Adhesion of Listeria monocytogenes to materials commonly found in domestic kitchens

The aim of this work was to investigate the adhesion of Listeria monocytogenes ATCC 15313 to glass, granite, marble, polypropylene from a bowl (PPb), polypropylene from a cutting board (PPcb) and stainless steel (SS), which are materials commonly used in kitchens. Marble and granite were chosen because they are applied as kitchen bench covers and pavements in many countries and there are no literature reports on their behaviour in terms of microbial adhesion. The effect of surface hydrophobicity and roughness on the adhesion process was also analysed. The results showed that the highest extent of adhesion of L. monocytogenes occurred to stainless steel, followed by glass and in less extent to the other materials studied. However, it was not possible to establish a correlation between surface hydrophobicity or roughness and the extent of adhesion of L. monocytogenes. The adherence of L. monocytogenes should be dependent on other factors, like the presence of exopolymers and surface charge.Fundação para a Ciência e a Tecnologia (FCT

The speciation and genotyping of Cronobacter isolates from hospitalised patients

The World Health Organization (WHO) has recognised all Cronobacter species as human pathogens. Among premature neonates and immunocompromised infants, these infections can be life-threatening, with clinical presentations of septicaemia, meningitis and necrotising enterocolitis. The neurological sequelae can be permanent and the mortality rate as high as 40 – 80 %. Despite the highlighted issues of neonatal infections, the majority of Cronobacter infections are in the elderly population suffering from serious underlying disease or malignancy and include wound and urinary tract infections, osteomyelitis, bacteraemia and septicaemia. However, no age profiling studies have speciated or genotyped the Cronobacter isolates. A clinical collection of 51 Cronobacter strains from two hospitals were speciated and genotyped using 7-loci multilocus sequence typing (MLST), rpoB gene sequence analysis, O-antigen typing and pulsed- field gel electrophoresis (PFGE). The isolates were predominated by C. sakazakii sequence type 4 (63 %, 32/51) and C. malonaticus sequence type 7 (33 %, 17/51). These had been isolated from throat and sputum samples of all age groups, as well as recal and faecal swabs. There was no apparent relatedness between the age of the patient and the Cronobacter species isolated. Despite the high clonality of Cronobacter , PFGE profiles differentiated strains across the sequence types into 15 pulsotypes. There was almost complete agreement between O-antigen typing and rpoB gene sequence analysis and MLST profiling. This study shows the value of applying MLST to bacterial population studies with strains from two patient cohorts, combined with PFGE for further discrimination of strains

The emergence of international food safety standards and guidelines: understanding the current landscape through a historical approach

Following the Second World War, the Food and Agriculture Organization (FAO) and the World Health Organization (WHO) teamed up to construct an International Codex Alimentarius (or 'food code') which emerged in 1963. The Codex Committee on Food Hygiene (CCFH) was charged with the task of developing microbial hygiene standards, although it found itself embroiled in debate with the WHO over the nature these standards should take. The WHO was increasingly relying upon the input of biometricians and especially the International Commission on Microbial Specifications for Foods (ICMSF) which had developed statistical sampling plans for determining the microbial counts in the final end products. The CCFH, however, was initially more focused on a qualitative approach which looked at the entire food production system and developed codes of practice as well as more descriptive end-product specifications which the WHO argued were 'not scientifically correct'. Drawing upon historical archival material (correspondence and reports) from the WHO and FAO, this article examines this debate over microbial hygiene standards and suggests that there are many lessons from history which could shed light upon current debates and efforts in international food safety management systems and approaches

Sensory, microbiological and chemical changes in vacuum-packaged Blue Spotted Emperor (Lethrinus sp), Saddletail Snapper (Lutjanus malabaricus), Crimson Snapper (Lutjanus erythropterus), Barramundi (Lates calcarifer) and Atlantic Salmon (Salmo salar) fillets stored at 4°C

