Motivation: Cardiovascular heart disease (CVD) is the leading cause of death worldwide. Risk markers for CVD include, amongst others, the haemostatic factors tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor type 1 (PAI-1), factor VII (FVII) and fibrinogen and more recently, C-reactive protein (CRP), a sensitive marker of inflammation. Epidemiological studies have demonstrated an inverse association between dietary fibre (DF) consumption and risk factors for CVD and CVD prevalence. Some research indicates that this protection may be related to favourable changes in the haemostatic profile and inflammatory markers. This is applicable for the consumption of total DF, as well as soluble and insoluble fibre. However, clinical intervention trials report conflicting data on the effects of DF on t-PA, PAI-1, FVII, fibrinogen and CRP. In addition, available literature is not clear on the mechanisms through which DF may have favourable effects. Objective: The main objective of this study was to review the results of randomised controlled trials systematically on the effects of DF on the above-mentioned selected haemostatic variables and CRP in healthy adults and subjects with hypertriglyceridaemia and the metabolic syndrome. Methods: Human adult intervention trials, at least two weeks in duration, with an increased and measurable consumption of DF were included. Electronic databases were searched from the earliest record to May/July 2006 and supplemented by crosschecking reference lists of relevant publications. From the literature search, two reviewers identified studies that were rated for quality based on the published methodology. No formal statistical analysis was performed due to the large differences in the study designs of the dietary intervention trials. The primary outcome measures were percentage changes between intervention and control groups, or baseline to end comparisons for t-PA, PAI-1, FVII, fibrinogen and CRP. Results t-PA activity increased significantly (14-167%) over the short and long-term following increased fibre intakes. PAI-1 activity decreased significantly between 15-57% over periods ranging from two to six weeks. These favourable changes in t-PA and PAI-1 occurred in healthy, hypertriglyceridaemic and metabolic syndrome subjects following consumption of diets containing ≥3.3 g/MJ DF and ≥4.5 g/MJ DF respectively. Mechanisms through which DF may affect t-PA and PAI-1 include its lowering effect on insulinaemic and glycaemic responses, decreasing triglycerides which are a precursor of very-low-density lipoproteins, fermentation of DF to short-chain fatty acids, which may reduce free fatty acid concentrations, as well as the role of DF in promoting weight loss. High DF intakes did not have a significant effect on fibrinogen concentrations possibly because of relatively little weight loss, too low DF dosages and maintaining a good nutritional status. Inadequate study designs deterred from meaningful conclusions. Significant decreases in FVll coagulant activity (6-16%) were observed with DF intakes of ≥3.3 g/MJ and concomitant decreased saturated fat intakes and weight loss in healthy and hypertriglyceridaemic subjects. Confounding factors include weight loss and a simultaneous decreased intake of saturated fats. The type of fibre seems to play a role as well. Mechanisms through which DF may reduce FVll concentrations include its effects on triglyceride-rich lipoproteins, insulin and weight loss. Increased DF consumption with dosages ranging between 3.3-7.8 g/MJ were followed by significantly lower CRP concentrations (25-54%), however, simultaneous weight loss and altered fatty acid intakes were also present in all the studies. Mechanisms are inconclusive but may involve the effect of DF on weight loss, insulin, glucose, adiponectin, interleukin-6, free fatty acids and triglycerides. Conclusions: Epidemiological evidence indicates an association between DF and the CVD risk factors t-PA, PAI-1, FVII, fibrinogen and CRP. In general, the risk of CVD may improve with high-fibre intakes as indicated by the favourable changes in some of the parameters. However, simultaneous reduced fat intakes and weight loss presented difficulties in separating out the effects of specific components. Furthermore, DF is consumed in a variety of different forms and different dosages that may have different effects. Overall, the study designs used in the intervention trials prevented significant conclusions. DF did, however, play a role in modifying t-PA, PAI-1, FVII and CRP. Potential effects on fibrinogen were not quantifiable. Recommendations: The results from this investigation provide the motivation for additional controlled clinical research to establish the effect and mechanisms of DF on haemostatic variables and CRP. A critical aspect of future studies would be to set up suitable protocols. The amount of subjects, duration of the trials, confounding factors such as weight loss and altered fat intakes and differentiation between types and dosage of DF are important. DF supplemental studies are recommended as they may be the most suitable method to reach meaningful conclusions. / Thesis (Ph.D. (Nutrition))--North-West University, Potchefstroom Campus, 2007

