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Juste A.,Campus Management | Juste A.,Scientia Terrae Research Institute | Juste A.,Nutrition Research Center oe | Van Trappen S.,Ghent University | And 11 more authors.
International Journal of Systematic and Evolutionary Microbiology | Year: 2011

Most bacteria recovered so far from sugar thick juice during storage represent strains of the species Tetragenococcus halophilus. Recently, several Gram-positive, non-motile, non-sporeforming cocci with other physiological and genetic traits were isolated from sugar thick juice samples from different origins. In this study, representative isolates were investigated using a polyphasic taxonomic approach. The 16S rRNA gene sequence similarity between these isolates and their closest relative, Tetragenococcus muriaticus, was 97.4 %. The level of DNA-DNA relatedness between isolate T1 T, representing the newly found Tetragenococcus isolates, and T. muriaticus was 57 %. Isolate T1 T had a DNA G+C content of 36.7 mol%. Phylogenetic data and genomic and phenotypic features demonstrated that the isolates represent a novel species, for which the name Tetragenococcus osmophilus sp. nov. is proposed with T1 T as the type strain (=LMG 26041 T =DSM 23765 T). Additionally, T. halophilus isolates from high-salt and highsugar environments showed clear differences in several physiological and genetic characteristics like RAPD fingerprints and 16S rRNA gene sequences. DNA-DNA hybridizations, however, showed 79 to 80% relatedness between osmophilic and halophilic T. halophilus isolates, demonstrating that the different strains belong to the same species. Based on the phenotypic and genotypic differences observed, as well as the different origins of the strains and the industrial relevance of thick juice degradation, two subspecies of T. halophilus are described in this manuscript: T. halophilus subsp. halophilus subsp. nov. for the strains isolated from salt media and T. halophilus subsp. flandriensis subsp. nov. for the strains isolated from sugar-rich environments, which were first isolated in Flanders, Belgium. The type strains for the subspecies are IAM 1676 T (=LMG 11490 T =DSM 20339 T) and T5 T (=LMG 26042 T =DSM 23766 T), respectively. © 2012 IUMS.


Geraylou Z.,Zoological Institute | Geraylou Z.,Catholic University of Leuven | Souffreau C.,Zoological Institute | Rurangwa E.,Zoological Institute | And 7 more authors.
Fish and Shellfish Immunology | Year: 2012

Arabinoxylan-oligosaccharides (AXOS) are a newly discovered class of candidate prebiotics that exert different properties depending on their structure. In this study the effects of two different structures of AXOS, namely AXOS-32-0.30 (average degree of polymerization: 32, average degree of substitution: 0.30) and AXOS-3-0.25, were investigated on growth performance, immune responses, gut microbial fermentation and gut bacterial composition of juvenile Siberian sturgeon (Acipenser baerii). After a two weeks acclimation, fish (25.9 ± 0.9 g) were distributed over 24 aquariums (8 replicates per treatment) and fed a control diet or a diet containing 2% AXOS-32-0.30 or AXOS-3-0.25 for 12 weeks. Growth performance and feed utilization tend to improve in sturgeon fed on diets supplemented with AXOS-32-0.30, however not significant. Survival was high in all groups. Both AXOS preparations significantly enhanced the phagocytic activity of fish macrophages compared to the control group, while the alternative haemolytic complement activity and total serum peroxidase content improved only in the group fed AXOS-32-0.30 (P < 0.05). The lysozyme activity was not affected by AXOS addition. Simultaneously, the amount of short-chain fatty acids (SCFAs) was highest in the hind gut of sturgeon fed AXOS-32-0.30. The concentrations of acetate, butyrate and total SCFAs in fish fed AXOS-32-0.30 was significantly higher than in the groups fed the control diet or AXOS-3-0.25. Study of the bacterial community in the sturgeon hindgut using PCR-denaturing gradient gel electrophoresis (PCR-DGGE) revealed that both preparations of AXOS induced changes in the bacterial composition. According to redundancy analysis (RDA), hindgut microbiota of each treatment group clustered apart from one another (P = 0.001). DNA sequencing of the dominant DGGE bands recovered from the different treatments showed that AXOS mainly stimulated the growth of lactic acid bacteria and Clostridium sp., with more pronounced effects of AXOS-32-0.30. It is concluded that AXOS improves sturgeon health through prebiotic action, but the induced effects depend on the specific structure of AXOS. A higher degree of polymerization of AXOS had a stronger beneficial impact in this sturgeon species. © 2012 Elsevier Ltd.


