The food-borne pathogen Listeria monocytogenes can attach to environmental surfaces and form biofilms which can be a source of food contamination, yet little is known about the molecular mechanisms of its biofilm development. The overall objective of this study was to identify the genetic requirements of biofilm formation by L. monocytogenes. In-frame deletion mutants of a putative mutarotase gene (lmo2476/lin2619 ) were constructed to investigate its influence on Listeria biofilm formation. No biofilm phenotype changes were observed between the wild type and the corresponding mutants, indicating that the putative mutarotase gene was not involved in Listeria biofilm formation under the conditions tested. A mariner-based transposon mutagenesis was performed to generate mutants of L. monocytogenes. A mutant library consisting of 6,500 colonies was screened for reduced biofilm formation. A total of 24 distinct loci were identified, 18 of which, to our knowledge, have not been previously reported to function in the biofilm formation of L. monocytogenes. A putative DNA translocase gene, lmo1386, was further characterized. The mutant was complemented, and the complemented mutant restored its biofilm phenotype. The lmo1386 mutants showed reduced initial attachment abilities, and had higher numbers of elongated cells when grown in a nutrient TSBYE broth. However, the exact mechanisms of how lmo1386 affects biofilm formation remain to be elucidated. The inhibitory effects of EDTA against biofilm formation of L. monocytogenes were investigated. EDTA at a concentration of 0.1 mM efficiently inhibited biofilm formation of L. monocytogenes without affecting its planktonic growth. EDTA functions in the early stage by affecting the initial attachment of L. monocytogenes cells to surfaces, though the mechanisms remain unclear. The role of extracellular DNA (eDNA) in the formation of L. monocytogenes biofilm was determined indirectly by treatments of DNase I. Our data adds to the knowledge that eDNA plays an essential role in attachment and maintenance of L. monocytogenes biofilm. The pre-formed biofilms on the wells of microtiter plates could be efficiently removed by DNase I, suggesting a potential use of DNase I to eradicate the existing L. monocytogenes biofilms.

This study investigated the effects of zinc fortification (to 100% of the USRDA) and calcium fortificant type (calcium carbonate or calcium phosphate) in various cereal products on zinc, iron and calcium solubility following an in vitro digestion procedure simulating the human process. Due to the dramatic increases in the consumption of high fiber cereal grains and the potential for essential mineral deficiencies, these effects have become increasingly important. In vitro systems included skim, 1 and 2% fat and whole milk because cereal grains are often consumed with such dairy products. In systems containing either highly or moderately fortified whole wheat cereals, zinc solubility significantly increased in response to zinc fortificant level. The superior solubility of calcium carbonate was evident, with associated increases in zinc and iron solubility apparently due to a competitive ion effect. Mineral solubility was significantly enhanced in the presence of milk, with this effect related to % milkfat and the process of homogenization. It was hypothesized that the superior mineral solubilization potential of homogenized whole milk was a function of interfacial protein denaturization during processing. Therefore, experimental dairy processes with the potential to alter native protein morphology (sonication, increased pressure and sequential homogenizations plus added surfactant, and microfluidization) were evaluated. In various cereal systems following the simulated digestion procedure, only a 20 min skim milk sonication treatment significantly enhanced mineral solubility, while surfactant addition inhibited it. Gel exclusion chromatography and photon correlation spectroscopy were used to characterize the effects of the various experimental dairy processes on milk particle hydrodynamic diameter. While surfactant addition prior to whole milk homogenization slightly increased particle diameters, microfluidization decreased them. Isolation and characterization of a milk fraction exhibiting maximal mineral sequesterization potential involved centrifugation, electrophoresis and electron microscopy. Centrifugal separation of zinc fortified whole and skim milk indicated that zinc was associated with a sedimentable fraction. Electrophoretic analysis demonstrated that this fraction was largely composed of sedimented casein and serum albumin. As well, electron microscopic analysis of this fraction confirmed the presence of sedimented casein micelles devoid of lipid globules, an observation supported by quantitative lipid and protein analyses.

