Title Participants Abstract "The role of mechanical collapse by cryogenic ball milling on the effect of high-pressure homogenization on the microstructural and texturizing properties of partially pectin-depleted tomato cell wall material" "Jelle Van Audenhove, Tom Bernaerts, Novita Putri, Ann Van Loey, Marc Hendrickx" "In the current study, the effect of different particle size reduction techniques, namely high-pressure homogenization (HPH) and cryogenic ball milling (CBM), on the microstructural and texturizing properties of the tomato acid-unextractable fraction (AcUF) in suspension was studied. Partial pectin depletion was performed by nitric acid pectin extraction on the alcohol-insoluble residue. In the absence of the aforementioned mechanical treatments, the partially pectin-depleted material, i.e., the AcUF, showed a cellular morphology and a high texturizing potential. By short-time CBM in dry-state, the AcUF was extensively fractured and clumped, resulting in a collapsed structure with negligible texturizing potential and low water binding capacity. In contrast, HPH could disrupt the cell wall network (destroying the cellular morphology) resulting in a continuum of interacting material having very similar texturizing potential and a slightly higher water binding capacity than the AcUF before HPH. Furthermore, the potential of HPH to (re)functionalize the collapsed cryo-ball milled AcUF by its shear-induced disruption was shown. Indeed, the debris-like cell wall remnants could to some extent be reopened by HPH, which resulted in a partial recovery of the original texturizing potential and an improved water binding capacity. However, the potential of HPH at 20 MPa to revert the detrimental effect of CBM decreased with increasing CBM treatment time." "Adaptation of Burkholderia cepacia complex bacteria to the cystic fibrosis lung : focus on lipopolysaccharide O-antigen and cell wall physical properties" "Amir Hassan" "Targeted processing of lemon peels to unlock the endogenous texturizing properties of its cell wall fibers" "Katleen Willemsen" "In the last decades, the increase of consumer interest in health and environmental issues has boosted the demand for overall natural sustainable food products and ingredients with health-related properties. Consequently, clean label products are gaining increasing market value, including products that are produced with more organic and natural formulations under sustainable conditions. In this context, the integrated use of fruit and vegetable by-products can provide an interesting solution to reduce food waste, enrich food products with dietary fibers, and generate clean label natural texturizers. However, despite the abundance of fruit and vegetable by-products, their exploitation as natural food ingredients is still limited. This under-exploitation is partly caused by the dense intertwined network formation of the cell wall fibers, limiting their hydration and texturizing potential. Within this PhD research it was aimed to functionalize the dense cell wall network by performing targeted processing, allowing for better hydration and swelling of the fibers, thereby improving the texturizing properties of the cell wall fibers. To achieve this objective, (non-)selective extraction of cell wall polymers, mechanical processing and adjustment of the intrinsic system properties of the cell wall fiber suspensions, being pH and salt concentration, were considered as targeted processing methods. In addition, lemon peels were selected as fiber rich plant material due to its abundant production as by-product from the juicing industry. The effect of targeted processing was evaluated by determining the physico-chemical, microstructural and viscoelastic properties of the processed lemon peel fiber suspensions. Throughout this research, physico-chemical characterization included the determination of the galacturonic acid content, neutral sugar content, degree of methoxylation and molar mass, microstructural characterization the determination of the particle size distribution and performance of light and epifluorescence microscopy using acridine orange staining, while viscoelastic characterization included the performance of rheological dynamic oscillatory measurements. Furthermore, a new measuring geometry for the latter analysis was specifically designed and validated, adapted to the specific nature of lemon peel cell wall suspensions studied here. In the first part of this research, the role of different polymers in determining the functionality of lemon peel fiber suspensions was investigated by performance of a (non-)selective pectin and/or hemicellulose extraction, resulting in insoluble residual fiber material with different physico-chemical characteristics and composition. However, extensive pectin removal, without changing the hemicellulose content, was found to be of utmost importance towards the functionalization of lemon peel fibers. No or only partial pectin removal resulted in a stiff intertwined network of cell wall polymers, that fragmented upon mechanical processing without improving its viscoelastic properties. Furthermore, extensive pectin extraction under acid or alkaline conditions improved the viscoelastic properties of the lemon peel fibers upon suspension, probably due to an enhanced flexibility of the fiber network by the creation of interfibrillar spaces between the cellulose/hemicellulose