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Gu G, Ding Q, Redding M, Yang Y, O'Brien R, Gu T, Zhang B, Zhou B, Micallef SA, Luo Y, Fonseca JM, Nou X. Differential microbiota shift on whole romaine lettuce subjected to source or forward processing and on fresh-cut products during cold storage. Int J Food Microbiol 2024; 416:110665. [PMID: 38457887 DOI: 10.1016/j.ijfoodmicro.2024.110665] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 02/28/2024] [Accepted: 03/05/2024] [Indexed: 03/10/2024]
Abstract
Romaine lettuce in the U.S. is primarily grown in California or Arizona and either processed near the growing regions (source processing) or transported long distance for processing in facilities serving distant markets (forward processing). Recurring outbreaks of Escherichia coli O157:H7 implicating romaine lettuce in recent years, which sometimes exhibited patterns of case clustering in Northeast and Midwest, have raised industry concerns over the potential impact of forward processing on romaine lettuce food safety and quality. In this study, freshly harvested romaine lettuce from a commercial field destined for both forward and source processing channels was tracked from farm to processing facility in two separate trials. Whole-head romaine lettuce and packaged fresh-cut products were collected from both forward and source facilities for microbiological and product quality analyses. High-throughput amplicon sequencing targeting16S rRNA gene was performed to describe shifts in lettuce microbiota. Total aerobic bacteria and coliform counts on whole-head lettuce and on fresh-cut lettuce at different storage times were significantly (p < 0.05) higher for those from the forward processing facility than those from the source processing facility. Microbiota on whole-head lettuce and on fresh-cut lettuce showed differential shifting after lettuce being subjected to source or forward processing, and after product storage. Consistent with the length of pre-processing delays between harvest and processing, the lettuce quality scores of source-processed romaine lettuce, especially at late stages of 2-week storage, was significantly higher than of forward-processed product (p < 0.05).
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Affiliation(s)
- Ganyu Gu
- Environmental Microbial and Food Safety Laboratory, USDA ARS, Beltsville, MD 20705, United States of America
| | - Qiao Ding
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742, United States of America
| | - Marina Redding
- Environmental Microbial and Food Safety Laboratory, USDA ARS, Beltsville, MD 20705, United States of America
| | - Yishan Yang
- Environmental Microbial and Food Safety Laboratory, USDA ARS, Beltsville, MD 20705, United States of America
| | - Regina O'Brien
- Food Quality Laboratory, USDA ARS, Beltsville, MD 20705, United States of America
| | - Tingting Gu
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, United States of America
| | - Boce Zhang
- Food Science and Human Nutrition Department, University of Florida, Gainesville, FL 32611, United States of America
| | - Bin Zhou
- Food Quality Laboratory, USDA ARS, Beltsville, MD 20705, United States of America
| | - Shirley A Micallef
- Department of Plant Science and Landscape Architecture, University of Maryland, College Park, MD 20742, United States of America; Centre for Food Safety and Security Systems, University of Maryland, College Park, MD 20742, United States of America
| | - Yaguang Luo
- Environmental Microbial and Food Safety Laboratory, USDA ARS, Beltsville, MD 20705, United States of America; Food Quality Laboratory, USDA ARS, Beltsville, MD 20705, United States of America
| | - Jorge M Fonseca
- Food Quality Laboratory, USDA ARS, Beltsville, MD 20705, United States of America
| | - Xiangwu Nou
- Environmental Microbial and Food Safety Laboratory, USDA ARS, Beltsville, MD 20705, United States of America.
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Arienzo A, Gallo V, Tomassetti F, Antonini G. Implication of Sodium Hypochlorite as a Sanitizer in Ready-to-Eat Salad Processing and Advantages of the Use of Alternative Rapid Bacterial Detection Methods. Foods 2023; 12:3021. [PMID: 37628019 PMCID: PMC10453429 DOI: 10.3390/foods12163021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Revised: 08/07/2023] [Accepted: 08/09/2023] [Indexed: 08/27/2023] Open
Abstract
The use of disinfection agents in the washing processing of ready-to-eat (RTE) vegetables, especially sodium hypochlorite, is a common industrial practice performed to enhance microbiological quality. However, some studies have reported a restart of bacterial growth and a substantial increase in bacterial load during early storage associated with the use of disinfection agents, which might represent a risk for consumers. We evaluated the effect of sodium hypochlorite on bacterial growth trends during the shelf-life in Lactuca sativa, simulating the industrial procedures for RTE vegetable packaging. Immediately after sodium hypochlorite treatment, an effective abatement of the bacterial load was observed, followed by a restart of growth throughout storage. After 5 days, the bacterial load was close to that reached by the control samples, indicating that the net increase in bacterial load was significantly higher in the treated samples. This might be ascribed to the reduction in competitive microflora and/or to the induction of adaptive responses by resting bacteria, which might select disinfectant-resistant bacteria. These findings elicit some concerns about the actual duration of the shelf-life; products might decrease their microbiological quality earlier during storage, pointing out the need to better clarify the impact of sodium hypochlorite as a sanitizer to closer consider its use in RTE vegetable processing. Furthermore, due to the importance of the rapid estimation of bacterial load and the early detection of foodborne pathogens throughout the food chain, the accuracy of the rapid bacteria detection method, the Micro Biological Survey (MBS), and its effectiveness for microbiological analyses of RTE vegetables were evaluated.
