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Due to emerging scarcity of oil resources associated with increase in oil prices, it is acceptable that the fossil sources of our energy supplywill be gradually replaced by renewable substrates. It comprises of intermittent energy sources such as solar, wind, etc. Biomass energy is considered as one of the most immediate and important renewable source for several reasons. The most important is that biomass energy can contribute to sustainable development with reduction in the emission of greenhouse gases. Moreover, biomass energy has a potential to produce new employment opportunities especially in the rural areas of the developing countries.Ethanol represents one ofthe major important source of renewable energy. Fermentation is an attractive process to produce ethanol from renewable biomass. In order to improve the efficiency of ethanol fermentation it is convenient to remove the produced ethanol from the fermentation broth periodically, to reducethe inhibitory effect of excess ethanol concentration. Existing techniques applied for the recovery of ethanol from fermentation broth are vacuum distillation, solvent extraction, gas stripping and membrane pervaporation.Amongst all, pervaporation is one of the most significant technique for the recovery of ethanol from the fermentation broth. It has many advantages over other techniques such as energy saving, cost effectiveness, and ecofriendly process. Pervaporation process comprises of amembrane for separation. It is unit operation in which two components are separated by using either polymeric or inorganic membrane through thecombination of different permeation rates of the components. Commonly, vacuum is applied to the downstream side of the membrane since, evaporative phase change occurs.The separation membrane is the key element in pervaporation equipments. Many membrane materials are considered for the purpose of recovering ethanol from dilute fermentation broth. Amongst these, hydrophobic membrane materials such as polydimethylsiloxane (PDMS) is the promising option. Since, PDMS membranes are hydrophobic innature and has high diffusivity for the ethanol owing to its low Tg resulting from the free rotation of Si-O bond. Although, pure PDMS membranes are less efficient in ethanol recovery, their efficiency can be increased by incorporation of certain class of additives / fillers.Objective of the present proposal is to prepare hydrophobic PDMS composite membranes incorporated with fillers / additives for enhanced bio-ethanol recovery from the dilute fermentation broth.These composite membranes comprises of a porous layer ofan organolphilic polymer as a support, synthesized by phase inversion method (PIM). A thin film of dense PDMS polymer incorporated with hollow fillers such as (MOFs, Silicates, ZIFs, HS etc.) will be applied on the surface of porous support layer by using different techniques such as dip coating, spin coating etc.The nature of the fillers / additives to be incorporated in these membranes will be hollow centered with functional shells forming the outer part. The hollow central part will increase the permeability, while outer part with shells will act as sieve to increase the selectivity.These membranes will be characterized by different techniques (AFM, SEM, Contact angle etc.).The permeation study of these membranes will be performed in order to monitor their pervaporation performance using model ethanol feed solution. Finally, the membranes withbetter performance can be tested in actual bioethanol process with realistic feed solution. Owing to the dual nature of fillers / additivesincorporated in the membranes, these membranes will be tested in organic solvent nanofiltration and gas separation as well.

