Master of Science in Chemical Engineering, University of Toledo, 2011, Chemical Engineering

The concern over the increasing depletion of our nation's fossil fuels, high oil prices and greenhouse gas emissions, has motivated research for alternative sources of energy. One alternative energy source, biofuels, provides liquid transportation fuels from biomass derived from plant or animal sources. First generation biofuels are produced from food crops abundant in sugars or lipids such as corn and soy. Second generation biofuels are produced from woody, inedible crops such as poplar and switchgrass. The third generation of biofuels is derived from algae and is of growing interest due to its high yield of energy per unit area, use of carbon dioxide for growth, and minimal contribution as a food product. The main carbon rich components of algal biomass include lipid, carbohydrates and protein. Products such as biodiesel and jet fuel can be derived from lipids. Carbohydrates, in the form of fermentable sugars, can be used to produce bioalcohols. Protein can be used as a dietary supplement or as feed for livestock. This work addresses algal characterization and processing techniques that are helpful in utilizing algae as a feedstock for bioproduct processing. Methods for lipid analysis are compared to select a technique for small sample sizes and ease of handling. The hydrolysis of soybean oil to convert triglycerides (lipids) to free fatty acids is evaluated. A kinetic model is developed to predict reaction behavior and serve as a platform for algal hydrolysis. Characterization techniques to determine the content of algal biopolymers; lipids, carbohydrates and protein are discussed and applied to multiple algal species. Lastly, protein extraction from alga is investigated to prepare species for successful algal hydrolysis.

Committee: Constance Schall (Advisor); Dong-Shik Kim (Committee Member); Cyndee Gruden (Committee Member) Subjects: Alternative Energy; Chemical Engineering

Master of Science, The Ohio State University, 1975, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Science, The Ohio State University, 1923, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, The Ohio State University, 2024, Food Science and Technology

This dissertation investigates the enzymatic parameters of a β-galactosidase derived from the probiotic candidate, Lactobacillus helveticus OSU-PECh-4A (Lb. helveticus), with a focus on its potential for galacto-oligosaccharide (GOS) production. β-galactosidase is a hydrolytic enzyme that catalyzes the breakdown of lactose into its simpler sugar, glucose, and galactose. Simultaneously with lactose hydrolysis and under specific conditions, β-galactosidase can also produce highly demanded prebiotics known as galacto-oligosaccharides (GOS). In this dissertation, a thermostable β-galactosidase from Lb. helveticus has been isolated through diafiltration and size-exclusion chromatography and characterized through enzymatic assay and differential scanning fluorimetry (DSF). The isolated enzyme consists of a heterodimer with a molecular mass of 110 kDa, with a small and large subunit of 36 kDa and 74 kDa, respectively. The Km and Vmax values for lactose hydrolysis were 29.87 ± 1.05 mM and 1.88 ± 0.02 μmol D-glucose released per min per mg of protein, respectively. The enzyme is stable under a wide range of pH and high temperatures in terms of activity (≥ 40 °C). Once characterized, the enzyme capacity to produce GOS was evaluated through a 2x2 factorial design using substrate concentration and temperature as variables. The GOS produced were quantified and identified using high-performance liquid chromatography coupled with a charged aerosol detector (HPLC-CAD) and liquid chromatography with electrospray ionization mass spectroscopy (LC-ESI-MS/MS), respectively. To provide a perspective of the many possible applications of the enzyme, the enzyme's capacity to use different sugar acceptors to produce fucose-containing GOS was also evaluated by comparison. A maximum GOS yield of 12% was obtained at an initial lactose concentration of 200 g/L under 45 °C for 12 h. The GOS mixture consisted of 82% GOS, from which 6'galactosyl-lactose (trisaccharide), lactulose (disaccharides) (open full item for complete abstract)

Committee: Rafael Jiménez-Flores (Advisor); Valente Álvarez (Committee Member); Monica Giusti (Committee Member); Osvaldo Campanella (Committee Member) Subjects: Food Science

Doctor of Philosophy, The Ohio State University, 2023, Food Science and Technology

