Onderzoek moet uniformer stek bij siergewassen opleveren (o.a. interview met Hendrik-Jan van Telgen)
Staalduinen, J. van; Telgen, H.J. van - \ 2007
Onder Glas 4 (2007)8. - p. 54 - 55.
siergewassen - rozen - potplanten - vermeerderingsmateriaal - stekken - fotosynthese - meting - technieken - koolhydraten - beworteling - onderzoek - glastuinbouw - snijbloemen - ornamental crops - roses - pot plants - propagation materials - cuttings - photosynthesis - measurement - techniques - carbohydrates - rooting - research - greenhouse horticulture - cut flowers
Het slagingspercentage en de uniformiteit van stekken worden mede bepaald door inwendige factoren, zoals fotosynthesecapaciteit en de koolhydraatstatus in het blad. Met behulp van diverse meettechnieken onderzoekt een projectteam of op basis van de gemeten waarden voorspellingen mogelijk zijn over de mate van beworteling en uitgroei. Als dat zo is, kunnen deze technieken bijdragen aan optimalisatie van de bedrijfsprocessen op vermeerderingsbedrijven
Het effect van voersamenstelling op bacteriële darmaandoeningen bij varkens = The effect of feed composition on bacterial intestinal diseases in pigs
Meulen, J. van der; Peet-Schwering, C.M.C. van der - \ 2007
Lelystad : Animal Sciences Group (Rapport / Animal Sciences Group, Divisie Veehouderij 83) - 14
varkens - dierhouderij - diervoeding - voersamenstelling - koolhydraten - darmziekten - diergezondheid - bacterieziekten - dysenterie - varkensdysenterie - colitis - enteritis - salmonellose - pigs - animal husbandry - animal nutrition - feed formulation - carbohydrates - intestinal diseases - animal health - bacterial diseases - dysentery - swine dysentery - colitis - enteritis - salmonellosis
Feed composition, and especially carbohydrate composition, may affect the development of enteric bacterial diseases. Also the kind of feed ingredients (soybean or not) and feed treatment (milling size, pelletizing, fermentation) may be important. A more coarse grinding, no pelletizing and fermentation may be preferable in the reduction of the development of enteric bacterial diseases.
Chemical composition of lamina and sheath of Lolium perenne as affected by herbage management
Hoekstra, N.J. ; Struik, P.C. ; Lantinga, E.A. ; Schulte, R.P.O. - \ 2007
NJAS Wageningen Journal of Life Sciences 55 (2007)1. - ISSN 1573-5214 - p. 55 - 73.
afsnijhoogte - grasbestand - voedergewassen - lolium perenne - hergroei - rotaties - chemische samenstelling - graslandbeheer - voedingswaarde - lignine - totale hoeveelheid droge stof - koolhydraten - stikstof - vezelgehalte - bloeiwijzen - cutting height - herbage - fodder crops - lolium perenne - regrowth - rotations - chemical composition - grassland management - nutritive value - lignin - total solids - carbohydrates - nitrogen - fibre content - inflorescences - water-soluble carbohydrate - neutral detergent fiber - dairy-cows - nitrogen application - nutritive-value - ryegrass varieties - animal nutrition - milk-production - rumen function - l. cultivars
The quality of grass in terms of form and relative amounts of energy and protein affects both animal production per unit of intake and nitrogen (N) utilization. Quality can be manipulated by herbage management and choice of cultivar. The effects of N application rate (0, 90 or 390 kg N ha¿1 year¿1), duration of regrowth period (2¿3, 4¿5, or 6¿7 weeks), and cutting height (8 or 12 cm) on the mass fractions of nitrogen (N), water-soluble carbohydrates (WSC), neutral detergent fibre (NDF), acid detergent fibre (ADF), lignin and ash in lamina and sheath material of a high-sugar (Aberdart) and a low-sugar (Respect) perennial ryegrass (Lolium perenne) cultivar, were studied in a factorial field experiment during four seasons in 2002 and 2003. Expressing NDF and ADF mass fractions in g per kg WSC-free dry matter (DM) increased the consistency of treatment effects. The high-sugar cultivar had generally higher WSC mass fractions than the low-sugar cultivar, especially during the late season. Moreover, the relative difference in WSC mass fraction between the two cultivars tended to be higher for the lamina material than for the sheath material, which suggests that the high-sugar trait may be more important under grazing conditions, when lamina forms the bulk of the intake, than under mowing regimes. Longer regrowth periods and lower N application rates increased WSC mass fractions and decreased N mass fractions; interactions between regrowth period and N application rate were highly significant. The mass fractions of NDF and ADF were much less influenced. The NDF mass fraction in terms of g per kg WSC-free DM tended to be higher at lower N application rates and at longer regrowth periods. The effect of cutting height on herbage chemical composition was unclear. In conclusion, high-sugar cultivars, N application rate and length of the regrowth period are important tools for manipulating herbage quality.
