The document describes the enzymatic synthesis of glucosyl rebaudioside A from rebaudioside A using recombinant dextransucrase from Leuconostoc lactis. Glucosyl rebaudioside A was produced with 86% yield and purified. It showed improved solubility and stability in acidic and thermal conditions compared to rebaudioside A, indicating its potential as a highly pure and stable sweetener. The structure of glucosyl rebaudioside A was characterized through NMR and LC-MS analysis.
Integration of sewage sludge digestion with advanced biofuel synthesiszhenhua82
The document describes integrating anaerobic digestion of sewage sludge with advanced biofuel production. Sewage sludge was treated with anaerobic digestion under two conditions: 1) low pH control and 2) chemical inhibition of methanogens. Both treatments resulted in accumulation of acetic acid. Acetic acid from digestion was then used as a carbon source for a fungus (Mortierella isabellina) and engineered Escherichia coli to produce fatty acids. The engineered E. coli strain had higher fatty acid yield and produced both medium and long chain fatty acids, while the fungus mainly produced long chain fatty acids. The study demonstrated a potential process to combine anaerobic digestion with microbial cultivation to simultaneously treat sewage
This document summarizes a study that investigated an alternative enzymatic method for producing microalgal biodiesel using an immobilized lipase from Bacillus sp.S23. The lipase was immobilized using sodium alginate beads. Various reaction parameters were optimized, including enzyme loading, temperature, water content, molar ratio, reaction time and agitation. Under optimal conditions of 1.5 g immobilized lipase, 1:12 oil to methyl acetate molar ratio, 35 °C, 8% water, 60 h reaction time and 250 rpm agitation, a maximum conversion efficiency of 95.68% was achieved. The immobilized lipase beads maintained high stability and activity even after 10 cycles of repeated use.
Synthesis, Characterization of Modified Guar Gum Copolymers through Graft Cop...ijtsrd
The graft copolymerization of acrylic acid AA initiated by potassium persulfate PPS progresses through free radical initiation mechanism carried out onto purified guar gum backbone and acrylamide AM which has been synthesized by grafting polyacrylamide chains onto carboxymethyl guar gum CMG backbone using conventional redox grafting. The graft copolymers were characterized using FT IR spectroscopy, elemental analysis, thermal analysis, scanning electron microscopy and rheologically. Reverse demulsification performance of the graft copolymers were evaluated using crude oil in water emulsion sample by a modified jar test method. It showed that graft copolymers based on acrylamide were better reverse demulsifiers than those based on acrylic acid. Among acrylamide synthetic graft copolymers CMG g AM CGA1 diluted to about 1 in a dose of 50ppm performed best when compared with the other synthetic graft copolymers of acrylamide with a reverse demulsification efficiency of 64.7 , while the best reverse demulsification efficiency for graft copolymers of acrylic acid GG g AA GGA2 diluted to about 1 in a dose of 50ppm is 59.2 , both products didn’t outperformed the Industrial Reverse Demulsifier IRD . Ayman Abu Reid | Yousif. A. Ragab | Salih. MAA | Imad. E. A. Mahajoub "Synthesis, Characterization of Modified Guar Gum Copolymers through Graft Copolymerization using Acrylamide and Acrylic Acid and its Effect in Treatment of Crude Oil Emulsified Water" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-5 , August 2022, URL: https://www.ijtsrd.com/papers/ijtsrd50661.pdf Paper URL: https://www.ijtsrd.com/chemistry/polymer-chemistry/50661/synthesis-characterization-of-modified-guar-gum-copolymers-through-graft-copolymerization-using-acrylamide-and-acrylic-acid-and-its-effect-in-treatment-of-crude-oil-emulsified-water/ayman-abu-reid
This document describes a study that used a Plackett-Burman experimental design to examine the effects of seven hydrocolloids on the textural properties and glucose dialysis retardation index (GDRI) of meat-based baby foods. Key findings include: 1) locust bean gum and kappa carrageenan increased food matrix force while iota-carrageenan increased pH and decreased acidity; 2) hydrocolloids did not clearly affect GDRI; and 3) locust bean gum showed potential for texture modification with minimal added glucose. The conclusions recommend further study using higher hydrocolloid concentrations and excluding those introducing significant free glucose.
Research Presentation for Moratuwa Engineering Research Conference, 2019B.K.T. Samarasiri
The document summarizes a presentation on developing an enzymatic hydrolysis pre-treatment strategy to improve batch anaerobic digestion of wastewater from desiccated coconut processing plants. It discusses conducting experiments with enzymatic hydrolysis using lipase, initial pH adjustment, and varying inoculum to substrate ratios. The highest initial biogas production rates and biomethane yields were achieved with wastewater pre-treated with lipase and when the initial pH and inoculum to substrate ratio were optimized. While inhibition occurred initially due to lipids, digestion was recovered after 60 days, indicating the inhibition was temporary rather than permanent.
This document describes the synthesis and characterization of a series of anionic liposaccharide derivatives intended to act as absorption enhancers and improve oral bioavailability of drugs. The liposaccharides were designed with a lipophilic lipid side chain and a hydrophilic head containing glucose and glutamic acid. Isothermal titration calorimetry was used to determine the critical aggregation concentrations and thermodynamic profiles of the liposaccharides. Two liposaccharides formed nanoparticles below 100 nm and had critical aggregation concentrations below 0.325 mM, indicating favorable aggregation in aqueous solution driven by entropy.
PREPARATION AND ANALYSIS OF NOVEL HYDROGELS PREPARED FROM THE BLEND OF GUAR G...msejjournal
This research work deals with the preparation of a series of hydrogels using renewable resources, in order
to decrease the adverse impact on the environment, and understand their swelling behavior. Hydrogels
were synthesized using guar gum and chitosan with glutaraldehyde as the cross-linking agent, protonated
with 98% conc. sulphuric acid. Concentration of chitosan was varied as 0, 12.5, 25, 37.5 and 50% (w/w) in
guar gum, while that of glutaraldehyde was varied as 0, 1.5, 3 and 6% (w/w) of the total quantity of guar
gum and chitosan. Prepared hydrogels were characterized for moisture content, equilibrium water
absorbency, re-swelling capacity, swelling ability in acidic (pH = 3) and basic (pH = 11) pH distilled
water, equilibrium saline water absorbency and Fourier transform infrared spectroscopy. It was
determined that moisture content, equilibrium water absorbency and equilibrium saline water absorbency
decreased with increased concentration of chitosan and glutaraldehyde, but they still had water swelling to
be classified as hydrogel. Re-swelling capacity of the hydrogels decreased with increased cycles of reswelling. Prepared hydrogels maintained high water swelling in acidic pH distilled water as compared to
basic pH distilled water. This hydrogels can be utilized as eco-friendly water manageable materials.
Integration of sewage sludge digestion with advanced biofuel synthesiszhenhua82
The document describes integrating anaerobic digestion of sewage sludge with advanced biofuel production. Sewage sludge was treated with anaerobic digestion under two conditions: 1) low pH control and 2) chemical inhibition of methanogens. Both treatments resulted in accumulation of acetic acid. Acetic acid from digestion was then used as a carbon source for a fungus (Mortierella isabellina) and engineered Escherichia coli to produce fatty acids. The engineered E. coli strain had higher fatty acid yield and produced both medium and long chain fatty acids, while the fungus mainly produced long chain fatty acids. The study demonstrated a potential process to combine anaerobic digestion with microbial cultivation to simultaneously treat sewage
This document summarizes a study that investigated an alternative enzymatic method for producing microalgal biodiesel using an immobilized lipase from Bacillus sp.S23. The lipase was immobilized using sodium alginate beads. Various reaction parameters were optimized, including enzyme loading, temperature, water content, molar ratio, reaction time and agitation. Under optimal conditions of 1.5 g immobilized lipase, 1:12 oil to methyl acetate molar ratio, 35 °C, 8% water, 60 h reaction time and 250 rpm agitation, a maximum conversion efficiency of 95.68% was achieved. The immobilized lipase beads maintained high stability and activity even after 10 cycles of repeated use.