Consumer demands for ethically sourced and environmentally friendly food products have led to development efforts to replace animal-based proteins with plant-based alternatives. However, plant-based protein ingredients can be limited by their functional and sensory properties, and thus processing techniques to improve these properties must be explored. Enzymatic hydrolysis has been suggested to improve key functional properties, such as solubility, but the research methodology in this area is questionable and hydrolysis does not fully address sensory deficits in plant-protein ingredients, notably bitterness. In this dissertation, commercial extruded snack products containing soy protein hydrolysates were used as a model to quantify bitterness and test the viability of reformulation with flavor maskers or alternatively processed proteins to improve off-flavor. This study revealed that commercial flavor maskers are not effective at reducing bitterness in products containing soy hydrolysate, but soy protein hydrolysates made by different manufacturers with different processing methods proved a viable replacement with improved off-flavor. In search for conclusive evidence that enzymatic hydrolysis results in improved functionality, a review of literature was conducted. This review concluded that enzymatic hydrolysis process may result in the formation of insoluble aggregates, which in most studies are removed by centrifugation or filtration during processing, thus artificially increasing the reported solubility values for plant-protein hydrolysates. The phenomenon of hydrolysis induced aggregation was confirmed for protein isolates from soy and as well as a pulse protein alternative to soy, chickpea, which were hydrolyzed by Flavourzyme and Alcalase. Analysis of physical and structural properties of the hydrolyzed proteins revealed that hydrolysis led to protein destabilization, causing hydrogen-bond mediated aggregation during thermal enzyme inactivation. The knowledge (open full item for complete abstract)

Committee: Farnaz Maleky (Advisor); Osvaldo Campanella (Committee Member); Emmanuel Hatzakis (Committee Member); John Litchfield (Committee Member); Lynn Knipe (Committee Member) Subjects: Biochemistry; Food Science

Master of Science, The Ohio State University, 2023, Food Science and Technology

Plant proteins are gaining significant attention as a potential alternative to animal proteins in many food and beverage products. However, these proteins possess inferior functionality and physicochemical properties as compared to animal proteins. The primary goal of this investigation was to evaluate enzymatic hydrolysis as an approach to changing the structural and functional properties of pea proteins, specifically the gelling properties. Inulin is a neutral oligosaccharide and soluble fiber. It has bifidogenic properties that promotes gut health. Thus, gels containing a combination of hydrolyzed pea protein and inulin can serve as a model mixed food system that can be investigated. A specific objective of this research was to evaluate the degree of hydrolysis and inulin to pea protein ratio needed for the optimum structural and functional properties of the gels formed. Pea protein isolate (PPI) solutions (7.5%) were subjected to limited enzymatic hydrolysis prepared using the enzyme Alcalase® at three hydrolysis times (0, 3 and 6 mins). The hydrolyzed protein solutions were placed in an ice water bath to limit enzyme activity. At this stage, addition of inulin was done in different ratios to the pea protein present in the solution. Gels were prepared with these solutions and characterization of their viscoelastic properties was done by subjecting the gels to amplitude and frequency sweep. The gels formed by the pea protein samples hydrolyzed for 3 mins with inulin to pea protein ratio of 1:4 exhibited the highest gel strength as described by the storage modulus (G') values, out of all samples. Whereas the lowest gel strength was observed for the gels formed by samples hydrolyzed for 0 mins (unhydrolyzed samples). It was apparent that hydrolysis time controlled the ability of the gel to incorporate inulin and had a greater effect on gel strength, as compared to inulin addition. The frequency sweep results demonstrated that the gels formed by samples hydrolyz (open full item for complete abstract)

Committee: Dennis Heldman (Advisor); Valente Alvarez (Advisor); Osvaldo Campanella (Committee Member) Subjects: Food Science

Master of Science in Chemistry, Youngstown State University, 2023, Department of Biological Sciences and Chemistry

