Tina Jeoh

Tina Jeoh
University of California, Davis | UCD · Department of Biological and Agricultural Engineering

About

70
Publications
9,797
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2,087
Citations
Citations since 2017
32 Research Items
1069 Citations
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
2017201820192020202120222023050100150200
Introduction

Publications

Publications (70)
Article
Oral delivery of therapeutic peptides faces substantial barriers, as peptides can be susceptible to denaturation, aggregation or hydrolysis in the stomach. This study explored the possibility to target enteric release of five model peptides, semaglutide, liraglutide, GLP-1, gonadorelin acetate and oxytocin acetate, by encapsulation in a novel, indu...
Article
Full-text available
Microbial inoculants are environmentally sustainable alternatives to petrochemical-derived herbicides, pesticides, and fertilizers in agriculture. We demonstrated the potential to develop a commercializable Klebsiella variicola product with storage and on-seed stability by encapsulating in cross-linked alginate matrix (CLAM) powder by spray drying....
Article
Full-text available
Limonene from citrus peel oil is valued as fragrance and flavor additives in food and beverages; however, D-limonene is highly volatile and oxygen-sensitive, thus present storage and stability challenges in food products. A novel, industrially-scalable microencapsulation by in situ complex coacervation during spray drying process (CoCo process) was...
Article
An industrially scalable complex coacervation process (referred to as the CoCo process) enables the formation of dry complex coacervated microcapsules in one step using a low-cost spray drying approach. Here, we demonstrated the feasibility of maintaining the activity of an enzyme directly coacervated with alginates in dry powder particles by the C...
Article
Full-text available
This study investigates methods to commercialize safer alternatives to chemical pesticides that pose risks to human safety and the environment. Spray-drying encapsulation of the plant-protective, antifungal bacterium Collimonas arenae Cal35 in in situ cross-linked alginate microcapsules (CLAMs) was optimized to minimize losses during spray-drying a...
Article
Microencapsulation of plant-beneficial bacteria for use as biopesticides is a growing area of interest in the search for alternatives to harmful chemical pesticides. In this study, we assessed the microencapsulation of the Gram-negative, non-spore-forming plant-beneficial bacterial strain Collimonas arenae Cal35 in novel cross-linked alginate micro...
Preprint
Full-text available
Synchrotron infrared hyperspectral microscopy is a label-free and non-invasive technique well suited for imaging of chemical events in situ. It can track the spatial and temporal distributions of molecules of interests in a specimen in its native state by the molecule's characteristic vibrational modes. Despite tremendous progress made in recent ye...
Article
One-step encapsulation of subtilisin by fluidized bed spray-coating in a cross-linked alginate matrix shell (CLAMshell) particle is introduced. The CLAMshell process maximizes process productivity, while simultaneously improving coating quality of spray-coated enzyme. Overall, higher spray rates were achieved with improved mechanical strength of th...
Article
Full-text available
Alginates gel rapidly under ambient conditions and have widely documented potential to form protective matrices for sensitive bioactive cargo. Most commonly, alginate gelation occurs via calcium mediated electrostatic crosslinks between the linear polyuronic acid polymers. A recent breakthrough to form crosslinked alginate microcapsules (CLAMs) by...
Article
Full-text available
A recently patented one-step in situ cross-linked alginate microencapsulation (CLAM) by spray-drying (i.e., the UC Davis CLAMs technology) can overcome the high cost of scale-up that limits commercial applications. While increasing calcium loading in the CLAMs process can increase the extent of cross-linking and improve retention and protection of...
Preprint
p>Alginates gel rapidly under ambient conditions and have widely documented potential to form protective matrices for sensitive bioactive cargo. Most commonly, alginate gelation occurs via calcium mediated electrostatic crosslinks between the linear polyuronic acid polymers. A recent breakthrough to form crosslinked alginate microcapsules (CLAMs) b...
