Development of a novel microbicide for control of foodborne pathogens

doi:10.15406/mojfpt.2015.01.00003

MOJ

eISSN: 2381-182X

Food Processing & Technology

Mini Review Volume 1 Issue 1

Development of a novel microbicide for control of foodborne pathogens

Tong Zhao

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Center for Food Safety, University of Georgia, Georgia

Correspondence: Tong Zhao, Center for Food Safety, University of Georgia, Georgia

Received: April 02, 2015 | Published: May 12, 2015

Citation: Zhao T. Development of a novel microbicide for control of foodborne pathogens. MOJ Food Process Technol. 2015;1(1):6-7. DOI: 10.15406/mojfpt.2015.01.00003

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Introduction

The efficacy of many chlorine-based sanitizers currently used in food processing facilities is reduced when organic matter is present, whereby their usefulness as an antimicrobial is mitigated. Effective sanitizers that are effective, practical, cost-efficient and environmentally-friendly are needed to control food borne pathogens and their biofilms in food processing facilities. To gain all these purposes and at the same time to ensure the quality of treated food unchanged, various organic acids and detergents were evaluated individually and in combination for their bactericidal activity. We revealed that either organic acids or detergents did not show significant bactericidal effect when used individually. However, a combination just including two chemicals, levulinic acid and sodium dodecyl sulfate (SDS) can inactivate all bacteria as tested. Results revealed that a solution with 0.5% levulinic acid and 0.05% SDS provided a ca. 7 log CFU/ml reduction of E. coli O157:H7, S. Enteritidis, and S. Typhimurium DT104 within 1 min (processing time). Its effect as a rinse solution to remove E. coli O157:H7 and Salmonella was confirmed with romaine lettuce and poultry skin.¹ The advantage of levulinic acid over other organic acids is its characteristics; including it does not produce corrosion, its safety to human, and it can keep the quality of treated produce.

The number of sprout-related outbreaks has an increased tendency. The method to kill all the pathogens (human and plant) in seeds and to guarantee their germination rate is not interfered is demanded. Studies were done to determine the best concentration and exposure time for treatment of the alfalfa seeds with levulinic acid plus SDS to inactivate E. coli O157:H7 and Salmonella and not adversely affect seed germination. Alfalfa seeds contaminated with E. coli O157:H7 were subsequently dried at 21°C in a laminar flow hood for up to 72 h. Results demonstrated that a 5-min treatment at 21°C of alfalfa seeds contaminated with 108 E. coli O157:H7 or S. Typhimurium DT 104 of a solution containing 0.5% levulinic acid plus 0.05% SDS reduced E. coli O157:H7 and S. Typhimurium DT 104 populations by 5.6 and 6.4 log10 CFU/g, respectively. Treatment of seeds contaminated with 104 E. coli O157:H7 or S. Typhimurium CFU in a glass beaker and then in a stomacher bag with 0.5% levulinic acid plus 0.05% SDS at 21°C for a total of 20 min reduced E. coli O157:H7 or S. Typhimurium DT 104 in all samples (25 g) to undetectable levels by a direct plating method (<0.7 log10 CFU/g), but 8 of 10 samples were detectable by selective enrichment culture. Germination rates of alfalfa seeds treated with 0.5% levulinic acid plus 0.05% SDS for up to 1 h at 21°C were compared with a treatment of 20 mg calcium hypochlorite/ml and tap water only treatment. Results revealed that treatment with 0.5% levulinic acid plus 0.05% SDS for 1 h at 21°C did not adversely affect alfalfa seed germination compared to the control treatment with tap water, whereas treatment with 20 mg calcium hypochlorite for 1 h substantially reduced germination.² Currently their efficacy to kill all the plant pathogens is in progress. Many food borne outbreaks were closely linked with the biofilm formation in food processing facilities. The antimicrobial efficacy of this sanitizer applied either as a liquid or as foam (under pressure) demonstrated excellent biofilm removal specificity when compared with other sanitizers.^3,4 Contaminated slicer surfaces sprayed with this sanitizer as a foam (45-55 psi) reduced within 1 min 6.0 to 8.0 log CFU of the three pathogens per blade. Results revealed that pathogenic transfer rate between slicers and foods depend on food contact locations on slicers, the composition of food, and the nature of pathogens. Also, Levulinic-based sanitizer applied as foam can be used as a potential method to remove microbial contamination on the surface of deli slicers.⁵

The safety of levulinic acid were tested for humans and thoroughly evaluated by world health organization because its addition in tobacco and it has GRAS status for direct addition to food as a flavoring substance or adjunct (FDA 2008, 21 CFR, 172.515). We confirmed its property by soaking whole Romaine lettuce in 0.5% levulinic acid plus 0.05% SDS for either 15 or 30 min, then rinsing the lettuce with water three times and storing the treated lettuce and lettuce rinsed with water only (control) at 5°C for up to 14 days to observe the color change. There were no visual differences between the lettuce treated with 0.5% levulinic acid plus 0.05% SDS for 15 or 30 min and the lettuce rinsed with water only. Sodium dodecyl sulfate has GRAS status for multipurpose additives (FDA 2007, 21 CFR, 172.822). Its safety has been demonstrated by dental industry. Since our first publication with development of this sanitizer, many researchers have validated its application in different field. Dental doctors use it as a mouth rinse to remove dental biofilms in vitro and in vivo. Their studies revealed its efficacy to remove dental biofilm is significantly better than the commonly used Listerine.⁶ Its efficacy as virocide to inactivate norovirus and influenza A virus in various foods has been validated by different researchers^7,8 at present its application in pre-harvested produce for inactivation of food borne pathogens and plant pathogens has been documented.

Conclusion

An alternative to chlorine-based sanitizer is developed and validated for its efficacy in various applications at food processing facilities for reduction of food borne pathogens and for their biofilm removal.^9,10 At present a patent for its application was issued by U.S. patent office and licensed by Health Pro Inc. Its efficacy has been validated in various applications.