Comparison of detection methods used to determine Escherichia coli and meat exudate removal from stainless steel surfaces following different physical cleaning methods.

Food products can be contaminated by residual organic materials and food-borne pathogenic microorganisms through contact with biofouling present on surfaces. Efficient cleaning is needed to maintain hygienic requirements and for quality assurance of food contact surfaces. To evaluate the efficacy of cleaning procedures, it is essential to use reliable detection and quantification methods that can detect both organic material and microorganisms retained on surfaces. Repeated fouling with both organic material (meat exudate) and microorganisms (Escherichia coli) on 304 2B finish stainless steel surfaces was carried out. The surfaces were then cleaned using either a soak, spray or wipe method (in water) in order compare various biofouling detection methods. Following enumeration of the microorganisms by plate counting, the results demonstrated that the soak and spray washes were the best cleaning methods, whereas the wipe clean produced the least hygienic surface. ATP bioluminescence further demonstrated that the spray cleaned surface was the most hygienic followed by the soaked cleaned surfaces. However, percentage coverage counts demonstrated that the number of retained cells on following the soak wash was the greatest (77.38 % after 30 washes) and the amount of organic material retained was greater than 50% on all the surfaces, and was not significantly different between the different types of cleans or number of washes. Visualisation of the surfaces using epifluorescence microscopy and scanning electron microscopy demonstrated that the soak clean was the least hygienic in terms of bacterial retention. This suggests that the biofouling on the surface was difficult to remove following the soak cleaning method. UV detection demonstrated that it was difficult to detect organic material, regardless of the cleaning method used. However, when using more intense UV at selected wavelengths, the 330 nm - 360 nm illuminated the retained biofouling on the surfaces with the greatest intensity. The use of the different cleaning assays resulted in differences in cell and organic material distribution across the surfaces. The recorded level of contamination varied depending on the detection method used in this study. Our results highlighted that, in addition to the quantification method, visual images and quantification may help to better understand the fouling process on surfaces since certain cleaning methods may result in organic material being difficult to remove and detect

Methylcellulose hydrogel with Melissa officinalis essential oil as a treatment of oral candidosis.

Candida spp. are the most prevalent fungi of the human microbiota and are opportunistic pathogens that can cause oral candidiasis. Management of such infections is limited due to the low number of antifungal drugs available, their relatively high toxicity and the emergence of antifungal resistance. Therefore, much interest in the antimicrobial potential of natural compounds has recently been evident. The use of hydrogels in the delivery of biocides has been explored due to their biocompatibility, ease with drug encapsulation, and due to their potential to confer mechanical and structural properties similar to biological tissue. Methylcellulose hydrogels (10% (w/v)) with 1% (v/v) and 2% (v/v) Melissa officinalis oil were synthesised. The rheological properties and gelation time of the hydrogels were evaluated. Antimicrobial action, the antifungal potential and ability to displace Candida were determined. Rheological tests revealed that the hydrogel jellified in three minutes at 37 °C. Loaded hydrogels successfully inhibited Candida albicans growth as evident by zone of inhibition and time-kill assays. A significant reduction in retained C. albicans was demonstrated with the hydrogel at 2% Melissa officinalis concentration. This work demonstrated that an essential oil-loaded hydrogel had the potential to provide a novel antimicrobial therapy for the treatment of oral candidiasis

Principal Component Analysis to Determine the Surface Properties That Influence the Self-Cleaning Action of Hydrophobic Plant Leaves

It is well established that many leaf surfaces display self-cleaning properties. However, an understanding of how the surface properties interact is still not achieved. Consequently, 12 different leaf types were selected for analysis due to their water repellency and self-cleaning properties. The most hydrophobic surfaces demonstrated splitting of the νs CH2 and ν CH2 bands, ordered platelet-like structures, crystalline waxes, high-surface-roughness values, high-total-surface-free energy and apolar components of surface energy, and low polar and Lewis base components of surface energy. The surfaces that exhibited the least roughness and high polar and Lewis base components of surface energy had intracuticular waxes, yet they still demonstrated the self-cleaning action. Principal component analysis demonstrated that the most hydrophobic species shared common surface chemistry traits with low intra-class variability, while the less hydrophobic leaves had highly variable surface-chemistry characteristics. Despite this, we have shown through partial least squares regression that the leaf water contact angle (i.e., hydrophobicity) can be predicted using attenuated total reflectance Fourier transform infrared spectroscopy surface chemistry data with excellent ability. This is the first time that such a statistical analysis has been performed on a complex biological system. This model could be utilized to investigate and predict the water contact angles of a range of biological surfaces. An understanding of the interplay of properties is extremely important to produce optimized biomimetic surfaces

The antimicrobial effect of metal substrates on food pathogens.

