1. Food containers with antimicrobial surface. Containers are used for fruits and vegetables in the field and storage, on display in stores and during transportation. Food containers are easily contaminated with foodborne pathogens. When a contaminated container is in contact with food, pathogens would transfer from the container to the food, resulting in cross contamination. Therefore, it is important to have a pathogen-free container. ARS researchers in Wyndmoor, Pennsylvania developed methods and coating formulas to produce food containers with antimicrobial surface. Specifically, TiO2 nanopowders incorporated into zein or other polymers were used to form antimicrobial coating on the container surface. The surface coatings were activated by visible light to inactivate E. coli O157:H7 on the container surface, which achieved more than 99.7% reductions of the pathogen. The research demonstrates that the developed methods and formula can be applied on different types of containers made of metal, wood, plastics, paperboard, etc., and for various foods, specially fruits and vegetables.
2. Novel antimicrobial phenolic fatty acids. New types of antimicrobials are needed as antibiotic resistance of bacteria has become more common. ARS researchers in Wyndmoor, Pennsylvania synthesized novel phenolic fatty acids and evaluated their antimicrobial properties against both Gram-positive and Gram-negative bacteria. Results showed that the compounds at low parts per million concentrations effectively inactivate Gram-positive bacteria. Further research indicates that carboxylic group in the fatty acid moiety and the hydroxyl group on the phenol moiety were responsible for the antimicrobial efficacy. The information could help scientists to develop more potent antimicrobials. Overall, the research demonstrates that the novel class of phenolic fatty acids has potential for use as antimicrobials against Gram-positive bacteria.
3. Development of high pressure processed cantaloupe puree. Cantaloupe is one of the most nutritious and popular fruits. It has a brief harvest period, and large amounts of cantaloupes spoil every year in the farm due to the lack of preservation techniques. ARS researchers in Wyndmoor, Pennsylvania developed a safe and effective method using high pressure to preserve cantaloupe as a puree. The high pressure processing achieved more than 99.999% reduction of inoculated Salmonella enterica and Listeria spp. without affecting quality. The information will help food processors to develop novel type of fresh fruit puree and to reduce food waste.
4. Lignin extracts as antimicrobials and antioxidants. Lignin is a natural component in plants and its extracts have antimicrobial and antimicrobial properties that can be incorporated into antimicrobial packaging materials. ARS researchers in Wyndmoor, Pennsylvania optimized extraction conditions for lignin extraction from corn stover residue. At these extraction conditions, lignin extract with the highest antimicrobial and antioxidant activities were obtained. Thus, optimized lignin extracts have the potential for their application in food and packaging materials.
5. Natural compounds to control human pathogens. Consumer concern over the use of synthesized antimicrobials to enhance microbial food safety has led to search of natural alternatives. Sophorolipids are a class of natural compounds that are composed of sugar and fat, and are produced by a number of yeasts. ARS researchers in Wyndmoor, Pennsylvania evaluated the antimicrobial activity of six sophorolipids purified from various culture media fermented by a highly productive yeast strain. Results demonstrated that sophorolipids in the cyclic configuration were more effective against Salmonella and Listeria spp. than those in the free acid form. The cyclic sophorolipids, when dissolved in low, non-toxic concentrations of ethanol, inactivated both aforementioned foodborne pathogens. Therefore, these newly purified natural antimicrobials may be applied to enhance microbial food safety.
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