Verrijssen T.A.J.,Nutrition Research Center oe | Vanierschot M.,Catholic University of Leuven | Ongena S.I.M.,Nutrition Research Center oe | Cardinaels R.,Smart Engineering | And 4 more authors.
Food Research International | Year: 2014

The objective of this study was to examine the impact of flow conditions during the stomach phase of a simple in vitro digestion procedure on the microstructural properties and the β-carotene bioaccessibility of carrot-based model food systems containing oil and different barriers for β-carotene bioaccessibility. A 'periodic forces' stomach model, in which the flow characteristics (measured by Particle Image Velocimetry) corresponded well with experimental in vivo and in silico literature data, was successfully developed and implemented and used in a two-step static in vitro digestion procedure. This stomach model was compared with a conventional end-over-end rotation stomach model in which flow conditions were uncontrolled. Both models in combination with an end-over-end intestinal phase revealed differences in β-carotene bioaccessibility of carrot-based fractions due to the presence of different barriers (the plant chromoplast structure and/or the cell wall). Absolute β-carotene bioaccessibility values however differed between the models. The periodic forces stomach flow behavior lowered the β-carotene bioaccessibility in the β-carotene-enriched emulsion (72% versus 45%), the chromoplast fraction (66% versus 36%) and the large cell cluster fraction (22% versus 13%). The model also resulted in the presence of clusters of small oil droplets interspersed by surface-active compounds while large, coalesced oil droplets (D(v;0.9) of 189. μm) were observed after digestion in the end-over-end stomach model. As a consequence of the periodic forces stomach flow behavior also a slightly higher disintegration of carrot particles (to a D(v;0.9) of 450. μm instead of 492. μm) was observed which was however not linked to a higher β-carotene bioaccessibility in carrot cell clusters. © 2013 Elsevier Ltd.


Cybulska J.,Polish Academy of Sciences | Vanstreels E.,Catholic University of Leuven | Ho Q.T.,Catholic University of Leuven | Courtin C.M.,Nutrition Research Center oe | And 4 more authors.
Journal of Food Engineering | Year: 2010

Artificial plant cell walls were produced from bacterial cellulose and cell wall constituents. The artificial cell walls were stored at low, medium and high relative humidity, and then subjected to micro-mechanical tests. From chemical composition and microstructure analysis it was found that, among all artificial cell wall materials produced, the most representative analogue of natural apple cell wall was based on bacterial cellulose supplemented with xyloglucan and pectin. Uniaxial tensile tests revealed that the different cell wall materials differed in their mechanical properties; increasing the humidity during storage resulted in a decrease in the value of the secant modulus. The cell wall model material obtained may be used for the simulation of the effect of external factors on the physical and chemical properties of cell walls. © 2009 Elsevier Ltd. All rights reserved.


Fraeye I.,Nutrition Research Center oe | Knockaert G.,Nutrition Research Center oe | Van Buggenhout S.,Nutrition Research Center oe | Duvetter T.,Nutrition Research Center oe | And 2 more authors.
Innovative Food Science and Emerging Technologies | Year: 2010

Strawberries were infused with fungal pectinmethylesterase (PME) and calcium chloride, followed by a thermal (70 °C-0.1 MPa), a high pressure (25 °C-550 MPa) or a combined thermal-high pressure (70 °C-550 MPa) process. Macroscopic (firmness) and microscopic characteristics were assessed to evaluate the texture of the fruits. In order to interpret the texture changes, the chemical structure of pectin was investigated. Processing of strawberries caused a decrease in firmness, which was limited by infusion of PME and calcium chloride, although the extent of beneficial effects depended on the type of processing. PME was able to decrease the degree of methoxylation of pectin, which was accompanied by an increased crosslinking of the chains. During high pressure or combined thermal-high pressure processing, the degree of methoxylation of pectin in infused strawberries was even further decreased, probably due to a higher activity of the fungal PME under high pressure. In case of the high pressure process, this was reflected in a very firm texture. However, the combined thermal-high pressure process caused more severe tissue damage, in spite of the advantageous pectin properties. Industrial relevance: During high pressure processing of strawberries many nutritional and sensorial characteristics are quite well preserved. Unfortunately, texture of strawberries deteriorates during such processes. This paper provides mechanistic insight into how infusion of fungal pectinmethylesterase and calcium ions in strawberries can preserve the firmness of these fruits during high pressure processing. © 2009 Elsevier Ltd. All rights reserved.


Gerits L.R.,Nutrition Research Center oe | Pareyt B.,Nutrition Research Center oe | Delcour J.A.,Nutrition Research Center oe
LWT - Food Science and Technology | Year: 2013

Wheat flour lipids present a complex mixture of components with varying polarities and have been classified as either starch or non-starch lipids, the latter being further subdivided in free and bound lipids depending on the extraction method and solvents used. A novel separation and detection method for wheat lipids in flour and dough that separates both non-polar and polar lipid classes in a single run HPLC analysis using a monolithic silica column and a quaternary gradient and detects them with evaporative light scattering is presented. The method was applied to study in-depth the changes in lipid distribution during bread dough development, thereby monitoring the fate of the different lipid classes. Full dough development was not necessary to decrease the extractability of both non-polar and polar free lipids and increase their levels in the bound lipid extract. The data for the first time also showed which specific lipid classes were redistributed and transferred from starch to gluten, as confirmed by analyzing starch fractions. In addition, not all redistributed lipids interacted in a similar way with the gluten proteins. Major changes occurred during the first 30s of mixing after which slight changes were observed for triacylglycerols, free fatty acids, lysophosphatidylcholine, and N-acylphosphatidylethanolamine. © 2013 Elsevier Ltd.