The enzyme β-galactosidase plays a role in the hydrolysis of lactose to galactose and glucose. Depending on the source, β-galactosidases can also carry out transglycosylation. This research was aimed at the biochemical characterization of β-galactosidase from Enterobacter sp. YSU. The enzyme is within the family of glycoside hydrolases. The Enterobacter sp. YSU β-galactosidase was overexpressed in E. coli. Subsequently, it was isolated using ammonium sulfate precipitation and a Q-Sepharose ion-exchange column. The single polypeptide chain protein contains 1056 amino acids with a molecular weight of 120 kDa. An in-gel activity test using 4-methylumbelliferyl-β-D-galactopyranoside established that the protein is active in its dimeric form. Dissociation of β-galactosidase into monomers in the presence of detergents like SDS results in the loss of enzymatic activity. The enzyme shows its optimal activity at pH 7.4 and a temperature of 40 °C. It has a limited substrate specificity of o-nitrophenyl-β-D-galactopyranoside (o-NPGal) and lactose. The catalytic parameters of the enzyme for o-NPGal were determined: KM is 0.3 mM, and kcat is 146 s-1. With respect to lactose, KM is 22 mM, and kcat is 3.86×103 min-1. Galactose competitively suppresses β-galactosidase activity, whereas glucose uncompetitively inhibits the enzyme. The enzymatic activity of β-galactosidase was affected by the presence of Mg2+ but not other divalent ions like calcium, zinc, or copper. Dimethyl sulfoxide caused a notable decrease in the activity of β-galactosidase while 2-mercaptoethanol had no effect on the activity of the enzyme. The β-galactosidase from Enterobacter sp. YSU showed a similar KM for lactose with most β-galactosidases isolated from other organisms but a higher kcat, and, therefore, there is a need to explore its applications in the hydrolysis of lactose.

Committee: Nina Stourman PhD (Advisor); Michael Serra PhD (Committee Member); Jonathan Caguiat PhD (Committee Member) Subjects: Biochemistry; Biology; Biomedical Research; Chemistry; Food Science; Health Sciences; Molecules

Master of Science, University of Toledo, 2023, Chemical Engineering

In this work, the impact of the co-monomer, furan dicarboxylate (FDCA), on depolymerization of poly (ethylene terephthalate) (PET) was investigated. Specifically, glycolysis and alkaline hydrolysis were used to depolymerize the following polyesters: (i) PET, (ii) polyethylene furonate (PEF), (iii) a copolymer with 10 % FDCA and 90 % TPA (PETF10-I) and (iv) a melt blend of 10 % PEF and 90 % PET (PETF10-B). The alkaline hydrolysis kinetics were studied at 110 oC in 1.1 M sodium hydroxide (NaOH) solution [45, 46, 65]. Glycolysis kinetics were studied at 180 oC in ethylene glycol (EG) with a zinc acetate catalyst [31, 47, 66]. Both reactions occur at the surface of the polyester flakes so that surface wetting by the solution, surface area of flakes, and backbone structure of the polymer are important in determining reaction kinetics. In addition, this work showed that the polyester configuration played a role in depolymerization kinetics for the PET/PEF mixed systems. The PEF exhibited much faster rates of depolymerization for both hydrolysis and glycolysis than pure PET, which was attributed to the presence of five member rings that are more labile than benzene ring. The inclusion FDCA based polyesters as a co-polymer or blend resulted in increases in depolymerization rates relative to the PET. The blend exhibited faster rates of kinetics than the co-polyester indicating that the configuration or macrostructure was important in determining depolymerization kinetics. The more rapid kinetics of the blends was attributed to a combination of (i) improved surface wetting by the reaction media and (ii) high degradation rates for PEF in blends which generated small pits in surface and increased surface area. The hydrolysis product for both the blend and co-polymers of PETF10 contained FDCA and TPA. However, high purity of BHET was recovered from the reaction mixture with only traces of BHEF following glycolysis of the blends and co-polyester. While it was difficult to rec (open full item for complete abstract)

Committee: Maria Coleman (Committee Chair); Joseph Lawrence (Committee Member); Dong -Shik Kim (Committee Member) Subjects: Chemical Engineering

