Research Highlights
On-farm Food Safety Research Helps Louisiana
Growers Comply with New Law
The Food Safety Modernization Act (FSMA) is one of the sweeping reforms of U.S. food safety laws in more than 70 years. The main focus of the act is to reduce foodborne hazards by preventing microbial contamination during production, processing, handling and transportation of food rather than relying on correction after problems occur. Under FSMA, “FDA will have a legislative mandate to require comprehensive, science-based preventive controls across the food supply.”
FSMA requires new standards for growing, harvesting, packing and holding produce for human consumption, also known as the “Produce Safety Rule.” The rule identifies five routes of on-farm microbial contamination – agricultural water, domesticated and wild animals, workers, biological soil amendments, and equipment and tools – and sets requirements to prevent or reduce the introduction of pathogens.
The potential introduction of foodborne pathogens during growing, harvesting and packing necessitates that producers understand the on-farm sources of harmful microorganisms and apply appropriate practices to reduce the risk of contamination. FSMA requires fresh-produce growers to follow practices that minimizes the level of harmful microorganisms before they harvest or market their produce. The rule states the waiting period between irrigation and harvesting or during storage depends upon the microbial quality of irrigation water and the survival of generic E. coli on the edible portion of the crops. [RIGHT: Cantaloupe irrigated with UV-C light treated irrigation water. Photo by Achyut Adhikari]
One of the long-term goals of the LSU AgCenter is to strengthen the productivity, profitability and competitiveness of Louisiana’s agriculture. Scientists focus on applied research that has immediate impact on the quality, safety and economic viability of Louisiana-based fresh produce. This is achieved by collaboration among scientists from several disciplines that bring expertise to address critical food safety issues along the production chain.
On-farm applied research contributes to the assessment of produce food safety and guides development of control strategies to mitigate the risks during pre- and post-harvest processing. Current research efforts focus on irrigation water treatments, the fate and persistence of microorganisms on fresh produce and the development of science-based post-harvest processing techniques for food safety risk reduction.
Irrigation water is one of the important sources of pathogen contamination. Several methods currently are available for water treatment, such as chlorine, ozone and filtration. Not all are suitable for surface water treatment, however, because of the complexity, variability and content of suspended particles.
In one on-farm study, AgCenter researchers evaluate the efficacy of ultraviolet light treatment on reducing the generic Escherichia coli levels from surface water used for irrigating cantaloupes. The preliminary results indicate significant reduction of generic E. coli even at low doses. This means growers who treat their water with ultraviolet light can harvest earlier because FSMA requires producers to apply a time interval between last irrigation and harvest using a microbial die-off rate based on the generic E. coli levels of irrigation water. In addition, producers will benefit from a water treatment process that does not leave any residue that adversely affects crop production or soil quality. An ultraviolet light treatment replaces use of chemical disinfectants and leaves no residue in the water. [LEFT: Achyut Adhikari works with students evaluating the efficacy of ultraviolet light for surface water treatments. Photo by Robert Williams]
Pecans are native to the lower Midwest and Midsouth. Native pecan areas have a long-standing tradition of double-cropping the land by allowing cattle to graze in pecan groves. Cattle manure is a primary source of foodborne pathogens such as E. coli O157:H7, Salmonella spp. and Listeria monocytogenes. With the potential food safety risk associated with raw manure, Louisiana pecan growers may not be able to have this second source of income by grazing cattle in pecan groves.
However, a provision in the food safety act exempts a farm from the produce safety rule if the produce is processed with a “kill step.” An LSU AgCenter team of food safety and quality specialists, pecan specialists and economists is working on a research project to address this issue. The study aims to optimize proper antimicrobial intervention techniques during pecan processing that can be regarded as a kill step and increase competitiveness of Louisiana-grown pecans.
The fate and persistence of pathogens on the edible portion of the crops is one of the important requirements set by the produce safety rule. Several factors affect the survival of pathogens, such as temperature, humidity, UV exposure and type of crops. Previous studies in this area have been performed in laboratory settings, simulating agriculture environmental conditions. Because of several variables in an actual farming and processing environment, laboratory settings may not accurately predict microbial response and die-off rates that would be in actual environmental conditions.
AgCenter on-farm studies with watermelons and cantaloupes are focused on examining the die-off rate of indicator organisms specific to Louisiana climate and weather conditions. Results from this applied research will help growers identify best growing practices and conditions to increase productivity and minimize food safety risks.
Critical knowledge gaps exist regarding the fate of pathogens in agricultural environments. Understanding the behavior of indicator organisms in on-farm settings will enable researchers to conduct pre- and post-harvest food safety risk assessments. The outcomes of this applied research on produce safety will enhance upon researcher and grower knowledge of the spread of foodborne hazards on fresh produce and will help in the development of preventive control practices, allowing Louisiana growers to comply with FSMA requirements. [RIGHT: From left, Robert Williams, Achyut Adhikari, Vijay Singh Chettri and Kathryn Fontenot perform microbial analysis of watermelon samples. Photo by Kathryn Parraga]
Achyut Adhikari is an assistant professor in the School of Nutrition and Food Sciences and is in charge of training and education about the Food Safety Modernization Act.
(This article was published in the fall 2015 issue of Louisiana Agriculture Magazine.)
Researcher Studies Food Safety in
Greenhouse Tomato Production
BATON ROUGE, La. – 20 March 2014 -Commercial greenhouse vegetable production is becoming increasingly popular in Louisiana. While there are benefits to local production, even small-scale growers must learn how to prevent and manage diseases.
LSU AgCenter plant pathologist Melanie Lewis Ivey is studying how diseases enter greenhouses and cost-effective prevention methods. The project is a collaboration with Ohio State University and is funded by a $2 million specialty grant from U.S. Department of Agriculture’s National Institute of Food and Agriculture. The AgCenter’s part is $130,000.
Ivey said the goal is to identify the entry points of high-risk pathogens and develop best practices for safeguarding greenhouse crops from bacteria, viruses and viroids. She also hopes to find out if plant pathogens and human pathogens enter systems at similar points.
Ivey said the project includes both small and large greenhouses, so researchers can determine how risk levels vary by size of the operation.
So far, researchers have identified listeria and salmonella in the greenhouses. Outbreaks of these bacteria can make people sick and prompt recalls that have a significant impact on the food industry.
In 2013, the total value of greenhouse tomato production in Louisiana was more than $2.4 million, according to the AgCenter’s Ag Summary.
"The greenhouse industry has really picked up, especially in the United States," Ivey said. "That has a lot to do with consumer interest in locally grown produce as well as you can make quite a bit of money growing greenhouse tomatoes. There's a high profit range."
Implementing changes that make produce safer can be costly, so some growers choose to take risks. Larger operations that sell globally tend to have more safety precautions in place because they must deal with international regulations, Ivey said. Even in those situations, however, compliance can be difficult.
Because food safety is ultimately up to the people who grow and process food, Ivey is assembling a guide that will help greenhouse producers learn about best practices for plant disease and food safety management.
Buying clean seed and growing disease-resistant varieties can minimize outbreaks. Sanitation is also important — workers should keep equipment clean to avoid spreading pathogens when pruning or harvesting, Ivey said. Good personal hygiene helps prevent the spread of human pathogens.
Water is another key issue in dealing with disease. Ivey said growers who recycle water should treat it before reintroducing it to plants. Surface water should also be treated to eliminate plant and human pathogens.
--Olivia McClure