Synthesis, Characterization of Modified Guar Gum Copolymers through Graft Cop...ijtsrd
The graft copolymerization of acrylic acid AA initiated by potassium persulfate PPS progresses through free radical initiation mechanism carried out onto purified guar gum backbone and acrylamide AM which has been synthesized by grafting polyacrylamide chains onto carboxymethyl guar gum CMG backbone using conventional redox grafting. The graft copolymers were characterized using FT IR spectroscopy, elemental analysis, thermal analysis, scanning electron microscopy and rheologically. Reverse demulsification performance of the graft copolymers were evaluated using crude oil in water emulsion sample by a modified jar test method. It showed that graft copolymers based on acrylamide were better reverse demulsifiers than those based on acrylic acid. Among acrylamide synthetic graft copolymers CMG g AM CGA1 diluted to about 1 in a dose of 50ppm performed best when compared with the other synthetic graft copolymers of acrylamide with a reverse demulsification efficiency of 64.7 , while the best reverse demulsification efficiency for graft copolymers of acrylic acid GG g AA GGA2 diluted to about 1 in a dose of 50ppm is 59.2 , both products didn’t outperformed the Industrial Reverse Demulsifier IRD . Ayman Abu Reid | Yousif. A. Ragab | Salih. MAA | Imad. E. A. Mahajoub "Synthesis, Characterization of Modified Guar Gum Copolymers through Graft Copolymerization using Acrylamide and Acrylic Acid and its Effect in Treatment of Crude Oil Emulsified Water" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-6 | Issue-5 , August 2022, URL: https://www.ijtsrd.com/papers/ijtsrd50661.pdf Paper URL: https://www.ijtsrd.com/chemistry/polymer-chemistry/50661/synthesis-characterization-of-modified-guar-gum-copolymers-through-graft-copolymerization-using-acrylamide-and-acrylic-acid-and-its-effect-in-treatment-of-crude-oil-emulsified-water/ayman-abu-reid
This document describes a study that used a Plackett-Burman experimental design to examine the effects of seven hydrocolloids on the textural properties and glucose dialysis retardation index (GDRI) of meat-based baby foods. Key findings include: 1) locust bean gum and kappa carrageenan increased food matrix force while iota-carrageenan increased pH and decreased acidity; 2) hydrocolloids did not clearly affect GDRI; and 3) locust bean gum showed potential for texture modification with minimal added glucose. The conclusions recommend further study using higher hydrocolloid concentrations and excluding those introducing significant free glucose.
Research Presentation for Moratuwa Engineering Research Conference, 2019B.K.T. Samarasiri
The document summarizes a presentation on developing an enzymatic hydrolysis pre-treatment strategy to improve batch anaerobic digestion of wastewater from desiccated coconut processing plants. It discusses conducting experiments with enzymatic hydrolysis using lipase, initial pH adjustment, and varying inoculum to substrate ratios. The highest initial biogas production rates and biomethane yields were achieved with wastewater pre-treated with lipase and when the initial pH and inoculum to substrate ratio were optimized. While inhibition occurred initially due to lipids, digestion was recovered after 60 days, indicating the inhibition was temporary rather than permanent.
This document describes the synthesis and characterization of a series of anionic liposaccharide derivatives intended to act as absorption enhancers and improve oral bioavailability of drugs. The liposaccharides were designed with a lipophilic lipid side chain and a hydrophilic head containing glucose and glutamic acid. Isothermal titration calorimetry was used to determine the critical aggregation concentrations and thermodynamic profiles of the liposaccharides. Two liposaccharides formed nanoparticles below 100 nm and had critical aggregation concentrations below 0.325 mM, indicating favorable aggregation in aqueous solution driven by entropy.
PREPARATION AND ANALYSIS OF NOVEL HYDROGELS PREPARED FROM THE BLEND OF GUAR G...msejjournal
This research work deals with the preparation of a series of hydrogels using renewable resources, in order
to decrease the adverse impact on the environment, and understand their swelling behavior. Hydrogels
were synthesized using guar gum and chitosan with glutaraldehyde as the cross-linking agent, protonated
with 98% conc. sulphuric acid. Concentration of chitosan was varied as 0, 12.5, 25, 37.5 and 50% (w/w) in
guar gum, while that of glutaraldehyde was varied as 0, 1.5, 3 and 6% (w/w) of the total quantity of guar
gum and chitosan. Prepared hydrogels were characterized for moisture content, equilibrium water
absorbency, re-swelling capacity, swelling ability in acidic (pH = 3) and basic (pH = 11) pH distilled
water, equilibrium saline water absorbency and Fourier transform infrared spectroscopy. It was
determined that moisture content, equilibrium water absorbency and equilibrium saline water absorbency
decreased with increased concentration of chitosan and glutaraldehyde, but they still had water swelling to
be classified as hydrogel. Re-swelling capacity of the hydrogels decreased with increased cycles of reswelling. Prepared hydrogels maintained high water swelling in acidic pH distilled water as compared to
basic pH distilled water. This hydrogels can be utilized as eco-friendly water manageable materials.
Synthesis of Oxygenated Fuel Additives via Acetylation of Bio-Glycerol over H...crimsonpublisherspps
1) The document discusses the acetylation of glycerol, a byproduct of biodiesel production, using sulfonated montmorillonite K10 catalysts.
2) A series of H2SO4-modified sulfonated montmorillonite K10 catalysts were synthesized and characterized. They were then evaluated for catalyzing the acetylation of glycerol with acetic acid to produce oxygenated fuel additives.
3) The 20% (w/w) SO4/K10 catalyst achieved 99% glycerol conversion and respective yields of 23% for MAG, 59% for DAG, 15% for TAG, and 2% for DGTA. This catalyst also maintained
This document summarizes an experiment to improve the production of glycolic acid (GA) through the bioconversion of ethylene glycol (EG) using Gluconobacter oxydans. The researchers tested three techniques: fed-batch catalysis (FBC), continuous feeding catalysis (CFC), and successive recycled-cell catalysis (SRC). SRC involved recycling the bacterial cells every 48 hours over five cycles, achieving a total GA production of 490.7 g with over 90% yield and average productivity of 2.04 g/L/h, significantly improving upon FBC and CFC. The twin strategies of end-product control and cell recycling successfully demonstrated large-scale bioconversion of EG to GA.
Synthesis of Oxygenated Fuel Additives via Acetylation of Bio-Glycerol over H...DanesBlake
Abstract
Growing global biodiesel production demands valorization of bio-glycerol derived from biodiesel, which is crucial to make biorefinery process economical. Hence, a series of H2SO4 modified sulfonated Montmorillonite K10 catalysts were synthesized, characterized, and evaluated for acetylation of bio- glycerol with acetic acid to produce mono acetin (MAG), di acetin (DAG), tri acetin (TAG), and di-glycerol tri-acetate (DGTA), which are the oxygenated fuel additives and facilitate the economic viability of biodiesel production so the biorefinery. The synthesized catalysts were characterized by a compressive suite of characterization techniques such as powder X-ray diffraction (XRD), low temperature N2 physisorption, temperature-programmed ammonia desorption (TPAD), and Fourier transform infrared (FTIR). The glycerol conversion and product distribution results were found to correlate with the acidity and textural properties of the catalyst. 20% (w/w) SO4/K10 was revealed to be a promising catalyst for glycerol acetylation with 99% glycerol conversion and with respective yield towards MAG, DAG, TGA and DGTA of 23%, 59%, 15%, and 2%. Moreover, 20% (w/w) SO4/K10 catalyst
was found to maintain the stable catalytic activity for three reaction cycles. However, the partial catalyst deactivation was observed after third reaction cycle, partly due to deposition of coke and loss of active sites during the reaction. https://crimsonpublishers.com/pps/fulltext/PPS.000501.php
Transcript Level of Genes Involved in “Rebaudioside A” Biosynthesis Pathway u...Premier Publishers
Stevia rebaudiana Bertoni is a plant which has recently been used widely as a sweetener. This medicinal plant has some components such as diterpenoid glycosides called steviol glycosides [SGs]. Rebaudioside A is a diterpenoid steviol glycoside which is 300 times sweeter than table sugar. This study was done to investigate the effect of GA3 (50 mg/L) on the expression of 14 genes involved in Rebaudioside A biosynthesis pathway in Stevia rebaudiana under in vitro conditions. The expression of DXS remarkably decreased by day 3. Also, probably because of the negative feedback of GA3 on MEP-drived isoprenes, GGDS transcript level reached its lowest amount after GA3 treatment. The abundance of DXR, CMS, CMK, MCS, and CDPS transcripts showed a significant increase at various days after this treatment. A significant drop in the expression levels of KS and UGT85C2 is detected during the first day. However, expression changes of HDR and KD were not remarkable. Results revealed that the level of transcript of UGT74G1 and UGT76G1 up regulated significantly 4 and 2 times higher than control, respectively. However, more research needs to shed more light on the mechanism of GA3 on gene expression of MEP pathway.