Orientador: Marise Aparecida Rodrigues Pollonio / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-21T13:23:32Z (GMT). No. of bitstreams: 1 Carraro_CarlaIvone_M.pdf: 1342581 bytes, checksum: 704953159961e17e7eccb8bbed399c09 (MD5) Previous issue date: 2012 / Resumo: As mudanças nas exigências dos consumidores e o aumento da competição global no mercado de alimentos fazem com que as indústrias de produtos cárneos adotem novas tecnologias de processamento e uso de novos ingredientes, para agregar valor, especialmente no atributo saúde. Neste contexto, os amidos resistentes são compostos, que apresentam propriedades semelhantes às fibras, exercendo a mesma função fisiológica, no entanto muito pouco estudados em produtos cárneos. O objetivo deste trabalho foi avaliar a utilização de amidos resistentes em produto cárneo emulsionado tipo mortadela com reduzido teor de gordura para a obtenção de um produto final com apelo saudável. Os amidos resistentes do tipo 2, 3 e 4 foram testados quanto à capacidade de retenção de água e apresentaram valores similares a outros extensores já utilizados. Na primeira etapa do trabalho, foi escolhido o amido resistente (conhecido pela sigla AR) tipo 3 para ser avaliado frente a três diferentes níveis de adição. Na sequência, foram realizados os ajustes de formulação e elaboradas duas formulações controle, seguidas de quatro substituições parciais e substituições totais com 2,5 e 5,0 % de AR. .As formulações: C1 (10% de gordura e 5% de fécula de mandioca), C2 (20% de gordura e 5% de fécula de mandioca), F2 (10% de gordura e 5% de AR tipo 3), F4 (10% de gordura e 5% de AR tipo 2) e F6 (10% de gordura e 5% de AR tipo 4) foram selecionadas para avaliação sensorial. As formulações com farinha de banana verde foram excluídas no teste preliminar de diferença de controle pela diferença de coloração e propriedades físico-químicas indesejadas resultantes no produto final. As amostras foram submetidas a testes sensoriais de aceitação: cego e informado e de diferença do controle. Na avaliação sensorial por diferença de controle foi observado que nos atributos de textura e sabor as amostras não apresentaram diferenças significativas e no atributo cor, a amostra C1 obteve notas mais altas que o controle C2,demonstrando que o produto com menor teor de gordura teve uma boa aceitação. As amostras F2, F4 e F6 não apresentaram diferença com relação ao controle C1, concluindo que a substituição da fécula de mandioca por amido resistente foi satisfatória. O teste cego de aceitação para os atributos: aparência, aroma e sabor não apresentaram diferenças significativas entre as amostras, sendo que o controle C1, obteve pontuação maior em relação ao controle C2. Nos atributos de textura e impressão global, as amostras F4 e F6 não apresentaram diferenças significativas e a amostra F2 obteve menor pontuação. No teste informado não houve mudança perceptível na avaliação dos consumidores, porém a amostra controle C2 teve uma aceitação melhor, demonstrando que o consumidor ainda não está preparado para o conceito de alimento com apelo saudável. Desta forma pode-se concluir que é possível reduzir a gordura de mortadelas sem prejudicar a composição físico-química, propriedades funcionais e sensoriais do produto através da utilização de amido resistente como ingrediente extensor / Abstract: Changes in consumer demand and the increase of competition in the global food market make meat product industries adopt new processing technologies and we use new ingredients to add value, especially in health attribute. In this context, the resistant starches are compounds that exhibit properties similar to fibers, with the same physiological function, however very little studied in meat products. The aim of this study was to evaluate the use of resistant starches in emulsified meat product as Bologna sausage with reduced fat to obtain a final product with healthy appeal. The resistant starches, type 2, 3 and 4 were tested for their ability to retain water with the same results of others extenders already used in meat products. In the first step, was chosen resistant starch (abbreviated as RS) type 3 to be evaluated against three different levels of addition. After, adjustments were made to formulate and elaborate: two control formulations, followed by four substitutions partial and total replacements with 2,5% and 5,0% of RS. These formulations were selected for sensory assessment: C1 (10% fat and 5% cassava starch), C2 (20% fat and 5% cassava starch), and formulations with starch replacement by resistant starch: F2 (10% fat and 5% RS Type 3), F4 (10% fat and 5% RS Type 2) and F6 (10% fat and 5% RS type 4). The formulations with green banana flour were excluded by difference from control, as the different colour and physicochemical properties resulting undesired final product. The samples were tested for sensory acceptance: blind and informed test and difference from the control. In sensory evaluation by difference from control was observed that the texture and flavor attributes of the samples showed no significant differences in the color attribute and the sample C1 was obtained higher scores than the control C2, demonstrating that the product with lower fat content had a good acceptance. The samples F2, F4 and F6 showed no difference compared to the control C1, concluding that the replacement of cassava starch by resistant starch was satisfactory. The blind acceptance for attributes: appearance, aroma and flavor showed no significant differences between the samples, and control C1, obtained higher scores than control C2. In texture attributes and overall impression, F4 and F6 samples showed no significant differences and F2 sample obtained lower scores. In reported test no noticeable change in the assessment of consumers, but the control sample C2 had a better acceptance, demonstrating that the consumer is not ready for the concept of meat products with healthy appeal. Thus it can be concluded that it is possible to reduce fat in Bologna sausage without impairing the physical and chemical composition, functional and sensory properties of the product through the use of resistant starch as an extender ingredient / Mestrado / Tecnologia de Alimentos / Mestra em Tecnologia de Alimentos

