Evaluating the microbial safety status of products from sustainable organic agriculture

Thumbnail Image
Elumalai, Sai Deepikaa
Major Professor
Angela Shaw
Committee Member
Journal Title
Journal ISSN
Volume Title
Research Projects
Organizational Units
Organizational Unit
Journal Issue
Is Version Of

There has been a steady increase in the demand for organic and sustainable agricultural products. Consumers increasingly prefer non – GMO products grown without pesticides and antibiotics. In order to satisfy the increasing demand, several agricultural producers have opted for use of different types of modern agricultural practices which are more efficient and sustainable than conventional methods. My research focuses on two such modern agricultural practices. Because the products from these methods do not have many food safety interventions applied to them, it is important to make sure that they are free of pathogens and are safe for human consumption. My research 1) Identifies the food safety hazards associated with an aquaponic food production system and studies the efficacy of UV intervention, and 2) Evaluates the food safety status of the initial phase of an integrated crop-livestock organic agricultural system.

Aquaponics is a growing trend in food production as it is seen as a sustainable, space- and energy-efficient approach for production of fruits, vegetables and seafood. Within aquaponics, few microbial studies have been conducted to determine the food safety status of its units. The aim of this study was to determine the food safety status and the effectiveness of ultraviolet treatment (15 watt UV light, luminous flux of 900 lumens) as a food safety intervention in reducing the microbial loads of the water system, in a model aquaponic unit that is growing lettuce, basil and barramundi (Australian Sea Bass). Large Leaf basil, Buttercrunch Bibb lettuce, water and fish swab samples were collected throughout the 118-day production period and microbial analysis was conducted for the presence of E. coli O157:H7, Aeromonas and Salmonella spp. and the prevalence of aerobic plate counts (APC), coliforms, and fecal coliforms in the systems in triplicates. Absence of foodborne pathogens was confirmed using ELISA technology (3M™ Tecra, Australia) and enumeration through petrifilms (coliform/E. coli Petrifilm™, 3M, St. Paul, MN) and agar (Aeromonas agar, OXOID, Hants, United Kingdom). A significant increase was observed in aerobic plate counts over the trial period (1 to 3 log CFU/mL), in the presence and absence of UV (p>0.05). Ultraviolet treatment did not significantly reduce the APC, Aeromonas or coliform counts when compared to the control systems samples. Though the UV intervention method was not effective in reducing microbial loads, future work should focus on improving the unit design, evaluation of bio-solid filtration and other food safety interventions that can be effective in the presence of living system while maintaining fish homeostatic environment.

Though several researchers have indicated the many benefits associated with the production and consumption of organic food such as restricted use of antibiotics and synthetic chemicals; it must be kept in mind that these benefits do not address the issue of microbial safety. With integrated crop-livestock production systems being relatively new practice in organic agriculture, the aim of this study was to develop and use a model agricultural system to check the food safety status of crops and beef and dairy calves (6-10 months old) produced in an integrated environment in Minnesota (MN), Iowa (IA), and Pennsylvania (PA). Pasture and fecal samples were collected 3 months apart and evaluated for presence of E. coli 0157:H7 and Salmonella using miniVIDAS and confirmation tests were performed according to FDA BAM and USDA standards. Results indicated very low probability for (0.0173-IA, 0.0032-MN, 0.0039-PA) E. coli 0157:H7 and (0.0077-IA, 0.0027-MN, 0.0022-PA) Salmonella occurrence (overall Pr<0.1). The three states were studied individually for occurrence of E. coli 0157:H7 or Salmonella. The probabilities of occurrence were again very low (0.0048-IA, 0.0003-MN, 0.0009-PA). Also, there was no significant difference between the three research sites (p>0.05) in terms of E.coli O157:H7 or Salmonella occurrence. At present, this model has low chance of E.coli O157:H7 and Salmonella being present in the feed and fecal matter, but long term studies including evaluation of meat products and rotational crops might help us better understand the stability of this system.

Fri Jan 01 00:00:00 UTC 2016