Rumen development in veal (preruminant) calves
Suárez, B.J. - \ 2006
Wageningen University. Promotor(en): Seerp Tamminga, co-promotor(en): Walter Gerrits; Jan Dijkstra. - [S.l.] : S.n. - ISBN 9789085045366 - 174
vleeskalveren - pensontwikkeling - pensfermentatie - concentraten - ruwvoer (roughage) - voer - samenstelling - koolhydraten - enzymactiviteit - mestresultaten - kalvervoeding - veal calves - rumen development - rumen fermentation - concentrates - roughage - feeds - composition - carbohydrates - enzyme activity - fattening performance - calf feeding
Historically, veal calves were fed until slaughter weight with only milk replacer and, in absence of solid feed the physiological development of the forestomachs was limited. In 1997, a new EU legislation stipulated that a minimum amount of solid feed (fiber) has to be provided for the welfare of the calves (solid feed supply reduce abnormal oral behaviors in veal calves; Van Putten, 1982; Veissier et al., 1998); however, no specifications were made about the type and source of feed.Rumen development is triggered by the production of VFA resulting from fermentation of
Limiting factors for the enzymatic accessibility of soybean protein
Fischer, M. - \ 2006
Wageningen University. Promotor(en): Harry Gruppen; Fons Voragen. - [S.l.] : S.n. - ISBN 9789085044963 - 139
sojaeiwit - hydrolyse - aggregatie - koolhydraten - eiwitextractie - eiwitvertering - eiwitverteerbaarheid - peptiden - soya protein - hydrolysis - aggregation - carbohydrates - protein extraction - protein digestion - protein digestibility - peptides
Soy is a commonly used ingredient is food and animal feed. With particular focus on the in-soluble fractions, this thesis deals with the effects of proteases and carbohydrate degrading enzymes on different soybean meals subjected to different extent of heating. The primary aim is to improve the understanding of enzymatic hydrolysis of SBM with emphasis on proteins and to identify barriers limiting the efficiency of the process. The results show that aggregation behavior of peptides during enzymatic processing of soy proteins is potentially a limiting factor for efficacy of protein extraction. Surprisingly, it is also demonstrated that aggregation is not limited to in vitro incubations, but is also occurring in vivo in the digestive system of pigs.
Prebiotics in piglet nutrition? Fermentation kinetics along the GI tract
Awati, A.A. - \ 2005
Wageningen University. Promotor(en): Martin Verstegen, co-promotor(en): B.A. Williams; M.W. Bosch. - Wageningen : S.n. - ISBN 9789085041641 - 143
biggen - anti-infectieuze middelen - koolhydraten - fermentatie - kinetica - voedertoevoegingen - microbiële ecologie - varkensvoeding - voedingsfysiologie - piglets - antiinfective agents - carbohydrates - fermentation - kinetics - feed additives - microbial ecology - pig feeding - nutrition physiology
Keywords: fermentation, gas production, pigletsThe generalized theory behind the carbohydrate to protein fermentation in the GIT is that in presence of fermentable carbohydrate substrate, microbes prefer to ferment carbohydrate source to derive energy and use the nitrogen available for their own growth. With this background information, it was hypothesized that inclusion of fermentable carbohydrates in the piglet diet will reduce the protein fermentation, which will be confirmed by reduced levels of ammonia and branched chain fatty acids in end product profile of the fermentation. The aim of this thesis was to study the effects of inclusion of fermentable carbohydrates in weaning piglets' diet, on GIT fermentation and any changes in microbial community composition and activity. Weaning process in an intensified pig production system brings many sudden changes in the environmental and physical factors in piglets' life. These sudden changes, especially in diet cause serious imbalance in the microbial community. Quicker stabilization and diversification of microbial community post weaning, is crucial in attending the gut health and reducing the risk of pathogenic infections by 'Colonization resistance: As part of this overall aim, the in vitro cumulative gas production technique was used to study the fermentation of selected fermentable substrates. While these substrates namely lactulose, inulin, wheat starch and sugar beet pulp (SBP) were included in test diet and their effect on GIT fermentation was studied in vivo. The combination of microbial community analysis based on fingerprinting techniques such as denaturing gradient gel electrophoresis (DGGE) with nutritional analysis of fermentation end product profiles, was used in vivo and in vitro studies. In in vivo trials, emphasis was given on using combination of slow fermenting carbohydrate sources such as, SBP and wheat starch with fast fermenting lactulose and inulin. The hypothesis behind this approach was to induce carbohydrate fermentation along the GIT, by providing carbohydrate substrate for the microbiota in different parts of GIT. Especially by taking in to account the difference in the transit time of feed in the different parts of GIT, it was expected that fast fermenting lactulose and inulin would be fermented in small intestine while wheat starch somewhere in the beginning