Environmental Science & Technology

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Subject: search.filters.subject.Agriculture, Food Science and Technology

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    Detection of Fecal Contamination on Cantaloupes and Strawberries Using Hyperspectral Fluorescence Imagery
    (2006-05-08) Vargas, Angela Maria; Tao, Yang; Kim, Moon; Biological Resources Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)
    Fluorescence methods are widely used for investigation of biological materials, and in recent years have also been used to monitor food quality and safety. In this research, fluorescence imaging techniques for detecting fecal contamination on cantaloupes and strawberries were evaluated. Fluorescence images at emission peaks were examined for fecal classification. These images were subjected to further analysis utilizing band ratios and principal component analysis. Two-band ratio images and principal component images, compared to the single-band images, enhanced the contrast between the feces-contaminated spots and untreated sample surfaces. The images exhibited useful results for contamination detection, however, false positives resulting from natural color variation on strawberry surfaces present a problem throughout the methods. This study confirmed the capability of hyperspectral fluorescence imaging in detecting fecal matter on cantaloupes and strawberries and the potential for this method to be used for developing on-line applications.
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    Relating Spore Population of Acid Producing Thermophilic Organisms and Artificially Inoculated Bacillus stearothermophilus to Processing Variables During Extrusion of a Standardized Feed Formulation
    (2003-12-04) Okelo, Phares Odiewuor; Wheaton, Fredrick W; Carr, Lewis E; Joseph, Sam W; Douglass, Larry W; Biological Resources Engineering
    Salmonella and other pathogenic organisms that infect poultry and other livestock can originate from feed or the environment. Technologies to control Salmonella infection in poultry are important measures taken to reduce turkey and poultry production losses. A study was designed to determine extrusion conditions that optimized microbial inactivation in feed using the Extru-tech E325 single-screw extruder. Bacillus stearothermophilus was selected as the indicator organism after no viable cells of Salmonella typhimurium were detected when 28.5 % moisture content mash feed (wet basis) was extruded at 83 C extruder barrel exit temperature with a 7 second feed retention time in the extruder barrel. Spores of B. stearothermophilus inoculated into a standardized feed formulation consisting of 60% corn meal, 30 % soybean meal,and 10% animal protein blend, by mass, respectively, was used to investigate the effect of 3 extrusion variables on microbial inactivation. The 3 variables were extruder barrel exit temperature (T), mash feed moisture content (Mc), and mean retention time of feed in the extruder barrel (Rt). A rotatable central composite statistical design was used with 3 factors and five levels. The quadratic response surface model fit to acid producing, thermophilic organisms and artificially inoculated Bacillus stearothermophilus spore inactivation data was used to predict extrusion conditions that maximized inactivation. The response surface indicated a stationary point within the design region that was a saddle at T = 81 C, Mc = 27.6 % wet basis (wb) and Rt = 8 s resulting in 0.170 log cycles of acid producing, thermophilic organisms and B. stearothermophilus spore inactivation. An estimated ridge of maximum inactivation showed a maximum of 1.03 log cycles at T = 110 C, Mc = 24.5 % wb and Rt = 11 s. Because the least severe extrusion conditions (T = 83 C, Mc = 28.5 % wb and Rt = 7 s) completely inactivated S. typhimurium in the standardized feed, it was speculated that all S. typhimurium cells would be inactivated at any set of extruder conditions within the central composite design region.
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    AN INFRARED AND LASER RANGE IMAGING SYSTEM FOR NON-INVASIVE ESTIMATION OF INTERNAL COOKING TEMPERATURE IN POULTRY FILLETS
    (2003-12-16) Ma, Ling; Tao, Yang; Lo , Y. Martin; Johnson, Arthur T; Wheaton, Fredrick W; Biological Resources Engineering
    Foodborne diseases caused by undercooked poultry products are noteworthy problems that have motivated research into the assessment of the endpoint temperature in meat. In this research, a novel infrared and laser range imaging system was proposed to estimate the internal cooking temperature of chicken breasts. It consisted of three subsystems: an IR imaging system, a laser range system, and an artificial neural network modeling system. Our experiments showed that geometric variables played an important role in the endpoint temperature estimation. The accuracy achieved by our system was 1.54° C for mean absolute error, 2% for mean absolute percent error, and 3.08(° C)2 for mean square error. The combined IR and laser range imaging system showed the potential for real-time, non-contact and non-invasive estimation of the internal cooking temperature in meat for enhanced food quality and safety.