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

ArticleinJournal of Food Science 77(7):M391-6 · July 2012with28 Reads
DOI: 10.1111/j.1750-3841.2012.02719.x · Source: PubMed
Unlabelled: 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.
    • "Organic acids are Generally Recognized As Safe (GRAS) and their bactericidal efficacy against E. coli O157:H7, Listeria monocytogenes and Salmonella on fresh produce was previously investigated (Akbas and Olmez, 2007; Ganesh et al., 2012; Huang and Chen, 2011; Sagong et al., 2011; Samara and Koutsoumanis, 2009). Lactic acid exhibits increased effectiveness against E. coli O157:H7 compared to other organic acids (malic, citric, tartaric or acetic acid) when applied on fresh spinach or lettuce leaves at ambient temperature (20–25 °C). "
    [Show abstract] [Hide abstract] ABSTRACT: Aqueous extract of Origanum vulgare (oregano), sodium hypochlorite (60 and 300ppm of free chlorine), Citrox® (containing citric acid and phenolic compounds [bioflavonoids] as active ingredients), vinegar, lactic acid, and double combinations of Citrox, lactic acid and oregano were evaluated against Escherichia coli O157:H7 and total mesophilic microbiota on fresh-cut spinach and lettuce and for their impact on color of treated vegetables. Spinach and lettuce leaves were inoculated with E. coli O157:H7 to a level of 5-6logCFU/g and immersed in washing solutions for 2 or 5min at 20°C, followed by rinsing with ice water (30s). Bacterial populations on vegetables were enumerated immediately after washing and after storage of the samples at 5°C for 7days under 20% CO2: 80% N2. No significant post-washing microbial reductions were achieved by chlorinated water, whereas after storage total microbiota was increased by 2.4logCFU/g on lettuce. Vinegar wash was the most effective treatment causing E. coli O157:H7 reductions of 1.8-4.3logCFU/g. During storage, pathogen was further decreased to below the detection limit level (<2logCFU/g) and total microbiota exhibited the highest reductions compared to other treatments. Lactic acid reduced pathogen by 1.6-3.7logCFU/g after washing; however levels of total microbiota increased by up to 2logCFU/g on packaged lettuce during storage. Washing lettuce samples with oregano for 2min resulted in 2.1logCFU/g reduction of E. coli O157:H7. When Citrox was combined with oregano, 3.7-4.0logCFU/g reduction was achieved on spinach and lettuce samples, with no significant effect on color parameters. Additionally, rinsing with ice water after decontamination treatments contributed to maintenance of color of the treated vegetables. In conclusion, the results indicated that vinegar, lactic acid or oregano aqueous extract alone or in combination, as alternative washing solutions to chlorine, may be effectively used to control E. coli O157:H7 and sustain acceptable appearance of fresh cut spinach and lettuce.
    Article · Dec 2015
    • "It was followed by electrostatic spraying of malic and lactic acids and grape seed extract on spinach and lettuce. It eliminated the pathogens, improved the safety and lowered the public health risk (Ganesh et al. 2012 ). Noroviruses are common causes of food-borne gastroenteritis . "
    [Show abstract] [Hide abstract] ABSTRACT: Grapes (Vitis vinifera) are universally appreciated fruits for their delicacy and nutrition. All the more fame stems from their fermentation products wines. The by-product pomace comprising of skin and seeds often ends up as wastes. Lately, the seeds have been discovered to contain an ample amount of diverse bioactive compounds. Polyphenols are found in abundance in the seeds, proanthocyanidin being the most prominent class. The seed extracts are increasingly being recognized as human food supplement for disease prevention and overall health promotion. Their uses have ramified to antioxidant, anti-inflammatory, antilipemic, antihypertensive, hepatoprotective, osteoprotectant, antidiabetic, neuroprotective, anticancer and antimicrobial agents. Now that nutrient recovery from food by-products and residues as well as fortification has emerged as thrust areas, the relevance of grape seed extract deserves exploration. This chapter presents a complete account of the current state of knowledge and future directions.
    Chapter · Jan 2015 · International journal of food microbiology
    • "Furthermore, grape seed extract has been shown to be very effective against S. aureus [11] and against S. Typhimurium on spinach, in conjunction with malic acid and lactic acid in electrostatic sprays, resulting in 2.3 to 3.3 log CFU g -1 reductions [14]. Similar studies against E. coli O157:H7 with spinach and iceberg lettuce, using grape seed extract at 2% and 3% concentration in electrostatic sprays, yielded a 2.1 and 3.8 log reduction, respectively , by day 14 [13]. In the present study, by day 3, treatment with 3% grape seed extract showed reductions of 2.6 log CFUg -1 (mature spinach), 2.3 log CFUg -1 (baby spinach), and 1.8 log CFUg -1 (iceberg lettuce). "
    Article · Nov 2014 · International journal of food microbiology
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