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Grants
- Excellence Department grant National Funding for Centers of Excellence (Science Department 2023-2027, Roma Tre University, MIUR, Articolo 1, Commi 314-337, Legge 232/2016)
- Missione 4 Componente 2, "Dalla ricerca all'impresa, Investimento 1.4 Next Generation EU PNRR Rome Technopole (ECS_00000024), by MUR, PNRR
- Project grant number CUP: F85F21001680009 LazioInnova SpA, IMPLEMENTA4GAMMA
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Affiliation(s)
- Alyexandra Arienzo
- National Institute of Biostructures and Biosystems (INBB), Viale delle Medaglie d’Oro 305, 00136 Rome, Italy;
| | - Valentina Gallo
- Department of Science, Roma Tre University, Viale Guglielmo Marconi 446, 00146 Rome, Italy; (V.G.); (F.T.)
| | - Federica Tomassetti
- Department of Science, Roma Tre University, Viale Guglielmo Marconi 446, 00146 Rome, Italy; (V.G.); (F.T.)
| | - Giovanni Antonini
- National Institute of Biostructures and Biosystems (INBB), Viale delle Medaglie d’Oro 305, 00136 Rome, Italy;
- Department of Science, Roma Tre University, Viale Guglielmo Marconi 446, 00146 Rome, Italy; (V.G.); (F.T.)
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Voutsinos-Frantzis O, Karavidas I, Petropoulos D, Zioviris G, Fortis D, Ntanasi T, Ropokis A, Karkanis A, Sabatino L, Savvas D, Ntatsi G. Effects of NaCl and CaCl 2 as Eustress Factors on Growth, Yield, and Mineral Composition of Hydroponically Grown Valerianella locusta. PLANTS (BASEL, SWITZERLAND) 2023; 12:1454. [PMID: 37050080 PMCID: PMC10097257 DOI: 10.3390/plants12071454] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 03/23/2023] [Accepted: 03/23/2023] [Indexed: 06/19/2023]
Abstract
Corn salad (Valerianella locusta) is a popular winter salad, cultivated as an ingredient for ready-to-eat salads. The application of mild salinity stress (eustress) can increase the flavor and reduce the nitrate content of certain crops but, at the same time, a wrong choice of the eustress type and dose can negatively affect the overall productivity. In this research, the effects of different isosmotic salt solutions, corresponding to two different electrical conductivity (EC) levels, were investigated on the yield and mineral composition of hydroponically grown Valerianella locusta "Elixir". Five nutrient solutions (NS) were compared, including a basic NS used as the control, and four saline NS were obtained by adding to the basic NS either NaCl or CaCl2 at two rates each, corresponding to two isosmotic salt levels at a low and high EC level. Corn salad proved moderately susceptible to long-term salinity stress, suffering growth losses at both low and high EC levels of saline solution, except from the low NaCl treatment. Hence, it appears that mild salinity stress induced by NaCl could be employed as an eustress solution and corn salad could be cultivated with low-quality irrigation water (20 mM NaCl) in hydroponic systems.