Pandemin har påverkat världen under 2020 och speciellt restaurangbranschen har varit i fokus för restriktioner. Svenska restaurangägare har varit upprörda kring hur de blivit påverkade av statens agerande och vilka konsekvenser det fått för deras verksamheter. I denna uppsats undersöktes tre svenska restaurangägares subjektiva erfarenheter av pandemin och ageranden i relation till statliga stöd och restriktioner. Studien har undersökt hur modellen för måltidsupplevelser Five Aspect Meal Model, FAMM, påverkats av pandemin och hur restaurangägarna påverkats både privat och företagsmässigt av pandemins konsekvenser. Studien har gjorts med en kvalitativ metod där tre djupgående intervjuer genomförts utifrån informantens perspektiv. Tematisk analys användes för att analysera det inkomna materialet och resulterade i fem teman: Företagarnas erfarenheter från pandemin, företagarnas anpassningar under pandemin, restriktionernas påverkan på restaurangägarna och deras verksamheter, restaurangägarnas upplevelse av regeringens beslutsfattande under pandemin och restaurangägarnas upplevelse av stödet från staten.  Resultatet av denna studie visar att restaurangägarna blivit påverkade i sättet de driver sina företag men även i sitt förtroende till regeringens bestämmelser och agerande. Deras kunder har ändrat sitt köpbeteende och restaurangägarna har fått göra ändringar i företaget för att minska den ekonomiska påverkan. Restaurangägarna i denna studie har även visat en förståelse för restriktionerna men ifrågasatt varför just restaurangbranschen varit så hårt begränsad. / The pandemic in 2020 affected the world and especially restaurant industry have been hit hard with restrictions. Swedish restaurateurs have been upset with the way they have been affected by the governments actions and the consequences that have made an impact on their businesses. This thesis studied three Swedish restaurant owner’s experiences of the pandemic and actions in relations to the government’s economic aid and restrictions. This study inspected how the model for meal experiences Five Aspect Meal Model, also known as FAMM, have been affected by the pandemic and how restaurateurs were affected both privately and in their businesses by the consequences of the pandemic.  This study is based on qualitative interviews with three different interviews which are from the respondent’s perspective. Thematic analyses were used to analyze the material received which resulted in five different themes: Business owners’ experiences from the pandemic, Business owners’ adaptions during the pandemic, the impact of the restrictions on restaurant owners and their businesses, restaurant owners experience of government management during the pandemic and restaurant owners experience of government support.  This study shows that restaurant owners have been affected in the way they run their businesses and also in their confidence in the government’s regulations and actions. The customers have changed their behavior and the owners have had to make changes in their businesses to reduce the financial impact. The restaurateurs in this study have also shown an understanding of the restrictions but questioned why the restaurant industry in particular have been so has been so severely restricted.

Bakgrund Koffein, kreatin, beta-alanin, bikarbonat och nitrat tillhör de kosttillskott som har en vetenskapligt bevisad prestationsökning hos idrottare. Om kosttillskotten användes av idrottarna skulle det kunna få den enskilde individen i lagidrotten att prestera bättre. Syfte Syftet med studien var att undersöka användningen av prestationshöjande kosttillskott bland seniora utövare av lagidrotterna fotboll, innebandy eller basket. Metod Kvantitativ metod användes där en webbenkät delades på olika Facebook-grupper som var relaterade till idrotterna och mejlades ut till olika idrottslag. Sammanlagt 106 personer besvarade webbenkäten. Data bearbetades i IBM SPSS Statistics version 26,0 där de statistiska analyserna Mann-Whitney U test, Kruskal Wallis test, Independent sampel t-test och Anova test genomfördes. Signifikans-nivån sattes till p <0,05. Resultat Majoriteten av respondenterna i studien (63%, n=67) konsumerade inte prestationshöjande kosttillskott. Det fanns ingen skillnad i konsumtionen mellan de tre idrotterna (p=0,215). Prestationshöjande kosttillskott användes i högre utsträckning av män än av kvinnor, av de som tränade fler timmar i veckan samt de som spelade på en högre nivå (p=0,001, p<0,001, p=0,035). Det vanligaste kosttillskottet var koffein, att bli pigg eller få energi var den största anledningen till att idrottarna tog kosttillskott utifrån webbenkäten. Slutsats Dem flesta idrottarna konsumerade inte kosttillskott. Lagidrotterna liknar varandra i det fysiska utförandet och det skulle kunna vara en förklaring till att konsumtionen mellan idrotterna inte skilde sig åt något nämnvärt. Männen konsumerade mer kosttillskott än kvinnorna i studien. Idrottare som satsade mer på sin idrott tog mer kosttillskott. Koffein var det vanligaste kosttillskottet och en möjlig anledning är att kaffe är en vanlig dryck.