Doctor of Philosophy, University of Toledo, 2022, Engineering

Polyethylene terephthalate (PET) is used in packaging and textile industries such as in productions of water bottles and packaging of soft drinks. As the PET products have short lifetimes, they turn into waste rapidly. Since the market for PET products has been constantly expanding, the rate of PET waste has been increased. This may negatively affect the environment and living species. In addition, PET is produced from fossil fuels, a limited resource that should be reserved to decrease the adverse effects of its applications on the environment. Therefore, recycling has been proposed as a resolution to PET waste. Chemical recycling can decompose PET to the associated oligomers and monomers. This may provide an alternative resource for reproduction of PET and subsequently PET products. In this dissertation, hydrolysis was studied- a technique for chemically recycling of PET waste. In chemical recycling, the factors affecting the rate of PET decomposition are PET shape, PET size, reaction temperature, reaction pressure, catalyst type, catalyst concentration, and surface wetting. Few studies are reported on surface wetting. So, the main interest of this dissertation was to explore the effect of surface wetting on the rate of PET decomposition in hydrolysis reactions. In this dissertation, series of catalysts were introduced that could increase the rate of PET decomposition due to the better surface wetting of PET particles occurring with the solutions of these catalysts during the hydrolysis of PET. This effect was explored by applying a shrinking core model to interpret the kinetics data of TPA yield for calculations of reaction rate constants. These constants were correlated to the partition coefficient and distribution coefficient values of catalysts for the octanol/water system to indirectly study the PET/water system in hydrolysis. This revealed the role of functional group in catalyst structure as a determining factor for the hydrophobicity of catalyst solution (open full item for complete abstract)

Committee: Maria R. Coleman (Committee Chair); G. Glenn Lipscomb (Committee Member); Defne Apul (Committee Member); Constance A. Schall (Committee Member); Dong-Shik Kim (Committee Member) Subjects: Chemical Engineering; Chemistry; Engineering; Environmental Engineering; Environmental Science; Experiments; Materials Science; Mathematics; Mechanical Engineering; Organic Chemistry; Packaging; Plastics; Polymer Chemistry; Polymers; Sustainability

Master of Science, University of Toledo, 2022, Chemical Engineering

The current study investigated the antibacterial activities of low acyl gellan gum (LA-GAGR) and its derivative, Mini-GAGR through two different methods. The first method involves the measurement of antibacterial activities of suspended LA-GAGR and Mini-GAGR in a liquid phase to determine their minimum inhibitory concentrations (MIC). The concentrations used for LA-GAGR and Mini-GAGR were 0.002 %, 0.003 %, and 0.015 %. As LA-GAGR and Mini-GAGR concentrations increased, their antibacterial activities became significantly high. The results also showed that LA-GAGR had a greater antibacterial activity than Mini-GAGR. The second method was via the growth inhibition experiment where 1.5% of LA-GAGR and 3% of Mini-GAGR in a gel phase were compared with two different types of polysaccharides, 2% chitosan and 7% dextran. Before running the growth inhibition experiment, confirmation of similar rheological properties for all samples was made. LA-GAGR, Mini-GAGR, chitosan and dextran showed similar rheological properties with gel-like behavior. The result of the growth inhibition experiment showed that the largest inhibition zone was formed in chitosan. While LA-GAGR has some inhibition zone, unlike Mini-GAGR where the gel is colorless, dextran did not inhibit the bacterial growth and allowed the bacteria to colonize on its gel.

Committee: Dong-Shik Kim Dr (Advisor); Joshua Park Dr (Committee Member); Maria Coleman Dr (Committee Member) Subjects: Biology; Biomedical Research; Chemical Engineering; Microbiology

Doctor of Philosophy (Ph.D.), Bowling Green State University, 2022, Chemistry

Materials Chemistry is an extremely important area of science touching everything from solar energy conversion to medical implants. The work of this dissertation has focused on developing porous materials, especially related to functional and stimuli responsive materials, including photochemical, for a variety of applications such as environmental remediation, soft robotics, and self-healing materials. We aimed to create silicon-based materials to overcome many of the technological barriers including low thermal stability, low selectivity, and poor mechanical properties of the typical materials used in these types of applications. Chapter 1 gives an overview and background of the types of materials that will be investigated in this dissertation. We will first introduce silsesquioxane (RSiO1.5)n chemistry, including synthesis methodologies, synthetic challenges and the properties that give reasons for their use. The research detailed in chapters 2 and 3 of this dissertation set out to contribute a new synthetic method for silicon-based porous materials involving fluoride catalyzed polymerization of R-alkoxysilanes. We aimed to gain a fundamental understanding of the reaction parameters and their impact on structure-property relationships in porous silsesquioxane-based gel materials. In chapter 4, we explored the interaction of fluoride with a silica-based cage called octa(dimethylsiloxy)silsesquioxane (Q8M8H). While it was expected that little interaction would occur with Q8M8H it was found that the outer siloxane units undergo rapid self-polymerization in the presence of a fluoride anion catalyst to form complex 3D porous structural network materials with specific surface areas up to 650 m2g-1. In chapter 5, we demonstrate our approach to photoswitchable silicon-based network polymers using Q8M8H as a cubic building block and azobenzene as a photo-actuatable cross-linker. We found that these photoswitchable silsesquioxane/azobenzene hybrid 3D–polymer gels can be e (open full item for complete abstract)

