Submitted to: Food Processing Automation Conference Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/17/2008
Publication Date: 6/28/2008
Citation: Jun, W., Lee, K., Millner, P.D., Sharma, M., Chao, K., Kim, M.S. 2008. Detection of bacterial biofilm on stainless steel by hyperspectral fluorescence imaging. Food Processing Automation Conference Proceedings, June 28 - July 2, 2008, Providence, Rhode Island. Interpretive Summary: Microbial biofilm formation on food processing equipment surfaces raises safety and health concerns in the food industry. In our study, bacterial biofilms were formed on stainless steel coupons in laboratory growth medium. A recently developed portable hyperspectral imaging system was evaluated for use in detection of biofilms on food processing equipment surfaces as a potential indicator of microbial contamination. The detection system is based on hyperspectral fluorescence line-scan imaging techniques. Preliminary results show that the fluorescence imaging technique, using two-band ratios, can detect microbial biofilms on stainless steel surfaces. The presented biofilm detection method is useful to food scientists, engineers, regulatory government agencies (FSIS and FDA), and food processing industries for food safety inspection.
Technical Abstract: In this study, hyperspectral fluorescence imaging techniques were investigated for detection of microbial biofilm on stainless steel plates typically used to manufacture food processing equipment. Stainless steel coupons were immersed in bacterium cultures consisting of nonpathogenic E. coli, Pseudomonas pertucinogena, Erwinia chrysanthemi, and Listeria innocua. Following a 1-week growth in rich medium tryptic soy broth (TSB) and M9 minimal medium with casamino acids (M9C), biofilm formations were evaluated using a recently developed portable hyperspectral fluorescence imaging system. Hyperspectral fluorescence images of the biofilm samples, in response to ultraviolet-A (320 to 400 nm) excitation, were acquired from 416 to 700 nm. Fluorescence images in the blue emission peak region exhibited the most contrast between biofilms and stainless steel coupons. On the basis of correlation analyses, two-band ratios compared with the single-band images enhanced the contrast between the biofilm forming area and untreated coupon surfaces. A two-band fluorescence ratio image, 444/588 nm, resulted in the greatest contrast between the biofilm formations and stainless coupon for the biofilms grown in M9C medium. TSB medium showed relatively high auto fluorescence, and thus further investigation is needed to mitigate the contribution of strong auto-fluorescence of the TSB medium.