Assessment of the Microbiological Quality of Ready-to-Eat Salads-Are There Any Reasons for Concern about Public Health?

Smart Packaging with Disposable NFC-enabled Wireless Gas Sensors for Monitoring Food Spoilage

Gas sensors present an alternative to traditional off-package food quality assessment, due to their high sensitivity and fast response without the need of sample pretreatment. The safe integration of gas sensors into packaging without compromising sensitivity, response rate, and stability, however, remains a challenge. Such packaging integration of spoilage sensors is crucial for preventing food waste and transitioning toward more sustainable supply chains. Here, we demonstrate a wide-ranging solution to enable the use of gas sensors for the continuous monitoring of food spoilage, building upon our previous work on paper-based electrical gas sensors (PEGS). By comparing various materials commonly used in the food industry, we analyze the optimal membrane to encapsulate PEGS for packaging integration. Focusing on spinach as a high-value crop, we assess the feasibility of PEGS to monitor the gases released during its spoilage at low and room temperatures. Finally, we integrated the sensors with wireless communication and batteryless electronics, creating a user-friendly system to evaluate the spoilage of spinach, operated by a smartphone via near-field communication (NFC). The work reported here provides an alternative approach that surpasses traditional on-site and in-line monitoring, ensuring comprehensive monitoring of food shelf life.

Extended-spectrum ß-lactamase (ESBL)- and Carbapenemase-producing Enterobacterales Isolated from Fresh Herbs and Salads at Retail Level in Switzerland

Fresh produce is usually consumed raw or minimally processed, making it a potential vehicle for the transmission of antimicrobial-resistant (AMR) microorganisms to humans. The objective of the study was to assess the occurrence of extended-spectrum ß-lactamase (ESBL)- and carbapenemase-producing Enterobacterales (ESBL-E and CPE), respectively, in 118 fresh herbs and 101 bagged salads collected at retail level in Switzerland and to characterize the isolates' phenotypic and genotypic properties using culture-based methods and whole genome sequencing (WGS). Of the fresh herbs, 6/118 contained ESBL-E and 7/118 yielded CPE. Of the salads, 13/101 contained ESBL-E and 1/101 CPE. Antimicrobial susceptibility testing (AST) identified 9/29 isolates as multidrug-resistant (MDR). ESBL-E were Escherichia coli (n = 6), Klebsiella pneumoniae (n = 4) Enterobacter chuandaensis (n = 1), and Kluyvera spp. (n = 1) carrying ß-lactamase (bla) genes belonging to the cefotaximase-München (blaCTX-M)-groups, Proteus spp. (n = 1) containing Hôpital-Universitaire-de-Genève-bla (blahugA), Raoultella ornithinolytica (n = 1) carrying sulfhydryl reagent variable bla (blaSHV), and Serratia fonticola (n = 7) carrying S. fonticula bla (blaFONA) genes. CPE were Enterobacter asburiae (n = 1) E. cloacae (n = 6) and E. vonholyi (n = 1) carrying imipenemase bla (blaIMI) genes. Several K. pneumoniae sequence types (STs) were identified (ST967, ST628, ST219, and ST1823), which have been linked to human disease and nosocomial outbreaks. They carried blaCTX-M-15 on plasmids detected globally in environmental and clinical samples. E. coli (ST10, ST48, ST609, ST2040, ST6215 and ST3580) and enterotoxigenic E. coli (ETEC) ST2040 carrying blaCTX-M-15 were found. E. cloacae (ST820 and ST1516) with blaIMI-1 have been found previously in clinical settings and community outbreaks. The occurrence and consumption of fresh produce containing MDR ESBL-E and CPE pose substantial public health risks and raise significant food safety concerns.

