Research Accomplishment Reports 2011

S1033: Control of Food-Borne Pathogens in Pre- and Post-Harvest Environments

M.C. Newman
Department of Animal and Food Sciences

 

Non-Technical Summary

The Centers for Disease Control and Prevention (CDC, 1999) reported new, more accurate estimates of foodborne illnesses that occur annually. An estimated 76 million cases of foodborne illness, 325,000 hospitalizations, and 5,000 deaths occur each year from food-borne microorganisms (Mead et al., 1999). The food safety surveillance system, FoodNet, indicates that more cases of food-borne illness occurred, but fewer deaths were caused by foodborne disease agents than previously reported. Campylobacter spp. was responsible for the most cases of foodborne illness. Salmonella (nontyphoidal) caused the most deaths; Listeria monocytogenes also causing a significant number of deaths. In summary, the report indicates that foodborne pathogens have a significant impact on human health and the food industry in the United States.

In addition to human suffering, foodborne illnesses also have a substantial economic impact in the United States. The annual cost of foodborne illness in the U.S. is estimated at $5-$6 billion for loss of productivity and medical expenses (Marks and Roberts, 1993). The most costly food-borne illnesses are caused by Toxoplasma gondii, Salmonella spp., Campylobacter spp., and enterohemorrhagic Escherichia coli. New methods to prevent, reduce or eliminate foodborne disease agents at all points of the food chain, from farm to fork , are needed to improve the safety of the food supply to prevent illnesses and deaths and to prevent economic losses to the food industry.

2011 Project Description

Raw and processed foods are vulnerable to contamination during their production, distribution and sale. Thus, a wide variety of chemical preservatives are used in the food industry to prevent the growth of food spoiling and pathogenic bacteria.

However, health and economic concerns have led to an intensive search for natural alternatives, such as plant extracts that can safely be used as substitutes for antimicrobials and preservatives to partially or completely inhibit the growth of bacteria.

Phenolic compounds, natural plant extracts, are secondary metabolites which have antimicrobial and antioxidant characteristics. studies focused revealing the antimicrobial effects of phenolic compounds, such as Quercetin, Myricetin, Xanthohumol, Coumarin, Curcumin, Rutin, Thymoquinine and Chlorogenic Acid.

The main objective was to determine the lowest concentration of phenolics to inhibit the visible growth of the pathogenic bacteria which is recorded as the minimum inhibitory concentration (MIC). These results have been presented in part in abstracts presented at the IFT International meeting

2011 Impact

Three of the most common pathogen and food spoilage bacteria E. coli 0157:H7 (ATTC 35150), E. coli 0157:H7( ATTC 43895), and E. coli (swine fecal isolate) were treated with the eight phenolics by using the treatment doses of 100microliter of 5 ppm, 10 ppm, 15 ppm, and 20 ppm of solutions (pH 5-6). Obtained results were compared with the antimicrobial effects of the pure compound, solvent, along with a negative control treatment (no antimicrobial agent and no solvent added). Incubation was performed in Mueller Hinton Broth at 37C for up to 60 hours. The MICs were determined using the broth micro-dilution method and density (OD) assay with Biotek Synergy 4 Multi-Mode Microplate Reader.

Our results showed that, all of the selected phenolics inhibited the microbial growth while Xanthohumol, Myricetin and Quercetin showed the highest antimicrobial effect with the MICs of >5 ppm. Natural sources of phenolic compounds contain major antibacterial components and have great potential to be used as natural antimicrobials and food preservatives.