (Li et al., 2006). In most cases, these methods are expensive and time-consuming, have low reproducibility, both in their commercial as well as in their technological implications. Several attempts have been made recently to classify wheat varieties using nondestructive methods such as machine vision (Douik and Abdellaoui, 2008;, near infrared spectrometer (Li et al., 2008) and thermal imaging (Manickavasagan et al., 2010). Most of them used kernel morphological features of a single grain for variety identification. It would be highly desirable to have an alternative method for classification of wheat varieties, which may use some characteristics of the kernels other than morphological features. A simple variety identification system with less complexity for bulk sample testing (not single grain analysis) would be most desirable in the grain-handling facilities.Electronic nose (E-nose) is instrument which mimics the sense of smell. These devices are typically array of sensors used to detect and distinguish odours precisely in complex samples and at low cost (Peris and EscuderGilabert, 2009). In contrast to the well known analytical gas chromatography mass spectrometry (GC-MS) and sensory techniques that have been used for the analysis of flavour compounds, the E-nose does not give any information about the compounds causing the investigated aroma; neither about the identity of the compounds nor their sensorial properties. Using E-nose the aroma is judged by the so-called 'aroma pattern', which should be characteristic to the investigated substrate (O'Sullivan et al., 2003). With the use of appropriate mathematical methods, E-nose should be capable of recognizing the aroma pattern or of distinguishing it from aroma patterns of other samples (Peris and EscuderGilab...