of the large intestine while, SBP will reach the distal part of colon. It was found that fermentation along the GIT was improved or in other words skewed more towards the carbohydrate fermentation in vivo. It was observed in vivo that inclusion of fermentable carbohydrates in the diet reduces the protein fermentation in the GIT and ammonia concentration in end product profile. This decrease was observed along the GIT and in time in faecal fermentation end product profiles post weaning. Microbial community analysis using fingerprinting techniques revealed that inclusion of fermentable carbohydrates stabilized and diversified microbial community in the ileum as well as in the colon by day 10 post weaning. This way, the prebiotic effects of fermentable carbohydrates was evidenced. -
Effects of prebiotics, probiotics and synbiotics in the diet of young pigs
Shim, S.B. - \ 2005
Wageningen University. Promotor(en): Martin Verstegen, co-promotor(en): J.M.A.J. Verdonk. - s.l. : S.n. - ISBN 9789085041931 - 178
biggen - probiotica - koolhydraten - anti-infectieuze middelen - voedertoevoegingen - microbiële ecologie - fermentatie - spijsverteringsstelsel - varkensvoeding - voer - diergezondheid - groei - voedingsfysiologie - piglets - probiotics - carbohydrates - antiinfective agents - feed additives - microbial ecology - fermentation - digestive system - pig feeding - feeds - animal health - growth - nutrition physiology
Keywords: prebiotics, piglets, gut health
Prebiotics are non-digestible carbohydrates that are not metabolized in the small intestine and fermented in the large intestine. Oligofructose are non-digestible oligosaccharides which may stimulate beneficial bacteria in the gut and may affect the gut ecosystem. Prebiotic effects will depend largely on their chemical structure (degree of polymerization). Dietary inclusion of probiotics in young pig diets may beneficially affect gut microbiota. Synbiotics, a combination of prebiotics and probiotics may also stimulate the gut ecosystem. The objective of this thesis was to evaluate the effects of pre-, pro- and synbiotics on the gut ecosystem, and some performance parameters. A series of in vivo and in vitro experiments were carried out using suckling and weaned piglets. The experimental results are discussed in this thesis. Overall, it was concluded that synbiotics, a combination of multi-strain probiotics and oligofructose, can positively affect performance especially feed intake, and can improve the gut health. However, we did not observe a clear synergistic effect compared to supplementing oligofructose or probiotics alone. A combination of high and low polymer inulin will probably be more beneficial for the intestinal ecosystem and health than using either high- or low polymer inulin alone. The present studies show that the pre-, pro- and synbiotic treatments affect gut microbiota and performance of young pigs.
Vitaliteit van Freesiaknollen: opsporen van kritische factoren voor de vitaliteit van freesiaknollen in verband met heterogeniteit in de oogstfase
Heij, G. ; Kersten, M. ; Slootweg, G. - \ 2004
Naaldwijk : Praktijkonderzoek Plant & Omgeving B.V. (Rapport PPO ) - 21
freesia - bloembollen - teelt onder bescherming - plantenontwikkeling - groeifasen, rijp - bollen - selectie - kwaliteit - planttijd - koolhydraten - nederland - freesia - ornamental bulbs - protected cultivation - plant development - maturity stage - bulbs - selection - quality - planting date - carbohydrates - netherlands
Gastrointestinal Health Benefits of Soy Water-soluble Carbohydrates in Young Broiler Chickens
Lan, Y. - \ 2004
Wageningen University. Promotor(en): Martin Verstegen; Seerp Tamminga; G. Erdi, co-promotor(en): B.A. Williams. - [S.I.] : S.n. - ISBN 9789064649240 - 265
vleeskuikens - pluimvee - koolhydraten - sojabonen - spijsverteringsstelsel - spijsverteringskanaal - diergezondheid - fermentatie - kinetica - darmen - morfologie - blindedarm - melkzuurbacteriën - immunoglobulinen - voedselbeperking - pluimveevoeding - diervoeding - broilers - poultry - carbohydrates - soyabeans - digestive system - digestive tract - animal health - fermentation - kinetics - intestines - morphology - caecum - lactic acid bacteria - immunoglobulins - food restriction - poultry feeding - animal nutrition
Odour from pig production facilities: its relation to diet
Dinh Phung, P.D. Le; Becker, P.M. ; Aarnink, A.J.A. ; Jongbloed, A.W. ; Peet-Schwering, C.M.C. van der - \ 2004
Wageningen : Agrotechnology and Food Innovations (Rapport / Agrotechnology & Food Innovations 115) - ISBN 9789067547666 - 66
varkensstallen - stankemissie - varkensvoeding - voersamenstelling - eiwitgehalte - koolhydraten - pig housing - odour emission - pig feeding - feed formulation - protein content - carbohydrates
Onderzoek naar de mogelijkheden om de geur van varkens aangenamer te maken
|Housing conditions and carbohydrate source affect within-day variation of energy metabolism in growing pigs
Rijnen, M.M.J.A. ; Borne, J.J.G.C. van den; Schrama, J.W. ; Gerrits, W.J.J. - \ 2003
In: Progress in research on energy and protein metabolism / Souffrant, W.B., Metges, C.C., Wageningen : Wageningen Academic Publishers (EAAP Scientific Series 109) - ISBN 9789076998244 - p. 367 - 370.