This document examines the process parameters for the biotransformation of benzaldehyde to L-phenylacetylcarbinol (L-PAC) using the yeast Torulaspora delbrueckii. The maximum L-PAC yield of 331 mg/100 ml was obtained with 8 hours of reaction at 30°C using 600 mg of benzaldehyde. Growing the yeast in 3% glucose reduced the reaction time to 120 minutes. Addition of 0.6% acetaldehyde increased the L-PAC yield to 450 mg%. Semi-continuous feeding of benzaldehyde and acetaldehyde produced 683 mg L-PAC/100 ml. The cell mass was reusable for biotransformation up to nine times when substrate concentrations were
Optimizing the Conversion of Pretreated Sila Sorghum Stalks to Simple Sugars ...IRJET Journal
This document summarizes research on optimizing the conversion of pretreated Sila sorghum stalks to simple sugars using immobilized enzymes. Key findings include:
- Sila sorghum stalks were dried, milled, pretreated with alkali, and subjected to hydrolysis using immobilized cellulase and cellobiase enzymes.
- Parameters like temperature, pH, and concentration of sodium alginate used to immobilize the enzymes were varied in the experiments.
- Under optimal conditions of 55°C, pH 6.0, and 2.0% sodium alginate concentration, a maximum glucose yield of 71.3% was achieved.
- Mathematical models were developed
Chemical and Physical properties of Cassava Starch-Cm-Chitosan-Acrylic Acid Hydrogel prepared from radiation –induced crosslinking
Gatot Trimulyadi Rekso
Center for Application of Isotopes and Radiation- National Nuclear Energy Agency
Jl. Lebak Bulus Raya No. 49, Jakarta-Selatan, Indonesia
Corresponding author; e-mail; gatot2811@yahoo.com ,
Fax: +62-21-.7513270, HP ; 08129419442
This study developed a process for producing L-lactic acid from potato starch waste using Lactococcus lactis in a novel dialysis sac bioreactor. Fermentation in the bioreactor was compared to shake flask fermentation. The bioreactor allowed for complete starch consumption within 24 hours compared to 48 hours in shake flasks. Maximum lactic acid concentration and productivity in the bioreactor were 1.2-fold and 2.4-fold higher than shake flasks, respectively. L. lactis cells remained viable for 4 cycles in the bioreactor compared to 1 cycle in shake flasks, demonstrating improved recycling of cells.
Effect of different pre-treatment methods on production of reducing sugars fr...Asheesh Padiyar
Bioethanol can be used as a second generation advanced biofuels. Currently it is mainly produced from starch but bioethanol production from starch leads to competition for food, land and price. Therefore, ligno-cellulosic agricultural residues are potentially used for bioethanol production to solve such challenges. The efficiency of the fermentation process mainly depends on the amount of reducing sugars which is further enhanced by selecting an efficient pre-treatment process. In the present work Tamarind seeds have been chosen as the substrate. The yield of bioethanol mainly depends on the yield of reducing sugars which is again dependent on the various pre-treatment methods used. So, the proposed work aims to carry out different pre-treatment methods to identify the best pre-treatment method for enhancing the yield of reducing sugars. The tamarind kernel powder will be extracted from tamarind seeds and the extracted tamarind kernel powder is subjected to various pre-treatment methods like acid pre-treatment, alkaline pre-treatment and steam explosion. The amount of reducing sugars obtained, were then determined by di-nitro salicylic acid method. It was found that acid pre-treatment with 0.3N HCl and 0.3N H2SO4 is the best pre-treatment method among the selected pre-treatment methods.
Recycling is an effective technology for minimization of process cost. Recycling of biocatalyst along with recycling of used oil is a new technique for the preparation of alternative fuel Preparation of alternative fuel through cost minimization is supposed to be the most challenging job in the present academicians and researchers. Biodiesel is one of the most important alternative fuels in the near future and it attracts considerable attention as environment friendly, renewable and non-toxic fuel. In the present research investigation, waste cooking oil (WCO) is utilized as cheap raw materials for this purpose and enzyme recycling technology has been adopted to prepare biodiesel. Recycling of enzyme is a novel technology which can reduce the process cost. In our study, nonspecific enzyme Novozyme 435 (Candida antarctica) is utilized and recycled ten times for the transesterification reaction of WCO and methanol maintaining definite reaction parameters like alcohol to oil molar ratio, reaction temperature, mixing intensity and biocatalyst concentration. The physical properties of WCO methyl ester and diesel fuel have been compared and it shows significant results. So recycling of enzyme for the production of alternative fuel from recycled oil can be utilized to mitigate scarcity of non-renewable fuel in the future world.
The document discusses the production of polyglutamic acid (PGA) by Bacillus subtilis isolates. Key points:
- Sixty-eight B. subtilis isolates were obtained from sugarcane fields, seawater, and marshes water, of which 21 could produce PGA. The highest PGA yields were obtained using isolates SC10 and SW5 in modified media.
- PGA was purified through various steps and identified using tests like ninhydrin, TLC, and spectroscopy. Molecular weights of PGA ranged from 97-131 kDa.
- Hydrogels were formed by treating PGA with gamma rays, alpha rays, beta rays and neutrons, with
PROMOTION AND SUPPRESSION OF THERMAL AGGREGATION OFβ-LACTOGLOBULIN BY ARGININ...cscpconf
Bovine β-lactoglobulin (β-lg), consisting of pronounced β-sheet content, have been chosen as a model protein which on prolonged thermal treatment forms large molecular aggregates similar
to Alzheimer’s type amyloid fibrils. The effects of L-arginine (free base) in thermal aggregation
process of β-lg were monitored at varying concentrations. Concentration dependent opposite
behaviour has been reported here for the first time where 0.2-0.3 M concentration was optimized as an apparent critical concentration above which arginine acts as a suppressor and
at below it behaves as a promoter of aggregation of β-lg. olubility study and SDS-PAGE pattern followed by densitometric analysis shows this fact. Solution behaviour of arginine and
its self assemblyformation were evidenced with the help of circular dichroism (CD) studies. The delocalized pi-pi (п→п) type of interaction is proposed to foster the energy stabilization during the attainment of planarity of the molecules accompanied with the self-clustering of arginine molecules.
This document summarizes a study that investigated the preparation and properties of octenyl succinic anhydride (OSA) modified early indica rice starch. The researchers prepared OSA starch from early indica rice starch through esterification reactions in aqueous slurry systems. They systematically studied factors that affected the esterification, including starch concentration, reaction time, pH, temperature, and amount of OSA. Analysis showed that OSA groups attached to the starch surface and pores formed, but crystallinity was unchanged. The OSA starch had improved viscosity and gelatinization properties. Optimal esterification parameters were identified.
International Journal of Engineering and Science Invention (IJESI)inventionjournals
International Journal of Engineering and Science Invention (IJESI) is an international journal intended for professionals and researchers in all fields of computer science and electronics. IJESI publishes research articles and reviews within the whole field Engineering Science and Technology, new teaching methods, assessment, validation and the impact of new technologies and it will continue to provide information on the latest trends and developments in this ever-expanding subject. The publications of papers are selected through double peer reviewed to ensure originality, relevance, and readability. The articles published in our journal can be accessed online
Effect of extrusion variables on the hydrogen cyanide and haemagglutinin cont...Alexander Decker
This document summarizes a study on the effect of extrusion variables on the hydrogen cyanide and haemagglutinin content of extruded blends of cassava products and African yam bean. High quality cassava flour and African yam bean flour were blended together at different ratios, as well as pregelatinized cassava chips and African yam bean flour. The blends were extruded at different screw speeds and moisture levels. Testing found that extrusion cooking significantly reduced both the hydrogen cyanide and haemagglutinin contents of the extrudates compared to the raw materials. Feed composition had the greatest effect on reducing hydrogen cyanide, while screw speed most influenced haemagglutinin reduction. All extrudate values
Depleting nature of nonrenewable energy sources and continuous environmental tribulations make the mankind to think differently regarding alternative renewable energy sources. In this regard, present research investigation contributes biodiesel from canola oil deodorizer distillate (CODD) using Lipase AY Amano 30 (Candida rugosa) and Novozyme 40013 (Candida antarctica) in the presence of methanol. Initially the neutral glycerides present in CODD were hydrolysed using lipase Amano AY 30 in the presence of water. The hydrolysed CODD was then esterified with methanol using non-specific immobilized enzyme NS 40013 for the production of biodiesel. The characteristics of final product were compared with diesel fuel and it showed good results. This bioprocess technology using biohydrolysis and bioesterification is a novel technology for biodiesel production from cheap raw materials like CODD.
This document summarizes a study on the rheological properties of chemically modified rice starch model solutions. Native rice starches have poor resistance to shear and stability to retrogradation, which can be altered through chemical modifications like acetylation, cross-linking, and dual modification. The study investigated the effects of different combinations of modification reagents on the rheological properties of starches isolated from three rice cultivars. Results showed that acetylation and dual modification increased viscosity while cross-linking decreased viscosity. Modified starches also showed improved flow behavior and consistency compared to native starches. The effect of modification was similar across cultivars but varied most for the cultivar with relatively higher amylose content.