Quality assessment of finfish fillets during storage is important to be able to predict the shelf life of the fresh product during distribution. Microbial, chemical (pH, TMA, and TVB‐N), and sensory (Quality index assessment QIA, Torry scheme) changes in vacuum‐packaged blue‐spotted emperor (Lethrinus sp), saddletail (Lutjanus malabaricus), crimson snapper (Lutjanus erythropterus), barramundi (Lates calcarifer), and Atlantic salmon (Salmo salar) fillets stored at 4°C were evaluated for 5 days. Microbiological study included evaluation of TVC (total viable counts), total psychrotrophic organisms, and H2S‐producing bacteria. Numbers increased during storage time and reached an average of 8.5, 8.5, and 9.2 log10 cfu/g, respectively, for the five different fish species. These levels were above accepted microbiological limits for fish fillets. Although the sensory analyses showed a decrease in quality, none of the finfish fillets were considered unacceptable at the end of the storage trial. Chemically, there was a slight pH increase, but trimethylamine (TMA) levels remained low. However, total volatile basic nitrogen (TVB‐N) levels increased over time, reaching levels above 35 mg/100 g for blue spotted emperor, saddletail snapper, and crimson snapper by the end of the storage period. Results show that the deterioration of finfish fillet quality is a complex event of biochemical, sensory, and microbial factors, and multiple analyses may be required to define acceptability

Influence of storage conditions and packaging materials on some quality attributes of water yam flour

The study investigated some quality attributes of water yam flour stored in three packaging materials [high and low density polyethylene and plastic container] under different storage conditions [relative humidity (36%, 56%, 75% and 96%), temperature (25±2, 35±2 and 45±2 °C)] for 24 weeks. The functional properties, proximate composition and microbial load of the samples were evaluated at 4 weeks interval. Significant differences (p<0.01) were observed for proximate composition, functional properties and microbial load of the samples during storage. The interactive effect of storage conditions and packaging materials was significant (p<0.01) on proximate composition and pasting properties (except trough viscosity). The yam flour samples were still shelf stable after the 24 weeks of storage

Assessment of heavy metals and microbial contamination of gari from Liberia

Open Access Journal; Published online: 20 Nov 2017Cassava is a staple mostly eaten in the form of gari, after rice in Liberia. The local method of gari processing often leads to product contamination, thus, a study was done to assess the heavy metals and microbial contamination of gari in eight counties of the country. A total of sixty-one gari samples were collected and packaged in an airtight polyethylene bag for analyses, using standard methods. Results depict that the mean of the heavy metals in the gari samples is iron (Fe) 43.87 ppm, copper (Cu) 0.94 ppm, zinc (Zn) 5.49 ppm and aluminum (Al) 257.45 ppm. Yellow gari had the highest Fe (64.90 ppm), Cu (1.25 ppm) and Zn (7.85 ppm) content, but with the least Al content (87.15 ppm). The Fe content was lower in groundnut-fortified gari (42.93 ppm), and the Cu (0.70 ppm) and Zn (3.50 ppm) content were lower in groundnut-moringa-fortified gari. The samples and counties have no significant statistical effect (p > .05) on the heavy metals composition of the products. No microbial growth was observed in groundnut-fortified and groundnut-moringa-fortified gari but with coconut-fortified gari having the highest total fungi count of 800 CFU/g. The major fungi identified in the gari samples are Penicillium and Aspergillus spps., but with their counts within the regulated level. Therefore, the gari consumed in Liberia are safe except for the high Fe and Al content, which needs to be addressed with the use of unpainted stainless steel materials as food contact surfaces

Development of a novel smoke-flavoured salmon product by sodium replacement using water vapour permeable bags