Assessment of the Microbiological Quality and Effect of Public Health of Ready-to-Eat Salad Samples in Isparta

Salmonella spp. and Citrobacter spp. are among the microorganisms causing important foodborne outbreaks. In this study, it was tried to determine the presence and rate of Salmonella spp. and Citrobacter spp. in salad samples collected from certain regions of province of Isparta in Türkiye. A total of 50 salad samples were analyzed. Classical culture technique was used for microbiological analysis of salad samples. Suspected isolates obtained were identified using the VITEK-2 system. Although no negative visual changes were observed in the salad samples used in the study, it was determined that the number of Gram-negative microorganisms was very high and six salad samples were not suitable for public health. In 50 salad samples, 2% Salmonella and 4% Citrobacter freundii were detected. In addition, it was determined that the Salmonella strain isolated from the salad sample was resistant to three different antibiotics and Citrobacter was resistant to two different antibiotics. Salmonella spp. and Citrobacter spp. are considered very dangerous to public health because they are associated with foodborne outbreaks and can develop antibiotic resistance very quickly. Salad producers should try to reduce the possibility of microbial contamination by using different technologies.

Detection of Listeria Species by Conventional Culture-Dependent and Alternative Rapid Detection Methods in Retail Ready-to-Eat Foods in Turkey

Foodborne pathogens, like Listeria monocytogenes, continue to inflict substantial financial losses on the food industry. Various methods for detecting Listeria in food have been developed and numerous studies have been conducted to compare the different methods. But, in recent years, new Listeria species have been identified, and currently the genus comprises 26 species. Therefore, it would be a more accurate approach to re-evaluate existing detection methods by considering new species. The present investigation involved the analysis of 42 ready-to-eat (RTE) foods, encompassing a variety of food categories, such as mezes, salads, dairy products, and meat products, with the aim of ascertaining the presence of Listeria. Among the traditional culture-dependent reference methods, the ISO 11290 method was preferred. The process of strain identification was conducted with the API Identification System. Furthermore, to ascertain the existence of L. monocytogenes and Listeria spp., the samples underwent additional analysis employing the VIDAS Immunoassay System, ELISA, and RT-PCR methodologies. Thus, four alternative approaches were employed in this study to compare not only the different methods used to determine Listeria while taking into account the newly identified Listeria species, but also to assess the compliance of retail RTE food items with microbiological criteria pertaining to the genus Listeria. Based on the conducted analyses, L. monocytogenes was conclusively determined to be present in one sample. The presence of Listeria spp. was detected in 30.9% of the samples, specifically in Turkish cig kofte, sliced salami, and salads.

One Health Perspectives on Food Safety in Minimally Processed Vegetables and Fruits: From Farm to Fork

While food markets and food production chains are experiencing exponential growth, global attention to food safety is steadily increasing. This is particularly crucial for ready-to-eat products such as fresh-cut salads and fruits, as these items are consumed raw without prior heat treatment, making the presence of pathogenic microorganisms quite frequent. Moreover, many studies on foodborne illnesses associated with these foods often overlook the transmission links from the initial contamination source. The prevention and control of the dissemination of foodborne pathogens should be approached holistically, involving agricultural production, processing, transport, food production, and extending to final consumption, all while adopting a One Health perspective. In this context, our objective is to compile available information on the challenges related to microbiological contamination in minimally handled fruits and vegetables. This includes major reported outbreaks, specific bacterial strains, and associated statistics throughout the production chain. We address the sources of contamination at each stage, along with issues related to food manipulation and disinfection. Additionally, we provide potential solutions to promote a healthier approach to fresh-cut fruits and vegetables. This information will be valuable for both researchers and food producers, particularly those focused on ensuring food safety and quality.

Minimally Processed Vegetables in Brazil: An Overview of Marketing, Processing, and Microbiological Aspects

