title: Rapid detection of Listeria monocytogenes in milk using confocal micro-Raman spectroscopy and chemometric analysis.
abstract: Listeria monocytogenes is a facultatively anaerobic, Gram-positive, rod-shape foodborne bacterium causing invasive infection, listeriosis, in susceptible populations. Rapid and high-throughput detection of this pathogen in dairy products is critical as milk and other dairy products have been implicated as food vehicles in several outbreaks. Here we evaluated confocal micro-Raman spectroscopy (785 nm laser) coupled with chemometric analysis to distinguish six closely related Listeria species, including L. monocytogenes, in both liquid media and milk. Raman spectra of different Listeria species and other bacteria (i.e., Staphylococcus aureus, Salmonella enterica and Escherichia coli) were collected to create two independent databases for detection in media and milk, respectively. Unsupervised chemometric models including principal component analysis and hierarchical cluster analysis were applied to differentiate L. monocytogenes from Listeria and other bacteria. To further evaluate the performance and reliability of unsupervised chemometric analyses, supervised chemometrics were performed, including two discriminant analyses (DA) and soft independent modeling of class analogies (SIMCA). By analyzing Raman spectra via two DA-based chemometric models, average identification accuracies of 97.78% and 98.33% for L. monocytogenes in media, and 95.28% and 96.11% in milk were obtained, respectively. SIMCA analysis also resulted in satisfied average classification accuracies (over 93% in both media and milk). This Raman spectroscopic-based detection of L. monocytogenes in media and milk can be finished within a few hours and requires no extensive sample preparation.
authors: Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457, China; Synergetic Innovation Center of Food Safety and Nutrition, Harbin 150030, China.
authors: Junping
authors: J
authors: Wang
authors: Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457, China.
authors: Xinfang
authors: X
authors: Xie
authors: Food, Nutrition, and Health Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
authors: Jinsong
authors: J
authors: Feng
authors: Food, Nutrition, and Health Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
authors: Jessica C
authors: JC
authors: Chen
authors: Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457, China.
authors: Xin-jun
authors: XJ
authors: Du
authors: Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457, China.
authors: Jiangzhao
authors: J
authors: Luo
authors: Food, Nutrition, and Health Program, Faculty of Land and Food Systems, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada. Electronic address: xiaonan.lu@ubc.ca.
authors: Xiaonan
authors: X
authors: Lu
authors: Key Laboratory of Food Nutrition and Safety, Ministry of Education, Tianjin Key Laboratory of Food Nutrition and Safety, Tianjin University of Science and Technology, Tianjin 300457, China. Electronic address: s.wang@tust.edu.cn.
authors: Shuo
authors: S
authors: Wang
mesh_terms: D000818:Animals; D015373:Bacterial Typing Techniques; D004926:Escherichia coli / Q000302:isolation & purification; D005516:Food Microbiology; D008089:Listeria monocytogenes / Q000145:classification* / Q000302:isolation & purification*; D008892:Milk / Q000382:microbiology*; D015203:Reproducibility of Results; D019779:Salmonella enterica / Q000302:isolation & purification; D013059:Spectrum Analysis, Raman / Q000379:methods*; D013211:Staphylococcus aureus / Q000302:isolation & purification
keywords: Chemometric analysis; Listeria monocytogenes; Milk; Raman spectroscopy