varkens - varkensstallen - energiemetabolisme - circadiaan ritme - koolhydraten - pigs - pig housing - energy metabolism - circadian rhythm - carbohydrates
In the present study, effects of housing conditions (i.e. individual vs. group housing) and carbohydrate source (i.e. sugar beet pulp vs. maize starch) on energy metabolism and circadian rhythms in energy expenditure and physical activity were studied in growing pigs in a 2 x2 factorial design. No interactions between housing conditions and diet composition were present. Digestibility and metabolisability of dietary energy was higher for individually housed pigs than for group-housed pigs. Circadian rhythms in energy expenditure and energy expenditure for physical activity were clearly affected by housing conditions and diet composition. Total energy expenditure, as well as activity related energy expenditure, was increased during the dark phase of the day in individually housed pigs when compared with group-housed pigs. Pigs fed the sugar beet pulp based diet had a reduced energy expenditure on physical activity, which mainly occurred during the night.
Effects of flavour absorption on foods and their packaging materials
Willige, R.W.G. van - \ 2002
Wageningen University. Promotor(en): A.G.J. Voragen; J.P.H. Linssen. - S.l. : S.n. - ISBN 9789058086402 - 140
geurstoffen en smaakstoffen - absorptie - verpakkingsmaterialen - voedselverpakking - eiwitten - koolhydraten - vetten - membraanpermeabiliteit - smaakpanels - modellen - flavour compounds - absorption - packaging materials - food packaging - proteins - carbohydrates - fats - membrane permeability - taste panels - models
Keywords: flavour absorption, scalping, packaging, food matrix, lldpe, ldpe, pp, pc, pet, pen,b-lactoglobulin, casein, pectin, cmc, lactose, saccharose, oil, modelling, storage, oxygen permeability, taste perception, sensory quality.
Absorption of flavour compounds by linear low-density polyethylene (LLDPE) was studied in model systems representing differences in composition of the food matrix. Proteins,b-lactoglobuline and casein, were able to bind flavours, resulting in suppression of absorption of flavour compounds. Polysaccharides, pectin and carboxymethylcellulose, increased viscosity, and consequently decreased absorption. Disaccharides, lactose and saccharose, increased absorption, probably caused by a "salting out" effect of less apolar flavour compounds. The presence of a relative small amount of oil (50 g/l) decreased absorption substantially. Combined oily model systems, oil/casein and oil/pectin, showed a similar effect. The extent of absorption of flavour compounds by LLDPE was influenced by food components in the order: oil or fat >> polysaccharides and proteins > disaccharides. A model based on the effect of the polarity (log P) of flavour compounds and on their partitioning coefficients between food(matrix) and packaging material was developed. The model is able to predict absorption of flavour compounds from foods into LLDPE when lipids in the food matrix are the determining factor in flavour absorption. Results show that the model fits nicely with experimental data of real foods skim and whole milk.
LLDPE, polypropylene (PP), polycarbonate (PC), polyethylene terephthalate (PET film and PET bottle) and polyethylene naphthalate (PEN) were immersed in a model flavour solution at different temperatures up to 14 days. The absorption rate and/or total amount of absorbed compounds increased considerably with increasing temperature. Depending on temperature, the total absorption of flavour compounds by the polyolefins (LLDPE and PP) was up to 2400 times higher than by the polyesters (PC, PET and PEN).
The effect of absorbed flavour compounds on the oxygen permeability of low-density polyethylene (LDPE), PP, PC and PET was studied. Due to swelling of the polymers as a result of absorption of flavour compounds, LDPE and PP showed a significant increase of oxygen permeability of 21% and 130%. The oxygen permeability of PC showed a significant decrease of 11% due to occupation or blockage of the "micro-cavities" by the absorbed flavour compounds. Flavour absorption by PET did not affect the oxygen permeability significantly.
The influence of flavour absorption LDPE, PC and PET on the taste perception of a flavour model solution and orange juice stored in glass bottles was studied with and without pieces of the respective plastic films. Although the content of flavour compounds between controls and polymer treated samples decreased substantially due to absorption, no significant effect on the taste perception of the model solution and orange juice were observed by triangular taste panel tests.
The role of sludge retention time in the hydrolysis and acidification of lipids, carbohydrates and proteins during digestion of primary sludge in CSTR systems
Miron, Y. ; Zeeman, G. ; Lier, J.B. van; Lettinga, G. - \ 2000
Water Research 34 (2000)5. - ISSN 0043-1354 - p. 1705 - 1713.