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Affiliation(s)
- Orfeas Voutsinos-Frantzis
- Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Ioannis Karavidas
- Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Dimitrios Petropoulos
- Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Georgios Zioviris
- Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Dimitrios Fortis
- Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Theodora Ntanasi
- Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Andreas Ropokis
- Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Anestis Karkanis
- Department of Agriculture Crop Production and Rural Environment, University of Thessaly, 38446 Volos, Greece
| | - Leo Sabatino
- Department of Agricultural, Food and Forest Sciences (SAAF), University of Palermo, Viale delle Scienze, Ed. 5, 90128 Palermo, Italy
| | - Dimitrios Savvas
- Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
| | - Georgia Ntatsi
- Laboratory of Vegetable Production, Department of Crop Science, Agricultural University of Athens, 11855 Athens, Greece
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Xylia P, Chrysargyris A, Botsaris G, Skandamis P, Tzortzakis N. Salmonella Enteritidis survival in different temperatures and nutrient solution pH levels in hydroponically grown lettuce. Food Microbiol 2022; 102:103898. [PMID: 34809930 DOI: 10.1016/j.fm.2021.103898] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Revised: 08/23/2021] [Accepted: 09/08/2021] [Indexed: 11/04/2022]
Abstract
Due to climate change, with contaminated and less fertile soils, and intense weather phenomena, a turn towards hydroponic vegetable production has been made. Hydroponic cultivation of vegetables is considered to be a clean, safe and environmentally friendly growing technique; however, incidence of microbial contamination i.e. foodborne pathogens, might occur, endangering human health. The aim of this study was to investigate the effects of different plant growth stages, pH (values 5, 6, 7, 8) and bacterial inoculum levels (3 and 6 log cfu/mL) on hydroponically cultivated lettuce spiked with Salmonella Enteritidis. The results revealed that the pH and inoculum levels affected the internalization and survival of the pathogen in the hydroponic environment and plant tissue. Younger plants were found to be more susceptible to pathogen internalization compared to older ones. Under the current growing conditions (hydroponics, pH and inoculum levels), no leaf internalization was observed at all lettuce growth stages, despite the bacterium presence in the hydroponic solution. Noticeably, bacteria load at the nutrient solution was lower in low pH levels. These results showed that bacterium presence initiates plant response as indicated by the increased phenols, antioxidants and damage index markers (H2O2, MDA) in order for the plant to resist contamination by the invader. Nutrient solution management can result in Taylor-made recipes for plant growth and possible controlling the survival and growth of S. Enteritidis by pH levels.
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Affiliation(s)
- Panayiota Xylia
- Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol, Cyprus
| | - Antonios Chrysargyris
- Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol, Cyprus
| | - George Botsaris
- Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol, Cyprus
| | - Panagiotis Skandamis
- Faculty of Food Science & Technology, Agricultural University of Athens, Athens, Greece
| | - Nikolaos Tzortzakis
- Department of Agricultural Sciences, Biotechnology and Food Science, Cyprus University of Technology, Limassol, Cyprus.
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Łepecka A, Zielińska D, Szymański P, Buras I, Kołożyn-Krajewska D. Assessment of the Microbiological Quality of Ready-to-Eat Salads-Are There Any Reasons for Concern about Public Health? INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2022; 19:ijerph19031582. [PMID: 35162605 PMCID: PMC8835243 DOI: 10.3390/ijerph19031582] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/03/2021] [Accepted: 01/27/2022] [Indexed: 01/01/2023]
Abstract
Ready-to-eat food products can be readily consumed without further preparation and are convenient for busy on-the-go consumers. The objective of the study was to assess the microbiological quality of ready-to-eat salads. Thirty RTE salads were tested for the presence of bacteria, yeasts, and molds using the TEMPO and agar plate method. The study demonstrated that most of the tested products were characterized by varying microbiological quality. The total number of mesophilic microbiotas was about 6 log CFU g-1. The high number of microorganisms was due to yeast and molds or Enterobacteriaceae. Half of the salads were contaminated with E. coli and three salads were contaminated with S. aureus. LAB were also found, which can be explained mainly by a dairy ingredient. In some salads, Salmonella spp. and L. monocytogenes were detected (26.7% and 33.3% of the samples, respectively). Based on the conducted tests, it was found that the microbiological quality was not satisfactory. The results presented in this study indicate that there is a significant problem of the presence of pathogens. Manufacturers should strive to reduce the possibility of microbial contamination through the use of widely understood hygiene of the production process, using hurdle technology, including the modified atmosphere and refrigerated storage.
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Affiliation(s)
- Anna Łepecka
- Department of Meat and Fat Technology, Prof. Waclaw Dabrowski Institute of Agriculture and Food Biotechnology—State Research Institute, 02-532 Warsaw, Poland;
- Correspondence:
| | - Dorota Zielińska
- Department of Food Gastronomy and Food Hygiene, Institute of Human Nutrition Sciences, Warsaw University of Life Sciences-SGGW, 02-776 Warsaw, Poland; (D.Z.); (I.B.); (D.K.-K.)
| | - Piotr Szymański
- Department of Meat and Fat Technology, Prof. Waclaw Dabrowski Institute of Agriculture and Food Biotechnology—State Research Institute, 02-532 Warsaw, Poland;
| | - Izabela Buras
- Department of Food Gastronomy and Food Hygiene, Institute of Human Nutrition Sciences, Warsaw University of Life Sciences-SGGW, 02-776 Warsaw, Poland; (D.Z.); (I.B.); (D.K.-K.)
| | - Danuta Kołożyn-Krajewska
- Department of Food Gastronomy and Food Hygiene, Institute of Human Nutrition Sciences, Warsaw University of Life Sciences-SGGW, 02-776 Warsaw, Poland; (D.Z.); (I.B.); (D.K.-K.)
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