The International Journal of Engineering and Science (The IJES)theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability
This document summarizes research on the conversion of N-acetyl-D-glucosamine (NAG), obtained from fishery waste, into platform chemicals and biochar using an aqueous dehydration process with boric acid and sodium chloride. Key results include obtaining a 90.6% selectivity and 75.4% molar yield of 3-acetamido-5-formylfuran (3A5AF), and a 86.5% selectivity and 69.5% molar yield of 5-hydroxymethylfurfural (5-HMF). Recycling the water phase was shown to increase selectivity and yield over multiple cycles. The biochar produced has potential soil and climate benefits.
This document discusses the optimization of supercritical carbon dioxide extraction (SCE) conditions for extracting c-linolenic acid (GLA) from Spirulina platensis. Response surface methodology (RSM) was used to optimize three extraction parameters: pressure, time, and ethanol concentration. SCE with ethanol as a co-solvent was found to significantly increase GLA yields compared to SCE alone. RSM analysis identified a pressure of 400 bars, extraction time of 1 hour, and minimum ethanol concentration of 13.7 ml per 16 g of biomass as optimal conditions for extracting 102% of the GLA content compared to conventional solvent extraction.
The facial nerve, also known as cranial nerve VII, is one of the 12 cranial nerves originating from the brain. It's a mixed nerve, meaning it contains both sensory and motor fibres, and it plays a crucial role in controlling various facial muscles, as well as conveying sensory information from the taste buds on the anterior two-thirds of the tongue.
As Mumbai's premier kidney transplant and donation center, L H Hiranandani Hospital Powai is not just a medical facility; it's a beacon of hope where cutting-edge science meets compassionate care, transforming lives and redefining the standards of kidney health in India.
Synthesis of Oxygenated Fuel Additives via Acetylation of Bio-Glycerol over H...crimsonpublisherspps
1) The document discusses the acetylation of glycerol, a byproduct of biodiesel production, using sulfonated montmorillonite K10 catalysts.
2) A series of H2SO4-modified sulfonated montmorillonite K10 catalysts were synthesized and characterized. They were then evaluated for catalyzing the acetylation of glycerol with acetic acid to produce oxygenated fuel additives.
3) The 20% (w/w) SO4/K10 catalyst achieved 99% glycerol conversion and respective yields of 23% for MAG, 59% for DAG, 15% for TAG, and 2% for DGTA. This catalyst also maintained
This document summarizes an experiment to improve the production of glycolic acid (GA) through the bioconversion of ethylene glycol (EG) using Gluconobacter oxydans. The researchers tested three techniques: fed-batch catalysis (FBC), continuous feeding catalysis (CFC), and successive recycled-cell catalysis (SRC). SRC involved recycling the bacterial cells every 48 hours over five cycles, achieving a total GA production of 490.7 g with over 90% yield and average productivity of 2.04 g/L/h, significantly improving upon FBC and CFC. The twin strategies of end-product control and cell recycling successfully demonstrated large-scale bioconversion of EG to GA.
Synthesis of Oxygenated Fuel Additives via Acetylation of Bio-Glycerol over H...DanesBlake
Abstract
Growing global biodiesel production demands valorization of bio-glycerol derived from biodiesel, which is crucial to make biorefinery process economical. Hence, a series of H2SO4 modified sulfonated Montmorillonite K10 catalysts were synthesized, characterized, and evaluated for acetylation of bio- glycerol with acetic acid to produce mono acetin (MAG), di acetin (DAG), tri acetin (TAG), and di-glycerol tri-acetate (DGTA), which are the oxygenated fuel additives and facilitate the economic viability of biodiesel production so the biorefinery. The synthesized catalysts were characterized by a compressive suite of characterization techniques such as powder X-ray diffraction (XRD), low temperature N2 physisorption, temperature-programmed ammonia desorption (TPAD), and Fourier transform infrared (FTIR). The glycerol conversion and product distribution results were found to correlate with the acidity and textural properties of the catalyst. 20% (w/w) SO4/K10 was revealed to be a promising catalyst for glycerol acetylation with 99% glycerol conversion and with respective yield towards MAG, DAG, TGA and DGTA of 23%, 59%, 15%, and 2%. Moreover, 20% (w/w) SO4/K10 catalyst
was found to maintain the stable catalytic activity for three reaction cycles. However, the partial catalyst deactivation was observed after third reaction cycle, partly due to deposition of coke and loss of active sites during the reaction. https://crimsonpublishers.com/pps/fulltext/PPS.000501.php
Transcript Level of Genes Involved in “Rebaudioside A” Biosynthesis Pathway u...Premier Publishers
Stevia rebaudiana Bertoni is a plant which has recently been used widely as a sweetener. This medicinal plant has some components such as diterpenoid glycosides called steviol glycosides [SGs]. Rebaudioside A is a diterpenoid steviol glycoside which is 300 times sweeter than table sugar. This study was done to investigate the effect of GA3 (50 mg/L) on the expression of 14 genes involved in Rebaudioside A biosynthesis pathway in Stevia rebaudiana under in vitro conditions. The expression of DXS remarkably decreased by day 3. Also, probably because of the negative feedback of GA3 on MEP-drived isoprenes, GGDS transcript level reached its lowest amount after GA3 treatment. The abundance of DXR, CMS, CMK, MCS, and CDPS transcripts showed a significant increase at various days after this treatment. A significant drop in the expression levels of KS and UGT85C2 is detected during the first day. However, expression changes of HDR and KD were not remarkable. Results revealed that the level of transcript of UGT74G1 and UGT76G1 up regulated significantly 4 and 2 times higher than control, respectively. However, more research needs to shed more light on the mechanism of GA3 on gene expression of MEP pathway.
This document examines the process parameters for the biotransformation of benzaldehyde to L-phenylacetylcarbinol (L-PAC) using the yeast Torulaspora delbrueckii. The maximum L-PAC yield of 331 mg/100 ml was obtained with 8 hours of reaction at 30°C using 600 mg of benzaldehyde. Growing the yeast in 3% glucose reduced the reaction time to 120 minutes. Addition of 0.6% acetaldehyde increased the L-PAC yield to 450 mg%. Semi-continuous feeding of benzaldehyde and acetaldehyde produced 683 mg L-PAC/100 ml. The cell mass was reusable for biotransformation up to nine times when substrate concentrations were
Optimizing the Conversion of Pretreated Sila Sorghum Stalks to Simple Sugars ...IRJET Journal
This document summarizes research on optimizing the conversion of pretreated Sila sorghum stalks to simple sugars using immobilized enzymes. Key findings include:
- Sila sorghum stalks were dried, milled, pretreated with alkali, and subjected to hydrolysis using immobilized cellulase and cellobiase enzymes.
- Parameters like temperature, pH, and concentration of sodium alginate used to immobilize the enzymes were varied in the experiments.
- Under optimal conditions of 55°C, pH 6.0, and 2.0% sodium alginate concentration, a maximum glucose yield of 71.3% was achieved.
- Mathematical models were developed
Chemical and Physical properties of Cassava Starch-Cm-Chitosan-Acrylic Acid Hydrogel prepared from radiation –induced crosslinking
Gatot Trimulyadi Rekso
Center for Application of Isotopes and Radiation- National Nuclear Energy Agency
Jl. Lebak Bulus Raya No. 49, Jakarta-Selatan, Indonesia
Corresponding author; e-mail; gatot2811@yahoo.com ,
Fax: +62-21-.7513270, HP ; 08129419442
This study developed a process for producing L-lactic acid from potato starch waste using Lactococcus lactis in a novel dialysis sac bioreactor. Fermentation in the bioreactor was compared to shake flask fermentation. The bioreactor allowed for complete starch consumption within 24 hours compared to 48 hours in shake flasks. Maximum lactic acid concentration and productivity in the bioreactor were 1.2-fold and 2.4-fold higher than shake flasks, respectively. L. lactis cells remained viable for 4 cycles in the bioreactor compared to 1 cycle in shake flasks, demonstrating improved recycling of cells.
Effect of different pre-treatment methods on production of reducing sugars fr...Asheesh Padiyar
Bioethanol can be used as a second generation advanced biofuels. Currently it is mainly produced from starch but bioethanol production from starch leads to competition for food, land and price. Therefore, ligno-cellulosic agricultural residues are potentially used for bioethanol production to solve such challenges. The efficiency of the fermentation process mainly depends on the amount of reducing sugars which is further enhanced by selecting an efficient pre-treatment process. In the present work Tamarind seeds have been chosen as the substrate. The yield of bioethanol mainly depends on the yield of reducing sugars which is again dependent on the various pre-treatment methods used. So, the proposed work aims to carry out different pre-treatment methods to identify the best pre-treatment method for enhancing the yield of reducing sugars. The tamarind kernel powder will be extracted from tamarind seeds and the extracted tamarind kernel powder is subjected to various pre-treatment methods like acid pre-treatment, alkaline pre-treatment and steam explosion. The amount of reducing sugars obtained, were then determined by di-nitro salicylic acid method. It was found that acid pre-treatment with 0.3N HCl and 0.3N H2SO4 is the best pre-treatment method among the selected pre-treatment methods.