afvalwaterbehandeling - rioolslib - anaërobe behandeling - koolhydraten - lipiden - eiwitten - verzuring - hydrolyse - waste water treatment - sewage sludge - anaerobic treatment - carbohydrates - lipids - proteins - acidification - hydrolysis
CSTR systems: completely stirred tank reactor systems
Physiology of exopolysaccharide biosynthesis by Lactococcus lactis
Looijesteijn, E. - \ 2000
Agricultural University. Promotor(en): J.A.M. de Bont; J. Hugenholtz. - S.l. : S.n. - ISBN 9789058082862 - 197
lactococcus lactis - industriële microbiologie - biosynthese - biochemie - fysiologie - oligosacchariden - koolhydraten - melkzuurbacteriën - lactococcus lactis - industrial microbiology - biosynthesis - biochemistry - physiology - oligosaccharides - carbohydrates - lactic acid bacteria
Several lactic acid bacteria (LAB) produce exopolysaccharides (EPS). EPSs produced by LAB are a potential source of natural additives and because LAB are food grade organisms, these EPSs can also be produced in situ . The amount of EPS in milk fermented with strain NIZO B40, which produces an anionic EPS composed of glucose, rhamnose, galactose and phosphate, is very low. This relatively low concentration could be increased by optimising the culture conditions and medium composition. Using pH-controlled fermentations and a chemically defined medium, the total EPS production was highest at pH 5.8 and 25 °C. Glucose was demonstrated to be the most efficient sugar source for EPS production by L. lactis NIZO B40. With fructose as the sugar source only a minor amount of EPS was produced. The intracellular levels of sugar nucleotides, the EPS precursors, were much lower in fructose- than in glucose-grown cultures. The activity of the enzymes involved in the biosynthesis of the sugar nucleotides were however unaffected by the source of sugar but the activity of fructose-1,6-bisphosphatase (FBPase) was very low. FBPase catalyses the conversion of fructose-1,6-diphosphate into fructose-6-phosphate, an essential step for the biosynthesis of sugar nucleotides from fructose but not from glucose. Overexpression of the fbp gene resulted in increased EPS synthesis on fructose.
Most culture conditions influenced growth as well as EPS formation and EPS synthesis itself was also influenced by the growth rate. EPS production by strain NIZO B40 starts at the exponential growth phase but continues during the stationary phase in batch cultures, indicating that EPS biosynthesis and growth are not strictly coupled. Indeed we found that non-growing cultures were still able to produce EPS, making it possible to study the influence of different culture conditions on EPS biosynthesis independent of growth.
The amounts of EPS produced by L. lactis NIZO B40 and NIZO B891 were comparable under glucose and leucine limitation. The efficiency of EPS production, the quantity of EPS produced per quantity of glucose consumed, was however much higher under conditions of glucose limitation. The production of phosphorylated B40 EPS and of unphosphorylated B891 EPS was strongly reduced under conditions of phosphate limitation. The sugar composition of both B40 and B891 EPS and the phosphate content of B40 EPS were unaffected by the type of limitation but surprisingly, glucose limitation resulted in the production of EPSs with strongly reduced molecular masses.
Anionic B40 EPS in suspension and a cell-associated layer of this EPS protected the bacteria against toxic copper ions and nisin, probably due to charge interactions. Furthermore, cell-associated EPS resulted in a decrease in the sensitivity of the bacteria to bacteriophages and lysozyme, most likely by masking the targets for the phages and the enzyme. The protection of EPS against nisin and bacteriophages could be a competitive advantage in mixed strain dairy starter cultures. Unfortunately, the EPS yields were not increased in the presence of copper, bacteriophages, nisin or lysozyme.
Prebiotic effects of non-digestible oligo- and polysaccharides
Hartemink, R. - \ 1999
Agricultural University. Promotor(en): F.M. Rombouts; M.J.R. Nout. - S.l. : S.n. - ISBN 9789058080516 - 205
koolhydraten - oligosacchariden - polysacchariden - darmmicro-organismen - carbohydrates - oligosaccharides - polysaccharides - intestinal microorganisms
This thesis is the result of work carried out within a four-year multi-disciplined program, entitled ' Non-digestible oligosaccharides in foods and feed'. Within the project, four Ph.D. students were employed at the Food Chemistry, Food Microbiology, Human Nutrition and Animal Nutrition groups of the Wageningen Agricultural University. This thesis describes the studies carried out at the Food Microbiology group.
Oligosaccharides are carbohydrates, with an average chain length of 2-10 sugar residues. Most oligosaccharides cannot be digested by the enzymes in the upper gut, nor can these compounds be absorbed. These oligosaccharides are considered non-digestible, and reach the large intestine unaltered. Non-digestible oligosaccharides (NDOs) are mainly of vegetable origin and are a normal part of the human diet. Some of the natural NDOs are now produced commercially using enzymatic methods.
Most NDOs are completely or partially degraded and fermented by the bacterial populations in the large intestine. Some of the NDOs are considered to have a beneficial effect on the health of the host, due to the specific fermentation by two groups of intestinal bacteria, the bifidobacteria and lactobacilli. Commercial NDOs are marketed as a healthy ingredient, due to this selective fermentation, in several Western countries.
Chapter 1 describes the gastrointestinal tract and the bacterial composition in each part thereof. The same chapter gives an overview of the current knowledge of the fermentation of NDOs by intestinal bacteria and the effects on the host health, as far as known.
