Electrostatic Spraying of Food-Grade Organic and Inorganic Acids and Plant Extracts to Decontaminate Escherichia coli O157:H7 on Spinach and Iceberg Lettuce

Dept of Food Science, Univ of Arkansas, Fayetteville, AR 72704, USA.
Journal of Food Science (Impact Factor: 1.7). 07/2012; 77(7):M391-6. DOI: 10.1111/j.1750-3841.2012.02719.x
Source: PubMed


The prevalence of foodborne illnesses is continually on rise. In the U.S.A., Escherichia coli O157:H7 (E. coli) has been associated with several outbreaks in minimally processed foods. Spinach and lettuce pose higher food safety risks and recurring food recalls suggest the insufficiency of current disinfection strategies. We aimed at offering a natural antimicrobial alternative using organic acids (malic, tartaric, and lactic acids [MA, TA, and LA, respectively]) and grape seed extract (GSE) and a novel application method using electrostatic spraying to evenly distribute the antimicrobials onto produce. Spinach and lettuce samples were washed, sanitized with sodium hypochlorite solution (6.25 mL/L), dip inoculated in water containing E. coli (7.0 log CFU/mL) for 24 h, and rewashed with sterile water to remove nonadhered pathogens. The samples were sprayed electrostatically with MA, LA, and GSE alone and in combinations and for comparison, with phosphoric acid (PA) and pH controls with deionized water adjusted to 1.5/2.3/3.6 and stored at 4 °C. When combined with LA (3%), MA (3%) showed 2.1 to 4.0 log CFU/g reduction of E. coli between the days 1 and 14 on spinach and 1.1 to 2.5 log CFU/g reduction on lettuce. Treatment with PA (1.5%) and PA (1.5%)-GSE (2%) exhibited 1.1 to 2.1 log CFU/g inhibition of E. coli on spinach during the 14-d storage. Our findings demonstrated the efficacy of electrostatic spraying of MA, LA, and GSE on fresh produce to improve the safety and lower the public health burden linked to produce contamination.

Practical application:
Electrostatic spraying is an emerging technique that can be adopted to improve the distribution and application of antimicrobials during fresh produce sanitation. Relatively simple and quick, the process can access most/all parts of produce surface and offer protection from food pathogens. The use of malic and lactic acids with or without grape seed extract can serve as effective antimicrobials when sprayed electrostatically, lowering the risk from postcontamination issues with spinach and iceberg lettuce. This application technology can be extended to improve the commercial food safety of other produce, fruits, poultry, and meat.