Committee: Joseph Furgal Ph.D. (Advisor); Gary Oates Ph.D. (Other); Pavel Anzenbacher Ph.D. (Committee Member); Alexis Ostrowski Ph.D. (Committee Member) Subjects: Chemistry; Materials Science; Polymer Chemistry; Polymers

Doctor of Philosophy, The Ohio State University, 2022, Food Science and Technology

Waste streams from the food industry have been associated with severe environmental pollution and an economic burden for producers. The Food and Agricultural Organization from the United Nations has stated that one-third of the global food chain production ends up as food waste. The dairy and fish industry has significant roles in producing waste streams that threaten the ecosystem due to their high biological and chemical oxygen demand. The by-products from both industries have shown several complications for its proper treatment of disposal. Therefore, science-based approaches that can handle the treatment more efficiently or, otherwise, transform them to add value and include them as part of other foods. The increasing demand for acidified and fresh-like dairy products has made the handling of acid whey a disposal burden for this industry. Acid whey is the milk serum left after the removal of caseins after fermentation and acidification. On the other hand, the most valuable part of fisheries is the fillet that only represents 40-45% of a fish; this value means that more than 50% of this food chain becomes waste. However, both waste streams are considered nutrient-dense co-products with potential complementary nutritional advantages suitable for biotechnological technologies and valuable products' production. In this work, we hypothesized that under appropriate conditions, a semi-controlled fermentation of the mix of acid whey and minced fish waste can break down the complex proteins from fish; a close follows up to understand the microbiome and chemical changes would lead to a safe and nutritionally bioavailable product. To this end, the first objective was to find the optimum conditions and materials ratios that would deliver the best proteolysis, including the addition of a starter culture and a simple carbohydrate source. Additionally, the innate microbiota from the co-products and changes during the fermentation was closely monitored using 16S-v4 rRNA a (open full item for complete abstract)

Committee: Rafael Jimenez-Flores (Advisor) Subjects: Food Science

PhD, University of Cincinnati, 2021, Arts and Sciences: Chemistry

Abstract This dissertation focuses on biomass conversion, including the investigation of the effects of lignin structure on enzymatic hydrolysis, and lignin valorization to valuable chemicals under mild conditions. In this work, four different types of lignin model polymers have been synthesized and employed in enzymatic hydrolysis to understand their effects on glucose release. A cobalt-based catalytic system has also been developed to cleave the ether C–O bonds in lignin model compounds and organosolv lignin. The lignin structure is complicated to allow in-depth studies of structure-reactivity relationships. Thus, the use of lignin model systems can simplify the analysis, representing a viable strategy in this research field. On the other hand, overly simplified lignin model compounds may not necessarily reflect how real lignin behaves. Herein four lignin model polymers bearing ß-O-4 and/or ß-ß linkages and guaiacyl and/or syringyl units have been synthesized, which involves polymerization, further derivatization, and polymer purification. With medium complexity in structures, these polymers are expected to bridge the gap between overly simplified lignin model compounds and real lignin in terms of understanding the biomass conversion. Lignin model polymers I and IV contain ß-O-4 linkages with syringyl and guaiacyl units, respectively. Lignin model polymer II is composed of ß-O-4 and ß-ß with the syringyl unit only. Lignin model polymer III is composed of ß-O-4 and ß-ß with both syringyl and guaiacyl units. The complexity in lignin structure plays a crucial, yet not well-understood, role in sugar production from biomass via enzymatic hydrolysis. To understand the well-defined lignin structure's influence, the aforementioned four lignin model polymers were employed in enzymatic hydrolysis. Lignin model polymers I and IV increase the glucose yield by 6% and 11%, while lignin model polymers II and III decrease the glucose yield by 3% and 2%, respe (open full item for complete abstract)

Committee: Hairong Guan Ph.D. (Committee Chair); Allan Pinhas Ph.D. (Committee Member); Maobing Tu Ph.D. (Committee Member); Peng Zhang Ph.D. (Committee Member) Subjects: Chemistry

