Detection of adulteration in freshly squeezed orange juice by electronic nose and infrared spectroscopy

Abstract

The use of electronic nose and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) as rapid tools for detection of orange juice adulteration has been preliminarily investigated and compared. Freshly squeezed orange juices were tentatively adulterated with 100% concentrated orange juices at levels ranging from 0% to 30% (v/v). Then the E-nose response signals and FTIR spectra collected from samples were subjected to multivariate analysis by principal component analysis (PCA) and linear discriminant analysis (LDA). PCA indicated that authentic juices and adulterated ones could be approximately separated. For the classification of samples with different adulteration levels, the overall accuracy obtained by LDA in prediction was 91.7 and 87.5% for E-nose and ATR-FTIR, respectively. Gas chromatography-mass spectrometry (GC-MS) results verified that there existed an obvious holistic difference in flavour characteristics between fresh squeezed and concentrated juices. These results demonstrated that both E-nose and FTIR might be used as rapid screening techniques for the detection of this type of juice adulteration.

Keywords

• chemometrics
• discrimination
• spectral analysis
• volatile compounds