Bakgrund Marknaden för proteinberikade produkter och proteintillskott har ökat kraftigt under de senaste åren, samtidigt som studier visar att vi får i oss tillräckligt med protein via kosten. Ett onödigt högt proteinintag kan påverka intaget av andra näringsämnen samtidigt som dessa berikade produkter är dyra. Syfte Syftet med studien var att undersöka konsumtionen av proteinrika livsmedel, proteinberikade produkter och proteintillskott hos unga personer som är regelbundet fysiskt aktiva samt deras inställning till protein i förhållande till fysisk aktivitet.Metod En kvantitativ metod i form av en webbaserad enkätundersökning med 24 frågor användes. Datainsamlingen skedde på Facebook och Instagram och målgruppen var unga personer (16–30 år) som var regelbundet fysiskt aktiva. Tvåhundrafyra respondenter medverkade. Olika statistiska analyser utfördes beroende på datanivå samt om data var normalfördelade eller inte.Resultat Resultat från studien tyder på att många äter mer protein än vad som behövs. Män konsumerade oftare proteinpulver (p <0,001) och rött kött (p <0,002) än kvinnor medan kvinnor oftare konsumerade färdigblandade aminosyradrycker (p=0,015) än män. De som tränade mer än sju timmar per vecka tyckte att proteinintaget var viktigare än de som tränade ≤7 timmar per vecka (p=0,020). Männen uppgav sig veta sitt proteinbehov i större utsträckning än kvinnorna (p=0,016).Slutsats Konsumtionen av protein kan misstänkas vara högre än rekommendationerna. Att män i större utsträckning ansåg sig veta sitt proteinbehov och samtidigt konsumerade mest av både proteinpulver och rött kött tyder på att kunskapen är felaktig. Ålder påverkade inte konsumtionen av proteinrika livsmedel. Antalet aktiva timmar påverkade inte inställningen till protein i förhållande till fysisk aktivitet. Majoriteten av respondenterna var nöjda med den egna konsumtionen av proteintillskott.

After observing enhanced binding of deoxycholic acid to dietary fiber-mineral complexes in vitro, this study focused on the ability of dietary fiber-mineral complexes to bind bile acids in vivo. The binding and removal of bile acids from the enterohepatic cycle may decrease liver cholesterol levels and the risk of colon cancer. Psyllium and locust bean gum were gavaged at 100mg with or without the addition of iron or calcium (100% USRDA/4g fiber). Cholestyramine was used as a positive control, and solka floc W-40 was used as a negative control. 0.2uCi of $\sp{14}$C-deoxycholic or cholic acids were duodenally injected 15 minutes post-gavage. Twenty-four hour fecal collections were assayed for $\sp{14}$C-bile acid activity. Psyllium-iron was found to bind more deoxycholic (8.1% $\pm$ 1.5; p $\le$ 0.36) and cholic (10.1% $\pm$ 1.3; p $\le$ 0.017) acids than psyllium alone (6.5% $\pm$ 0.9 and 5.3% $\pm$ 1.3, respectively). No significant differences were seen between locust bean gum with or without the addition of minerals. Cholestyramine bound more deoxycholic and cholic acids than any of the dietary fibers or dietary fiber-mineral complexes (28.8% $\pm$ 2.0 and 20.7% $\pm$ 2.9, respectively). No significant differences were observed between single (100mg) and double gavages (200mg) for the psyllium or psyllium-iron. It appears that dietary fiber-mineral complexes can withstand in vivo conditions. Dietary fibers supplemented with mineral(s) may offer a suitable alternative to cholesterol lowering drugs, such as cholestyramine. In the future other dietary fiber combinations may be evaluated on both deoxycholic and lithocholic acids.

No description available.