Master of Science, University of Toledo, 2021, Chemical Engineering

Two bio-based comonomers, isosorbide (ISB) and 2,5-Furan dicarboxylic acid (FDCA) was used to partially or completely replace the diol, Ethylene glycol (EG) or diacid, Terephthalic acid (TPA) of petroleum-based polyester, Polyethylene terephthalate (PET). The effect of the co-monomers on the alkaline hydrolysis reaction of bio-based co-polyesters, PEIxT and PETFy or polyester, Polyethylene furanoate (PEF) was investigated to compare the rate of depolymerization for their reaction kinetics and the factors contributing to the reaction mechanism were studied. Different compositions of ISB (3%, 8% and 12%) was used to replace the EG in PET to produce the PEIxT co-polyesters and different composition of FDCA (10% and 100%) was used to replace the TPA to produce the PETFy co-polyesters. The 100% replacement of TPA with FDCA, produced the furan analogous of PET, PEF. The alkaline hydrolysis reaction kinetics were studied at temperatures between 130oC-150oC in 1.1 M Sodium Hydroxide (NaOH) solution in a glass reactor system and a Parr reactor system. The comonomers exhibited increase in the reaction rates under alkaline hydrolysis relative to the pure PET for all systems. Since alkaline hydrolysis occurs in the amorphous region near the surface of the polymers, the crystallinity, surface wetting and water uptake properties of the polymers have an impact on the hydrolysis reaction kinetics. To understand the cause for the improved reaction kinetics with inclusion of the co-monomers, the impact of comonomers on the physical properties such as crystallinity, surface wetting and water uptake were studied. The reactive bonds of the co-monomers can have a significant impact on the ester linkage in the co-polyesters that make them susceptible to hydrolytic degradation. Literature on the hydrolytic degradation in the environment suggests that the ester-linkage of isosorbide with TPA might be more susceptible to hydrolysis than the linkage of EG with TPA, which could be a factor (open full item for complete abstract)

Committee: Maria Coleman Dr. (Committee Chair) Subjects: Chemical Engineering

Master of Science in Chemistry, Youngstown State University, 2021, Department of Biological Sciences and Chemistry

Oligosaccharides are a class of carbohydrates which play important roles in several areas including therepeutics, food, phamaceuticals, animal feed and their use as prebiotics. Current commercial production of oligosaccharides involves lengthy multistep procedures with lowbyields. To improve oligosaccharide yield, a broad range of factors related to oligosaccharide synthesis by transglycosylation was evaluated. Three enzymes, β-galactosidase from Aspergillus oryzae, lactase from lactose intolerance supplements, and Enterobacter β-galactosidase were tested for their ability to catalyze a transglycosylation reaction. The enzymes were applied in both free and immobilized forms and the activities toward transglycosylation were compared. Immobilization of enzymes led to increased oligosaccharide synthesis and improved enzyme stability under different conditions. Lactose, which is a main milk carbohydrate, was used as the major substrate for synthesis of oligosaccharides. Factors like organic solvents, temperature, and pH were varied with the aim of obtaining the conditions with higher transglycosylation results. The analysis of products was done by thin layer chromatography. The yield of transglycosylation products was dependent on both temperature and pH. The preferred conditions for formation of oligosaccharides are pH 8 and 50 - 60 °C. High concentrations of glucose and galactose, the products of lactose hydrolysis, suppressed both transglycosylation and hydrolysis reactions. When sucrose and lactose were used together, an increase in the sucrose to lactose ratio led to an increase in transglycosylation products. Addition of alcohols resulted in formation of alkyl-glycosides instead of oligosaccharides. Enterobacter β-galactosidase was successfully overexpressed in E. coli cells and demonstrated transglycosylation and hydrolysis activity.