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The fermentation of cocoa pulp, the first step in the production process of chocolate, is crucial for chocolate flavor development and pulp degradation. Despite the large annual production of cocoa beans, about 4 million tonnes per year, this fermentation process is one of the few remaining large-scale spontaneous fermentations in today’s food industry. Spontaneous cocoa pulp fermentations contain a wide variety of microorganisms, with lactic acid bacteria, acetic acid bacteria and yeasts being the main players. Previous studies revealed that many different yeasts are recovered from spontaneous fermentations, whereas the variation in the prokaryotic microbiome is much more limited. Because spontaneous fermentations lead to unwanted product variability and possibly off-flavor formation, there is a growing interest in microbial starter cultures that can be used to inoculate cocoa pulp fermentations, yet with limited success. Starter cultures have been successfully applied in the production process of many foods and beverages, where they greatly increase the efficiency and reproducibility of the fermentation process and result in augmented product consistency. We therefore aimed to develop optimal yeast-based cocoa starter cultures able to outcompete wild contaminants, consistently produce high-quality chocolate and tune chocolate flavor. We differentiated between starter cultures for the production of regular (bulk) chocolate, and specialty, aromatic chocolate with distinct fruity notes.We first characterized different spontaneous cocoa pulp fermentations in the two most prominent cocoa-exporting regions to investigate and characterize the microbiota involved. We established that the spontaneous fermentations were characterized by a core and a variable microbiota. The core microbiota consisted of a prokaryotic fraction, largely unaffected by geographical location, and a region-specific yeast fraction. A recurring multi-phase yeast profile was observed, characterized by a transient dominance of fast glucose-fermenting yeasts (Hanseniaspora spp.), which are quickly outcompeted by more thermotolerant yeasts (Saccharomyces and/or Pichia spp.).In a second part, we developed yeast hybrids with an improved thermotolerance that efficiently ferment cocoa pulp, starting from specifically selected industrial and indigenous cocoa Saccharomyces cerevisiae strains. The aromatic hybrids that were developed for a specialty, aromatic chocolate were additionally able to produce high concentrations of fruity esters. These esters, such as isoamyl acetate, are important flavor compounds in fermented beverages, lending a pleasant, fruity aroma to the product. Several laboratory and field trials showed that the new hybrids often outperformed their parental strains and were able to dominate pilot scale fermentations, resulting in much more consistent microbial profiles. Gas chromatography-mass spectrometry analysis of the cocoa liquor revealed a decrease in spoilage-related off-flavors in S. cerevisiae inoculated fermentations compared to spontaneous fermentations, and a specific increase in various acetate ester concentrations for fermentations inoculated with the aromatic yeast hybrids. Analysis of the resulting chocolate by an expert and a consumer panel showed that some cocoa batches fermented with specific starter cultures yielded superior chocolate, indicating that these starter cultures can be used for commercial production.In a last part, we characterized pectin and hemicellulose cell wall polysaccharides in cocoa pulp and their role in the degradation of the pulp. It is assumed that pulp degradation is the result of pectin breakdown caused by pectinolytic yeasts, while the contribution of the hemicellulose fraction has been neglected. Therefore, we first provided a comprehensive overview of the composition of pectin and hemicellulose cell wall polysaccharides. By consequently subjecting the cocoa pulp to different physicochemical, enzymatic and microbial treatments that mimicked the changing conditions during a fermentation process, we showed that increasing temperatures, endo-polygalacturonase and xyloglucanase reduce the viscosity of cocoa pulp, thereby contributing to the desired liquefaction.Taken together, the results describe the development of optimal S. cerevisiae starter cultures for cocoa pulp fermentations that improve the consistency and quality of commercial chocolate production and introduce desired product diversification. This work further provides a comprehensive overview of what contributes to changing the viscosity of cocoa pulp during fermentation.

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Electrodeposition is frequently used in fabrication of microelectronic components primarily due to its ability to fill high aspect ratio features with complex geometries at high deposition rates, leading to high throughput and lower manufacturing costs. For example, Copper (Cu) plating of interconnects in integrated circuits is the fabrication method of choice, where characteristic size of Cu lines can range from tens of nanometers to tens of microns, and aspect ratios could be as high as 25. However, there are numerous other applications requiring plating elements such as Sn, Ni, Co, Ag, or alloys such as Sn-Cu, Cu-Ni, Sn-Ag, Sn-Bi, etc.In this project a thorough understanding of the CuNi alloy plating process for possible applications in 3D SIC (Three-dimensional stacked integrated circuits) and Energy Storage applications will be developed. Typical plating bath consists of the base electrolyte and possibly both inorganic and organic components, often referred to as additives, which have a critical role in fabrication of defect-free structures. The mechanism in which they interact with each other is often not completely understood, the consequence being that both extensive and expensive trial-and-error lab-bench and macroscopic (wafer-level) experiments need to be performed every time the given feature size and its aspect ratio change. Thorough understanding of the plating mechanism and its effect on the elemental composition (Cu:Ni 9:1) and morphology of the deposited structure would allow easier determination of deposition parameters and matching design requirements for a given material and application.The main goal of this project is to accomplish galvanostatic deposition of a CuNi10% alloy with a smooth top surface roughness, inside photoresist patterns distributed over a whole wafer area.Physical-chemical characterization techniques (SEM, EDX, XRD, XPS, etc.) will be used together with classical electrochemistry tools and techniques, such as rotating disc electrode (RDE) and cyclic voltammetry, providing information on the reaction mechanism in the relevant plating baths. Data obtained will be used to advance and support development of new 3D SIC and Energy Storage Applications.