The development of surfaces as antimicrobial materials is important to the food industry. This study investigated the antimicrobial potential of a range of metal coated surfaces including silver, titanium, copper, iron, molybdenum, zinc and silicon (control) against Staphylococcus aureus, Escherichia coli and Listeria monocytogenes. The leaching potential of the metals were measured by inductively coupled plasma-atomic adsorption spectroscopy and were compared to the antibacterial activity of the metals using a nitroblue tetrazolium assay and an adapted BS ISO 22196:2011 standard. Leaching into solution from the coatings alone was not related to the antimicrobial activity of the coatings. Copper and zinc showed the greatest propensity to leach from the coatings; silver, titanium, iron and molybdenum leached at lower rates and silicon showed no leaching. Copper demonstrated the greatest antimicrobial potential followed by silver and zinc. Titanium displayed the least antimicrobial potential, however using the standard method in humid conditions resulted in increased growth of Listeria. This study provides evidence of the efficacy of copper and silver as effective antimicrobial metal surface coatings, however use of titanium under humid conditions suggest that surfaces for use in the food industry needs to be given careful consideration before application

Potentiel nutritionnel du microbiote d’aliments fermentés à base de céréales : le cas des folates

Cereals are staple foods in most African countries. Numerous African cereal-based foods are spontaneously fermented. As the nutritional quality of cereal products could be enhanced through spontaneous fermentation, these food products might be good sources of micronutrients. However, various micronutrients deficiencies, such as folate deficiency, are still common in many African countries where these food products are consumed. Folate deficiency leads to different pathologies, such as megaloblastic anemia and neural tube defects. The objective of this work was to evaluate the nutritional potential of the microbiota of ben-saalga, a traditional pearl-millet-based fermented food from Burkina Faso. Genes encoding enzymes involved in different nutritional activities were screened in 50 metagenomes extracted from samples collected in Ouagadougou. Certain genes were never detected in the metagenomes (e.g. genes involved in carotenoid synthesis) while other were frequently detected (e.g. genes involved in folate synthesis). In spite of the high rate of detection (80%) of both genes folP and folK, encoding enzymes involved in folate synthesis, the folate content in ben-saalga was rather low (median: 0.5 µg/100g fresh weight basis). To better understand the impact of the fermentation on the folate content of ben-saalga, the evolution of the folate content was measured during the fermentation of porridges produced in laboratory. The fermentation had no significant impact on the folate content, which may be due to a balance between folate auxotrophy and prototrophy. In order to produce pearl-millet based fermented porridges with higher folate content, starter cultures of folate-producing microorganisms were used to inoculate porridges in laboratory. We obtained a porridge with 10 µg of folate/100 g of fresh weight basis, which is significantly higher than the folate content of ben-saalga produced in Burkina Faso, but still too low knowing that ben-saalga is frequently used as a complementary food for children under five in Burkina Faso.Les céréales sont des aliments de base dans la plupart des pays africains. De nombreux aliments céréaliers africains sont fermentés naturellement. Comme la qualité nutritionnelle des aliments céréaliers pourrait être améliorée grâce aux fermentations spontanées, ces aliments pourraient être de bonnes sources de micronutriments. Cependant, différentes carences en micronutriments, comme les carences en folates par exemple, sont toujours fréquentes dans de nombreux pays africains où ces aliments sont consommés. Les carences en folates peuvent mener à différentes pathologies, comme des anémies mégaloblastiques et des malformations du tube neural par exemple. L’objectif de ce travail était d’évaluer le potentiel nutritionnel du microbiote du ben-saalga, un aliment fermenté traditionnel à base de mil consommé au Burkina Faso. Des gènes codant des enzymes impliquées dans différentes activités nutritionnelles ont été recherchés dans 50 métagénomes extraits d’échantillons collectés à Ouagadougou. Certains gènes n’ont jamais été détectés dans les métagénomes (e.g. les gènes impliqués dans la synthèse de caroténoides), alors que d’autres ont été fréquemment détectés (e.g. les gènes impliqués dans la synthèse de folates). En dépit du haut niveau de détection (80%) des deux gènes folP et folK, codant des enzymes impliquées dans la synthèse de folates, la teneur en folates du ben-saalga était plutôt faible (médiane : 0,5 µg/100g de base humide). Pour mieux comprendre l’impact de la fermentation sur la teneur en folates du ben-saalga, l’évolution de la teneur en folates a été mesurée durant la fermentation de bouillies produites en laboratoire. La fermentation n’a pas eu d’impact significatif sur la teneur en folates, ce qui pourrait être dû à une balance entre les micro-organismes auxotrophes et les micro-organismes prototrophes pour les folates. Dans le but de produire des bouillies fermentées à base de mil avec des teneurs en folates plus élevées, des cultures starters de micro-organismes producteurs de folates ont été utilisés pour inoculer des bouillies au laboratoire. Nous avons obtenu une bouillie avec une teneur en folates de 10 µg/100g de base humide, ce qui est significativement plus élevé que la teneur en folates du ben-saalga produit au Burkina Faso, mais qui reste trop faible sachant que le ben-saalga est fréquemment utilisé comme un aliment de complément à l’allaitement maternel pour les enfants de moins de cinq ans