The global demand for minimally processed vegetables (MPVs) has grown, driven by changes in the population's lifestyle. MPVs are fresh vegetables that undergo several processing steps, resulting in ready-to-eat products, providing convenience for consumers and food companies. Among the processing steps, washing-disinfection plays an important role in reducing the microbial load and eliminating pathogens that may be present. However, poor hygiene practices can jeopardize the microbiological quality and safety of these products, thereby posing potential risks to consumer health. This study provides an overview of minimally processed vegetables (MPVs), with a specific focus on the Brazilian market. It includes information on the pricing of fresh vegetables and MPVs, as well as an examination of the various processing steps involved, and the microbiological aspects associated with MPVs. Data on the occurrence of hygiene indicators and pathogenic microorganisms in these products are presented. The focus of most studies has been on the detection of Escherichia coli, Salmonella spp., and Listeria monocytogenes, with prevalence rates ranging from 0.7% to 100%, 0.6% to 26.7%, and 0.2% to 33.3%, respectively. Foodborne outbreaks associated with the consumption of fresh vegetables in Brazil between 2000 and 2021 were also addressed. Although there is no information about whether these vegetables were consumed as fresh vegetables or MPVs, these data highlight the need for control measures to guarantee products with quality and safety to consumers.

Quantitative microbiological risk assessment of nontyphoidal Salmonella in ground pork in households in Chengdu, China

Foodborne disease caused by nontyphoidal Salmonella (NTS) is one of the most important food safety issues worldwide. The objectives of this study were to carry out microbial monitoring on the prevalence of NTS in commercial ground pork, investigate consumption patterns, and conduct a quantitative microbiological risk assessment (QMRA) that considers cross-contamination to determine the risk caused by consuming ground pork and ready-to-eat food contaminated during food handling in the kitchen in Chengdu, China. The food pathway of ground pork was simplified and assumed to be several units according to the actual situation and our survey data, which were collected from our research or references and substituted into the QMRA model for simulation. The results showed that the prevalence of NTS in ground pork purchased in Chengdu was 69.64% (95% confidence interval [CI], 60.2-78.0), with a mean contamination level of -0.164 log CFU/g. After general cooking, NTS in ground pork could be eliminated (contamination level of zero). The estimated probability of causing salmonellosis per day was 9.43E-06 (95% CI: 8.82E-06-1.00E-05), while the estimated salmonellosis cases per million people per year were 3442 (95% CI: 3218-3666). According to the sensitivity analysis, the occurrence of cross-contamination was the most important factor affecting the probability of salmonellosis. To reduce the risk of salmonellosis caused by NTS through ground pork consumption, reasonable hygiene prevention and control measures should be adopted during food preparation to reduce cross-contamination. This study provides valuable information for household cooking and food safety management in China.

Microbiological quality of ready–to–eat vegetables salads served at meat restaurants under the COVID-19 in Turkey

In Turkish cuisine, ready–to–eat vegetable salads (REVS) served with pide/lahmacun, kebab types, and tantuni from animal source in meat restaurants were evaluated since they have the potential to carry risks in terms of Public Health. The microbiological properties of REVS were investigated using agar plate method. Antimicrobial resistance of foodborne pathogens including Escherichia coli and Staphylococcus aureus was tested using Kirby–Bauer disc diffusion method. Moreover, the presence of important enteric viruses was detected by Polymerase Chain Reaction (PCR). The number of total aerobic bacteria, coliform bacteria, yeast and molds and, Staphylococcus and Micrococcus spp. ranged from less than 1 to 6.40, 1 to 6.26, less than 1–5.82 and less than 1–5.66 log10 colony forming units·grams-1 (CFU·g–1) in REVS samples, respectively. None of the REVS tested in this study contained Salmonella spp., whereas E. coli and S. aureus were isolated in 38.1% (16/42) and 2.4% (1/42), respectively. S. aureus was resistant to gentamicin, kanamycin, aztreonam, and ciprofloxacin in the disc diffusion assay, however, it was not harboring the mecA gene. E. coli strains (n=16) were resistant (100%) to aminoglycoside antibiotics and 35.7% (6/16) of the isolates were extended spectrum beta lactamase (ESBL) producing. blaTEM and blaCTXM8/25 were detected in two isolates, whereas one isolate carried blaCTXM–1 and blaTEM together by PCR. Of the REVS, two were evaluated as positive for rotavirus (4.8%), six for hepatitis A (14%), and hepatitis E virus (14%). These results indicate the high microorganism load, presence of ESBL E. coli, and viral enteric pathogens in REVS, hence it is important to perform routine hygiene practices.