Chapters 2 and 3 describe the effect of the two types of NDOs, currently available on the Dutch market, on the etiology of dental caries. When consumed, residues of NDOs in foods may remain in the oral cavity. In the oral cavity many different bacteria are capable of degrading and fermenting carbohydrates, which results in the formation of acid and, possibly, dental lesions and caries. NDOs, being carbohydrates, may thus be fermented and are, in theory, a risk factor for dental caries.
In Chapter 2 the degradation and fermentation of fructooligosaccharides (FOS) by the oral microflora is described. It can be concluded that this class of NDOs can be fermented by the most common bacterial species. These NDOs can be considered cariogenic, in vitro , but in vivo studies have to be carried out to determine the actual risk for dental caries.
In Chapter 3, the degradation and fermentation of transgalactosyl-oligosaccharides (TOS) by the oral microflora is described. It was concluded that this class of NDOs is not, or very slowly, degraded and fermented. These NDOs are not considered a risk factor for dental caries.
Within the framework of the project, the Food Chemistry group synthesized and purified a large number of oligosaccharide mixtures from plant cell walls. As these purifications are laborious and the total quantities of pure oligosaccharides are very small, it was decided to determine the fermentation of plant cell wall compounds by intestinal bacteria. These plant cell wall compounds are available in large quantities and thus could be used for screening studies.
Chapter 4 describes the degradation and fermentation of such a plant cell wall polysaccharide, xyloglucan. Xyloglucan is present in many edible plants, but it is commercially prepared from tamarind seeds. The more (chemically) complex the compound the more enzymes are necessary for degradation, and the less bacteria are capable of fermenting the compound. Xyloglucan has a relatively simple chemical structure, but, surprisingly, only very few intestinal bacteria were capable of degrading this compound. The second remarkable conclusion was that most of the bacteria capable of degrading xyloglucan, belonged to the genus Clostridium . Previously, this genus has not been considered of major importance for polysaccharide degradation in the intestine.
Chapter 5 describes the degradation of a second plant cell wall polysaccharide, guar gum, a galactomannan. Like xyloglucan, galactomannans are part of the cell wall of many plants. Guar is commercially produced from the seeds of the Cyamopsis tetragonoloba tree and used as a thickening agent in many foods. Guar also has a relatively simple structure. Nevertheless, only three different bacterial species, capable of degrading guar, could be isolated from human and animal faeces. One of these, Bifidobacterium dentium was considered to be mainly an oral species, but, using guar, could also be isolated from faeces. The same species could also be isolated from samples of saliva from 19 out of 20 volunteers. A second species, Streptococcus bovis could only be isolated from animal faeces, whereas the third species, Clostridium butyricum was present in human and animal faeces. The latter species produced large amounts of gas, and can thus be considered responsible for the increased flatulence observed after the ingestion of guar.
Chapter 6 describes the differences in the fermentation of different oligosaccharides by human faecal inocula. In addition three polysaccharides were used in these studies. All donors had received the same diet and four samples were taken from each volunteer. The results show large differences between test compounds within the same volunteer, and large differences between volunteers on the same test compound. It can be concluded that the fermentation is largely dependent on host (genetic) factors, and not on dietary factors. It was also concluded that formation of gas is correlated with the formation of butyric acid. Butyric acid is considered to be important for the health of the intestinal wall. Gas production can thus be used as a simple screening method for butyrate production.
Within the project the variations in the bacterial composition of human and pig faeces have been studied. It was concluded in the early stages of the project that no methods existed for the reliable quantification of two major intestinal bacterial groups, bifidobacteria and lactobacilli. Two new methods had to be developed for the quantification of these bacterial groups.
Chapter 7 describes the development of a new medium for bifidobacteria, the RB medium. Selectivity is based on raffinose, propionate and lithiumchloride. The medium is not yet an ideal medium for the isolation and quantification for bifidobacteria but, compared with media currently used, it is more selective.
Chapter 8 describes the development of a new medium for lactobacilli, the LAMVAB medium. Selectivity is based on vancomycin and a low pH (5.0). The combination of vancomycin and low pH inhibits practically all other intestinal bacteria. LAMVAB has successfully been employed to isolate lactobacilli from faeces from a large number of animals.
The two newly developed media were compared with two other media, that are used regularly. The results of this comparison is described in Chapter 9 . The media were used to isolate bifidobacteria and lactobacilli in human and cat faeces and pig small intestinal contents. The three media for bifidobacteria performed equally well for human faeces, but for the other two kinds of samples, the RB medium performed better. For lactobacilli, LAMVAB performed better for all three types of samples tested.
Chapter 10 discusses the results of this thesis and some recommendations for further research are given.
As conclusion it can be stated that very few NDOs are degraded and fermented selectively by bifidobacteria. This was confirmed in Chapters 2 and 6, in which degradation and fermentation of FOS by other bacterial groups is described.
Although FOS and TOS are found to be possibly cariogenic, it is not likely that either oligosaccharide will cause caries under normal conditions.