Recycling is an effective technology for minimization of process cost. Recycling of biocatalyst along with recycling of used oil is a new technique for the preparation of alternative fuel Preparation of alternative fuel through cost minimization is supposed to be the most challenging job in the present academicians and researchers. Biodiesel is one of the most important alternative fuels in the near future and it attracts considerable attention as environment friendly, renewable and non-toxic fuel. In the present research investigation, waste cooking oil (WCO) is utilized as cheap raw materials for this purpose and enzyme recycling technology has been adopted to prepare biodiesel. Recycling of enzyme is a novel technology which can reduce the process cost. In our study, nonspecific enzyme Novozyme 435 (Candida antarctica) is utilized and recycled ten times for the transesterification reaction of WCO and methanol maintaining definite reaction parameters like alcohol to oil molar ratio, reaction temperature, mixing intensity and biocatalyst concentration. The physical properties of WCO methyl ester and diesel fuel have been compared and it shows significant results. So recycling of enzyme for the production of alternative fuel from recycled oil can be utilized to mitigate scarcity of non-renewable fuel in the future world.
The document discusses the production of polyglutamic acid (PGA) by Bacillus subtilis isolates. Key points:
- Sixty-eight B. subtilis isolates were obtained from sugarcane fields, seawater, and marshes water, of which 21 could produce PGA. The highest PGA yields were obtained using isolates SC10 and SW5 in modified media.
- PGA was purified through various steps and identified using tests like ninhydrin, TLC, and spectroscopy. Molecular weights of PGA ranged from 97-131 kDa.
- Hydrogels were formed by treating PGA with gamma rays, alpha rays, beta rays and neutrons, with
PROMOTION AND SUPPRESSION OF THERMAL AGGREGATION OFβ-LACTOGLOBULIN BY ARGININ...cscpconf
Bovine β-lactoglobulin (β-lg), consisting of pronounced β-sheet content, have been chosen as a model protein which on prolonged thermal treatment forms large molecular aggregates similar
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behaviour has been reported here for the first time where 0.2-0.3 M concentration was optimized as an apparent critical concentration above which arginine acts as a suppressor and
at below it behaves as a promoter of aggregation of β-lg. olubility study and SDS-PAGE pattern followed by densitometric analysis shows this fact. Solution behaviour of arginine and
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Effect of extrusion variables on the hydrogen cyanide and haemagglutinin cont...Alexander Decker
This document summarizes a study on the effect of extrusion variables on the hydrogen cyanide and haemagglutinin content of extruded blends of cassava products and African yam bean. High quality cassava flour and African yam bean flour were blended together at different ratios, as well as pregelatinized cassava chips and African yam bean flour. The blends were extruded at different screw speeds and moisture levels. Testing found that extrusion cooking significantly reduced both the hydrogen cyanide and haemagglutinin contents of the extrudates compared to the raw materials. Feed composition had the greatest effect on reducing hydrogen cyanide, while screw speed most influenced haemagglutinin reduction. All extrudate values
Depleting nature of nonrenewable energy sources and continuous environmental tribulations make the mankind to think differently regarding alternative renewable energy sources. In this regard, present research investigation contributes biodiesel from canola oil deodorizer distillate (CODD) using Lipase AY Amano 30 (Candida rugosa) and Novozyme 40013 (Candida antarctica) in the presence of methanol. Initially the neutral glycerides present in CODD were hydrolysed using lipase Amano AY 30 in the presence of water. The hydrolysed CODD was then esterified with methanol using non-specific immobilized enzyme NS 40013 for the production of biodiesel. The characteristics of final product were compared with diesel fuel and it showed good results. This bioprocess technology using biohydrolysis and bioesterification is a novel technology for biodiesel production from cheap raw materials like CODD.
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This document summarizes research on the conversion of N-acetyl-D-glucosamine (NAG), obtained from fishery waste, into platform chemicals and biochar using an aqueous dehydration process with boric acid and sodium chloride. Key results include obtaining a 90.6% selectivity and 75.4% molar yield of 3-acetamido-5-formylfuran (3A5AF), and a 86.5% selectivity and 69.5% molar yield of 5-hydroxymethylfurfural (5-HMF). Recycling the water phase was shown to increase selectivity and yield over multiple cycles. The biochar produced has potential soil and climate benefits.
This document discusses the optimization of supercritical carbon dioxide extraction (SCE) conditions for extracting c-linolenic acid (GLA) from Spirulina platensis. Response surface methodology (RSM) was used to optimize three extraction parameters: pressure, time, and ethanol concentration. SCE with ethanol as a co-solvent was found to significantly increase GLA yields compared to SCE alone. RSM analysis identified a pressure of 400 bars, extraction time of 1 hour, and minimum ethanol concentration of 13.7 ml per 16 g of biomass as optimal conditions for extracting 102% of the GLA content compared to conventional solvent extraction.
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G-RebA-2019.pdf
1. Food
Engineering,
Materials
Science,
&
Nanotechnology
Enzymatic Synthesis of Glucosyl Rebaudioside A
and its Characterization as a Sweetener
So-Hyeon Lee, Jin-A Ko, Hae-Soo Kim, Min-Ho Jo, Joong-Su Kim, Doman Kim, Jeong-Yong Cho, Young-Jung Wee,
and Young-Min Kim
Abstract: Rebaudioside A was modified via glucosylation by recombinant dextransucrase of Leuconostoc lactis EG001
in Escherichia coli BL21 (DE3), forming single O-α-D-glucosyl-(1
→6
) rebaudioside A with yield of 86%. O-α-D-
glucosyl-(1
→6
) rebaudioside A was purified using HPLC and Diaion HP-20 and its properties were characterized
for possible use as a food ingredient. Almost 98% of O-α-D-glucosyl-(1
→6
) rebaudioside A was dissolved after
15 days of storage at room temperature, compared to only 11% for rebaudioside A. Compared to rebaudioside A, O-α-
D-glucosyl-(1
→6
) rebaudioside A showed similar or improved acidic or thermal stability in commercial drinks. Thus,
O-α-D-glucosyl-(1
→6
) rebaudioside A could be used as a highly pure and improved sweetener with high stability in
commercial drinks.
Keywords: glucosylation, glucansucrase, Leuconostoc lactis, Rebaudioside A, sweetener
PracticalApplication: The proposed method can be used to generate glucosyl rebaudioside A by enzymatic glucosylation.
Simple glucosyl rebaudioside A exhibited high acid/thermal stability and improved sweetener in commercialized drinks.
This method can be applied to obtain high value-added bioactive compounds by enzymatic modification.
Introduction
Steviol glycosides are plant-derived zero-calorie sweeteners
from Stevia rebaudiana BERTONI (Philippe, De Mey, Anderson
Ajikumar, 2014). Leaf extract of S. rebaudiana BERTONI con-
tains more than 30 steviol glycosides (Chaturvedula et al., 2011;
Wolwer-Rieck, Tomberg Wawrzun, 2010). Stevia leaf extract
also contains various ent-kaurene-type diterpene glycosides; re-
baudioside C–E, dulcoside A, rubusoside, stevioside, and rebau-
dioside A as major components. Steviolbioside and rebaudioside B
are obtained by partial degradation during the extraction and pu-
rification process (Makapugay, Nanayakkara Kinghorn, 1984).
Commercial production of stevioside began in the 1970s. Since
then, stevioside has been mainly used as a cheap sweetener in
seasonings, salted foods, and pickles (Ko et al., 2012). However,
its bitter aftertaste restricts its use for human consumption. It also
limits its application in other food and pharmaceutical products.
Many researchers have tried to modify glucosylation at steviol C-
13 hydroxyl group and/or C-19 carboxylic acid of stevioside to
enhance its sweetness (Chaturvedula Prakash, 2011a, 2011b).