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Solvent resistant nanofiltration (SRNF) is a separation technique with large applicability in the (petro-)chemical, pharmaceutical and food industry. Development of better performing membranes will boost the implementation of SRNF membranes in the coming years. The key factors that still need optimization to achieve this growth, are membrane stability in extreme pH conditions, thermal, mechanical and solvent stability and membrane cost. The majority of SRNF membranes are polymeric, since they are cheaper and easier to process than ceramic membranes. Most polymers applied to produce membranes are soluble in harsh solvents and sometimes in extreme pH conditions, a limitation that needs to be addressed. Another factor limiting the performance of SRNF membranes is the trade-off which is typically found between selectivity and permeability through the membrane. Membranes with very tight pores are known to combine a high selectivity with low flow rate. Optimization of the membrane preparation process can however improve this trade-off.One type of material is proposed in this research to produce SRNF membranes. Poly(ether ether ketone) (PEEK) was chosen as hydrophobic, mechanically and thermally stable lab-synthesized polymer. Some modifications were added to the standard polymer, making it soluble in polar aprotic solvents and usable for the production of membranes via phase inversion. Some of the prepared PEEKs contained carboxylic acid groups in the polymer chain to allow crosslinking, thus producing a solvent-stable membrane.In a first part of this research, uncrosslinked membranes were prepared that are stable in mainly alcohols and alkanes. The lab-synthesized PEEKs were dissolved first in the polar aprotic solvents n-methylpyrrolidone (NMP) and tetrahydrofuran (THF), after which they were spread onto a non-woven backing and immersed in water to ensure phase transition to the solid phase – the membrane. A number of phase inversion parameters were altered to investigate the potential of these materials for membrane preparation. First of all, polymer specific properties were investigated, namely molar mass and polydispersity. The influence of some synthesis parameters, such as composition of the polymer solution and evaporation time before immersion in the water bath, were subsequently investigated. The importance of post-treatment on membrane performance was also studied.In a second part of this research, a novel series of PEEKs were synthesized that could produce crosslinked membranes with good chemical stability in polar, aprotic solvents. For this, amines were used as crosslinkers, producing amide bonds between the polymer chains. The crosslinking occurred simultaneously with the phase inversion process, namely during immersion of the polymer films, by adding the amines to the water bath. These membranes can be implemented for separations in harsh solvents such as THF and NMP.In a final part of this research, SRNF membranes were developed to separate edible oils from solvents. By adapting the type of crosslinker, membranes were synthesized that are more hydrophilic than the abovementioned ones, making them more suitable for the purification of edible oils from solvents. This is indeed a very interesting industrial application in which the membranes developed in this research can be implemented.

