The use of electronic nose to differentiate entire males from immunocastrat es (association with levels of androstenone and skatole)

The aim of this work was to test the ability of the electronic nose (designed and fabricated by CNR-Institute for Microelectronics and Microsystems Rome, Italy) for the differentiation of subcutaneous fat samples from entire or immunocastrated pigs. Seven pigs immunocastrated with Improvac® (IC) and eight entire males (EM) from genotype Pietrain × (Large White × Landrace) were used. After the slaughter, samples of backfat were taken for the determination of androstenone and skatole concentrations. Thighs from experimental pigs (n = 30) were processed to dry-cured ham Kraški pršut. After the “riposo” phase, subcutaneous fat was sampled from thighs for the analysis with electronic nose. The device is based on eight gravimetric sensors (quartz crystal microbalances-QCMs) oscillating at 20 MHz of fundamental frequency and coated with a proper set of organic polymers and macromolecules. Principal Component Analysis (PCA) was used to discriminate IC and EM, based on the signal acquired with electronic nose. The first two components explained 93.5% of variance. The discrimination of EM from IC was good but not flawless, because four EM samples were false negative, but only one pig was false negative for both samples/repetitions. It can be concluded that the results are promising and that the tested electronic nose is able to discriminate fat samples of EM, however, due to the methodological uncertainties (sampling fat after “riposo”) results should be considered preliminary and further work is needed.