Among major components in Stevia, rebaudioside A is a target
compound, because it has an additional glucose attached to the
JFDS-2019-0492 Submitted 4/5/2019, Accepted 8/24/2019. Authors Lee, Kim,
Jo, Cho, and Kim are with Dept. of Food Science Technology, Chonnam National
Univ., Gwangju 61186, Republic of Korea. Author Ko is with Radiation Breeding
Research Center, Advanced Radiation Technology Inst., Korea Atomic Energy Resea-
rch Inst., Jeongeup, Republic of Korea. Author Kim is with Bio-industrial Pro-
cess Research Center, Korea Research Inst. of Bioscience and Biotechnology, Jeongeup
56212, Republic of Korea. Author Kim is with Research Inst. of Food Industrial-
ization, Inst. of Green Bio Science Technology, Seoul National Univ., Pyeongchang
25354, Korea Author Wee is with Dept. of Food Science and Technology, Yeungnam
Univ., Gyeongsan Gyeongbuk, 38541, Republic of Korea. Direct inquiries to author
Cho, Wee, and Young-Min Kim (E-mail: jyongcho17@jnu.ac.kr; yjwee@ynu.ac.kr;
u9897854@jnu.ac.kr).
Authors So-Hyeon Lee and Jin-A Ko contributed equally to this work.
C-13 hydroxyl position of stevioside, making it sweeter and more
pleasant-tasting than stevioside (Brandle, Starratt Gijzen, 1998).
Some researchers have tried to synthesize rebaudioside A from
stevioside using microbial enzymes such as extracellular enzymes
from Actinomycete Kusakabe Watanabe, Morita, Terahara Mu-
rakami, 1992), alternansucrase from Leuconostoc citreum SK24.002
(Musa, Miao, Zhang Jiang, 2014), dextransucrase from L. cit-
reum (Ko et al., 2012), dextrin-dextranse from Acetobacter capsula-
tus (Yamamoto, Yoshikawa Okada, 1994), β-fructofuranosidase
from Arthrobacter sp. (Ishikawa Kitahata, Ohtani, Ikuhara Tanaka,
1990), cyclomaltodextrin glucanotransferase from Bacillus mega-
terium (CGTase; Darise et al., 1984; Jaitak et al., 2009; Li, Li,
Xiao Xia, 2013), and β-glucosidase from Streptomyces W19-1
(Kusama, Kusakabe, Nakamura, Eda Murakami, 1986). More-
over, it has shown that plant-derived glucosyltransferases such as
UGT76G1 (Wang et al., 2016) can insert and produce rebau-
dioside A from stevioside in Saccharomyces cerevisiae (Olsson et al.,
2016; Li et al., 2016) and Escherichia coli system (Wang et al., 2016).
Production of rebaudioside I, rebaudioside D, and glucosyl rebau-
dioside A from rebaudioside A by enzymatic biotransformation
has also been reported (Gerwig, Te Poele, Dijkhuizen Kamer-
ling, 2017; Te Poele et al., 2018; Chen et al., 2018). Lactobacillus
reuteri 180 glucansucrase can transferred several glucosyl residues
from one moiety to nine moieties into rebaudioside A from sucrose
(Gerwig et al., 2017). Although there have been many biotransfor-
mation trials for stevioside or rebaudioside A, cyclomaltodextrin
glucanotransferase is the most well-known enzyme for stevioside
derivatives and the sole one used in industrial production of enzy-
matically modified stevioside. To elucidate the structure-sweetness
relationship, the stevioside or rebaudioside A derivatives produced
by cyclomaltodextrin glucanotransferase, glucansucrase from L. cit-
reum (Ko et al., 2012), β-fructofuranosidase, or glucansucrase from
Lactobacillus returi by transglucosylation (Te Poele et al., 2018).
However, the structure-sweetness relationship of various steviol
derivatives remains to be elucidated.
C
2019 Institute of Food Technologists R
doi: 10.1111/1750-3841.14821 Vol. 0, Iss. 0, 2019 r Journal of Food Science 1
Further reproduction without permission is prohibited
2. Food
Engineering,
Materials
Science,
Nanotechnology
Production of glucosyl rebaudioside A . . .
Dextransucrase can transfer the α-d-glucosyl moiety from su-
crose onto a hydroxyl group of carbohydrates as well as noncarbo-
hydrates. It has been investigated for the modification of various
bioactive compounds, including salicin (Seo et al., 2004), acarbose
(Yoon Robyt, 2002), gallic acid (Nam et al., 2017), and cate-
chin (Moon et al., 2006). These glycoconjugates are useful for the
manufacture of pharmaceuticals, fine chemicals, and food ingre-
dients under mild reaction conditions in white biotechnology. In
a previous study, we have found that Leuconostoc-derived dextran-
sucrase can transferred a glucosyl moiety to stevioside with high
regio-selectivity, high conversion yield, and improved sweetness
(Ko et al., 2012). We have also optimized the production process
of glucosyl rebaudioside A using a combination of factorial design
and response surface methodology (RSM).
Here, we report enzymatic modification and structural deter-
mination of glucosyl rebaudioside A. We also evaluated its thermal
stability and water solubility after long-term storage. In addition,
we also investigated the stability of glucosyl rebaudioside A in
commercial drinks by analyzing its hydrolysis products. Moreover,
we described parameters required for the maximum production
of glucosyl rebaudioside A by RSM.
Materials and Methods
Compound and enzyme
Rebaudioside A with a purity of ࣙ96% was purchased from
Sigma-Aldrich (St. Louis, MO, USA). It was used as a standard ma-
terial. The recombinant dextransucrase of Leuconostoc lactis EG001
was produced in E. coli BL21 (DE3) and purified by Ni-NTA
affinity chromatography as described previously (Kim et al. 2010).
Enzyme assay
A reaction mixture containing 0.4 M sucrose, 30 mM sodium
acetate buffer (pH 5.2), 13 mM MgCl2, and 0.42 U/mL dex-
transucrase was incubated at 30 °C for 30 min. Free fructose
released from sucrose was measured using fructose assay kit (Ab-
nova, Taoyuan, Taiwan). One unit of enzyme activity was defined
as the enzyme amount required to generate 1 µmol of fructose
per minute at given reaction conditions.
Synthesis and carbohydrate analysis
To glucosylate rebaudioside A, a reaction mixture (1 L) con-
sisting of 80 mM rebaudioside A, 0.4 M sucrose, 30 mM sodium
acetate buffer (pH 5.2), 13 mM MgCl2, and 2.1 U/mL dextransu-
crase was incubated at 30 °C for 6 hr. After enzymatic conversion,
the reaction mixture was placed in a water bath at 90 °C for
10 min to halt enzymatic activity. At designated time intervals,
10-µL aliquots were withdrawn to analyze the reaction products
via high performance liquid chromatography (HPLC). For
quantitative analysis, chromatographic separation was achieved
using a Shimadzu Prominence modular HPLC system (Shimadzu,
Tokyo, Japan) consisting of an LC-20AD liquid chromatograph
with a DGU-20A3R degassing unit. A SIL-20A auto sampler,
a CBM-20A communications bus module, a SPD-20A UV/vis
detector set at 210 nm, a CTO-20A column oven set at 30 °C.
Separation was performed on a ZORBAX 300SB-C18 (5 µm,
4.6 × 150 mm; Agilent Technologies, Palo Alto, CA, USA). Elu-
tion was done by a linear gradient of 100% H2O and 100% acetoni-
trile: starting with 100% H2O and increasing to 100% acetonitrile
for 60 min. The flow rate was 1.0 mL/min and the compounds
were monitored at 210 nm. The calibration curves (N = 6 point)
were constructed using transglucosyl rebaudioside A product
(1 to 50 µM) isolated in this study. Accuracy and reproducibility
was evaluated using the standard spike method. External standards
of the transglucosyl rebaudioside A product were added to enzy-
matic reaction solution and other samples at three concentrations
(N = 3, six replicates). The external calibration curve of the
transglucosyl rebaudioside A product at a concentration range of 1
to 50 µM produced a good linear correlation (Y = 1196770X +
74183, R2
0.999) and its precision was 5.0%. The content of
the transglucosyl rebaudioside A in each sample was determined
in triplicate experiments.
Isolation and structural elucidation of glucosyl
rebaudioside A
Reaction digests were centrifuged at 12,000 rpm for 10 min at
4 °C. Then the supernatant was collected, added to two volumes
of chilled ethanol, and incubated at −80 °C for 50 min to elimi-
nate glucan. After separation by centrifugation (at 12,000 rpm for
10 min at 4 °C) again, the mixture containing target materials was
concentrated under a vacuum using a rotary evaporator (Eyela,
Tokyo, Japan) at 40 °C. The concentrated mixture was then sub-
jected to a two-step separation procedure. After the resultant digest
(4 g/150 mL) was loaded onto a Diaion HP-20 column (2.2 ×
16 cm) washed with water to remove by-products, and then eluted
with ethanol to afford target materials. The target materials were
purified and isolated from ethanol fraction by a semipreparative
ODS-HPLC equipped with YMC-Pack Pro C18 column (5 µm,
20 × 250 mm; YMC Co., Ltd., Kyoto, Japan). Elution was per-
formed by a linear gradient of 100% H2O and 50% acetonitrile:
starting with 100% H2O and increasing to 50% acetonitrile for
60 min. The flow rate was 7.0 mL/min and the compounds were
monitored at 210 nm. The target materials were collected by the
repeated purification of ODS-HPLC and concentrated by vac-
uum rotary evaporation. The production yield (%) of glucosyl
rebaudioside A was calculated as the concentration (mM) of the
purified product to initial rebaudioside A.
