Discrimination of fresh-cut broccoli freshness by volatiles using electronic nose and gas chromatography-mass spectrometry

This work was aimed to monitor the freshness of fresh-cut broccoli during refrigerated storage using electronic nose (e-nose) and solid phase microextraction (SPME) combined with gas chromatography-mass spectrometry (GC–MS). Traditional quality indices such as mass loss, chlorophyll content, aerobic plate count, sensory evaluation, malondialdehyde content and membrane permeability were also measured and the result of canonical discriminant analysis (CDA) can distinguish between fresh (on 0∼3 d), medium fresh (on 6∼9 d), and spoiled samples (on 12∼15 d). A total of 43 volatiles (including hydrocarbons, alcohols, esters, ethers, aldehydes, ketones, sulfur compounds and sulfur nitrogen compounds) were detected in broccoli samples using GC–MS analysis. Significant accumulation of sulfur compounds like dimethyl disulfide was observed as storage time increased. Both principal components analysis (PCA), hierarchical cluster analysis (HCA) and CDA on e-nose data could discriminate freshness of fresh-cut broccoli. The result of e-nose analysis was in good agreement with that of GC–MS analysis. This study suggested that e-nose has potential for applying as a rapid technique to determine freshness of fresh-cut vegetables.