Nutritional potential of the microbiota of cereal based fermented foods : the case of folate

Les céréales sont des aliments de base dans la plupart des pays africains. De nombreux aliments céréaliers africains sont fermentés naturellement. Comme la qualité nutritionnelle des aliments céréaliers pourrait être améliorée grâce aux fermentations spontanées, ces aliments pourraient être de bonnes sources de micronutriments. Cependant, différentes carences en micronutriments, comme les carences en folates par exemple, sont toujours fréquentes dans de nombreux pays africains où ces aliments sont consommés. Les carences en folates peuvent mener à différentes pathologies, comme des anémies mégaloblastiques et des malformations du tube neural par exemple. L’objectif de ce travail était d’évaluer le potentiel nutritionnel du microbiote du ben-saalga, un aliment fermenté traditionnel à base de mil consommé au Burkina Faso. Des gènes codant des enzymes impliquées dans différentes activités nutritionnelles ont été recherchés dans 50 métagénomes extraits d’échantillons collectés à Ouagadougou. Certains gènes n’ont jamais été détectés dans les métagénomes (e.g. les gènes impliqués dans la synthèse de caroténoides), alors que d’autres ont été fréquemment détectés (e.g. les gènes impliqués dans la synthèse de folates). En dépit du haut niveau de détection (80%) des deux gènes folP et folK, codant des enzymes impliquées dans la synthèse de folates, la teneur en folates du ben-saalga était plutôt faible (médiane : 0,5 µg/100g de base humide). Pour mieux comprendre l’impact de la fermentation sur la teneur en folates du ben-saalga, l’évolution de la teneur en folates a été mesurée durant la fermentation de bouillies produites en laboratoire. La fermentation n’a pas eu d’impact significatif sur la teneur en folates, ce qui pourrait être dû à une balance entre les micro-organismes auxotrophes et les micro-organismes prototrophes pour les folates. Dans le but de produire des bouillies fermentées à base de mil avec des teneurs en folates plus élevées, des cultures starters de micro-organismes producteurs de folates ont été utilisés pour inoculer des bouillies au laboratoire. Nous avons obtenu une bouillie avec une teneur en folates de 10 µg/100g de base humide, ce qui est significativement plus élevé que la teneur en folates du ben-saalga produit au Burkina Faso, mais qui reste trop faible sachant que le ben-saalga est fréquemment utilisé comme un aliment de complément à l’allaitement maternel pour les enfants de moins de cinq ans.Cereals are staple foods in most African countries. Numerous African cereal-based foods are spontaneously fermented. As the nutritional quality of cereal products could be enhanced through spontaneous fermentation, these food products might be good sources of micronutrients. However, various micronutrients deficiencies, such as folate deficiency, are still common in many African countries where these food products are consumed. Folate deficiency leads to different pathologies, such as megaloblastic anemia and neural tube defects. The objective of this work was to evaluate the nutritional potential of the microbiota of ben-saalga, a traditional pearl-millet-based fermented food from Burkina Faso. Genes encoding enzymes involved in different nutritional activities were screened in 50 metagenomes extracted from samples collected in Ouagadougou. Certain genes were never detected in the metagenomes (e.g. genes involved in carotenoid synthesis) while other were frequently detected (e.g. genes involved in folate synthesis). In spite of the high rate of detection (80%) of both genes folP and folK, encoding enzymes involved in folate synthesis, the folate content in ben-saalga was rather low (median: 0.5 µg/100g fresh weight basis). To better understand the impact of the fermentation on the folate content of ben-saalga, the evolution of the folate content was measured during the fermentation of porridges produced in laboratory. The fermentation had no significant impact on the folate content, which may be due to a balance between folate auxotrophy and prototrophy. In order to produce pearl-millet based fermented porridges with higher folate content, starter cultures of folate-producing microorganisms were used to inoculate porridges in laboratory. We obtained a porridge with 10 µg of folate/100 g of fresh weight basis, which is significantly higher than the folate content of ben-saalga produced in Burkina Faso, but still too low knowing that ben-saalga is frequently used as a complementary food for children under five in Burkina Faso