LC-MS analysis of isolated compounds was then performed
with a Surveyor HPLC in line with an Agilent 6410B (Ag-
ilent technology, Wilmington, PA, USA). The isolated com-
pounds were separated under the following HPLC conditions:
column, XDB C18 (5 µm, 2.0 × 150 mm) (Agilent); flow rate,
0.23 mL/min. The sample was eluted using a gradient system of
10% water containing 0.1% formic acid to 100% acetonitrile con-
taining 1% formic acid for 20 min. LC-MS mass spectrometer
equipped with an ESI source. To confirm the position of sugar
bound in rebaudioside A, glucosyl rebaudioside A (8 mg) was hy-
drolyzed by the addition of 2 N sodium hydroxide (2 mL) and
heating at 90 °C for 2 hr. After neutralization by 1 N HCl solu-
tion, the reaction mixture was partitioned with water-saturated n-
butanol (3 mL, two times) and the organic layer was concentrated
in vacuo to afford glucosyl rebaudioside A hydrolysate, which was
analyzed by LC-MS analysis. For the structural elucidation of the
glucosylaton products, approximately 20 mg of the isolated glu-
cosyl rebaudioside A was dissolved in 600 µL of pyridine-d5 and
placed into 4.2-mm nuclear magnetic resonance (NMR) tubes.
The NMR spectra were acquired on an INOVA 500 spectrome-
ter (Varian, Palo Alto, CA, USA) operating at 500 MHz for 1
H
and 13
C. Connection between the steviol and glucoses were as-
signed using the 2D-NMR experiments, including nuclear over-
hauser effect spectroscopy (NOESY), homonuclear correlation
spectroscopy (COSY), heteronuclear single quantum coherence
(HSQC), heteronuclear multiple bond correlation (HMBC), and
total correlation spectroscopy (TOCSY).
2 Journal of Food Science r Vol. 0, Iss. 0, 2019
3. Food
Engineering,
Materials
Science,
Nanotechnology
Production of glucosyl rebaudioside A . . .
Retention time (min)
0 10 20 30 40
a
Rebaudioside A
Glucosyl
rebaudioside A
b
c
d
A
Alkaline hydrolys
[M-H]-
B
[M
sis
M+Na]+
Figure 1–Time course of glucosyl rebaudioside A synthesis from rebaudioside A and sucrose with dextransucrase (A) and LC-MS spectrum and structural
elucidation of glucosyl rebaudioside A (B).
a–d: Reaction time of 0, 2, 4, and 6 hr. The reaction mixture consisting of 80 mM rebaudioside A, 0.4 M sucrose, and 2.1 U/mL dextransucrase in
30 mM sodium acetate buffer (pH 5.2) was incubated at 30 °C for 6 hr.
Table 1–1H- and 13C-NMR data of O-α-D-glucosyl-(1→6) rebaudioside A.
Position δH (int., mult., J in Hz) δC Position
δH (int., mult., J in
Hz) δC Position
δH (int., mult., J
in Hz) δC
1a 1.78 (1H, d, 12.0) 41.1 1 6.05 (1H, d, 8.0) 95.8 1 5.57 (1H, d, 7.5) 105.2
1b 0.75 (1H, td, 12.0, 3.5)
2a 2.19 (1H, m) 19.8 2 4.10 74.0 2 4.20 76.7
2b 1.43 (1H, d, 13.5)
3a 2.38 (1H, d, 13.0) 38.6 3 4.11 79.3 3 4.29 78.9
3b 0.99 (1H, td, 12.5, 4.5)
4 - 44.4 4 4.14 71.9 4 4.30 72.3
5 1.03 (1H, br. d, 12.0) 57.6 5 3.98 77.4 5 3.94 78.6
6a 2.43 (1H, m) 22.6 6a 4.49 68.2 6a 4.44 63.0
6b 1.92 (1H, br. d, 12.0) 6b 4.23 6b 4.09
7 1.28 (2H, m) 42.0 1 5.37 (1H, d, 3.5) 100.8 1 5.34 (1H, d, 7.5) 105.1
8 - 43.0 2 4.13 (1H, dd, 8.0, 3.5) 74.3 2 4.07 75.6
9 0.88 (1H, br. d, 6.0) 54.3 3 4.58 (1H, t, 8.0) 75.7 3 4.24 79.0
10 - 40.2 4 4.27 (1H, t, 8.0) 72.2 4 4.19 71.9
11 1.69 (2H, m) 21.0 5 4.26 (1H, m) 79.0 5 4.10 (1H, m) 74.4
12a 2.27 (1H, m) 37.3 6a 4.59 62.7 6a 4.47 63.2
12b 2.01 (1H, m) 6b 4.32 6b 4.39
13 - 86.8 1 5.08 (1H, d, 8.0) 98.6
14a 2.65 (1H, d, 11.0) 44.7 2 4.38 (1H, dd, 8.0, 8.0) 82.0
14b 1.82 (1H, d, 11.0)
15 2.05 (1H, s) 48.0 3 4.21 (1H, dd, 8.0, 8.0) 88.2
16 - 154.6 4 3.88 (1H, dd, 8.0, 8.0) 71.0
17a 5.65 (1H, d, 15.5) 104.9 5 3.78 (1H, m) 77.7
17b 5.00 (1H, d, 15.5)
18 1.32 (3H, s) 15.9 6a 4.46 62.9
6b 4.39
19 - 177.4
20 1.29 (3H, s) 28.6
Long-term storage test at room temperature
Aqueous solutions of 0.04 to 2% (w/v) rebaudioside A and O-α-
D-glucosyl-(1
→6
) rebaudioside A were prepared in volumetric
flasks. These solutions were transferred to 1.5 mL microtubes.
Each tube was stored at 25 °C for up to 1 month. After 0, 7, 17,
and 30 days, aliquots were analyzed by the same HPLC method
described in section of synthesis and carbohydrate analysis.
Stability of glucosyl rebaudioside A at different pH
conditions
Aqueous solutions of rebaudioside A and O-α-D-glucosyl-
(1
→6
) rebaudioside A (0.8 mg/mL) were mixed with each
Robinson-Britton buffer at different pH conditions ranging from
pH 1.4 to pH 10. As a result, the final concentration of glucosyl
rebaudioside A was 0.4 mg/mL. Samples were heated in a dry
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Production of glucosyl rebaudioside A . . .
Im
1
H
N
mportant HMBC correla
H-1
H COSY and /or TC
OESY correlation
ations
COSY correlations
Figure 2–Structure of O-α-D-glucosyl-(1→6) rebaudioside A.
oven at 80 °C for 2 hr. For quantitative analysis, the remaining
undecomposed glucosyl rebaudioside A was measured by the same
HPLC method described in section of synthesis and carbohydrate
analysis.
Heat stability of O-α-D-glucosyl-(1
→6
) rebaudioside A
To confirm that the material was stable at high temperatures, re-
baudioside A and O-α-D-glucosyl-(1
→6
) rebaudioside A were
prepared to a concentration of 0.4 mg/mL and incubated at 40,
60, and 80 °C for up to 2 hr. The degree of stability was confirmed
by HPLC analysis.
Stability of O-α-D-glucosyl-(1
→6
) rebaudioside A in
commercial drinks
Degradation of steviol glycosides was analyzed in two com-
mercial drinks, Coke (Coca Cola Co., Atlanta, GA, USA) and
orange juice (Coca Cola Co.), following published procedures
(Wolwer-Rieck et al. 2010). Briefly, degassed samples were added
to volumetric flasks containing 0.4 mg/mL of rebaudioside A and
O-α-D-glucosyl-(1
→6
) rebaudioside A. Each sealed tube was
stored for up to 48 hr in such a way that air was used as heat
transfer medium at 24 °C, 40 °C, 60 °C, and 80 °C. After 0,
24, and 48 hr, aliquots were removed and analyzed by the same
HPLC method described in section of synthesis and carbohydrate
analysis.