By-products of fruit, cereal and vegetable processing are often regarded as waste while they contain significant amounts of dietary fibre and phytochemicals that can positively contribute to the human diet when reused as food ingredient. The application of fibre from by-products in baked goods could increase the sustainability of the processing chain but is usually associated with changes in product characteristics, such as lower volume, denser structure and increased hardness. In the current study, the interactions of fibres from by-products and wheat macromolecules were analysed in muffins, starch slurries and wheat doughs. The three selected fibres differed significantly in their chemical composition and technofunctional properties. In muffins wheat flour replacement by apple fibre was assessed by rheological measurements of batter and determination of product characteristics. Water proportion adaption based on batter viscosity to create isoviscosity was evaluated as a promising method to develop muffins with satisfying characteristics, where a wheat flour replacement of 30 % is suggested. The addition of apple fibre influenced starch gelatinisation in muffins during baking as indicated by the results of pasting experiments and in vitro starch digestion. Starch slurries with apple and wheat fibre were analysed in pasting experiments. Soluble dietary fibre, mainly pectin, strongly influenced the pasting profile of wheat starch, in comparison to insoluble dietary fibre, that acted as an inert filler and did not interact with the starch. Wheat doughs with fibre from by-products were analysed for rheology, texture and microstructure. The gluten development was negatively influenced by the fibres, which resulted in less extensible doughs. Soluble dietary fibre resulted in increased dough stickiness and limited dough handling at high application levels. It can be reasoned that dough with 10% fibre from by-products would produce products with satisfying characteristics, whereas higher application levels cannot be recommended without using additives to increase the gluten strength. Fibres from by-products are suitable wheat flour replacers in bakery products, where the negative effects of the high water binding capacity of the fibre, can be partly balanced by water proportion adaption, especially in products were gluten development is not that dominating for product structure, like in muffins or cakes. / Nebenprodukte der Obst-, Getreide- und Gemüseverarbeitung werden oft als Abfall betrachtet, wobei sie signifikante Gehalte an Ballaststoffen und sekundären Pflanzeninhaltsstoffen aufweisen, und bei der Verwendung als Lebensmittelzutat positiv zur menschlichen Ernährung beitragen können. Die Anwendung von Fasern aus Nebenprodukten in Backwaren könnte die Nachhaltigkeit der Verarbeitungskette erhöhen, ist jedoch mit Änderungen der Produkteigenschaften verbunden, wie verringertes Volumen, dichtere Struktur und erhöhte Härte. In der vorliegenden Studie wurden die Wechselwirkungen von Fasern und Weizenmakromolekülen in Muffins, Stärkesuspensionen und Weizenteigen analysiert, wobei sich die drei ausgewählten Fasern in ihrer chemischen Zusammensetzung und ihren technofunktionellen Eigenschaften unterschieden. In Muffins wurde die Mehlsubstitution durch Apfelfaser anhand von Teigrheologie und Produkteigenschaften analysiert. Die Anpassung des Wassergehaltes basierend auf der Teigviskosität wurde als vielversprechende Methode zur Entwicklung von Muffins mit akzeptablen Eigenschaften bewertet, wodurch ein Mehlersatz von 30% möglich war. Die Zugabe von Apfelfasern beeinflusste die Stärkeverkleisterung in Muffins, wie durch die Ergebnisse von Verkleisterungsexperimenten und In vitro-Stärkeverdauung gezeigt wurde. Stärkesuspensionen mit Apfel- und Weizenfasern wurden auf ihr Verkleisterungsverhalten analysiert. Lösliche Ballaststoffe beeinflussten das Verkleisterungsprofil von Weizenstärke im Vergleich zu unlöslichen Ballaststoffen, die als inerter Füllstoff fungierten und nicht mit der Stärke in Wechselwirkung traten. Weizenteige mit Fasern wurden auf Rheologie, Textur und Mikrostruktur untersucht. Die Glutenentwicklung wurde durch die Fasern negativ beeinflusst, was zu weniger dehnbaren Teigen führte. Lösliche Ballaststoffe führten zu einer erhöhten Teigklebrigkeit. Weizenteig mit 10% Faser besitzt zufriedenstellenden Eigenschaften, während höhere Fasermengen nicht zu empfehlen sind, ohne Zusatzstoffe, um die Glutenfestigkeit zu erhöhen. Fasern aus Nebenprodukten sind geeignet als Mehlersatz in Backwaren, wobei die negativen Auswirkungen der hohen Wasserbindekapazität der Faser teilweise durch Wasseranpassung ausgeglichen werden können, insbesondere in Produkten, bei denen die Glutenentwicklung nicht die Produktstruktur dominiert, wie in Muffins oder Kuchen.

