Detection of Volatiles in Dark Chocolate Flavored with Orange Essential Oil by Electronic Nose

The aim of this study was the application of the electronic nose for detection of volatile release from dark chocolate flavored with orange essential oil during the storage. The detection of volatile in chocolate without and with different concentrations of orange oil (0–10 ppm) was performed using polyaniline (Pani) gas sensor array with different dopants. Orange oil and chocolate were analyzed in relation to water activity, moisture, and acidity. The chocolate maintained unchanged the water activity; however, the moisture and acidity presented alterations during the storage. It was verified a decrease in resistance response of the sensor array with the chocolate during the storage time. The sensor doped with TSA (toluenesulfonic acid) presented the higher sensitivity of the array. Principal component analysis (PCA) revealed five distinct groups corresponding to the volatiles released during the storage time (0, 20, 40, 60, and 100 days). This work demonstrates that the electronic nose technology with Pani gas-sensing array can be effective and successfully applied to discriminate different concentrations of orange essential oil during the dark chocolate storage.