Verbeyst L.,Nutrition Research Center oe | Oey I.,Nutrition Research Center oe | Van der Plancken I.,Nutrition Research Center oe | Hendrickx M.,Nutrition Research Center oe | Van Loey A.,Nutrition Research Center oe
Food Chemistry | Year: 2010

The degradation of anthocyanins (pelargonidin-3-glucoside) in a strawberry paste during high-temperature/high-pressure treatments was investigated over a temperature range of 80-130 °C and a pressure range of 200-700 MPa, compared to 0.1 MPa. A first-order kinetic model fitted well to all data. At constant pressure, anthocyanin concentration decreased as a function of time and the degradation was accelerated at higher temperatures. At constant temperature, anthocyanins were more rapidly degraded as the pressure increased, but the effect of increasing pressure was smaller than the effect of increasing temperature. Temperature dependence of the degradation rate constants, described by the Arrhenius equation, was higher at atmospheric pressure than at elevated pressures, where all activation energies were comparable. Activation volumes, estimated by the Eyring equation, demonstrated a small pressure dependence of the reaction rate constants. Finally, a model to describe the combined temperature-pressure dependence of the degradation rate constants was proposed. © 2010 Elsevier Ltd. All rights reserved.


De Roeck A.,Nutrition Research Center oe | Mols J.,Nutrition Research Center oe | Duvetter T.,Nutrition Research Center oe | Van Loey A.,Nutrition Research Center oe | Hendrickx M.,Nutrition Research Center oe
Food Chemistry | Year: 2010

Texture degradation kinetics of carrots during traditional thermal and novel high-pressure/high-temperature (HP/HT) processing were compared. Carrots were thermally (0.1 MPa) or HP/HT (600 MPa) treated in a temperature range from 95 to 110 °C. The residual texture (hardness) was determined using a texture analyzer. Kinetic parameters were estimated using a fractional-conversion model. In comparison to the thermal treatments, the HP/HT treatments resulted in a 10-fold slower texture degradation. The retarded texture loss was accompanied by a significantly lower degree of methyl-esterification (DM) of the cell wall pectin. Additionally, the effect of lowering the DM (by applying an HP pretreatment) and adding exogenous calcium ions prior to the HP/HT treatment on the texture of carrots was investigated. It was observed that this combined pretreatment resulted in a notably harder texture of HP/HT-treated carrots. However, a similar outcome was obtained by HP/HT treating carrots directly in a calcium chloride solution without preceding DM reduction and calcium soak. Excluding a separate pretreatment step will lead to time savings and a lower cost. This study demonstrated that HP/HT processing has great potential, concerning texture preservation of processed fruits and vegetables. © 2009 Elsevier Ltd. All rights reserved.


Jolie R.P.,Nutrition Research Center oe | Duvetter T.,Nutrition Research Center oe | Houben K.,Nutrition Research Center oe | Vandevenne E.,Nutrition Research Center oe | And 4 more authors.
Food Chemistry | Year: 2010

Two surface plasmon resonance (SPR)-based interaction analysis methods were successfully implemented to explore the binding between plant PME and kiwi PMEI. In a first method, plant PMEs were immobilised on a chip surface via amine coupling. This experimental setup allowed studying the effect of pH and ionic strength on the PME-PMEI interaction kinetics. Strong binding was obtained at pH < 7 and at low salt concentrations, whereas both pH ≥ 8 and [NaCl] of ca. 1.0 M effectively caused dissociation. In a second method, kiwi PMEI was immobilised on a chip surface to which streptavidin had been covalently attached. Hereto, PMEI was biotinylated by means of a NHS-biotin reagent. With this immobilisation strategy, the effect of (partial) thermal or high pressure-induced denaturation of PME on its affinity towards PMEI was investigated. A notable degree of enzyme inactivation was required before interaction characteristics were significantly altered. Any incomplete inactivation of PME resulted in binding to the PMEI surface. © 2009 Elsevier Ltd. All rights reserved.


Palmero P.,Nutrition Research Center oe | Panozzo A.,Nutrition Research Center oe | Colle I.,Nutrition Research Center oe | Chigwedere C.,Nutrition Research Center oe | And 3 more authors.
Food Chemistry | Year: 2016

A specific approach to investigate the effect of high pressure homogenization on the carotenoid bioaccessibility in tomato-based products was developed. Six different tomato-based model systems were reconstituted in order to target the specific role of the natural structural barriers (chromoplast substructure/cell wall) and of the phases (soluble/insoluble) in determining the carotenoid bioaccessibility and viscosity changes upon high pressure homogenization. Results indicated that in the absence of natural structural barriers (carotenoid enriched oil), the soluble and insoluble phases determined the carotenoid bioaccessibility upon processing whereas, in their presence, these barriers governed the bioaccessibility. Furthermore, it was shown that the increment of the viscosity upon high pressure homogenization is determined by the presence of insoluble phase, however, this result was related to the initial ratio of the soluble:insoluble phases in the system. In addition, no relationship between the changes in viscosity and carotenoid bioaccessibility upon high pressure homogenization was found. © 2015 Elsevier Ltd. All rights reserved.

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