Article
A facile method for preparing colloidal cellulose nanofibrils (CNF) from potato tubers is presented comprising alkaline treatment to remove non-cellulosic polysaccharides, followed by hypochlorite oxidation and homogenization. The CNF consisted of ~94% cellulose, and carboxyl groups on the surface of CNF prevented their agglomeration. Aqueous suspe...
Article
Interfacial enzyme reactions require formation of an enzyme-substrate complex at the surface of a heterogeneous substrate, but often multiple modes of enzyme binding and types of binding sites complicate analysis of their kinetics. Excess of heterogeneous substrate is often used as a justification to model the substrate as unchanging; but using the...
Article
Full-text available
Microencapsulating bioactive compounds, such as polyunsaturated fatty acids (PUFA), in dry cross-linked alginate serves to enhance their shelf life, mask unwanted flavors and odors, facilitate their incorporation into food products, and provide an intestinal release mechanism. Alginate microencapsulation is challenging to implement at industrial sc...
Article
To improve simultaneous characterization of structural and compositional features of infant formula powder the objectives of this study were to: 1) advance micro and macroscale fluorescence imaging methods to characterize the distribution of sugars, proteins and lipids in infant formula powder and 2) understand the impact of processing conditions a...
Article
Full-text available
Background: Molecular-scale mechanisms of the enzymatic breakdown of cellulosic biomass into fermentable sugars are still poorly understood, with a need for independent measurements of enzyme kinetic parameters. We measured binding times of cellobiohydrolase Trichoderma reesei Cel7A (Cel7A) on celluloses using wild-type Cel7A (WTintact), the catal...
Article
Microencapsulation by conventional complex coacervation, though highly effective and achievable at the bench-scale, is challenging to scale-up because of the complexity of the process. A novel, industrially-scalable microencapsulation process by in situ complex coacervation during spray drying (the ‘CoCo process’) is introduced, where the multiple...
Article
Calcium alginate microencapsulation is a popular laboratory technique, but implementing the traditional external gelation process in the food industry requires a series of costly unit operations. Alternatively, a consolidated process accomplishes alginate cross-linking in situ during spray-drying to form cross-linked alginate microcapsules (‘the CL...
Preprint
Full-text available
div>The food, chemical, and biotechnology industries offer many potential applications for calcium alginate microencapsulation, but this technique is largely confined to the laboratory bench due to scalability challenges. Scaling up the traditional external gelation method requires several costly unit operations. Alternatively, a consolidated proce...
Preprint
Full-text available
The success of hyaluronic acid in over-the-counter cosmetics has been limited by its poor storage stability in aqueous environments due to premature swelling and hydrolysis. Here, hyaluronic acid was prepared in dry microparticles, encapsulated by spray-drying in patented in situ calcium cross-linked alginate microcapsules (CLAMs) to minimize swell...
Preprint
Full-text available
Interfacial enzyme reactions require formation of an enzyme-substrate complex at the surface of a heterogeneous substrate, but often multiple modes of enzyme binding and types of binding sites complicate analysis of their kinetics. Excess of heterogeneous substrate is often used as a justification to model the substrate as unchanging; but using the...
Article
Functionality of whole egg was evaluated after several treatments and storage conditions. Treatment 1 (Trt 1) contained untreated eggs. Alpha‐linolenic acid, eicosapentaenoic acid, and docosahexaenoic acid were added to whole egg (Trt 2). A control layer ration (Trt 3) and Trt 4 (control + chia seed, flaxseed, and fish oil) was provided to laying h...
Article
Encapsulation in dry cross-linked alginate microbeads has numerous applications in pharmaceutics, food, and agriculture. Recently, we developed an innovative, industrially scalable, and cost-effective method in which alginates are cross-linked in-situ during spray-drying to form cross-linked alginate microcapsules (CLAMs), consolidating a series of...