Xyloglucan and guar are degraded only by a limited number of bacteria. Unexpectedly, clostridia played a major role in the degradation of both substrates. Both substrates may be a good substrate for the production of new NDOs, but considering the results it is unlikely that these oligosaccharides are a good substrate for lactobacilli or bifidobacteria.
RB and LAMVAB are new media, which are suitable for the quantitative isolation of bifidobacteria and lactobacilli from human faeces. LAMVAB is also suitable for animal faeces. Both media are more selective than the media used at present.
|Verwijdering oligosachariden uit reactor verhoogt opbrengst.
Boon, M.A. ; Janssen, A.E.M. - \ 1998
Voedingsmiddelentechnologie 25 (1998). - ISSN 0042-7934 - p. 11 - 13.
oligosacchariden - koolhydraten - opbrengsten - enzymprecursors - kinematica - lactose - disacchariden - oligosaccharides - carbohydrates - yields - enzyme precursors - kinematics - disaccharides
De enzymatische productie en toepassing van oligosachariden uit lactose. Resultaten van modelberekeningen zijn belicht
Seed development and carbohydrates
Wittich, P.E. - \ 1998
Agricultural University. Promotor(en): M.T.M. Willemse; A.A.M. van Lammeren; C.J. Keijzer. - Wageningen : Wittich - ISBN 9789054858553 - 178
zaadzetting - zaden - formatie - plantenfysiologie - plantenontwikkeling - vruchten - rijp worden - planten - embryologie - metabolisme - plantenvoeding - assimilatie - koolhydraten - vicia faba - gasteria verrucosa - organische scheikunde - seed set - seeds - formation - plant physiology - plant development - fruits - ripening - plants - embryology - metabolism - plant nutrition - assimilation - carbohydrates - vicia faba - gasteria verrucosa - organic chemistry
Seeds assure the plant the onset of a next generation and a way of dispersal. They consist of endosperm and an embryo (originating from gametophytic tissue), enveloped by a seed coat (sporophytic tissue). Plants generate different types of seeds. For instance, the endosperm may either be consumed by the embryo during seed development or retained for use by the embryo during germination. Differences in timing of endosperm digestion can be illustrated with broad bean ( Vicia faba ) and Gasteria verrucosa . Broad bean forms seeds in which the endosperm has been consumed by the fully developed embryo, while the embryo of Gasteria is less developed and surrounded by a large amount of endosperm for use during germination.
An important factor in seed development is the distribution, storage, and utilization of carbohydrates, since carbohydrates are a major source of energy for cell growth. In this thesis the carbohydrate distribution is studied in developing ovules and seeds of maize ( Zea mays ) and Gasteria , by identifying the cells and tissues in which sucrose is degraded. Sucrose is the main carbohydrate supplied by these plants in the developing seeds. The sucrose degrading activity of the enzymes sucrose synthase and invertase indicates the destination of the sucrose transport (Chapters 9 and 10). Immunocytochemical and histochemical techniques are used for the localization of these enzymes in situ .
The results obtained in this study on maize (Chapter 2 and 3) and Gasteria seed development (Chapters 4 and 5) show a general pattern of carbohydrate transport. First, the greatest amount of carbohydrates is applied for the development of the seed coat and nucellus (sporophytic tissues). An example of such a carbohydrate consuming process is the deposition of phytomelan in the seed coat of Gasteria . Phytomelan is a black cell wall component and chemically very inert. Histochemical and electron microscopy observations (Chapters 6 and 7) show that callose forms a mould for the deposition of phytomelan. The breakdown products of callose (glucose monomers and polymers) seem to be used for the synthesis of the phytomelan. Chemical analysis reveals that phytomelan is a complex polyphenolic polymer, and not a melanin (Chapter 8). Second, carbohydrate transport to the sporophytic tissues is followed by transport of most carbohydrates into the endosperm. These carbohydrates will be used for endosperm growth and for storage. Finally the main carbohydrate flow will go to the embryo. The pattern of carbohydrate usage observed in maize and Gasteria was used to generate a general model for angiosperm seed development (Chapter 10). The model explains differences between seeds by relating carbohydrate distribution during seed development to the timing of seed dispersal.
|Qualitätsbestimmung bei Lagerkartoffeln
Hak, P.S. ; Oosterhaven, J. - \ 1997
Der Kartoffelbau 48 (1997)11. - ISSN 0022-9156 - p. 418 - 420.