network. Moreover, targeted mechanical processing by high pressure homogenization (HPH) of the pectin depleted cell wall fiber suspensions was found to be crucial to open up the remaining cell wall fiber network. In fact, investigation of the effect of shearing intensity showed that optimal viscoelastic properties are obtained by blending and subsequent HPH at a minimal pressure of 20 MPa. Increasing the HPH pressure above 20 MPa up to 80 MPa did not further enhance the fiber suspension functional properties. Furthermore, targeted processing by adjustment of the pH and salt concentration prior to HPH greatly influenced the functional properties of the pectin depleted lemon peel fibers. Specifically, pH adjustment to a pH ranging between 4.5 and 7 prior to HPH enhanced the viscoelastic properties of the fiber suspensions. Within this pH range, it is suggested that the residual pectin polymers are negatively charged, favoring the fiber separation upon HPH due to repulsion. By contrast a high salt concentration, obtained after pH adjustment to pH 10 or after excessive addition of NaCl or CaCl2, decreased the fiber functionality probably due to shielding of the repulsive fiber interactions. Lastly, small molecule diffusion was used as method to determine the volume occupancy of differently functionalized lemon peel fibers, to gain insight in the mechanism underlying the rheological properties of the lemon peel fibers upon suspension. Interestingly, from this work it is concluded that the viscoelastic properties of lemon peel fiber suspensions are determined by the fiber network opening induced by HPH. Nevertheless, the intrinsic system properties affect both the extent of network formation by HPH as also the hydration properties of the fibers. In conclusion, targeted processing under the specified processing conditions resulted in lemon peel fiber suspensions with viscoelastic properties befitting their exploitation as natural clean label texturizer." "Variation of Burkholderia cenocepacia cell wall morphology and mechanical properties during cystic fibrosis lung infection, assessed by atomic force microscopy" "Amir Hassan, Miguel V. Vitorino, Tiago Robalo, Mario S. Rodrigues, Isabel Sa-Correia" "The influence that Burkholderia cenocepacia adaptive evolution during long-term infection in cystic fibrosis (CF) patients has on cell wall morphology and mechanical properties is poorly understood despite their crucial role in cell physiology, persistent infection and pathogenesis. Cell wall morphology and physical properties of three B. cenocepacia isolates collected from a CF patient over a period of 3.5 years were compared using atomic force microscopy (AFM). These serial clonal variants include the first isolate retrieved from the patient and two late isolates obtained after three years of infection and before the patient's death with cepacia syndrome. A consistent and progressive decrease of cell height and a cell shape evolution during infection, from the typical rods to morphology closer to cocci, were observed. The images of cells grown in biofilms showed an identical cell size reduction pattern. Additionally, the apparent elasticity modulus significantly decreases from the early isolate to the last clonal variant retrieved from the patient but the intermediary highly antibiotic resistant clonal isolate showed the highest elasticity values. Concerning the adhesion of bacteria surface to the AFM tip, the first isolate was found to adhere better than the late isolates whose lipopolysaccharide (LPS) structure loss the O-antigen (OAg) during CF infection. The OAg is known to influence Gram-negative bacteria adhesion and be an important factor in B. cenocepacia adaptation to chronic infection. Results reinforce the concept of the occurrence of phenotypic heterogeneity and adaptive evolution, also at the level of cell size, form, envelope topography and physical properties during long-term infection." "Microstructural and Texturizing Properties of Partially Pectin-Depleted Cell Wall Material: The Role of Botanical Origin and High-Pressure Homogenization" "Jelle Van Audenhove, Tom Bernaerts, Novita Putri, Ann Van Loey, Marc Hendrickx" "In the current study, the texturizing properties of partially pectin-depleted cell wall material (CWM) of apple, carrot, onion and pumpkin, and the potential of functionalization by high-pressure homogenization (HPH) were addressed. This partially pectin-depleted CWM was obtained as the unextractable fraction after acid pectin extraction (AcUF) on the alcohol-insoluble residue. Chemical analysis was performed to gain insight into the polysaccharide composition of the AcUF. The microstructural and functional properties of the AcUF in suspension were studied before HPH and after HPH at 20 and 80 MPa. Before HPH, even after the pectin extraction, the particles showed a cell-like morphology and occurred separately in the apple, onion and pumpkin AcUF and in a clustered manner in the carrot AcUF. The extent of disruption by the HPH treatments at 20 and 80 MPa was dependent on the botanical origin. Only for the onion and pumpkin AcUF, the water binding capacity was increased by HPH. Before HPH, the texturizing potential of the AcUFs was greatly varying between the different matrices. Whereas HPH improved the texturizing potential of the pumpkin AcUF, no effect and even a decrease was observed for the onion AcUF and the apple and carrot