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Liao C, Wang L. Evaluation of the bacterial populations present in Spring Mix salad and their impact on the behavior of Escherichia coli O157:H7. Food Control 2021. [DOI: 10.1016/j.foodcont.2021.107865] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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Dakwa V, Powell S, Eyles A, Gracie A, Tamplin M, Ross T. Effect of peroxyacetic acid treatment and bruising on the bacterial community and shelf-life of baby spinach. Int J Food Microbiol 2021; 343:109086. [PMID: 33631605 DOI: 10.1016/j.ijfoodmicro.2021.109086] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Revised: 01/25/2021] [Accepted: 01/27/2021] [Indexed: 10/22/2022]
Abstract
The importance of leaf integrity, i.e. the effects of bruising (mechanical damage), and sanitisation with peroxyacetic acid (PAA) on bacterial communities of ready-to-eat baby spinach remains unclear. Two shelf-life studies were conducted at 4 °C to investigate the effect of bruising and sanitisation on the growth of spoilage microorganisms. In the first experiment, both bruising treatments (100% and 40% of leaves) halved shelf life to 12 d, whereas intact leaves had a shelf-life of 23 d. Bruising had no influence on bacterial diversity during shelf-life, though some differences in the relative abundance of minor genera were observed. Pseudomonas and Pantoea were the most dominant bacterial genera, regardless of bruising treatment. High throughput amplicon sequencing also identified other spoilage bacteria including Chryseobacterium, Stenotrophomonas, Bacillus, Sphingobacterium, Erwinia and Flavobacterium. In the second experiment, washing of intact baby spinach with a sanitiser (80 mg/L: PAA) reduced microbial load as determined by aerobic plate count but did not immediately affect the presence/relative abundance of most of the genera of spoilage bacteria observed. During shelf-life, the bacterial diversity of sanitised leaves was significantly lower than on water-washed leaves. Although sanitisation resulted in a higher initial log reduction in microbial load compared to control (portable tap water), sanitisation did not extend the shelf life of baby spinach (23 d). Sanitised spinach had reduced bacterial diversity however, by the end of shelf life, both sanitised and water-washed spinach was dominated by Pseudomonas and Pantoea spoilage bacteria. This study demonstrated for the first time that the shorter shelf life of bruised leaves was related to faster microbial growth rather than changes in bacterial diversity or community composition.
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Affiliation(s)
- Vongai Dakwa
- ARC Training Centre for Innovative Horticultural Products, Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania 7001, Australia.
| | - Shane Powell
- ARC Training Centre for Innovative Horticultural Products, Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania 7001, Australia.
| | - Alieta Eyles
- ARC Training Centre for Innovative Horticultural Products, Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania 7001, Australia.
| | - Alistair Gracie
- ARC Training Centre for Innovative Horticultural Products, Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania 7001, Australia.
| | - Mark Tamplin
- ARC Training Centre for Innovative Horticultural Products, Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania 7001, Australia.
| | - Tom Ross
- ARC Training Centre for Innovative Horticultural Products, Tasmanian Institute of Agriculture, University of Tasmania, Private Bag 54, Hobart, Tasmania 7001, Australia.