Bakgrund Anorexia nervosa är en komplex psykiatrisk diagnos som karakteriseras av svält och undernäring. Behandlingen kräver ett tvärvetenskapligt team där dietisten anses vara mest lämpad att ge kostråd. Det har tidigare konstaterats att behandlingspersonal upplever patienter med anorexia nervosa som svåra och vårdkrävande.Syfte Syftet med studien var att beskriva dietistens erfarenheter och upplevelser av att behandla patienter med anorexia nervosa.Metod Åtta yrkesverksamma dietister inom behandling av anorexia intervjuades via Zoom utifrån en semistrukturerad intervjuguide. Intervjuerna spelades in, transkriberades och analyserades med kvalitativ innehållsanalys. Dietisterna arbetade i åtta olika svenska städer.Resultat Dietisterna upplevde att sjukdomen var komplex att behandla, bland annat på grund av bristande motivation och samsjuklighet hos patienten. Samarbeten och goda relationer lyftes fram som förutsättningar för en lyckad behandling och det upplevdes krävas erfarenhet för att lära sig ett förhållningssätt för just denna patientgrupp. Dietisterna upplevde sig betydelsefulla samtidigt som det fanns en känsla av otillräcklighet i psykiatriska frågor. Vidareutbildning rekommenderades för att bland annat bli tryggare i dessa frågor.Slutsats Dietisternas upplevelse av att behandla anorexia baserades på evidensbaserad kunskap, men också på erfarenhet och social kompetens. För att dietisten ska känna sig trygg inom alla delar i behandlingen av anorexia nervosa konstateras det krävas ytterligare utbildning utöver dietistutbildningen alternativt längre arbetserfarenhet inom området. Genom att redan under dietistutbildningen informera om det särskilda förhållningssätt som verkade krävas gentemot patientgruppen skulle chansen öka att framtida dietister redan från start känner sig tillräckligt förberedda och trygga inför detta arbetsområde.

In line with global trends, chicken meat is the most consumed source of animal protein in South Africa. Raw chicken meat is frequently contaminated with Salmonella spp. and Campylobacter spp., and is highly susceptible to bacterial spoilage if improperly handled. Although the chicken industry is primarily responsible for the quality and safety of chicken meat, consumers have an active role to play as they represent the final line of defence against the occurrence of foodborne illnesses and food waste. This study was undertaken to investigate and assess the practices, knowledge and perceptions of a group of South African consumers with respect to handling raw chicken meat, and to identify the associated risks to meat safety and quality. Subsequently, the odour and appearance attributes of raw chicken meat during refrigerated storage under aerobic packaging were characterised and the relationship with microbial and physicochemical quality changes was established. Finally, the link between consumers’ perceptions, handling practices and sensory, microbial and physicochemical characteristics of chicken meat was elucidated. A web-based cross-sectional consumer survey (n = 863) was conducted using convenience sampling. The survey questionnaire collected information on consumers’ handling practices, knowledge of temperature related factors affecting the safety and quality of chicken meat and perceptions on intrinsic and extrinsic attributes as indicators of the safety and quality of chicken meat. Furthermore, raw chicken legs obtained from a commercial poultry processing plant were stored at 4 °C and microbiological (total viable counts, Pseudomonas spp., Enterobacteriaceae and lactic acid bacteria), physicochemical (pH and instrumental colour) and descriptive sensory analyses (odour and appearance) were conducted during storage for 14 days. Overall, only 38% of the surveyed respondents were rated as following good practices and 28% as having good knowledge about temperature related factors affecting the safety and quality of chicken meat. Gaps in handling practices and knowledge that potentially result in breaking of the chicken meat cold chain, the transmission of pathogenic bacteria and cross-contamination were identified. Moreover, smell, use-by date, sell-by date and colour were perceived by a large majority of respondents as highly important attributes when judging chicken safety and quality at point of purchase and the home. Smell was considered significantly more important than colour. Extrinsic attributes such as absence of brine use and growth-promoting hormones in chicken feed were also considered as relatively important. The storage study revealed that odour attributes of chicken meat (fresh chicken, bloody, pungent, fishy, rotten egg, ammonia-like and intense overall odour) changed at a faster rate than colour (L* and saturation) and appearance attributes (creamy skin, pink flesh, green/blue colouration and slimy). Odour attributes were also highly correlated (r > 0.8) with microbial growth. On the other hand, no correlations were found between colour and appearance attributes and microbial growth in chicken meat. Consumers’ handling practices and knowledge levels suggest that there is potential for unacceptable growth of spoilage and pathogenic bacteria in chicken meat. Additionally, the smell of chicken meat is perceived as a more important attribute than colour probably due to the significant differences in the rate of deterioration and relation with microbial growth during storage. The results from this study reflect a need for educational interventions focused on microbial risks in chicken meat and the consequences of mishandling on safety and quality, guidelines to prevent temperature abuse, the transmission of bacteria and cross-contamination. / Thesis (PhD (Food Science))--University of Pretoria, 2020. / The World Academy of Sciences (TWAS) / National Research Foundation (NRF) / Australia-Africa Universities Network (AAUN) / Food Science / PhD (Food Science) / Unrestricted

