Assessment of the microbial safety and quality of cooked chilled foods and their production process

Deterministic Approach and Monte Carlo Simulation to Predict Listeria monocytogenes Time to Grow on Refrigerated Ham: A Study Supporting Risk-based Decisions for Consumers' Health

This study assessed the growth of Listeria monocytogenes in ready-to-eat (RTE) ham during storage under conditions simulating domestic practices with the intention to offer support in the elaboration of food safety policies that should better protect consumers against food poisoning at home. RTE ham, artificially contaminated at either medium (10²-10³ CFU/g) or high (10⁴-10⁵ CFU/g) concentration, was stored at both isothermal (4℃ in a refrigerator able to maintain a relatively constant temperature and 5℃ and 7℃ in a refrigerator with fluctuating temperature) and dynamic (5℃ and 7℃ with intermittent exposure to ambient temperature, e.g. 25℃) conditions. Under isothermal conditions, the increasing storage temperature determined a significantly increased (p < 0.05) capacity of L. monocytogenes to grow. The kinetic growth parameters were derived by fitting the Baranyi and Roberts model to the experimental data and, based on the maximum specific growth rates, it was estimated the temperature dependence of L. monocytogenes growth in RTE ham. At medium contamination level, sanitary risk time calculation revealed that, unlike storage at 5℃ and 7℃, storage at 4℃ of the RTE ham extends the time period during which the product is safe for consumption by ∼40 and 52%, respectively. However, the real temperature fluctuations included in the Monte Carlo simulations at low L. monocytogenes counts (1, 5 and 10 CFU/g) have shortened the safety margins. Stochastic models also proved to be useful tools for describing the pathogen's behavior when refrigeration of the RTE ham alternates with periods of ham being kept at room temperature, considered dynamic conditions of growth.

Microbial Contamination and Occurrence of Aflatoxins in Processed Baobab Products in Kenya

Baobab fruit demand has been on the rise in the recent past, and in an attempt to match the demand, farmers and middlemen are forced to harvest immature fruits which are not fully dried. To ensure an acceptable moisture content, baobab fruits are subjected to solar drying, which is a slow process and often carried out in open and unhygienic conditions raising safety concerns. This study was conducted to investigate the microbial and aflatoxin contamination levels in ready-to-eat baobab products from selected formal and informal processors in specific counties of Kenya. Selected processed baobab products were sampled randomly from formal and informal processors and analyzed for the total aerobic count, Enterobacteriaceae, yeast and molds, ergosterol, aflatoxins, moisture, and water activity. The moisture and water activity of baobab pulp and candies from formal processors ranged between 7.73% and 15.06% and 0.532 and 0.740 compared to those from informal processors which ranged from 10.50% to 23.47% and 0.532 to 0.751, respectively. In this study, baobab pulp from formal processors had significantly ( $p=0.0008$ , 0.0006) lower Enterobacteriaceae and yeast and molds loads ( $0.7\pm 0.29$ and $3.1\pm 0.38$ log 10 CFU/g, respectively) than pulp from informal processors ( $3.1\pm 0.70$ and $5.3\pm 0.11$ log 10 CFU/g, respectively). Similarly, the Enterobacteriaceae counts of candies from formal processors (nondetectable) were considerably lower ( $p=0.015$ ) than those from informal processors ( $1.8\pm 0.56$ log 10 CFU/g). The ergosterol content in these baobab product samples ranged between 0.46 and 1.92 mg/100 g while the aflatoxin content ranged between 3.93 and $11.09\times 103\mu \text{g}/\text{kg}$ , respectively. Fungal and aflatoxin contamination was detected in 25% and 5% of pulp from formal and informal processors, respectively, and in 5% of candies from informal processors. Microbial contamination in processed baobab products shows an unhygienic processing environment while the fungal and aflatoxin contamination may indicate poor postharvest handling, transport, and storage conditions of baobab fruits along the baobab value chain.

Methicillin- and Vancomycin-Resistant Staphylococcus aureus From Humans and Ready-To-Eat Meat: Characterization of Antimicrobial Resistance and Biofilm Formation Ability

