Progress 09/01/10 to 12/31/12
Outputs
Progress Report Objectives (from AD-416): ARS is interested in integrated approaches to improve produce safety while maintaining quality. The Cooperator, University of Maryland, is interested in evaluating the produce surface characteristics and sanitizer efficacy on pathogen reduction. The Cooperator has the expertise and infrastructure to effectively conduct the proposed research activities. Approach (from AD-416): ARS will acquire the basic knowledge of the factors influencing sanitizer degradation, pathogen attachment and internalization during leafy greens and tomato wash process. The Cooperator will provide the expertise in anti-microbial, surface adsorption, topography, and other characteristics in relation to sanitizer performance on pathogen reduction. Essential oils (EOs) have antimicrobial activities, but their insolubility in water and strong flavor restrict their application in fresh or fresh-cut produce. Metal-Organic Frameworks (MOFs) or porous coordination polymers (PCPs) are a new class of hybrid materials which can act as carriers for other molecules. In this study, MOFs were developed and applied for the first time to encapsulate thymol as a novel antimicrobial agent. MOFs in this study were synthesized using Zinc nitrate hexahydrate and 2-aminoterephthalic acid in N, N- dimethylformamide (DMF). Thymol was then loaded inside the MOFs at the loading rate of 3.95%. The structure of porous crystal MOFs was confirmed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Inhibition of E. coli O157:H7 was measured both in TSB medium and on TSA agar. An E. coli O157:H7 reduction of 4.4 log was achieved at a thymol concentration of 0.04%. An inhibition area of 223.73 mm2 was observed after a 12h incubation. Loading thymol into MOFs increases the thymol contact area, thus enabling improved antimicrobial activity in broth and slow-release activity on agar.
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): ARS is interested in integrated approaches to improve produce safety while maintaining quality. The Cooperator, University of Maryland, is interested in evaluating the produce surface characteristics and sanitizer efficacy on pathogen reduction. The Cooperator has the expertise and infrastructure to effectively conduct the proposed research activities. Approach (from AD-416): ARS will acquire the basic knowledge of the factors influencing sanitizer degradation, pathogen attachment and internalization during leafy greens and tomato wash process. The Cooperator will provide the expertise in anti-microbial, surface adsorption, topography, and other characteristics in relation to sanitizer performance on pathogen reduction. Tomato packing houses in Florida were audited for wash water quality and concentration of active sanitizer ingredient during tomato dump tank wash operations. The correlations among water quality measurement parameters were determined, and functional limits where wash water replenishment or replacement is needed were assessed. Laboratory tests were conducted to evaluate the dynamic interaction between chlorine concentration and oxygen reduction potential (ORP) as impacted by organic load simulated with tomato juice. In other studies the effects of various factors on incidence of Salmonella infiltration were investigated. Factors assessed included tomato variety, post-stem removal time, and the temperature differential between tomato pulp and bacterial suspension. Information generated has been shared with the produce industry and the FDA for establishing science-based tomato handling standards to prevent pathogen contamination and internalization.
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) ARS is interested in integrated approaches to improve produce safety while maintaining quality. The Cooperator, University of Maryland, is interested in evaluating the produce surface characteristics and sanitizer efficacy on pathogen reduction. The Cooperator has the expertise and infrastructure to effectively conduct the proposed research activities. Approach (from AD-416) ARS will acquire the basic knowledge of the factors influencing sanitizer degradation, pathogen attachment and internalization during leafy greens and tomato wash process. The Cooperator will provide the expertise in anti-microbial, surface adsorption, topography, and other characteristics in relation to sanitizer performance on pathogen reduction. The agreement was formalized by the recruitment of a visiting scientist to undertake the studies on the effect of tomato packing house operations on dump tank water quality and Salmonella infiltration. We audited the tomato packing house operations and investigated the incidence of Salmonella infiltration as impacted by tomato variety, post-stem removal time, and the temperature differential between tomato pulp and bacteria suspension. We reported that tomato varieties and post-stem removal time significantly affected the frequency and population of Salmonella infiltration. Information generated will help to establish science-based tomato handling standards to prevent pathogen contamination and internalization. The progress of this project has been closely monitored by the ADODR via frequent contact with the PI at the University of Maryland via conference calls, face-to-face meetings, and e-mails.
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