This is the peer reviewed version of the following article: Rizo Parraga, Arancha Maria, Fuentes López, Ana, Barat Baviera, José Manuel, Fernández Segovia, Isabel. (2018). Development of a novel smoke-flavoured salmon product by sodium replacement using water vapour permeable bags.Journal of the Science of Food and Agriculture, 98, 7, 2721-2728. DOI: 10.1002/jsfa.8767, which has been published in final form at http://doi.org/ 10.1002/jsfa.8767. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.[EN] BACKGROUND: Food manufacturers need to reduce sodium contents to meet consumer and public health demands. In this study the use of sodium-free (SF) salt and KCl to develop a novel smoke-flavoured salmon product with reduced sodium content was evaluated. Fifty percent of NaCl was replaced with 50% of SF salt or 50% KCl in the salmon smoke-flavouring process carried out using water vapour permeable bags. RESULTS: Triangle tests showed that samples with either SF salt or KCl were statistically similar to the control samples (100% NaCl). Since no sensorial advantage in using SF salt was found compared with KCl and given the lower price of KCl, the KCl-NaCl samples were selected for the next phase. The changes of physicochemical and microbial parameters in smoke-flavoured salmon during 42 days showed that partial replacement of NaCl with KCl did not significantly affect the quality and shelf-life of smoke-flavoured salmon, which was over 42 days. CONCLUSION: Smoke-flavoured salmon with 37% sodium reduction was developed without affecting sensory features and shelf-life. This is an interesting option for reducing sodium content in such products to help meet the needs set by both health authorities and consumers.We gratefully acknowledge the support of Tub-Ex Aps (Taars, Denmark) for suppling the water vapour permeable bags and for providing all of the necessary technical information. Arantxa Rizo thanks the Universitat Politecnica de Valencia for the FPI grant.Rizo Parraga, AM.; Fuentes López, A.; Barat Baviera, JM.; Fernández Segovia, I. (2018). Development of a novel smoke-flavoured salmon product by sodium replacement using water vapour permeable bags. Journal of the Science of Food and Agriculture. 98(7):2721-2728. https://doi.org/10.1002/jsfa.8767S2721272898

Postharvest quality of refrigerated tomato fruit (Solanum lycopersicum, cv. Zinac) at two maturity stages following heat treatment

This study evaluated the effect of water heat treatment (WHT, immersion in a water bath at 40C - 30 min) application in alternative to the conventional decontamination treatment of chlorinated water (150 ppm at 5C, pH 6.5 during 2 min) on tomato (cv. Zinac) at two maturity stages (turning and pink). Physiochemical attributes, enzymatic activities and microbial load were evaluated after treatments and during 14 days of storage at 10C. The WHT applied was very effective on microbial reduction and delayed physiochemical changes of tomato, namely firmness loss and red color development during storage period, especially at turning maturity stage. Based on the firmness parameter, shelf-life of control and WHT samples were determined. Our results provide strong evidence that postharvest WHT (40C - 30 min) for tomato fruits at turning maturity stage guarantees the overall quality at 10C twice as long of fruits washed with chlorinated water.info:eu-repo/semantics/acceptedVersio

Predictive models for bacterial growth in sea bass (Dicentrarchus labrax) 1 stored on ice

The final publication is available at Springer."The purpose of this paper was to estimate microbial growth through predictive modelling as a key element in determining the quantitative microbiological contamination of sea bass stored on ice and cultivated in different seasons of the year. In the present study, two different statistical models were used to analyse changes in microbial growth in whole, ungutted sea bass (Dicentrarchus labrax) stored on ice. The total counts of aerobic mesophilic and psychrotrophic bacteria, Pseudomonas sp., Aeromonas sp., Shewanella putrefaciens, Enterobacteriaceae, sulphide-reducing Clostridium and Photobacterium phosphoreum were determined in muscle, skin and gills over an 18-day period using traditional methods and evaluating the seasonal effect. The results showed that specific spoilage bacteria (SSB) were dominant in all tissues analysed but were mainly found in the gills. Predictive modelling showed a seasonal effect among the fish analysed. The application of these models can contribute to the improvement of food safety control by improving knowledge of the microorganisms responsible for the spoilage and deterioration of sea bass.