Methicillin-resistant and vancomycin-resistant Staphylococcus aureus (MRSA and VRSA) are zoonotic life-threatening pathogens, and their presence in food raises a public health concern. Yet, scarce data are available regarding MRSA and VRSA in both ready-to-eat (RTE) meat and food handlers. This study was undertaken to determine the frequency, antimicrobial resistance, and biofilm-forming ability of MRSA and VRSA isolated from RTE meat (shawarma and burger) and humans (food handlers, and hospitalized patients) in Zagazig city, Sharkia Governorate, Egypt. We analyzed 176 samples (112 human samples: 72 from hospitalized patients and 40 from food handlers, 64 RTE meat samples: 38 from shawarma and 26 from burger). Using phenotypic, PCR-based identification of nuc gene and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), 60 coagulase-positive S. aureus (COPS) isolates were identified in the samples as follow: RTE meat (15/64, 23.4%), hospitalized patients (33/72, 45.8%) and food handlers (12/40, 30%). All the COPS isolates were mecA positive (and thus were classified as MRSA) and multidrug resistant with multiple antibiotic resistance indices ranging from 0.25 to 0.92. Overall, resistance to cefepime (96.7%), penicillin (88.3%), were common, followed by ampicillin-sulbactam (65%), ciprofloxacin (55%), nitrofurontoin (51.7%), and gentamicin (43.3%). VRSA was detected in 30.3% of COPS hospitalized patient's isolates, 26.7% of COPS RTE meat isolates and 25% of COPS food handler's isolates. VanA, vanB, or both genes were detected in 64.7, 5.9, and 29.4% of all VAN-resistant isolates, respectively. The majority of the COPS isolates (50/60, 83.3%) have biofilm formation ability and harbored icaA (76%), icaD (74%), icaC (50%), and icaB (46%) biofilm-forming genes. The bap gene was not detected in any of the isolates. The ability of MRSA and VRSA isolates to produce biofilms in addition to being resistant to antimicrobials highlight the danger posed by these potentially virulent microorganisms persisting in RTE meat, food handlers, and patients. Taken together, good hygiene practices and antimicrobial surveillance plans should be strictly implemented along the food chain to reduce the risk of colonization and dissemination of MRSA and VRSA biofilm-producing strains.

Prevalence of pathogens harbouring mobile antimicrobial resistance genes and virulence factors in retail beef and mutton

Food safety is always a global issue, due to the increased dissemination of antimicrobial resistance and food poisoning related to foodborne bacterial pathogens. The purpose of this study was to assess the risk of potential foodborne bacteria of beef and mutton in retail stores. A total of 134 samples were collected from 24 local markets in Beijing, including raw and cooked beef or mutton, as well as samples derived from the corresponding environment and human beings. We obtained 674 isolates, of which Klebsiella spp. and Staphylococcus spp. were the dominant bacterial species in the meat samples and the environmental samples, respectively. Additionally, environmental bacteria are common in samples from different sources. Based on the results of antimicrobial sensitivity testing, resistance to tetracycline (with a resistance rate of 47.40%), amoxicillin + clavulanate (47.13%) and erythromycin (28.03%) were the major resistant phenotypes. According to the whole genome analysis, the extended spectrum beta-lactamase genes harboured by two K. pneumoniae strains isolated from cooked and raw beef were located on mobile elements. The major toxin genes of Bacillus cereus and adhesion- or invasion-related virulence factors were also shared among isolates from different sources. These factors pose potential risks to public health and need attention.

Guidance on date marking and related food information: part 2 (food information)

A risk‐based approach was used to develop guidance to be followed by food business operators (FBOs) when deciding on food information relating to storage conditions and/or time limits for consumption after opening a food package and thawing of frozen foods. After opening the package, contamination may occur, introducing new pathogens into the food and the intrinsic (e.g. pH and a_w), extrinsic (e.g. temperature and gas atmosphere) and implicit (e.g. interactions with competing background microbiota) factors may change, affecting microbiological food safety. Setting a time limit for consumption after opening the package (secondary shelf‐life) is complex in view of the many influencing factors and information gaps. A decision tree (DT) was developed to assist FBOs in deciding whether the time limit for consumption after opening, due to safety reasons, is potentially shorter than the initial ‘best before’ or ‘use by’ date of the product in its unopened package. For products where opening the package leads to a change of the type of pathogenic microorganisms present in the food and/or factors increasing their growth compared to the unopened product, a shorter time limit for consumption after opening would be appropriate. Freezing prevents the growth of pathogens, however, most pathogenic microorganisms may survive frozen storage, recover during thawing and then grow and/or produce toxins in the food, if conditions are favourable. Moreover, additional contamination may occur from hands, contact surfaces or contamination from other foods and utensils. Good practices for thawing should, from a food safety point of view, minimise growth of and contamination by pathogens between the food being thawed and other foods and/or contact surfaces, especially when removing the food from the package during thawing. Best practices for thawing foods are presented to support FBOs.

Target specific post-harvest treatment by gamma radiation for the microbial safety of dried Melissa officinalis and Aloysia citrodora

This study aimed to assess a specific gamma radiation dose to be applied as a post-harvest process to guarantee the microbial safety of two medicinal plants, Melissa officinalis and Aloysia citrodora. Dried plants treated with gamma radiation indicated that a dose of 5 kGy could be applied as a post-harvest treatment process of M. officinalis and A. citrodora, assuring the microbial safety of dried medicinal plants and lowering the potentiality of deleterious effects on plants' quality attributes. This will enhance the safety and quality of the dried plants to be used as raw materials in industrial applications.