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Banach JL, van Bokhorst-van de Veen H, van Overbeek LS, van der Zouwen PS, Zwietering MH, van der Fels-Klerx HJ. Effectiveness of a peracetic acid solution on Escherichia coli reduction during fresh-cut lettuce processing at the laboratory and industrial scales. Int J Food Microbiol 2020; 321:108537. [PMID: 32070904 DOI: 10.1016/j.ijfoodmicro.2020.108537] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 11/14/2019] [Accepted: 01/22/2020] [Indexed: 11/17/2022]
Abstract
Fresh leafy greens like lettuce can be consumed raw and are susceptible to foodborne pathogens if they become contaminated. Recently, the number of reported pathogenic foodborne outbreaks related to leafy greens has increased. Therefore, it is important to try to alleviate the human health burden associated with these outbreaks. Processing of fresh-cut lettuce, including washing, is a step in the supply chain that needs to be well controlled to avoid cross-contamination. Current measures to control the quality of lettuce during washing include the use of chemicals like chlorine; however, questions regarding the safety of chlorine have prompted research for alternative solutions with peracetic acid (PAA). This study evaluates the effectiveness of a PAA (c.a. 75 mg/L) solution on the reduction of a commensal E. coli strain during the washing of fresh-cut lettuce. Experiments were performed at the laboratory scale and validated at the industrial scale. We observed that the use of PAA was not adversely affected by the organic load in the water. The contact time and dose of the PAA showed to be relevant factors, as observed by the approximately 5-log reduction of E. coli in the water. Results showed that once introduced during washing, E. coli remained attached to the lettuce, thus supporting the need to control for pathogenic bacteria earlier in the supply chain (e.g., during primary production) as well as during washing. Moreover, our results showed that the use of PAA during washing did not have an apparent effect on the levels of fluorescent pseudomonads (FP) and total heterotrophic bacteria (THB) in lettuce. Overall, our results at the laboratory and industrial scales confirmed that during the processing of fresh-cut produce, where the accumulation of soil, debris, and other plant exudates can negatively affect washing, the use of a PAA (c.a. 75 mg/L) solution was an effective and safe wash water disinfectant that can potentially be used at the industrial scale.
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Affiliation(s)
- J L Banach
- Wageningen Food Safety Research, P.O. Box 230, 6700 AE Wageningen, the Netherlands.
| | | | - L S van Overbeek
- Wageningen Plant Research, P.O. Box 16, 6700 AA Wageningen, the Netherlands
| | - P S van der Zouwen
- Wageningen Plant Research, P.O. Box 16, 6700 AA Wageningen, the Netherlands
| | - M H Zwietering
- Food Microbiology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, the Netherlands
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Meireles A, Faia S, Giaouris E, Simões M. Antimicrobial susceptibility and sessile behaviour of bacteria isolated from a minimally processed vegetables plant. BIOFOULING 2018; 34:1150-1160. [PMID: 30663892 DOI: 10.1080/08927014.2018.1554742] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Revised: 11/24/2018] [Accepted: 11/24/2018] [Indexed: 06/09/2023]
Abstract
In this study, 20 heterotrophic bacteria from a minimally processed vegetables (MPV) plant were tested for their susceptibilities to five antibiotics (tetracycline, erythromycin, ampicillin, levofloxacin and ciprofloxacin), their (co)aggregation abilities and their survival under gastric simulated conditions. Peracetic acid (PA) and sodium hypochlorite (SH), both at 50 ppm, were evaluated for their abilities to control biofilms of these bacteria. In general, the Gram-negative bacteria were found to be more resistant to the selected antibiotics. Two isolates, Rhanella aquatilis and Stenotrophomonas maltophilia, demonstrated multidrug resistance. Only Rhodococcus erythropolis presented aggregation potential, while no bacterium survived under the gastric conditions. The biofilm experiments showed PA as less efficient than SH in killing biofilms and neither of the disinfectants was able to fully eliminate the biofilms. Significant regrowth was observed for most of the biofilms. The results indicate that alternative and/or complementary disinfection strategies are required to guarantee food safety.
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Affiliation(s)
- Ana Meireles
- a LEPABE, Department of Chemical Engineering, Faculty of Engineering , University of Porto , Porto , Portugal
| | - Sílvia Faia
- a LEPABE, Department of Chemical Engineering, Faculty of Engineering , University of Porto , Porto , Portugal
| | - Efstathios Giaouris
- b Department of Food Science and Nutrition, Faculty of the Environment , University of the Aegean , Myrina , Lemnos , Greece
| | - Manuel Simões
- a LEPABE, Department of Chemical Engineering, Faculty of Engineering , University of Porto , Porto , Portugal
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