Committee: Nina Stourman PhD (Advisor); Michael Serra PhD (Committee Member); Jonathan Caguiat PhD (Committee Member) Subjects: Biochemistry; Chemistry

PhD, University of Cincinnati, 2020, Engineering and Applied Science: Chemical Engineering

Biofuels, derived from lignocelluloses, is an attractive supplement to fuel produced from non-renewable resources. Various pretreatment methods have been developed to overcome the recalcitrance of lignocelluloses to provide highly digestible substrates for enzymatic hydrolysis. Organosolv pretreatment with ethanol is a promising method for increasing cellulose accessibility, releasing sugars from hemicellulose, and recovering relatively pure lignin as a by-product. The use of other short-chain aliphatic alcohols in the organosolv pretreatment, such as methanol and propanol, was considered to have high-efficiency delignification. The following step of biochemical conversion is enzymatic hydrolysis, by which cellulose and hemicellulose are converted into fermentable sugars. The high cost of enzymes is one of the major bottlenecks in biochemical conversion. In this work, methanol, ethanol, and propanol organosolv lignins from poplar, eucalyptus, aspen, Loblolly pine, and kenaf have been evaluated for their effects on enzymatic hydrolysis of lignocelluloses. Two dimension heteronuclear single quantum coherence spectroscopy (2D-HSQC), heteronuclear single quantum coherence-total correlated spectroscopy (HSQC-TOCSY), and heteronuclear multiple bond correlation spectroscopy (HMBC) have been used to characterize the structure changes of lignins before and after organosolv pretreatment. The spectra of HSQC, HSQC-TOCSY, and HMBC revealed that the alkylation (e.g., methylation, ethylation and propylation) of hydroxyl groups took place not only at Ca, but also at Cß and C?, and potentially also at the phenolic hydroxyl group of lignin. These results showed that propanol organosolv lignins (POLs) from poplar and aspen had higher stimulatory effects than the ethanol and methanol organosolv lignins (EOLs and MOLs) on the enzymatic hydrolysis of Avicel. The alkylation degree will affect the hydrophobicity of resulting organosolv lignins, which in turn will control their positive (open full item for complete abstract)

Committee: Maobing Tu Ph.D. (Committee Chair); Mingming Lu Ph.D. (Committee Member); Yoonjee Park Ph.D. (Committee Member); Jingjie Wu Ph.D. (Committee Member); Wei Yuan Ph.D. (Committee Member) Subjects: Agricultural Engineering

Master of Science, University of Akron, 2020, Chemical Engineering

Nanocellulose has been investigated for use in food packaging, biomedical applications, and electronics. This work attempted to isolate and evaluate crystalline nanocellulose from soybean hulls in the form of cellulose nanofibrils (CNFs) as reinforcing fillers in natural rubber composites. CNFs and nanocrystalline cellulose (CNCs) have previously been derived from different types of lignocellulosic biomass. Previous work in this area used alkali pretreatments and acid hydrolysis to break down the complex network of cellulose, hemicellulose, and lignin present in plant cell walls. CNCs and CNFs have previously been isolated using high shear microfluidization, cryocrushing, freeze drying, and ultrafiltration. In this work, enzyme cocktails of carbohydrases produced from Aspergillus niger were used to hydrolyze the polysaccharides in soybean hull and soybean flour. Solids were separated from soluble sugars and other components after enzyme hydrolysis for 24 hours, and these washed solids were treated with sonication, blending, and homogenization to reduce the size of these solids. Particle size analysis showed that enzyme hydrolysis did indeed generate nanoparticles, the majority of which were between 150-200 nm. The quantity of these insoluble nanoparticles was found to be small, however, relative to that of solids and seed coat fragments approximately 100-200 µm in length. Further analysis with microscopy and SEM imaging revealed that the enzyme hydrolysis was able to cleave sclereid structures from the seed coat and breakdown soybean hull into fragments. Smaller particle size loading at the beginning of enzyme hydrolysis was found to release more sugar, so intermediate sizes were sieved in order to maximize solids recovery and minimize sugar release. These washed and mechanically treated solids were next mixed at alkaline pH (9.8–10) with natural rubber latex and oven dried overnight to create rubber composites. The resulting composites were masticated, vulcanized, (open full item for complete abstract)

Committee: Lu-Kwang Ju (Advisor); Jie Zheng (Committee Member); Qixin Zhou (Committee Member) Subjects: Chemical Engineering

Master of Science in Chemistry, Youngstown State University, 2020, Department of Chemistry