AcUF, respectively." "Inflammatory Properties and Adjuvant Potential of Synthetic Glycolipids Homologous to Mycolate Esters of the Cell Wall of Mycobacterium tuberculosis" "Rudi Beyaert" "Modeling of elastic properties of the cell wall material in nanoclay-reinforced foams" "Oxana Shishkina, Larissa Gorbatikh, Stepan Lomov, Ignace Verpoest" "Water transport properties of artificial cell walls" "Solomon Fanta, Willem Vanderlinden, Metadel Abera, Pieter Verboven, Steven De Feyter, Bart Nicolai" "The cell wall is an essential structural component of the fruit cell. It is also an important barrier for water exchange between the intercellular space and the cytoplasm and as such affects moisture loss of fruit during commercial storage. In this manuscript the nanostructure and water exchange properties of different artificially produced cell walls were investigated. Three artificial cell walls, bacterial cellulose (BC), bacterial cellulose with pectin (BCP) and bacterial cellulose with pectin and xyloglucan (BCPX), were prepared using a culture of Gluconoacetobacter xylinus in Hestrin and Schramm medium. The microscopic structure of three artificial cell walls was studied by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The surface images showed clear differences in the diameter of the microfibrils and the density of the fibril network. The degree of compactness was highest for BCPX, than BCP and BC. Desorption isotherms of the three artificial cell walls were measured. It was found that the water retention capacity at the same water activity was higher for BC than for the other two artificial cell walls; BCP had higher water retention capacity than BCPX. Cellulose has a high water retention capacity that increases with increasing void space ratio in cellulose containing membrane. The resulting water conductivity values of the different artificial cell walls at 3°C/95% RH and 25°C/85% RH were measured. The lowest value of water conductivity was found for BCPX while the highest value was found for the pure BC. Adding pectin had a strong effect on the water conductivity, while xyloglucan did not have any appreciable additional effect. The structural properties were related to the water transport properties." "Starch isolation method impacts soft wheat (Triticum aestivum L. cv. Claire) starch puroindoline and lipid levels as well as its functional properties" "Anneleen Pauly, Bram Pareyt, Niels De Brier, Ellen Fierens, Jan Delcour" "Wheat (Triticum aestivum L.) kernel hardness is a major quality characteristic, which has been ascribed to the presence of puroindolines a and b. These proteins occur in higher levels at the surface of water-washed starch granules from soft wheat cultivars than at that of starch from hard wheat cultivars. In the present study, prime starch was isolated from flour from soft wheat (cultivar Claire) using a dough ball or batter based separation method. Starch isolated with the dough ball method contained lower levels of puroindolines, as well as of other starch granule associated proteins and lipids than that isolated with the batter method. Similar patterns of puroindoline and lipid levels after starch isolation can presumably be related to (polar) lipid binding by puroindolines. Both isolated starch fractions showed comparable differential scanning calorimetry thermograms, whereas higher levels of starch surface associated components restricted starch swelling. Necessary controls demonstrated that the observed differences did not arise from artefacts associated with hydration, fractionation or freeze-drying in the experimental protocols. Apparently, proteins and lipids at the starch granule surface impact water absorption and, as such, starch swelling, but they do not affect starch granule internal phenomena such as melting of the crystalline amylopectin chains." "Well shaped $Mn_{3}O_{4}$ nano-octahedra with anomalous magnetic behavior and enhanced photodecomposition properties" "Yu Li, Haiyan Tan, Xiao-Yu Yang, Bart Goris, Johan Verbeeck, Bals, Pierre Colson, Rudi Cloots, Staf Van Tendeloo, Bao-Lian Su" "Very uniform and well shaped Mn3O4 nano-octahedra are synthesized using a simple hydrothermal method under the help of polyethylene glycol (PEG200) as a reductant and shape-directing agent. The nano-octahedra formation mechanism is monitored. The shape and crystal orientation of the nanoparticles is reconstructed by scanning electron microscopy and electron tomography, which reveals that the nano-octahedra only selectively expose {101} facets at the external surfaces. The magnetic testing demonstrates that the Mn3O4 nano-octahedra exhibit anomalous magnetic properties: the Mn3O4 nano-octahedra around 150 nm show a similar Curie temperature and blocking temperature to Mn3O4 nanoparticles with 10 nm size because of the vertical axis of [001] plane and the exposed {101} facets. With these Mn3O4 nano-octahedra as a catalyst, the photodecomposition of rhodamine B is evaluated and it is found that the photodecomposition activity of Mn3O4 nano-octahedra is much superior to that of commercial Mn3O4 powders. The anomalous magnetic properties and high superior photodecomposition activity of well shaped Mn3O4 nano-octahedra should be related to the special shape of the nanoparticles and the abundantly exposed {101} facets at the external surfaces. Therefore, the shape preference can largely broaden the application of the Mn3O4 nano-octahedra."