L’optimisation de l’utilisation de phosphore reste un enjeu majeur pour assurer la durabilité de nos filières avicoles et porcines. Aujourd’hui, l’utilisation de coproduits, relativement riches en fibres alimentaires, est grandissante. Or, les fibres alimentaires sont reconnues pour moduler les processus de digestion et la digestibilité des nutriments. Ce travail de thèse a permis de progresser sur les mécanismes digestifs engendrés par l’apport de coproduits riches en fibres alimentaires et leurs effets sur la digestion des minéraux, en lien avec la phytase microbienne, spécifiquement chez le porc et le poulet. Leurs conséquences métaboliques en terme de balance minérale et d’équilibre acidobasique ont également été mises en évidence Les connaissances acquises vont contribuer à l’amélioration de l’apport en minéraux, notamment de phosphore et de calcium, dans des formules diversifiées chez le porc et le poulet. A terme, ceci permettra de mieux adapter nos systèmes d’alimentations au regard des enjeux de durabilité. / The optimisation of the use of phosphorus remains a major challenge to ensure the sustainability of poultry and pig industry. Today, the use of co-product, relatively rich in dietary fibre, is increasing. However, dietary fibre is known to modulate digestion processes and digestibility of nutrients. This work contributed to progress on the digestive mechanisms generated by the intake of dietary fibre from coproducts and their effects on the digestion of minerals, in relation with microbial phytase, specifically in pigs and chickens. Their metabolic consequences in terms of mineral and acid-base balance have also been demonstrated. The knowledge gained will contribute to the improvement of the intake of minerals, in particular phosphorus and calcium, in diversified formulas in pigs and the chicken. Finally, this will allow us to better adapt our feeding systems to the challenges of sustainability.

It is currently accepted that the most appropriate diet in the treatment of non-insulin-dependent diabetes mellitus &quoteNIDDM&quote is high in carbohydrates, high in fibre and low in fat. Dietary fibre reduces the rate of carbohydrate absorption, which may have a beneficial effect on insulin action. Furthermore, high fibre diets also increase the amount of carbohydrates which are not absorbed from the small intestine. These malabsorbed carbohydrates are fermented by the bacterial population in the large intestine, producing short chain fatty acids &quoteSCFA&quote, including propionate, which has been shown to alter liver carbohydrate metabolism. This thesis investigated the actions of slowed carbohydrate absorption and carbohydrate malabsorption in streptozotocin-induced &quoteSTZ&quote diabetic rats. High carbohydrate diet supplemented with guar gum, a soluble dietary fibre, fed to STZ diabetic rats improved insulin sensitivity. investigation of the alterations in the stomach and small intestine demonstrated that guar increased the viscosity of the meal in the intestine. The action of increased fermentation, producing more propionate, was investigated by supplementing propionate into the diets of STZ diabetic rats or when perfused into isolated rat livers. No changes in insulin action or liver glucose metabolism were measured. in addition, it was shown that guar gum reduces food intake in STZ diabetic rats. Mild reductions in food intake in STZ diabetic rats were shown to increase insulin action. In summary, STZ diabetic rats fed high carbohydrate, high fibre diets reductions in food consumption and slowed carbohydrate absorption are important factors which may lower blood glucose concentrations and increase insulin action. increased SCFA production is unlikely to contribute significantly to the improvements in insulin action.