Microbiological Stability and Overall Quality of Ready-To-Heat Meals Based on Traditional Recipes of the Basilicata Region

The quality of ready meals is affected by several factors that may impair stability and nutritional value. In this work, we evaluated the overall quality of four traditional meals (Basilicata region) prepared according to the cook&chill method, packaged in air or modified atmosphere packaging (MAP; 70% N₂ and 30% CO₂), and stored at 4 °C for seven days. The shelf-life was determined by Listeria monocytogenes challenge testing and inactivation by microwave (MW) heating was assessed. The counts at the production day were excellent in three meals out of four, whereas one had high levels of spoilage and pathogens both as soon as the preparation and after seven days. MAP was partially effective only against the growth of the aerobic mesophilic species, whereas sensory analysis revealed that MAP may preserve many of sensory attributes. The average shelf-life of the meals ranged from 11 to 13 days, however, the potential shelf-life was undetectable in one out four meals, as L. monocytogenes growth was inhibited two days after the inoculum. In the inoculated meals, MW heating provided a partial inactivation (25%) of the pathogen. The overall quality of type the meals was partially satisfactory; post-cooking contaminations may affect the microbial load and reduce the palatability over the storage period and, above all, may involve biological hazards which consumers' habits may not be able to eliminate.

Food Handling Behaviors Associated with Reported Acute Gastrointestinal Disease That May Have Been Caused by Food

Family food handling by women plays a key role in the risk of foodborne acute gastroenteritis. Nevertheless, the data indicating the association between women's food handling and foodborne disease has not been reported in the People's Republic of China. The purpose of this study was to determinate the status of food handling for women and the association between food handling behaviors and foodborne acute gastroenteritis. A cross-sectional survey was conducted from 1 September 2015 to 30 August 2016 in Anhui Province, China. Data on foodborne disease and food handling was collected via a questionnaire. Of the 630 respondents included in the study, 99 (16.0%) reported having experienced symptoms in the past 4 weeks of acute gastroenteritis that may have been caused by food. The following behaviors were prevalent in respondents: (i) infrequently boiling kitchen utensils to disinfect (70.6%); (ii) infrequently heating cooked food purchased from outside the home (64.3%); (iii) infrequently storing leftovers in the refrigerator (38.6%); and (iv) often purchasing stale raw vegetables, meat, and other ingredients (23.3%). Urban and rural respondents differed significantly in their answers to the food handling questions. Foodborne acute gastroenteritis was associated with the following behaviors: (i) infrequently heating milk (odds ratio [OR] = 2.587, 95% confidence interval [CI] = 1.396 to 6.458); (ii) infrequently heating leftovers stored in the refrigerator (OR = 16.967, 95% CI = 9.030 to 31.882); (iii) infrequently thoroughly heating kidney beans (OR = 3.524, 95% CI = 1.834 to 6.773); (iv) often storing raw and cooked meat in the same container (OR = 10.216, 95% CI = 5.109 to 20.431); and (v) often eating raw seafood (OR = 2.587, 95% CI = 1.424 to 4.700). Inappropriate food handling behaviors of women in the family are associated with foodborne acute gastroenteritis. Infrequent thorough heating and improper food storage are the most critical risk factors in foodborne acute gastroenteritis.

The correlation between family food handling behaviors and foodborne acute gastroenteritis: a community-oriented, population-based survey in Anhui, China

BACKGROUND

Foodborne acute gastroenteritis is a significant public health concern. Food handling plays a key role in the risk of foodborne acute gastroenteritis. However, research focused on the correlation between foodborne acute gastroenteritis and food handling in the family environment is limited. The purpose of the current study was to determinate the association between food handling behaviors in the family environment and foodborne acute gastroenteritis.

METHODS

A cross-sectional investigation was conducted from September 1, 2015 to August 30, 2016 in Anhui Province, China. A multistage stratified cluster sampling method was designed to select subjects. Data on foodborne acute gastroenteritis and food handling were collected via questionnaire survey.