Article
BACKGROUND Cassava leaves are an abundant global agricultural residue because the roots are a major source of dietary carbohydrates. Although cassava leaves are high in protein, the protein is not bioavailable. This work aimed to convert cassava leaves to a bioavailable protein‐rich animal feed ingredient using high‐protein yeasts. RESULTS The str...
Article
Mechanistic kinetic models are vital tools to elucidate rate-limiting interactions and processes hampering complete hydrolysis of cellulose by cellulases. Properly formulated, the models should ultimately simulate experimental cellulose hydrolysis time courses given that model parameters are known a priori. Here, we review reported values of critic...
Article
Full-text available
Microencapsulation of plant-beneficial bacteria, such as pink pigmented facultative methylotrophs (PPFM), may greatly extend the shelf life of these Gram-negative microorganisms and facilitate their application to crops for sustainable agriculture. A species of PPFM designated Methylobacterium radiotolerans was microencapsulated in cross-linked alg...
Article
Full-text available
In the shadow of a burgeoning biomass-to-fuels industry, biological conversion of lignocellulose to fermentable sugars in a cost-effective manner is key to the success of second-generation and advanced biofuel production. For the effective comparison of one cellulase preparation to another, cellulase assays are typically carried out with one or mor...
Article
Low-field Nuclear Magnetic Resonance (LFNMR) relaxometry examines the influence of the local environments within porous materials on the responses of the water-associated ¹H to magnetic fields, yielding information on the chemical and physical surroundings of the water. 1D NMR relaxometry has been used to examine the relationship between water cons...
Article
Bioconversion of lignocellulose forms the basis for renewable, advanced biofuels and bioproducts. Mechanisms of hydrolysis of cellulose by cellulases have been actively studied for nearly 70 years with significant gains in understanding of the cellulolytic enzymes. Yet, a full mechanistic understanding of the hydrolysis reaction has been elusive. W...
Article
Cellulosic biomass is the most promising feedstock for renewable biofuel production; however, the mechanisms of the heterogeneous cellulose saccharification reaction are still unsolved. As cellulases need to bind isolated molecules of cellulose at the surface of insoluble cellulose fibrils or larger aggregated cellulose structures in order to hydro...
Article
Full-text available
Tomato pomace is an abundant lignocellulosic waste stream from industrial tomato processing and therefore a potential feedstock for production of renewable biofuels. However, little research has been conducted to determine if pretreatment can enhance release of fermentable sugars from tomato pomace. Ionic liquids (ILs) are an emerging pretreatment...
Article
Microencapsulation of emulsified lipophilic bioactive compounds in dry, cross-linked alginate microcapsules (CLAMs) is a promising strategy to facilitate their incorporation into food systems, prolong shelf life, and target delivery within the gastrointestinal tract. However, current technology to produce CLAMs requires multiple time- and energy-in...
Article
Full-text available
Water-in-oil emulsions containing silica nanoparticles (Aerosil R974) have the potential to stabilize microalgae for long-term storage. Studies were completed to determine if smectite clays could be used as an alternative to Aerosil R974. Emulsions were prepared with Aerosil R974, and hectorite and bentonite clays in the continuous phase and Chlore...
Article
The enzymatic hydrolysis of cellulosic biomass is a key step in the biochemical production of fuels and chemicals. Economically feasible large-scale implementation of the process requires operation at high solids loadings, i.e., biomass concentrations >15% (w/w). At increasing solids loadings, however, biomass forms a high viscosity slurry that bec...
Article
The origin of the recalcitrance of cellulose fibrils to enzymatic hydrolysis is still poorly understood. In this study we examined the role of cellulose fibril lengths and fibril architecture, i.e. the fibrillar structure from lateral association of cellulose microfibrils, on the accessibility to a reducing-end specific cellobiohydrolase, Trichoder...
Article
Full-text available
The corn grain biofactory was used to produce Cel7A, an exo-cellulase (cellobiohydrolase I) from Hypocrea jecorina. The enzymatic activity on small molecule substrates was equivalent to its fungal counterpart. The corn grain-derived enzyme is glycosylated and 6 kDa smaller than the native fungal protein, likely due to more sugars added in the glyco...