<p>The glycaemic responses to various carbohydrate-rich foods are partly dependent on the rate at which the carbohydrate is digested and absorbed. The glycaemic index (GI) is a way of ranking foods according to their glycaemic response and is recommended as a useful tool in identifying starch-rich foods that give the most favourable glycaemic response. This investigation was undertaken to determine whether carbohydrate-rich foods with a low GI and a high content of dietary fibre (DF) could have beneficial metabolic effects in the insulin resistance syndrome. This question was addressed both in single-meal studies and in randomised controlled clinical trials. Starch-rich foods with low GI values incorporated into composite meals resulted in lower postprandial responses of both glucose and insulin than foods with a high GI in meals with an identical macronutrient and DF composition, in subjects with type 2 diabetes. After three weeks on a diet including low GI starchy foods metabolic profile was improved in subjects with type 2 diabetes, compared with a corresponding high GI diet. The glucose and insulin responses throughout the day were lower, the total and low density lipoprotein cholesterol was decreased, and the fibrinolytic activity was normalised. In subjects with impaired insulin sensitivity and diabetes low GI foods rich in soluble DF for breakfast gave a more favourable metabolic profile, with smaller glucose fluctuations from baseline during the day, than a breakfast with high GI foods low in DF. A low GI breakfast high in DF also resulted in lower responses of insulin and C-peptide after breakfast and a lower triacylglycerol response after a standardised lunch. However, none of the tested breakfasts improved the glucose and insulin responses after lunch. Similar results were obtained in obese subjects after including a breakfast with a low GI high in soluble DF for a period of four weeks in comparison with a breakfast with a high GI and low content of DF.</p><p>These results support the therapeutic potential of a diet with a low GI in the treatment of diabetes and also in the treatment of several of the metabolic disturbances related to the insulin resistance syndrome.</p>

In einer Zeit, in der eine Zunahme von ernährungsbedingten Erkrankungen in steigendem Maße zu beobachten ist, wird dem Getreide als Grundlage der menschlichen Ernährung erhöhte Aufmerksamkeit gewidmet. Ein hoher Verzehr von Ballaststoffen ist ein wesentlicher Aspekt in der präventiv-medizinischen Ernährung. Die von der Deutschen Gesellschaft für Ernährung vorgeschlagene tägliche Ballaststoffzufuhr liegt bei 30 g. Die Aufnahme von Ballaststoffen ist jedoch in Deutschland deutlich unterhalb dieser empfohlenen Menge.<br><br> Getreideprodukte, besonders vom Vollkorntyp, sind die wichtigste Quelle für Ballaststoffe. Deshalb sollten im Rahmen dieser Arbeit direkt verzehrsfähige, Ballaststoff-angereicherte Haferprodukte (vorwiegend Extrudate) mit hohen Gehalten an b-Glucanen und resistenter Stärke hergestellt, analysiert und nachfolgend auf relevante ernährungsphysiologische Wirkungen geprüft werden. Als Basis für die Produkte wurden Hafermehl und Haferkleie eingesetzt.<br> Der erste Teil der Arbeit beschäftigte sich mit der Analyse der Haferprodukte. Diese wiesen eine hohe Wasserbindungskapazität auf. Bei den Untersuchungen am Tiermodell wurde gezeigt, dass im Dünndarm eine größere Menge an Wasser durch die Haferprodukte gebunden wurde, was zu einem höheren Feuchtigkeitsanteil der gastrointestinalen Inhalte der Tiere führte, die ballaststoffreiches Futter erhielten.<br><br> Trotz der hydrothermischen Behandlung während der Extrusion wurden Produkte gewonnen, deren β-Glucane im hochmolekularen Zustand erhalten blieben und somit eine hohe Viskosität in wässrigen Lösungen beibehielten. In rheologischen Untersuchungen wurde bestätigt, dass die aus Haferprodukten isolierten β-Glucane ein pseudoplastisches Fließverhalten besitzen. Demgegenüber führte ein Autoklavieren der Produkte zu einer starken Depolymerisation der b-Glucane, was sich in einer Änderung der funktionellen Eigenschaften der b-Glucane widerspiegelte.<br><br> Im Mittelpunkt der Untersuchungen standen ernährungsphysiologische In-vitro- und In-vivo-Experimente mit Extrudaten und Proben auf der Basis von Hafer, die einen erhöhten Anteil an Ballaststoffen, speziell an b-Glucan und an resistenter Stärke, besaßen und die direkt verzehrbar sind. Diese Haferprodukte zeigten eine Reihe von ernährungsphysiologisch vorteilhaften und protektiven Wirkungen in In-vitro-Experimenten. So traten sie mit Gallensäuren unter den Bedingungen des Dünndarms in Wechselwirkung und waren gut mit Faecesflora vom Menschen fermentierbar. Die In-vitro-Verdauung von Maisstärke durch Pankreatin, wurde durch die ballaststoffreichen Haferprodukte partiell gehemmt. Dieser Befund lässt eine Abschwächung des postprandialen Glukoseanstieges erwarten.