Geographical origin determination of Red Huajiao in China using the electronic nose combined with ensemble recognition algorithm

Overcoming the Limits of Cross-Sensitivity: Pattern Recognition Methods for Chemiresistive Gas Sensor Array

As information acquisition terminals for artificial olfaction, chemiresistive gas sensors are often troubled by their cross-sensitivity, and reducing their cross-response to ambient gases has always been a difficult and important point in the gas sensing area. Pattern recognition based on sensor array is the most conspicuous way to overcome the cross-sensitivity of gas sensors. It is crucial to choose an appropriate pattern recognition method for enhancing data analysis, reducing errors and improving system reliability, obtaining better classification or gas concentration prediction results. In this review, we analyze the sensing mechanism of cross-sensitivity for chemiresistive gas sensors. We further examine the types, working principles, characteristics, and applicable gas detection range of pattern recognition algorithms utilized in gas-sensing arrays. Additionally, we report, summarize, and evaluate the outstanding and novel advancements in pattern recognition methods for gas identification. At the same time, this work showcases the recent advancements in utilizing these methods for gas identification, particularly within three crucial domains: ensuring food safety, monitoring the environment, and aiding in medical diagnosis. In conclusion, this study anticipates future research prospects by considering the existing landscape and challenges. It is hoped that this work will make a positive contribution towards mitigating cross-sensitivity in gas-sensitive devices and offer valuable insights for algorithm selection in gas recognition applications.

Comparison and discrimination of the terpenoids in 48 species of huajiao according to variety and geographical origin by E-nose coupled with HS-SPME-GC-MS

The unique flavor and aroma characteristics of huajiao were not only influenced by cultivated varieties, maturity, but also geographic origin. This study compared the terpenoids of 48 species of huajiao using headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and electronic nose (E-nose). The E-nose results showed differences in huajiao from different origins and varieties, and from the PCA loading plots it was possible to conclude that some samples contained higher levels of hydrocarbons and alcohols, providing a preliminary discrimination between different species of huajiao. Further, GC-MS results showed that six key biomarkers could be used to distinguish red and green huajiao. Red huajiao in Central China contained more terpenoids than in other regions. Nine key biomarkers could be used to distinguish red huajiao from different regions. Oil huajiao exhibited a more distinct aroma in red huajiao. Green huajiao from Yunnan Province had more terpenoids than that from other provinces. The terpenoids content of Yunnan zhuyeqing was higher than other green huajiao. Heatmap analysis helped to find the most contributors of huajiao, which could be used as key terpenoids to differentiate huajiao of different regions or cultivars. Finally, through the correlation analysis of E-nose and GC-MS, it was found that the E-nose sensors could distinguish different huajiao by specific responses to some terpenoids in the samples.