Article
The role of endocellulases and endoxylanase during liquefaction and saccharification of hydrothermally pretreated wheat straw was studied. The use of a flow-loop setup with in-line magnetic resonance imaging (MRI) enabled frequent measurements of viscosity at 55°C during saccharification at 6 % total solids content. Viscosity data were complemented...
Article
Rice straw was pretreated with sodium hydroxide and subsequently conditioned to reduce the pH to 5-6 by either: (1) extensive water washing or (2) acidification with hydrochloric acid then water washing. Alkali pretreatment improved the enzymatic digestibility of rice straw by increasing the cellulose accessibility to cellulases. However, acidifica...
Article
Enzymatic hydrolysis of cellulose for conversion to chemicals or fuels presents engineering challenges due to the large changes in suspension viscosity and yield stress that occur. A flow reactor with an on-line rheometer was used to investigate the role of changes in fiber structure on rheology. The evolution of the suspension yield stress was com...
Patent
Full-text available
Provided herein is an isolated Cel7A polypeptide comprising mutations in the catalytic domain of the polypeptide relative to the catalytic domain of a wild type Cel7A polypeptide, wherein the mutations reduce N-linked glycosylation of the isolated polypeptide relative to the wild type polypeptide. Also provided herein is an isolated Cel7A polypepti...
Conference Paper
Enzymatic hydrolysis of cellulosic biomass is a key step of biological routes for production of fuels and chemicals. Economic considerations for large-scale implementation of the process demand operation in the high solids regime. In this regime, the biomass is processed at concentrations of 15% or higher by weight, forming a high viscosity slurry...
Article
There is a need to understand how cellulose structural properties impact productive cellulase-cellulose interactions toward solving the mechanisms of the heterogeneous reaction. We coupled biochemical studies of cellulose hydrolysis by a purified Trichoderma reesei Cel7A (TrCel7A) cellobiohydrolase with atomic force microscopy (AFM) to study the im...
Article
Full-text available
Banana cultivation is widespread in tropical and subtropical regions where many rural agricultural communities exist. The banana plant bears fruit once in its life cycle, leaving behind a significant amount of usable agricultural residue. Current practice leaves this residue to decompose in the field spreading diseases and polluting water supplies....
Article
Full-text available
The efficient catalytic conversion of biomass to bioenergy would meet a large portion of energy requirements in the near future. A crucial step in this process is the enzyme-catalyzed hydrolysis of cellulose to glucose that is then converted into fuel such as ethanol by fermentation. Here we use single-molecule fluorescence imaging to directly moni...
Conference Paper
The initial stage of cellulose hydrolysis, or liquefaction, is of particular importance in bioprocesses that use microorganisms to produce chemicals or fuels. A rapid liquefaction stage is desirable to reduce mixing energy input and reactor volume. During this process large changes in rheology occur that are relevant for economical scale up of the...
Article
Full-text available
Microencapsulation of biomolecules, cells and chemicals is widely used in the food and pharmaceutical industries to improve stability, delivery and to control the release of encapsulated moieties. Among encapsulation matrices, alginate is preferred due to its low cost, biodegradability and biocompatibility. Current methods for producing stable algi...
Article
Cellulosic biomass is recalcitrant to enzymatic hydrolysis which greatly reduces the efficiency of biofuels production. Specifically, the lignin component of biomass is thought to provide non-productive binding sites for glycosyl hydrolases, effectively disabling the enzymes from completing further digestion. A thorough understanding of the adsorpt...
Conference Paper
Biochemical conversion is a promising route to produce fuels and chemicals from cellulosic biomass. A key step in the process is biomass liquefaction, where enzymes are used to break down pretreated cellulosic particles. During this process, drastic changes in the mechanical properties of the cellulosic slurry cause a transition from a solid-like m...