<br><br> In einem sechswöchigen Fütterungsversuch erhielten Ratten Diäten, die zu 50 % aus ballaststoffreichen Haferprodukten bestanden. Diese Haferprodukte bewirkten einen erhöhten Transport von Gallensäuren und neutralen Sterolen in den unteren Intestinaltrakt sowie deren verstärkte Ausscheidung. Durch den Verzehr der ballaststoffreichen Haferprodukte kam es zu Veränderungen in der Mikroflora, wobei sich besonders die coliformen Keime verminderten und die Keimzahlen der Lactobacillen sowie die Bifidobakterien erhöhten. Die Fermentation der Ballaststoffe führte zur erhöhten Bildung von kurzkettigen Fettsäuren einschließlich von Butyrat. Die Bildung der kurzkettigen Fettsäuren geht mit einer pH-Wert-Absenkung im Caecum und Colon einher, die wiederum für eine geringere Bildung von sekundären Gallensäuren verantwortlich ist.<br><br> Die Ergebnisse des Fütterungsversuchs an Ratten wurden prinzipiell durch eine vierwöchige Pilotstudie am Menschen, in der Probanden täglich 100 g Haferextrudat erhielten, bestätigt. Das Extrudat wurde von den Probanden gut akzeptiert. In der 4. Woche wurden eine geringe Abnahme der Cholesterolfraktionen im Serum, höhere Keimzahlen für Lactobacillen, Bifidobacterien und Bacteroides, geringere pH-Werte und Trockenmassegehalte in den Faeces, eine Zunahme der individuellen und Gesamt-SCFA sowie des Butyratanteils in den Faeces, eine erhöhte Ausscheidung an Steroiden, eine Zunahme der primären Gallensäuren und eine Abnahme des prozentualen Anteils an sekundären Gallensäuren sowie der Cholesterol-Metaboliten gefunden. Diese Parameter gingen 2 Wochen nach Beendigung der Intervention mit dem Haferextrudat wieder in Richtung der Ausgangswerte (0. Woche) zurück.<br><br> Die untersuchten Haferprodukte erwiesen sich als gut fermentierbare Substrate für die intestinale Mikroflora und können deshalb als ein Präbiotikum mit Ballaststoffcharakter eingeschätzt werden. Diese Produkte, die mit einem erhöhten Anteil an resistenter Stärke und wertvollen Haferballaststoffen hergestellt wurden, können dazu beitragen, die Ballaststofflücke in unserer Ernährung zu schließen und positive ernährungsphysiologische Effekte zu bewirken. / Cereal products, particularly from whole grains, are the most important source of dietary fibre in the western diet. A high intake of dietary fibre, which is an essential component in nutrition, is positively related to several physiological and metabolic effects. However, the daily intake of dietary fibre is below the recommended levels (30d/day) in most industrials country. Oat (Avena sativa L.) products are well accepted in human nutrition. Oats is an excellent source of different dietary fibre types, such as β-glucan, arabinoxylans and cellulose, and it contains high levels of proteins, lipids, vitamins, antioxidants and minerals.<br> A series of extrudates was prepared from oat meal, oat bran and Novelose 330®, differing in concentrations of individual dietary fibre components, such as β-glucan and resistant starch, as well as total dietary fibre.<br><br> The cereal dietary fibre, β-glucan, has outstanding functional and nutritional properties, because of its viscosity in aqueous systems and in the intestinal tract. The rheological behaviour of β-glucan (concentrations: 2% and 4%) isolated from extruded oat meal and from oat bran was evaluated using oscillatory and rheological measurements. In frequency sweep, the storage and loss moduli G′ and G″ of β-glucan preparations from extruded meal and from bran increased continuously with increasing frequency, showing a dominantly viscous behaviour. With increasing frequency, the elastic properties improved.<br><br> After simulated digestion, the digested dietary fibre-rich oat-based extrudates were used to evaluate their physiological effects in vitro. A strong interaction occurred between the digested extrudates and bile acids. The binding of bile acids increased with increasing proportions of oat bran, total dietary fibre, insoluble dietary fibre and β-glucan in the extrudates. Dihydroxy-bile acid was more strongly bound to the extrudates than trihydroxy- bile acid. Interactions at pH 5.0 were greater than at pH 6.5. During fermentation of digested extrudates with human faecal samples, concentrations of short-chain fatty acid formed and the molar proportion of butyrate increased continuously. Higher short-chain fatty acid concentrations were found when extrudates contained more oat bran, soluble and insoluble dietary fibre and β-glucan. Extrudates, on the basis of oat, have several beneficial nutritional and protective effects in vitro. Therefore, physiological effects occurring in the small and large intestine are also related to the dietary fibre composition of the cereal products.