Original article Possibility of using near infrared spectroscopy for evaluation of bacterial contamination in shredded cabbage Phunsiri Suthiluk, 1 Sirinnapa Saranwong, 2 Sumio Kawano, 2 Sonthaya Numthuam 1 & Takaaki Satake 1 * 1 Graduate School of Life and Environmental Sciences, University of Tsukuba, Tennodai 1-1-1, Tsukuba, Ibaraki, 305-8572, Japan 2 National Food Research Institute, Kannondai 2-1-12, Tsukuba, Ibaraki, 305-8642, Japan (Received 22 May 2006; Accepted in revised form 25 July 2006) Summary The possibility of near infrared (NIR) spectroscopy to measure the amount of bacterial contamination in shredded cabbage was investigated. NIR measurements in the short wavelength region from 700 to 1100 nm were done using two types of saline solutions: one was used to stomach with the samples as the conventional method and the other was used to wash the outer surface of the sample to examine the possibility of a non- destructive method. Partial least squares regression (PLS) was used to develop the equations for bacterial amount. Spectra from the stomacher solution and the washing solution produced similar results. Sufficiently accurate results could be obtained with the bias-corrected standard error of prediction (SEPs) of 0.46 log CFU g )1 for the stomacher solution and 0.44 log CFU g )1 for the washing solution. NIR spectroscopy was clarified to be a rapid and non-destructive method for prediction of bacterial contamination in shredded cabbage. Keywords Food safety, fresh-cut vegetables, NIR, non-destructive, total plate count. Introduction Production and consumption of fresh-cut vegetables have been growing rapidly in recent years. Commer- cially available fresh-cut vegetables have become increasingly popular because of their high sensory quality and convenience (Lund, 1989). However, one of the most crucial problems of this product is its short shelf life because of the rapid deterioration caused by micro-organisms. The process of fresh-cut produce such as shredding, cutting or trimming affects the micro- organism in several ways. First, it exposes nutritious internal tissue fluids to the micro-organism and thereby accelerates their growth and the product’s spoilage (Bracket, 1992). Second, it provides more surface area on which the micro-organisms can grow. Micro-organ- ism will affect overall product quality consequently; the amount of micro-organism contamination is a very important food safety indicator for ready-to-eat fresh- cut vegetables. For determination of micro-organisms, conventional microbiological methods such as total plate count and coliform count have been employed. However, these techniques have a major disadvantage as the time needed to obtain the results is 48 h or more. Therefore, the system for facilitating a rapid and non- destructive evaluation of micro-organism contamination in fresh-cut products should be developed for precise and real-time quality control and monitoring. Near infrared (NIR) spectroscopy has been widely used in quality evaluation of many agricultural and food products. In place of conventional chemical analyses that usually are destructive, expensive, time-consuming and create a high level of waste, NIR quality evaluation can be non-destructive, less cost, rapid, repeatable and chemical-free. After the establishment of an analytical system using NIR, the analysis is very simple and can be performed by unskilled personnel (Osborne et al., 1993). Screening for micro-organisms by NIR spectroscopy is still in the beginning stages because of the small size of their concentrations. Davies et al. (1987) first attempted to determine the excessive mould content in tomatoes. After that, Sørensen & Jepson (1997) used NIR spectroscopy for detection of Clostridium tyrobutyricum in cheese. Rodriguez-Saona et al. (2001) tried to identify bacterial strains by applying the DESIR method. These works demonstrated the promise of NIR for microbial qualitative analysis. In addition, Lin et al. (2004) also used NIR for the quantitative analysis of determination of microbial contamination in chicken meat. However, in order to develop a practical and stable system, more sophisticated work must be done. The objective of this *Correspondent: Fax: +81 29 853 6130; e-mail: satake@sakura.cc.tsukuba.ac.jp International Journal of Food Science and Technology 2008, 43, 160–165 160 doi:10.1111/j.1365-2621.2006.01416.x Ó 2007 The Authors. Journal compilation Ó 2007 Institute of Food Science and Technology Trust Fund