Interest in gluten-free (GF) bakery products due to wheat allergies and the incidence of coeliac disease, has led to research that continually explores new ingredients and formulations. One aim is to manufacture GF breads as similar as possible to wheat breads. In many African countries the high cost to import wheat particularly into no or low wheat-producing regions, where the climatic conditions do not favour its cultivation, demand that alternative sources of baking flours for bread are required. The cotyledons of marama beans (Tylosema esculentum) and starch from cassava roots (Manihot esculenta Crantz) contain no gluten. Marama bean has great potential as an oilseed legume. The isolated protein from marama flour has high foaming capacity, and produces a dough with high extensibility and good viscoelasticity, while cassava starch has better performance in gluten-free composite bread formulations than other cereal starches commonly available in Africa. Cassava starch is more similar in functional properties to wheat starch than other tropical cereal starches like maize and sorghum considering its high ratio of amylopectin to amylose which gives it good granule expansion at a low temperature. The dough properties of composites of defatted marama flour (DMF) and cassava starch (CS) were compared with wheat flour dough with the aim of determining the potential of such DMF-CS composites as a functional nutritious gluten-free ingredient in bread. GF breads from DMF and CS combined in different proportions were studied against wheat breads as standards. Freshly produced breads were assessed for colour, height, specific volume and spread ratio. The crumb texture of breads stored at 5 ° C was measured one day and three days after baking by conducting a texture profile analysis using an EZ-L Shimadzu texture analyser. The measured parameters were expressed as crumb firmness (N) and springiness (%). The crumb structures of GF composite breads were visualized using stereomicroscopy and a sensory panel described the sensory properties of the breads using the Flash Profiling method. DMF-CS doughs with similar strength to wheat flour dough were produced. However, the DMF-CS doughs had much shorter Mixolab development times and stability. Alveography revealed that the DMF-CS doughs could inflate a bubble, with the 33:67 DMF-CS ratio having the most similar bubble size, extensibility and deformation energy as wheat flour dough. With the highest proportion of DMF (57:43 DMF-CS), these parameters were lower possibly because of the highly hydrophilic marama protein which tended to form aggregates rather than distribute homogenously throughout the dough as revealed by confocal laser scanning microscopy. Rheofermentometry showed that similar to wheat flour dough, the DMF-CS composite doughs also held gas produced by yeast fermentation. In this regard, DMF appears to have considerable potential as a functional gluten replacement for making protein- and fibre-rich GF bread. Indeed, DMF-CS breads with brown crusts and a uniform aerated crumb structure were produced. Higher inclusion of DMF in the formulation led to a higher specific bread volume with a lower spread ratio. The DMF-CS bread crumbs were less soft than wheat bread with a more intense fermented, nutty, bean-like flavour as well as chewier texture. Higher inclusion of DMF in the formulation led to more bitter taste because DMF contains bitter compounds such as saponins, gallic and protocatechuic acids. DMF-CS breads presented different, more intense flavour sensory profiles compared to wheat bread which was blander. This is the first study to clearly demonstrate the utilisation of DFM in gluten-free formulations for bread making. The research covers an interesting and highly relevant topic, which is the overall food supply in Africa through creation of a new ingredient for the bakery industry and manufacturing of a staple food product such as bread. The findings of this work serve an important purpose. Domestication of marama bean plants and successful processing of the seeds to functional flour may revolutionise the bakery industry and could potentially have significant economic impact. More research is needed to optimise the formulations and baking methods along with the use of effective technologies to mask the bitter taste of the DMF-CS bread flavour to enhance consumer acceptance and potential success on the market. Further research possibilities should also include altering recipes to improve the flavour and adopting alternative processing techniques including sourdough fermentation, frozen storage of dough, and partial baking to accomplish longer shelf life. The findings of this work should contribute to stimulating the development of marama bean as a commercial oilseed legume crop. DMF appears to have considerable potential as a highly functional gluten replacement in the production of “additive-free,” protein- and dietary fibre-rich gluten-free bread or as a partial wheat flour replacement in composite flour breads. / Thesis (PhD (Food Science))--University of Pretoria, 2020. / University of Pretoria / Food Science / PhD (Food Science) / Unrestricted