Improving Food Safety and Quality of Fresh-cut Fruits and Vegetables

APPROACH: Our cooperative approach will be: <ol> <li>Evaluate the effect of electrolyzed water and ultra-sound on microbial inhibition and shelf-life improvement of fresh-cut produce;
<li>Study the effect of new sanitizers, including SANOVA and Tsunami etc. on pathogen reduction, product quality and shelf-life;
<li>Evaluate produce.</ol>
PROGRESS: 2006/10 TO 2007/09<BR>
Progress Report Objectives (from AD-416) The objective of this proposed research will be: (1) Develop techniques to improve food safety and quality of fresh and fresh-cut produce using electrolyzed water, ultra-sound and other emerging technology; (2) Investigate the effect of various new sanitizers on pathogen reduction and shelf-life extension of fresh-cut fruits and vegetables; (3) Gain a greater understanding of how fresh-cut processing conditions affect plant metabolism, microbial growth, and their interactions. Approach (from AD-416) Our cooperative approach will be: (1) Evaluate the effect of electrolyzed water and ultra-sound on microbial inhibition and shelf-life improvement of fresh-cut produce; (2) Study the effect of new sanitizers, including SANOVA and Tsunami etc. on pathogen reduction, product quality and shelf- life; (3) Evaluate produce. Significant Activities that Support Special Target Populations This report serves to document research conducted under a Specific Cooperative Agreement between ARS and University of Illinois. Additional details of the research can be found in the report for the parent project 1275-42000-004-00D, "Microbial Food Safety of Fresh and Fresh-cut Produce. " Intensive research has been conducted in the proposed research areas and the progress of this project has been closely monitored by the ADODR via frequent contact with the PI at the University of Illinois via conference calls and e-mail communications. Recently, several serious food-borne illness outbreaks in the United States were attributed to the consumption of packaged baby spinach and fresh-cut lettuce contaminated with human pathogenic microorganisms. In order to minimize food safety risks pertaining to ready-to-eat fresh-cut produce, it is important to understand the survival and growth patterns of human pathogens during growth, harvest and post harvest handling and processing of produce. The development of new technologies to limit the growth of pathogens on fresh fruits and vegetables at all stages of produce life is critical. Through a collaborative effort between ARS and the University of Illinois, we identified the environmental factors that influence the growth of pathogens on lettuce, and also developed an ultra sound technology that significantly improved the efficacy of commercial anti-microbial agents, such as chlorine and acidified sodium chlorite, to reduce pathogens on baby spinach. Our results provide critical information for the development and implementation of Good Agricultural Practice (GAP) and Hazardous Analysis and Critical Control Point (HACCP) by the FDA and the produce industry in order to minimize the potential food safety risks associated with the consumption of fresh-cut lettuce. Consumers and the fresh-cut produce industry will both benefit as a consequence of our research.
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PROGRESS: 2005/10/01 TO 2006/09/30<BR>
Progress Report 4d Progress report. This report serves to document research conducted under a Specific Cooperative Agreement between ARS and the University of Illinois. Additional details of this research can be found in the report for the parent project 1275-42000-004-00D, entitled "Microbial Food Safety of Fresh and Fresh-cut Produce." The agreement was formalized in 2004 by the recruitment of one Visiting Scientist to undertake the studies on the dual controls of browning reaction and pathogen growth of fresh-cut apples, and the quality improvement of fresh-cut produce. The inactivation mechanism of sanitizing agents on E.coli cells was investigated with atomic force microscopy (AFM). We found that peroxyacetic acid (POAA) treatment caused separation of cell membranes from cell cytoplasm and significant changes in surface topography and morphology. This indicates that electrolyzed water (AEW) and chlorine treatments inactivated E.coli cells by damaging cell surfaces. Adhesion force between the AFM tip and cell surface sharply decreased when morphological changes were observed. The difference in cell morphology between E. coli cells treated with POAA and that with AEW and chlorine may indicate a different bactericidal mechanism. This information is of importance to the future development of effective sanitizers to reduce microbial populations and maintain food quality and safety of fresh produce. Surface roughness and topography of fresh produce affects the attachment and removal of human pathogens. A novel scientific method was developed to objectively quantify the surface roughness of fresh produce. A confocal laser scanning microscope was used to obtain a series of 2-D layered images by optically slicing the surface of a selected fruit. Average surface roughness (Ra) was then determined with MetLab software from a 3-D image reconstructed from the 2-D layered images. A positive linear correlation was found between surface roughness and microbial reduction rates from both metal and produce surfaces. These findings will provide insight into the mechanism of microbial attachment and removal and help to find means to improve produce washing efficiency.

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PROGRESS: 2004/10/01 TO 2005/09/30<BR>
4d Progress report. This report serves to document research conducted under a Specific Cooperative Agreement between the Produce Quality and Safety Laboratory (ARS) and the University of Illinois. Additional details of this research can be found in the report for the parent Project Plan 1275- 42000-003-00D, entitled "Post harvest Survival Strategies and Biocontrol of Human Pathogens on Fresh Fruits and Vegetable." The agreement was formalized last year by the recruitment of one Visiting Scientist to undertake the studies on the dual controls of browning reaction and pathogen growth of fresh-cut apples, and the quality improvement of fresh- cut produce. Evaluated the effect of the emerging novel technologies, i.e. electrolyzed water and ozone, on the microbial growth and quality of fresh-cut cilantro. Data revealed that cilantro leaves received ozone treatment maintained a better aroma than those without the treatment. This research provides the fundamental information for the future development of strategies to control microbial growth and improve food quality and safety. Explored the possibility of using acidic electrolyzed water (AEW), in combination with other sanitizer or browning inhibitor to control both browning reaction and the growth of human pathogens on fresh-cut apples. Results indicate that AEW and peroxyacetic acid (POAA) achieved the highest reduction rates of E.coli O157:H7 on apple slices. The combination of AEW and calcium ascorbate also exhibited a strong control of the browning reaction of fresh-cut apples. This information is of importance to future development of effective sanitizers to reduce microbial populations and maintaining food quality and safety of fresh produce.