One Friday evening in the spring of 2019, Abhi Upadhyay, assistant professor of food microbiology and safety in the Department of Animal Science, found himself watching a video showing microbubbles for pet care and grooming. He started thinking about using this technology for food safety and spent the weekend researching its potential, current state of the field and appropriate grant opportunities.
In spring of 2020, Upadhyay received a $148,874 grant from Northeast Sustainable Agriculture Research and Education to conduct a three-year collaborative study on the use of ultra-fine ozone bubbles as a novel antimicrobial wash against food pathogens on eggs and fresh produce. His team includes Assistant Extension Educator Shuresh Ghimire and Assistant Extension Educator Indu Upadhyaya, both in UConn Extension in the College of Agriculture, Health and Natural Resources.
Ultra-fine bubbles are small, spherical, gas-filled cavities within liquids with a diameter of less than 100 nanometers. They have very peculiar characteristics (for example, high surface charge, high gas pressure, taut inflexible surfaces with high tension, increased surface area, prolonged survival in liquid) that can be used in many fields such as wastewater treatment, soil remediation and aquaculture. Many of these applications depend on the choice of gas for the bubbles. Ozone is an antimicrobial gas widely used for sterilization, deodorization and organic matter decomposition. It has a short half-life and readily decomposes to oxygen without leaving any harmful residues, which makes it ideal for food washing applications. Upadhyay is testing the efficacy of ultra-fine ozone (UFO) bubbles for food washing, a process that involves dipping produce in water containing UFO bubbles for five to ten minutes. The ozone poses no threat to either the applicator or end user as the ozone in water dissipates in about twenty minutes.
“Our aim is to increase the antimicrobial efficacy of ozone by converting it into these ultra-fine bubbles that can stay in the solution for an extended duration to kill pathogens,” says Upadhyay. “Because of the small size of the bubbles, which are not visible to the naked eye but observable through diffraction technologies, we are able to have a higher concentration of ozone in the water.”
Upadhyay will be testing the most dangerous pathogens that lead to food poisoning, including Salmonella, Escherichia coli O157 and Listeria monocytogenes, on eggs as well as spinach, lettuce, cucumber and cantaloupes. The team will also be evaluating the effect of treatment on color, quality and shelf life of products. In addition to laboratory research, the project includes field demonstrations and outreach to both extension personnel and vegetable growers and egg producers in the Northeast.
In a larger collaborative project studying ultra-fine bubbles, Upadhyay is working with Ghimire, Michael Darre, professor emeritus of animal science; Nathan Fiala, associate professor agricultural and resource economics; Ann Donoghue of the USDA Agricultural Research Service; Komala Arsi of the University of Arkansas; Anne Fanatico of Appalachian State University; and Ondieki Gekara of CalPoly, Pomona, funded by a four-year, $500,000 grant from USDA.
“We are aiming to control Salmonella and Campylobacter, which are the two major foodborne pathogens transmitted through chicken meat,” Upadhyay says. “These two pathogens infect more than two million people with gastrointestinal disease every year.”
As a postdoctoral fellow at the University of Arkansas, Upadhyay worked with veterans to assist them in starting small and medium-sized poultry farms. When he came to CANHR, he realized that many veterans in the Northeast were seeking similar business opportunities. Although the work initially focused on farmers who are military veterans, after a review, the team decided to open the research and training opportunity to all small and medium-sized poultry farms where the farmers were interested in the technology.
“One of the challenges they faced was finding a way to produce chicken meat that was microbiologically safe,” says Upadhyay. Ultra-fine bubble technology could provide an affordable way for small farmers to produce safer chicken as it is portable, so several farmers could share one equipment system.
In addition to his work with ultra-fine bubble technology, Upadhyay is a member of the involved in the recently announced $10 million research and outreach project headed by Kumar Venkitanarayanan, professor of animal science and associate dean for CAHNR’s research and graduate studies. The project is designed to improve the sustainability and food safety of the production of antibiotic-restricted broiler chickens. Upadhyay will be investigating the potential of plant-based nanoemulsions for reducing Salmonella colonization in broiler chickens. These essential oils are derivatives of common herbs such as cinnamon and cloves.
“We need to find antibiotic substitutes that can provide health benefits to birds while reducing the pathogen load in the gut,” explains Updadhyay. “We need to do this to create safer chicken that will contribute to the sustainability of the poultry industry in the years to come.”
“I am looking forward to this research,” Upadhyay says. “I’m fortunate to be involved in these studies that address both the pre-harvest (animal health) and post-harvest (chicken, fresh produce, eggs) sides of the equation to enhance food safety.”
The research related to ultra-fine bubble technology is funded by USDA project #CONS2019-05760 and NE-SARE project #LNE20-412R. The nanoemulsion research is funded by USDA NIFA project #CONS2019-08297.