<br><br> The results found in vitro was examined in feeding experiments with animal models and in nutritional studies with human subjects.<br><br> Male Wistar rats were fed either an oat-free diet (control group) or diet containing 50% oat-based products (test groups) for 6 week. In most of the test group, following effects were observed compared with control group: higher water intake; slightly decreased total and LDL cholesterol in serum; higher count of Bifidobacteria as well as lower count numbers of Coliforms; greater mass of cecum walls and cecal contents; lower pH values in intestinal contents; higher concentration of acetate, propionate and butyrate in cecal contents and greater excretion of short-chain fatty acids; significantly more total bile acids in cecal contents; higher excretion of total bile acids and primary bile acids; lower proportion of secondary bile acids as well as higher concentration of neutral sterols in cecal contents, colonic contents and feces.<br><br> In the human study 12 volunteers consumed 100 g fiber-rich oat-based product (to the habitually diet) daily for 4 week. Following results were observed in the week 4 compared with the beginning of the experiment: higher water intake; slightly decreased total cholesterol in serum; lower pH values in feces; higher concentration of acetate, propionate and butyrate in feces; higher excretion of total bile acids and primary bile acids; lower proportion of secondary bile acids as well as higher concentration of neutral sterols in feces.<br><br> In conclusion, application of the dietary fiber-rich oat-based diets had a variety of beneficial physiological and protective effects in rats and human depending on their composition and amount, their technological pre-treatment and their functional properties. The major effects connected whit fermentation of dietary fibre components and their high formation of short-chain fatty acids as well as with higher excretion of steroids.

The glycaemic responses to various carbohydrate-rich foods are partly dependent on the rate at which the carbohydrate is digested and absorbed. The glycaemic index (GI) is a way of ranking foods according to their glycaemic response and is recommended as a useful tool in identifying starch-rich foods that give the most favourable glycaemic response. This investigation was undertaken to determine whether carbohydrate-rich foods with a low GI and a high content of dietary fibre (DF) could have beneficial metabolic effects in the insulin resistance syndrome. This question was addressed both in single-meal studies and in randomised controlled clinical trials. Starch-rich foods with low GI values incorporated into composite meals resulted in lower postprandial responses of both glucose and insulin than foods with a high GI in meals with an identical macronutrient and DF composition, in subjects with type 2 diabetes. After three weeks on a diet including low GI starchy foods metabolic profile was improved in subjects with type 2 diabetes, compared with a corresponding high GI diet. The glucose and insulin responses throughout the day were lower, the total and low density lipoprotein cholesterol was decreased, and the fibrinolytic activity was normalised. In subjects with impaired insulin sensitivity and diabetes low GI foods rich in soluble DF for breakfast gave a more favourable metabolic profile, with smaller glucose fluctuations from baseline during the day, than a breakfast with high GI foods low in DF. A low GI breakfast high in DF also resulted in lower responses of insulin and C-peptide after breakfast and a lower triacylglycerol response after a standardised lunch. However, none of the tested breakfasts improved the glucose and insulin responses after lunch. Similar results were obtained in obese subjects after including a breakfast with a low GI high in soluble DF for a period of four weeks in comparison with a breakfast with a high GI and low content of DF. These results support the therapeutic potential of a diet with a low GI in the treatment of diabetes and also in the treatment of several of the metabolic disturbances related to the insulin resistance syndrome.