Article
Water is essential to the hydrolysis and conversion of lignocellulosic materials as it is both the medium through which enzymes diffuse to and products diffuse away from the reaction sites and a reactant in the hydrolysis reaction of the glycosidic bonds within the polysaccharides. However, little is known about how water interactions with the biom...
Article
Changes in cellulose microstructure have been proposed to occur throughout hydrolysis that impact enzyme access and hydrolysis rates. However, there are very few direct observations of such changes in ongoing reactions. In this study, changes in the microstructure of cellulose are measured by simultaneous confocal and atomic force microscopy and ar...
Article
The filamentous fungi Trichoderma reesei and Penicillium funiculosum produce highly effective enzyme mixtures that degrade the cellulose and hemicellulose components of plant cell walls. Many fungal species produce a glycoside hydrolase family 7 (Cel7A) cellobiohydrolase, a class of enzymes that catalytically process from the reducing end of cellul...
Article
It has previously been shown that the improved digestibility of dilute acid pretreated corn stover is at least partially due to the removal of xylan and the consequent increase in accessibility of the cellulose to cellobiohydrolase enzymes. We now report on the impact that lignin removal has on the accessibility and digestibility of dilute acid pre...
Article
Full-text available
The cellulase producing ascomycete, Trichoderma reesei (Hypocrea jecorina), is known to secrete a range of enzymes important for ethanol production from lignocellulosic biomass. It is also widely used for the commercial scale production of industrial enzymes because of its ability to produce high titers of heterologous proteins. During the secretio...
Article
Development of high-quality, dedicated biomass feedstocks requires an understanding of the chemical, anatomical and physical traits of plants that make biomass more amenable to chemical and biological processing. The availability of sequenced plant genomes, such as Arabidopsis, rice, and Populus, helps create the genomic resources needed to improve...
Article
Full-text available
Attempts to correlate the physical and chemical properties of biomass to its susceptibility to enzyme digestion are often inconclusive or contradictory depending on variables such as the type of substrate, the pretreatment conditions and measurement techniques. In this study, we present a direct method for measuring the key factors governing cellul...
Article
Elucidating the molecular mechanisms that govern synergism is important for the rational engineering of cellulase mixtures. Our goal was to observe how varying the loading molar ratio of cellulases in a binary mixture and the recalcitrance of the cellulose to enzymatic degradation influenced the degree of synergistic effect (DSE) and degree of syne...
Article
Full-text available
The cellobiase activities of nine thermal stable mutants of Thermobifida fusca BglC were assayed by isothermal titration microcalorimetry (ITC). The mutations were previously generated using random mutagenesis and identified by high-temperature screening as imparting improved thermal stability to the beta-D-glucosidase enzyme. Analysis of the subst...
Article
The conclusions of this presentation are: (1) The dilute-acid pretreatment reduces xylan content in corn stover. This reduction in xylan content appears to render the substrate less recalcitrant. Below 8%, xylan content is no longer the dominant factor in biomass recalcitrance. (2) Decreasing xylan content of corn stover also created more binding s...
Article
Synergism between cellulases facilitates efficient hydrolysis of microcrystalline cellulose. We hypothesize that the effects of synergism, observed as enhanced extents of hydrolysis, are related to cellulase binding to the substrate in mixtures. In this study, direct measurements of bound concentrations of fluorescence-labeled T. fusca Cel5A, Cel6B...
Article
Cotton gin waste was collected from a cotton ginning plant in Virginia and characterized before and after steam explosion to evaluate its potential applications for higher value products such as ethanol. The raw cotton gin waste had high levels of ash () and acid insoluble material (). The xylan and cellulose contents were, respectively, 9 and . Th...
Chapter
Preliminary results show separation of Cel9A and Cel5A cellulases in a diffusion based microfluidic device and they are in agreement with the model that we present. These proteins are difficult to separate with conventional separation techniques.

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