RESULTS

Of the 1516 subjects included in the study, 165 (10.9%) reported having experienced symptoms of foodborne acute gastroenteritis in the past 4 weeks. The following behaviors were more prevalent in those that experienced acute gastroenteritis: (1) infrequently thoroughly heating milk (75.6%); (2) infrequently thoroughly heating cooked food purchased from outside (71.3%); (3) infrequently thoroughly heating leftovers stored in the refrigerator (32.5%), and (4) infrequently storing leftovers in the refrigerator (41.6%). A multivariate logistic regression analysis found that foodborne acute gastroenteritis was associated with the following behaviors: (1) often eating raw seafood (P < 0.001, OR = 3.250, 95% CI = 2.136-4.946); (2) often storing raw meat and cooked meat in the same container (P < 0.001, OR = 4.291, 95% CI = 2.722-6.765); (3) infrequently thoroughly heating milk (P < 0.001, OR = 4.665, 95% CI = 2.526-8.617); (4) infrequently thoroughly heating leftovers stored in the refrigerator (P < 0.001, OR = 3.416, 95% CI = 2.139-5.454); (5) infrequently storing leftovers in the refrigerator (P < 0.05, OR = 1.775, 95% CI = 1.169-2.696); and (6) infrequently thoroughly cooking green beans (P < 0.001, OR = 2.859, 95% CI = 1.798-4.545).

CONCLUSIONS

Poor food handling behaviors in the family environment are associated with foodborne acute gastroenteritis. Infrequent thorough heating and improper food storage are the most critical risk factors in foodborne acute gastroenteritis.

Occurrence and characterization of Listeria monocytogenes from beef jerky processing line

Beef jerky is a ready-to-eat product that does not require refrigeration at the point of sale. Here, we evaluated the occurrence of Listeria monocytogenes in the production process of beef jerky, the presence of virulence genes and the genomic relatedness of the isolates, to assess the safety of the final product. The raw material, surfaces with and without contact with the product and the final product were evaluated along the beef jerky processing line. The samples were evaluated by VIDAS immunoassay system, and the L. monocytogenes isolates were confirmed and evaluated for the presence of several virulence genes by PCR. Listeria monocytogenes was identified in six of the 84 samples (7.14%), and no genetic relationship was observed among isolates. Samples of raw material (2/7), food contact surface (1/56), and work surfaces without contact with food (3/14) presented contamination by L. monocytogenes. The final product was not contaminated, demonstrating that barriers to multiplication of pathogens used during the production process were effective for its control.

A comparative study of infrared and microwave heating for microbial decontamination of paprika powder

There is currently a need in developing new decontamination technologies for spices due to limitations of existing technologies, mainly regarding their effects on spices’ sensory quality. In the search of new decontamination solutions, it is of interest to compare different technologies, to provide the industry with knowledge for taking decisions concerning appropriate decontamination technologies for spices. The present study compares infrared (IR) and microwave decontamination of naturally contaminated paprika powder after adjustment of water activity to 0.88. IR respectively microwave heating was applied to quickly heat up paprika powder to 98°C, after which the paprika sample was transferred to a conventional oven set at 98°C to keep the temperature constant during a holding time up to 20 min. In the present experimental set-up microwave treatment at 98°C for 20 min resulted in a reduction of 4.8 log units of the total number of mesophilic bacteria, while the IR treatment showed a 1 log unit lower reduction for the corresponding temperature and treatment time. Microwave and IR heating created different temperature profiles and moisture distribution within the paprika sample during the heating up part of the process, which is likely to have influenced the decontamination efficiency. The results of this study are used to discuss the difficulties in comparing two thermal technologies on equal conditions due to differences in their heating mechanisms.

Semi-direct lysis of swabs and evaluation of their efficiencies to recover human noroviruses GI and GII from surfaces

Enteric viruses such as noroviruses (NoVs) continue to be the cause of widespread viral outbreaks due to person-to-person transmission, contaminated food, and contaminated surfaces. In order to optimize swabbing methodology for the detection of viruses on (food) contact surfaces, three swab elution/extraction strategies were compared in part one of this study, out of which, one strategy was based on the recently launched ISO protocol (ISO/TS 15216-1) for the determination of hepatitis A virus and NoV in food using real-time RT-PCR (RT-qPCR). These three swab elution/extraction strategies were tested for the detection of GI.4 and GII.4 NoV on high-density polyethylene (HD-PE) surfaces with the use of cotton swabs. For detection of GI.4 and GII.4, the sample recovery efficiency (SRE) obtained with the direct lysis strategy (based on ISO/TS 15216-1) was significantly lower than the SRE obtained with both other strategies. The semi-direct lysis strategy was chosen to assess the SRE of two common swabs (cotton swab and polyester swab) versus the biowipe (Biomérieux, Lyon, France) on three surfaces (HD-PE, neoprene rubber (NR), and nitrile gloves (GL)). For both surfaces, HD-PE and GL, no significant differences in SREs of GI.4 and GII.4 NoVs were detected between the three different swabs. For the coarser NR, biowipes turned out to be the best option for detecting both GI.4 and GII.4 NoV.