opslag - chemische samenstelling - planten - chemische analyse - koolhydraten - aldehyden - ketonen - zetmeel - cellulose - kwaliteit - prestatieniveau - fabrieksaardappelen - storage - chemical composition - plants - chemical analysis - carbohydrates - aldehydes - ketones - starch - quality - performance - starch potatoes
Onderzoek naar oorzaken van veroudering bij het bewaren van fabrieksaardappelen. De balans tussen het zetmeel- en suikergehalte is een indicator voor de kwaliteit van frieten
Wheat bran glucuronoarabinoxylans : biochemical and physical aspects
Schooneveld - Bergmans, M.E.F. - \ 1997
Agricultural University. Promotor(en): A.G.J. Voragen; G. Beldman. - S.l. : Schooneveld-Bergmans - ISBN 9789054857167 - 125
graansoorten - maling - Triticum aestivum - tarwe - hexaploïdie - voedsel - voedingsmiddelen - koolhydraten - zetmeel - vezel - polysacchariden - structuur - chemische reacties - cereals - milling - Triticum aestivum - wheat - hexaploidy - food - foods - carbohydrates - starch - fibre - polysaccharides - structure - chemical reactions
Arabinoxylans are present in cereal cell walls and in vitro they have interesting physicochemical properties, such as viscosity and gelation. Although many studies on these properties were reported for wheat flour arabinoxylan, not much research has been directed towards exploitation of these polysaccharides as food gum. For that purpose glucuronoarabinoxylans of wheat bran, a cheap by-product of the cereal industry, were studied with regard to their extractability, their structural and physicochemical properties.
Approximately 50% of the glucuronoarabinoxylans of wheat bran cell wall material were recovered in high purity by barium hydroxide extraction at 70 to 95°C. Delignification or other treatments to open up the cell wall structure were not effective in increasing the yield. The extracted glucuronoarabinoxylans were very diverse in chemical structure and physicochemical properties. About 30% of them had a low degree of substitution, were easily degradable by xylanolytic enzymes and hardly influenced the viscosity of the solvent as a result of extensive aggregation. Over 50% of them had a high degree of substitution, were supposed to contain dimeric branches of arabinose and xylose, were scarcely degradable by xylanolytic enzymes, gave moderate viscosity to solutions and were very effective in stabilizing emulsions. The structure of these glucuronoarabinoxylans could only be speculated upon and it could not be enzymatically modified as a consequence of its complexity and the lack of appropriate enzymes. The remaining glucuronoarabinoxylans either had an intermediate or very high degree of substitution, of which the latter was presumed to be connected to lignin-fragments.
Gel-forming glucuronoarabinoxylans were recovered only in low yield by dilute alkali extraction and subsequent purification was necessary. These feruloylated glucuronoarabinoxylans gelled upon addition of oxidative agents, of which peroxide - peroxidase, glucose - glucoseoxidase - peroxidase and ammonium persulphate were investigated. In comparison with wheat flour arabinoxylans, those of wheat bran appeared to give less flexible networks at high concentration, which was ascribed to their high degree of substitution and high ferulic acid content. Of the dimers formed upon cross-linking, the generally known diferulic acid, being a 5-5 coupled dimer, was only present in relatively low amounts. Dimers, in which the 8-position of the ferulic acid residue is involved were preponderant. The distribution of the dimers was not affected by the type of cross- linking agent or the type of arabinoxylan. However, the presence of lignin fragments in the bran extract was presumed to cause a low ferulic acid recovery upon cross-linking.
Physiological effects of consumption of resistant starch
Heijnen, M.L. - \ 1997
Agricultural University. Promotor(en): A.C. Beynen; P. Deurenberg; J.M.M. van Amelsvoort. - S.l. : Heijnen - ISBN 9789054856511 - 163
voeding - zetmeel - voedingsmiddelen - voedsel - koolhydraten - vezel - nutrition - starch - foods - food - carbohydrates - fibre
Resistant starch (RS) is defined as the sum of starch and products of starch degradation not absorbed in the small intestine of healthy individuals. Thus, RS enters the colon where it may be fermented. In this respect, RS resembles some types of dietary fibre. Three types of RS are being discerned: RS 1 , physically entrapped starch; RS 2 , uncooked starch granules; RS 3 , retrograded starch. The estimated current mean per capita RS intake in the Netherlands is 5 g/d. The amount of RS in foods can be manipulated by the choice of raw products and food processing techniques. This is of potential interest if an increased RS consumption would be beneficial for human health. In this thesis several of the hypotheses concerning putative positive effects of RS consumption on human physiology are studied. Daily consumption of up to 32 g RS 2 or RS 3 was tolerated well by healthy individuals and increased colonic fermentative activity and stool weight. Replacement of 27 g digestible starch by RS 2 reduced diet-induced thermogenesis and postprandial glucose and insulin responses proportionally to the amount of indigestible carbohydrate consumed. When compared with an equivalent amount of glucose, daily supplementation of 30 g RS 2 or RS 3 for 3 wk did not affect serum lipid concentrations in healthy subjects, and daily supplementation with 32 g RS 2 or RS 3 for 1 wk did not affect putative risk factors for colon cancer, subjective feelings of hunger, faecal ammonia excretion and apparent absorption of magnesium, calcium and phosphorus in healthy individuals. No differences were observed between RS 2 and RS 3 , in the parameters studied. In piglets, dietary RS 3 , but not RS 2 , shifted nitrogen excretion from urine to faeces, and RS 2 reduced apparent magnesium and calcium absorption. In rats, dietary RS 2 , but not RS