Researchers at Louisiana State University (LSU) are investigating multiple approaches to reduce microbial contamination in fresh produce systems, focusing on risks that occur pre-harvest and throughout the production chain, such as hydroponic production, manure fertilizer treatment, sanitation of food contact surfaces, and antimicrobial packaging development.

The work is led by Achyut Adhikari, Ph.D., Interim Director of LSU’s Food Innovation Institute (FOODii) and professor in the LSU School of Nutrition and Food Sciences. The Achyut Adhikari Research Group focuses on practical interventions that growers and food producers can implement to improve food safety.

Preventive-Minded Research Helps Growers Meet FSMA Requirements

The research conducted under Dr. Adhikari reflects a preventive approach aligned with the U.S. Food and Drug Administration’s (FDA’s) Food Safety Modernization Act (FSMA), which shifted U.S. food safety policy toward preventing foodborne illness rather than responding to outbreaks.

Dr. Adhikari said FSMA requirements create operational challenges for some growers. For example, FSMA Produce Safety Rule guidance regarding the use of untreated manure as fertilizer recommends extended intervals between application and harvest (FDA recently published the findings of a new risk assessment providing evidence for this practice). However, for operations that exercise double cropping and raise cattle in orchards before harvest, such as Louisiana pecan growers, those intervals proved difficult to meet.

To address this issue, Dr. Adhikari and collaborators developed a validated hot-water treatment process that decontaminates pecans harvested from cattle-grazed orchards while preserving kernel quality. The method has since been adopted by pecan growers across Louisiana.

Graduate Research Projects Focus on Key Contamination Hazards

Several Ph.D. students in Dr. Adhikari’s lab are also investigating specific microbiological contamination risks and prevention measures. For example:

• Pathogen control in hydroponic production systems: Ivannova Lituma is leading a project that examines contamination risks associated with recirculating nutrient solutions, substrates, seeds, and system surfaces in hydroponic controlled environment agriculture (CEA) operations. She is evaluating hot water and steam treatments to disinfect substrates and is studying biofilm formation on hydroponic equipment. Ms. Lituma is also testing seed treatments using antimicrobial compounds derived from pecan shells.
• Mitigating bacterial biofilms on food-contact surfaces: Sheetal Jha is researching quorum sensing, the communication process bacteria use to coordinate biofilm formation. Ms. Jha is studying antimicrobial peptides that interfere with this signaling process, potentially preventing biofilm development and improving sanitation effectiveness in food processing environments.
• Alternative methods to treat animal manure used as fertilizer: FSMA mandates validated composting processes for untreated manure used as fertilizer to reduce pathogens such as Escherichia coli, which can take weeks or months to achieve sufficient pathogen reduction. Looking to develop a faster alternative, Daniel Leiva is testing a solar drying system designed to rapidly heat manure and reduce microbial populations. Early results suggest that high-temperature solar drying may significantly reduce bacterial levels within one day. If this treatment can achieve mandatory pathogen reductions, it could potentially provide farmers with an accessible, energy-efficient treatment option that reduces labor, cost, and time demands.
• Biodegradable, antimicrobial food packaging: Aakankshya Dhakal is leading the development of packaging made from bacterial cellulose produced through fermentation. The material is engineered into thin films and combined with silver nanoparticles synthesized through a low-chemical process to provide antimicrobial properties. Laboratory testing indicated that the films inhibited foodborne pathogens and degraded in soil within approximately four weeks under controlled conditions.

A Systems-Level Approach to Food Safety

Although the projects address different stages of the food supply chain, the research group frames them as part of a systems-level approach to food safety. The goal is to develop practical, science-based interventions that reduce contamination risks from production through packaging, while supporting sustainable agricultural practices.