92D-1 |
Alternative use of a machine vision system for automated plate counting |
G. FOLKES1, B. R. Warren2, and M. O. Balaban1. (1) Dept. of Food Science & Human Nutrition, Univ. of Florida, 359 FSHN Bldg., Newell Dr., PO Box 110370, Gainesville, FL 32611-0370, (2) University of Florida, PO Box 110370, Gainesville, FL 32611 Counting colonies manually is a tedious task requiring much time and concentration. Automating the process and recording the results accurately and consistently is desired, however prices of most plate counters is prohibitive. An accurate, fast, and economical plate counting system is needed. The objective was to assess the effectiveness a machine vision (MV) system, usually used for color analysis, for counting colonies on microbiological plates. Twenty-seven plates of varying media and bacteria were grown to represent many color combinations relevant to the food industry. Digital images of plates were captured using a CCD digital camera and light box with machine vision software. Colonies were identified and enumerated by using their L-value to differentiate them from their growth medium. Images of plates were then manually counted. Plates were categorized into: plates that could not be counted by computer, plates that allowed for computerized enumeration and no manual enumeration, optimized plates, and non-optimized plates. Plates that could not be counted by computer had colonies and media of similar lightness, colonies running together, and over-crowding. Plates that allowed for computerized enumeration, but were too numerous to count manually, had great differences in colony an media lightness and distinct colonies. Counting methods of non-optimized and optimized plates were compared using paired t-tests. Non-optimized plates showed significantly different means for counting methods (p-value=.004), concluding optimization for these combinations of colonies and media is needed. Manual and computerized counts for optimized plates were not significantly different (p-value=.872), showing MV is an acceptable alternative to manual counting in certain cases. The alternative use of a machine vision system for automated plate counting can provide fast and cost effective enumeration of colonies. Because commercial enumeration units are expensive the machine vision system is a feasible alternative after minimal optimization.
Session 92D, Quality Assurance: General
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