Gastrointestinal microflora has been shown to have a bi-directional relationship with the host immune system. A variety of fermentable carbohydrate polymers largely pass through the small intestine, providing fermentable substrates for gut microflora. Dietary fibre supplementation may provide a strategy for manipulating the intestinal bacterial profile, changing the interaction with the mucosal immune system, thereby modulating the host immune system. We used a BBc rat animal model to evaluate the effects of oat bran and wheat bran dietary fibre on the immune system. Previous collaborative efforts have shown that these dietary fibres can change the intestinal microflora, with wheat bran fibre showing a greater ability to influence colonic microbial community diversity. We have shown that dietary wheat bran fibre led to reduced IL-4 levels in the liver and T lymphocyte numbers in the Mesenteric Lymph Node and may be involved in reduced IgA levels in the cecal contents. In addition, IgA in the cecal contents was decreased while MLN B cell numbers increased in response to dietary wheat bran fibre. It was observed that neither wheat bran or oat bran treatments exerted any pro-inflammatory effects, with oat bran actually improving antioxidant status. These results suggest that both oat and wheat bran fibre treatments induce changes in the intestinal microflora, and that the microflora changes due to wheat fibre are associated with immunomodulatory effects on the host. This type of dietary fibre supplementation could ultimately provide a potential strategy for promoting health through microflora-associated effects on the immune system.

Aquaculture represents a sustainable alternative to natural fisheries for provision of high quality, animal protein. Crustaceans make a significant contribution to global aquaculture production, of which decapods are the most economically important group. Among freshwater crayfish, the genus Cherax includes several species that have emerged as important culture species. A suite of favourable biological attributes, including fast growth and an omnivorous feeding habit, have contributed to establishment of successful culture of Cherax quadricarinatus (redclaw) in many countries. Aspects of redclaw production, however, remain relatively undeveloped, in particular feed formulation. To better understand the digestive processes and nutritional requirements of redclaw, this study examined the relationship between diet composition and digestive enzyme activity, growth performance and diet digestibility coefficients. The extent to which redclaw can efficiently utilise complex polysaccharides, such as cellulose, has been speculated on by authors who reported endogenous cellulase activity in this species. I evaluated the use of insoluble α-cellulose by redclaw, demonstrated that high dietary levels (30%) can significantly reduce the specific activity of selected digestive enzymes (amylase and cellulase), while also lowering apparent digestibility coefficients. Inclusion of α-cellulose above 12% also significantly reduced survival rate, specific growth rate and feeding efficiency in this organism which corresponds with low tolerance for insoluble fibre by other decapods. Even though redclaw possess endogenous cellulases, they appear to have only a limited capacity to utilise insoluble fibre in their diets. Further, I assessed the impact of different nutrient profiles on digestive enzyme activity, growth and tail muscle composition in redclaw. Purified diets containing varying levels of dietary protein significantly affected activity of digestive enzymes (protease, amylase and cellulase) and the composition of the tail muscle tissue. Redclaw have a relatively low protein requirement, which was reflected here, as little significant difference was observed in growth rates and the feed conversion ratio was only significantly affected by the lowest protein diet. Manipulation of the non-protein energy component in purified diets (protein to lipid ratio) had no effect on growth performance indices in redclaw. Digestive enzyme activity (protease) was however, strongly influenced by both the amount of protein and lipid in the diet and a significant correlation was observed between protease activity and growth performance indices. The findings here, provide preliminary data for consideration of digestive enzymes such as proteases as potential growth indicators for freshwater crayfish. These enzymes are already recognised as reliable biological indicators for comparison of digestive efficiency and potential growth rate in fish. The relationship between diet composition and digestive enzyme expression observed here, stress the need for further empirical evaluation of specific ingredients in artificial diets for redclaw. A range of single cell, plant and animal-based, agricultural products were assessed for their potential use in diets formulated for redclaw. Analysis of dietary supplements revealed that apparent digestibility of crude protein was generally higher for diets containing plant-based ingredients. A similar outcome was observed for digestibility coefficients of test ingredients. Ingredient type also had a significant effect on digestive enzyme activity. Importantly, a significant correlation was observed for enzyme activity and apparent digestibility coefficients. It appears that redclaw have the capacity to utilise nutrients from a broad range of dietary ingredients successfully including animal, single cell and in particular, plant matter in their diet. Taken together, the results presented here demonstrate that digestive enzyme activities in redclaw are significantly influenced by diet composition. I show clearly that the ability of redclaw to utilise various nutrients (measured as digestibility coefficients) is highly correlated with digestive enzyme activity. Finally, protease activity demonstrated a potential for use as an indicator of redclaw growth performance. The data presented here will contribute to development of better and cheaper feed formulations for use in redclaw aquaculture and have broader applications to freshwater crustacean culture. In particular, the potential for use of plant-based ingredients in aqua-feeds for redclaw will contribute to a more economically and environmentally sustainable redclaw culture.