基于电子鼻检测鸭梨新鲜度及损伤程度

目的 探究鸭梨果实流通过程中新鲜度变化及损伤程度。方法 以不同跌落角度处理（0°、20°、40°、60°）的鸭梨为试材，测定鸭梨果实呼吸速率、乙烯释放速率的变化，同时利用电子鼻结合主成分分析（principal components analysis，PCA）、线性判别分析（linear discriminant analysis，LDA）和载荷分析（loading analysis，LA）研究不同贮藏时间和不同损伤程度下果实的挥发性气体变化。结果 完好果实在贮藏4 d时出现呼吸高峰和乙烯释放高峰；与完好果实相比，机械伤处理提高了呼吸速率和乙烯释放速率，并且损伤越严重，变化趋势越明显。电子鼻的10个传感器对不同贮藏期和损伤程度的响应值有显著性差异(P<0.05)。LDA可明显区分不同贮藏点和不同损伤程度鸭梨挥发性气体。LA表明果实成熟和受损时，传感器W1S、W5S、W1W、W2W、W2S的响应值变化较为明显，意味着刺激了甲烷、氮氧化合物、硫化物和萜烯类、有机硫化物和芳香族化合物、醇类和部分芳香族化合物类物质的生成。结论 传感器W1S、W5S、W1W、W2W、W2S可反映鸭梨的挥发性气体变化情况，其中W2S传感器响应值可区分果实损伤程度，这对于实时监测果实品质具有重要意义。

Detection of freshness and damage degree of Pyrus bretschneideri Rehd. based on electronic nose

ABSTRACT: Objective To study the change of freshness and damage degree of ?Yali? pear during the circulation. Methods In this study, ?Yali? pear with different damaged treatments (drop angle as 0°, 20°, 40°and 60°) was used as the material to measure the changes of respiration and ethylene release rates, and of response values by electronic nose combined with principal component analysis (PCA), linear discriminant analysis (LDA) and loading analysis (LA) in different storage time and different damage degrees. Results Peaks of the respiration and ethylene release rates were found at fourth day of storage in intact (undamaged) fruit. The respiration and ethylene release rates increased greatly in damaged fruit, and change trends showed more obvious with damaged more seriously. The response values of the ten sensors to different storage time and damage degrees were significantly different (P<0.05). The electronic nose could distinguish the volatile gas by LDA under different storage time and damage degrees. LA showed that the response values of sensors, such as W1S, W5S, W1W, W2W and W2S, were changed significantly, indicating to stimulate the production of methane, nitrogen oxides, sulfides and terpenes, organosulfides and aromatic compounds, alcohols and some aromatic compounds during fruit ripening and damage process. Conclusion The electronic nose sensors W1S, W5S, W1W, W2W and W2S can detect the change of volatile gas of ?Yali? pear. Among them, the response value of W2S sensor can determine damage degree of the fruit, which is of great significance for timely monitoring quality.