20 Reads
  • [Show abstract] [Hide abstract]
    ABSTRACT: The objective of the study was to determine the effects of organic acids and plant extract alone and in combination when applied by electrostatic spraying on Escherichia coli O157:H7-inoculated cantaloupe cubes. Inoculated cubes were sprayed with malic (M) and lactic (L) acids and grape seed extract at different concentrations (alone and various combinations) then stored at 4C. Under optimized concentrations, ML 2% was able to reduce E. coli O157:H7 by 1.9 logs after 12 days of storage and was significantly different from the controls (P < 0.05). Increasing the concentration of M (4%) alone and in combination with L (2%) caused an increase in log reduction (4.6 logs). These treatments can be used as alternatives to commercial sanitizers in order to improve the safety of fresh-cut cantaloupe cubes. Multiple hurdle technology of electrostatic sprayer combined with natural antimicrobials can be effective in improving the safety of food. Electrostatic sprayer is a technology that can be used to enhance the effectiveness of antimicrobials. Organic acids and plant extracts can be used as antimicrobials to efficiently reduce contaminated cantaloupe cubes when combined with electrostatic sprayer. This multiple hurdle technology can be used in different food industry settings.
    Journal of Food Safety 02/2013; 33(1). DOI:10.1111/jfs.12024 · 0.93 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose of the review: Fresh cut produce continues to be implicated in foodborne illness outbreaks with the principle pathogens being norovirus, Escherichia coli O157:H7, Salmonella, Listeria monocytogenes and enteric protozoan. There has been a strong reliance on post-harvest washing to remove field acquired contamination and has been the subject of intensive research over the last 15 years. This review focuses on recent advances in the efficacy of different approaches to inactivate, remove or minimize cross-contamination of human pathogens associated with post-harvest fresh produce. Findings: Post-harvest washing only achieves a negligible reduction in human pathogen levels but can significantly increase the potential of cross-contamination between batches. Consequently recent advances in produce washing have focused on reducing crosscontamination events through stabilizing sanitizers (ie, chlorine) in the presence of high organic loading to retain residual antimicrobial activity (organic acids). Alternative interventions such as electrochemical oxidation are directed at decontaminating wash water as opposed to inactivating pathogens directly on produce. More successful produce decontamination technologies are not based on washing but rather on sanitizers applied in the gas phase or physical techniques such as gas plasma, UV and E-beams. Directions for future research: With the limitations of aqueous-based washing it can be envisaged that a post-wash intervention step will be implemented for controlling human pathogens associated with fresh produce. Transferring technologies from the laboratory to commercial processing will be challenging and the focus of future research.
    Stewart Postharvest Review 03/2013; 9(1):1-8. DOI:10.2212/spr.2013.1.3
  • [Show abstract] [Hide abstract]
    ABSTRACT: A screening in a sugar snap packaging company showed a converged build-up of aerobic psychrotrophic plate count (APC) (ca. 6.5logCFU/100mL), yeasts and molds (Y&M), and lactic acid bacteria (LAB) (both ca. 4.5logCFU/100mL) in the wash water in the absence of water sanitizer, and a low build-up of chemical oxygen demand (30±5mgO2/L) and turbidity (5.2±1.1NTU). Decontamination experiments were performed in the lab with Purac FCC 80® (80% L(+) lactic acid), two other commercial water sanitizers based on organic acids (NATRApHASe-ABAV®, and NATRApHASe-FVS®) and chlorine to evaluate their performance in reduction of the sugar snap microbial load as well as their functionality as disinfectant of the wash water to avoid cross-contamination. An additional 1log reduction of APC on the sugar snaps was achieved with lactic acid in the range 0.8 to 1.6%, ABAV 0.5%, and free chlorine 200mg/L when compared to a water wash, while no significant difference in the numbers of Y&M was obtained when washing in sanitizer compared to water. There was no significant influence of the studied concentration and contact time on decontamination efficiency. Treatment with lactic acid 0.8% resulted in a lower APC contamination on the sugar snaps than on the untreated and water washed samples for 10days. Chlorine 200mg/L was the only treatment able to maintain the Y&M load lower than the untreated samples throughout the entire storage duration. The use of water sanitizers could not extend the sensorial shelf-life. Microbial loads were not indicative/predictive of visual microbial spoilage (shelf-life limiting factor), whereas maturity and amount of damage at the calyx end of the pods were. The APC wash water contamination (5.2logCFU/100mL) was reduced significantly by chlorine 20 to 200mg/L (to 1.4logCFU/100mL), ABAV 0.5 to 1.5% (to 2.7logCFU/100mL), FVS 0.5% (to 2.7logCFU/100mL) and lactic acid 0.8 to 1.6% (to 3.4logCFU/100mL). Only the use of chlorine enabled the reduction of the Y&M wash water contamination significantly (from 3.4 to 1.4logCFU/100mL). The low physicochemical build-up of the sugar snap wash water during the industrial washing process makes free chlorine attractive as a water disinfectant to prevent bacterial and fungal cross-contamination, whereas the sanitizers based on organic acids are not, due to their weak water disinfection efficiency.
    International journal of food microbiology 09/2013; 167(2):161-169. DOI:10.1016/j.ijfoodmicro.2013.09.007 · 3.08 Impact Factor
Show more

Similar Publications