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With an annual worldwide production exceeding 1.96 billion hectolitre, beer is by far the most produced and consumed fermented beverage. More so, it is considered to be the third most consumed beverage worldwide (after water and tea). Traditionally, beer can be divided into two general styles, namely top-fermented ('ale') beer and bottom-fermented ('lager') beer.Lager (or Pilsner type) beer accounts for 90% of the total beer production, and is exclusively fermented by Saccharomyces pastorianus. Interestingly, this yeast species is not a clean yeast species, but is rather the result of a cross between the brewing and baker's yeast S. cerevisiae and a cold tolerant wild yeast, S. eubayanus. The limited genetic diversity of lager yeasts is reflected in the relative limited influence of the yeast on the aroma profile of lager beer, especially when compared to the immense genetic and aromatic diversity of ale S. cerevisiae yeast strains. While the characteristically clean, fresh flavour and aroma of lager beers is one of their most distinctive and praised traits, diversification and differentiation have become increasingly important in today's market.The development of new lager hybrids may help generating a set of distinct beers that bridge the gap between diverse, aromatic ales and fresh and drinkable lagers, this without the need to change the standard production process or the need for different and more expensive ingredients.In chapter one, a detailed and comprehensive literature overview is given regarding the role of yeast during industrial beer fermentations and its effect on the aromatic properties and taste of fermented products, as well as the history, genetic- and phenotypic properties of the bottom-fermenting yeast S. pastorianus and its future perspectives.In chapter two, a spore-to-spore breeding strategy was applied, in order to generate novel interspecific hybrids between six carefully selected S. cerevisiae and two S. eubayanus yeasts. The generated 31 interspecific hybrids were assessed for their temperature tolerance, as well as their fermentation capacity and aroma production in lab scale and (for some) pilot scale lager beer fermentation trials. Overall, generated interspecific hybrids showed a significantly higher growth capacity at low temperatures (4°C-16°C) compared to their respective S. cerevisiae parental strains, combined with a significantly higher growth capacity at high temperatures (30°C and 37°C) compared to their S. eubayanus parental strains. This broadened temperature tolerance of the generated interspecific hybrids not only equips them with a competitive advantage compared to their S. cerevisiae parent in cold temperature driven fermentations. More so, it also shows that generated interspecific hybrids can combine interesting phenotypes of both parental species into one organism. Besides a broadened temperature tolerance, most of the generated interspecific hybrids showed hybrid vigour in terms of their fermentation capacity during lager fermentation trials at 16°C and 12°C, with some interspecific hybrids producing similar ethanol levels compared to our best reference S. pastorianus strains. Aroma production of the generated interspecific hybrids also differed significantly from the commercially used S. pastorianus yeasts, underlying the potential of these novel yeasts for the production of novel beer types, bridging the gap between easy drinkable lager beers and aroma rich and diverse top fermented beers.Besides only wanted phenotypes, generated interspecific hybrids inherited also some unwanted phenotypes, with the production of phenolic off-flavours (POF) being the most important one. Indeed, the majority of generated interspecific hybrids are POF+, and are able to convert ferulic acid into its decarboxylated product 4 -vinylguaiacol (4VG), introducing often unwanted spicy and clove-like aromas in the fermented product. In order to investigate and remediate this unwanted phenotype of novel interspecific hybrids, we first developed a high-throughput absorbance-based screening tool to quickly assess the POF phenotype of hundreds of yeasts in parallel with only a limited amount of labour, consumables or expensive machines needed (chapter three). The developed new assay not only increased the throughput and lowered the cost significantly compared to the current state of art, it also showed an increased accuracy in the determination of the POF phenotype of industrial yeasts.The novel rapid screening method for POF production in yeast was later on used in chapter four, where a CRISPR-Cas9-based gene editing strategy was developed and applied in order to generate cis-genic POF- variants of novel generated, and genetic complex interspecific hybrid yeasts, increasing their industrial applicability. Specifically, a natural occurring single nucleotide polymorphism (SNP) in the ferulic decarboxylase coding gene FDC1, shared by the vast majority of the current POF- ale beer yeasts, was selected and introduced into the S. eubayanus derived genome of novel interspecific hybrids. Interestingly, the developed CRISPR -Cas9-based gene editing strategy was successful in introducing the selected SNP, without introducing loss of heterozygosity, as reported previously when trying to apply CRISPR -Cas9-based gene editing in genetically complex interspecific hybrid genomes. Besides no observed genetic side effects, no phenotypic side effects were detected, generating aromatic diverse but POF- novel lager yeasts.