Immobilized multienzyme systems catalyzing cascade reactions have shown to be an effective industrial strategy. These systems reduce production cost by increasing both reusability and stability of enzymes under extreme conditions. Development of a stable support for enzyme immobilization further improves the process. The objective of this study was to improve lactose hydrolysis by designing a two-component system comprised of lactase and glucose oxidase immobilized independently on a modified chitosan support. The structural stability of chitosan was enhanced by addition of fortifying agents such as activated charcoal, silica, and magnetic particles followed by crosslinking beads with glutaraldehyde. Lactase was immobilized on chitosan-magnetic beads, chitosan-charcoal beads, and chitosan-silica beads. Glucose oxidase was immobilized on chitosan-charcoal beads and chitosan-silica beads. The physical properties, immobilization efficiency, and enzymatic activity were determined for each immobilized enzyme. Both enzymes, lactase and glucose oxidase, retained their activity after immobilization. Assays performed with the combinations of the chitosan beads indicated that the immobilized enzymes are capable of catalyzing two sequential reactions - lactose hydrolysis and glucose oxidation.

Committee: Nina Stourman PhD (Advisor); Michael Serra PhD (Committee Member); Douglas Genna PhD (Committee Member) Subjects: Biochemistry; Chemistry

Master of Science in Chemistry, Youngstown State University, 2018, Department of Chemistry

Enzyme immobilization refers to any technique by which an enzyme is restrained or localized to a support system. This can provide retention of catalytic activity and reusability of the enzyme, both of which are important in industrial processes. Enzyme supports can be made of organic materials, typically naturally occurring polysaccharides, such as cellulose, agarose, or chitosan. The objective of this study was to immobilize beta glycosidase BglX and its mutant E293Q on chitosan gel beads while retaining catalytic activity. The beads were fortified with activated charcoal or silica and cross-linked with glutaraldehyde to increase their mechanical stability and immobilization efficiency. Lactase was used as a model enzyme to determine which type of chitosan gel bead was the most suitable for immobilization. The chromogenic substrate ortho-nitrophenyl ß-D-galactopyranoside (oNPGal) and a lactose solution were used to test the catalytic activity of immobilized lactase. Upon successfully immobilizing lactase, BglX and E293Q were tested similarly. Since BglX showed higher percent conversion of substrate, it was used in a packed bed column and the ability of the immobilized enzyme to hydrolyze the lactose present in milk whey was tested in a small-scale continuous production system.

Committee: Nina Stourman PhD (Advisor); Michael Serra PhD (Committee Member); Clovis Linkous PhD (Committee Member) Subjects: Biochemistry; Chemistry; Food Science

Master of Science, University of Toledo, 2018, Chemical Engineering

The large increase in the generation of post-consumer plastic in past few decades has led to an increased interest in eco-friendly recycling technologies. Polyethylene terephthalate (PET) is a highly valued packaging material with broad applications because it is strong, lightweight, non-reactive, non-toxic and shatterproof. To extend its applications, the packaging industry adds co-monomers, additives, multilayered structures and forms polymer blends to improve the mechanical and barrier properties of the base polyester. These additives can pose challenges to the mechanical recycling methods that are commonly used in the industry. While mechanical recycling is economical and broadly commercially used, the recycled PET (RPET) tends to have reduced molecular weight and can degrade in the presence of impurities (i.e. polyvinyl chloride (PVC)). Chemical recycling is an attractive alternative approach that results in recovery of monomers and other chemical constituents that can be used as precursors for new polymers. Several chemical recycling methods were reported in literature to address the end-of-life PET waste, but little work was done on co-polyesters that are of interest to the packaging industry. The focus of this thesis is to investigate alkaline hydrolysis of traditional PET and a co-polyester (will be referred to as PETF20) containing ethylene glycol, 80% terephthalic acid (TPA) and 20% 2,5-furan dicarboxylic acid (FDCA). Studies on chemical/mechanical recycling of PETF20 were not reported in the literature. Alkaline hydrolysis of PET and PETF20 was investigated at atmospheric pressure and a range of temperatures (= 150¿) using sodium hydroxide solution (1.1 M) to recover TPA and FDCA. The impact of time, temperature, co-solvent (i.e. ¿- Valero lactone) and impurity (i.e. PVC) on conversion of PET was investigated at = 150¿, rate of depolymerization and impact of co-solvents (¿-Valero lactone, ¿- butyral lactone, ethylene glycol diacetate, propylene gl (open full item for complete abstract)

Committee: Maria Coleman (Committee Chair); Joseph Lawrence (Committee Co-Chair); Sridhar Viamajala (Committee Member) Subjects: Chemical Engineering