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United States Department of Agriculture

Agricultural Research Service

Research Project: Improving Food Safety and Quality of Fresh and Fresh-Cut Fruits and Vegetables

Location: Environmental Microbial and Food Safety Laboratory

2013 Annual Report


1a.Objectives (from AD-416):
The objective of this research will be: (1) Develop techniques to improve food safety and quality of fresh and fresh-cut produce using 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; and (3) Gain a greater understanding of how fresh-cut processing conditions affect plant metabolism, microbial growth, and their interactions.


1b.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; and (3) Evaluate produce.


3.Progress Report:

Infiltration of pathogens into fresh produce is a serious food safety problem troubling the produce industry. Understanding the pathways by which pathogens may enter and disperse within produce, and mapping the distribution of contaminates within the plant tissues, are first steps towards developing strategies to reduce risks of infiltration and associated contamination. A nondestructive X-ray computed microtomography (Micro-CT) technique was used to visualize infiltration of human pathogens into fresh produce. Fresh samples of spinach, romaine lettuce, pepper, and tomato were inserted into polyimide tubing, and scanned with a Micro-CT. An X-ray tube with a tungsten anode was adapted for the transmission of the X-ray images of the specimens. The 3D images were constructed using 720 images taken at 10 s per image by a software program provided with the Xradia scanner. Further, the leaf pieces (2 mm X 10 mm) of the spinach were inoculated with microscopic gold particles, and the tomatoes injected with potassium iodide at the stem scar, to mimic penetration by human pathogens. The Micro-CT images provided a clear view of the internal structure of the selected vegetables. The images taken from the sample cross sections showed that the potassium iodide (KI) concentrated in the vascular bundles of the tomatoes and infiltrated into the surrounding tissue. The images also showed good contrast between the gold particles and the spinach leaf tissue. The Micro-CT technique provides a new and nondestructive means for visualizing the infiltration of human pathogens into fresh and fresh-cut produce.


Last Modified: 8/19/2014
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