Optimization procedure and experimental design
A three-level Box-Behnken design with three-factors was ap-
plied to produce glucosyl rebaudioside. An optimization procedure
using Design Expert 7.00 software, including six replicates at the
central point, was utilized in the fitting of a second-order response
surface. Dextransucrase (8.4 U/mL) (x1), sucrose (x2), and rebau-
dioside A concentrations (x3) were modified to prepare each of 18
cultivation conditions summarized in Table 3. Optimization was
conducted using a desirability function to determine the effects
of x1, x2, and x3 on glucosyl rebaudioside A production. A total
of 18 experiments composed of 16 factorial points, eight axial
points, and six center points were conducted to determine the 14
coefficients of the model as follows (1):
y = β0 + β1x1 + β2x2 + β3x3 + β12x1x2 + β13x1x3 + β23x2x3
+ β11x1
2
+ β22x2
2
+ β33x3
2
(1)
where y was the predicted response; β0 was the intercept; β1, β2,
and β3 were linear coefficients; β11, β22, and β33 were squared
coefficients; and β12, β13, and β23 were interaction coefficients.
Once an appropriate model was obtained, it was used to determine
the optimum conditions for the process.
Results and Discussion
Enzymatic glucosylation of rebaudioside A
For glucosylation of rebudioside A, sucrose was added to the
reaction mixture (1 L) consisting of 80 mM rebaudioside A,
30 mM sodium acetate buffer (pH 5.2), 13 mM MgCl2, and
2.1 U/mL dextransucrase at 2-hr intervals. The 2-hr interval was
chosen because sucrose would be completely consumed within
2-hr. After stopping the reaction to remove glucans, each reaction
mixture containing rebaudioside A was analyzed by HPLC. HPLC
analysis of the mixture showed that rebaudioside A (retention time
= 23.93 min) was converted into putative transglucosyl product
(retention time = 20.93 min) identified as glucosyl rebaudioside
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Figure 3–Stability of rebaudioside A (A) and glucosyl rebaudioside A (B) in long-term storage, and pH stability (C) of rebaudioside A (•) and O-α-D-
glucosyl-(1→6) rebaudioside A (), and thermal stability of rebaudioside A (D) and O-α-D-glucosyl-(1→6) rebaudioside A (E).
Each sample was dissolved at a concentration of 0.4 mg/mL (•), 1 mg/mL (◦), 5 mg/mL (), 10 mg/mL (), and 20 mg/mL () in an aqueous solution
and incubated at room temperature for 0, 7, 17, and 30 days. Stabilities of these compounds were evaluated at pH 1.4 to pH 10 after incubating at
80 °C for 2 hr. The mount of soluble compound was analyzed by HPLC, and calculated based on the original amount added. Vertical bars represent
standard deviations.
A, showing a high conversion rate of 86.5% (Figure 1A). The
synthesized rebaudioside A were separated from the transglucosyl
product mixture by Diaion HP-20 column chromatography and
semipreparative ODS-HPLC.
Structural elucidation of glucosyl rebaudioside A
The molecular weight (M.W.) of the synthesized rebaudioside A
was determined to be 1,128, as established by its quasi-molecular
ion peak of m/z 1151.50 [M+Na]+
in LC-MS (positive) spectrum
(Figure 1B). The synthesized rebaudioside A was suggested to be
mono-glucosyl rebaudioside A conjugated with one molecule of
glucose to rebaudioside A (M.W. 966.4). The M.W. of the synthe-
sized rebaudioside A hydrolysate (steviol 13-O-triglucoside) after
alkaline hydrolysis was 804, as established by its quashi molecular
ion peak at m/z 803.1 [M-H]−
in LC-MS (negative) spectrum
(Figure 1B), indicating that diglycose esterified to the C-19 of
rebaudioside A was hydrolyzed. Therefore, it was suggested that
one sugar moiety was conjugated to glucose bound to the C-19 of
rebaudioside A (Figure 1B). When the 1
H and 13
C-NMR spectra
of the transglucosyl product were compared to those of rebaudio-
side A, one sugar moiety corresponding to seven proton signals
(δ 4.13, 4.26, 4.27, 4.32, 4.58, 4.59, and 5.37) and six carbon
signals (δ 62.7, 72.2, 74.3, 75.7, 79.0, and 100.8) was additionally
observed (Table 1; Supplementary NMR data S1 and S2). In par-
ticular, the coupling constant (J) of the anomeric proton (δ 5.37)
in the 1
H-NMR spectra was 3.5 Hz and coupling constant (J) of
other protons confirmed by 1
H-1
H COSY, 1D-ROESY, and 1D-
TOCSY experiments (Figure 2 and Supplementary NMR data)
were 8.0 Hz, indicating that the sugar moiety bound to rebaudio-
side A was α-D-glucose. In addition, to confirm the position of
the sugar moiety bound to rebaudioside A, we analyzed the 2D-
NMR of 1
H-1
H COSY, TOCSY, HSQC, and HMBC (Supple-
mentary NMR data). Specifically, the 1
H-1
H COSY and TOCSY
analyses were able to determine proton and carbon signals corre-
sponding to five sugar moieties. The compound was confirmed
as rebaudioside A by the correlations of δ 5.57 (H-1
) → δ 82.0
(C-2
), δ 5.57 (H-1
) → δ 82.0 (C-2
), δ 5.34 (H-1
) → δ
88.2 (C-3
), and δ 6.05 (H-1
) → δ 177.4 (C-19) observed in the
HMBC experiment (Figure 2 and Supplementary NMR data S9).
In particular, the correlation of δ 5.37 (H-1
) → δ 68.2 (C-6
) was
observed, indicating that C-1
of α-D-glucose was etherified with
C-6
of rebaudioside A. This result was additionally confirmed by
the 1D-NOESY experiment that irradiation of H-1
at δ 5.37
enhanced signals of H-6
at δ 4.49 and 4.23 (Figure 2 and Sup-
plementary NMR data S8). Therefore, the transglucosyl product
was determined to be O-α-D-glucosyl-(1
→6
) rebaudioside A.
Stability of O-α-D-glucosyl-(1
→6
) rebaudioside A in an
aqueous solution
From the above mentioned results, dextransucrase hydrolyzes
sucrose to form a glucosyl enzyme intermediate complex and
acts as the effective acceptor molecule in glucosylation at the
19-hydroxyl group of rebaudioside A. The main glucosyl prod-
uct, glucosyl rebaudioside A, was purified and used for the
food additive stability experiments. To observe storage stability in
aqueous solutions, rebaudioside A and O-α-D-glucosyl-(1
→6
)
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Table 2–Stability of rebaudioside A and O-α-D-glucosyl-(1→6)
rebaudioside A in drinks.
Stability in commercial
drinks (%)
Drink
Temperature
(°C)
Time
(hr)
Rebaudioside
A
O-α-D-glucosyl-
(1→6)
rebaudioside A
4 24 100 100
48 100 100
24 24 100 100
48 100 100
Coke (pH
2.49)
40 24 99.8 99.9
48 99.1 99.2
60 24 88.3 91.0
48 78.5 82.2
80 24 25.5 32.6
48 7.2 11.6
4 24 100 100
48 100 100
24 24 100 100
48 100 100
Orange juice
(pH 3.52)
40 24 99.3 99.6
48 98.8 98.3
60 24 91.5 97.0
48 73.5 96.8
80 24 77.7 84.9
48 66.1 74.0
rebaudioside A were incubated at 25 °C for 30 days. As a result,
rebaudioside A showed low stability in 1% to 2% (w/v) aqueous
solution. After adding to 1% and 2% aqueous solutions, rebau-
dioside A showed 46.35% or 74.72% of the initial compounds,
respectively. It precipitated as a white colored product (Figure 3A
and 3B). In contrast, in 2% (w/v) aqueous solution, O-α-D-
glucosyl-(1
→6
) rebaudioside A only showed a tiny amount of
precipitation (0.04% of compound initial compound). These prop-
erties of O-α-D-glucosyl-(1
→6
) rebaudioside A were due to
glucosylation of the glucosyl molecule bound to the 19-carboxyl
group of rebaudioside A. The synthesized O-α-D-glucosyl-
(1
→6
) rebaudioside A could be used as a high-intensity sweet-
ener since it improved water solubility of rebaudioside A that
would be easily precipitated in aqueous solution. Moreover, due
to glucosylation of 19-carboxyl groups of rebaudioside A, O-α-
D-glucosyl-(1
→6
) rebaudioside A may affect water solubility in
aqueous solutions as previously reported for stevioside (Ko et al.,
2012).
pH stability and thermal stability of
O-α-D-glucosyl-(1
→6
) rebaudioside A
Quantitative analysis of the stability at different pH conditions
and high temperature revealed that rebaudioside A was more than
82% stable while glucosyl rebaudioside A was slightly more stable
(86.4%) at different pH conditions (2.0 to 10). At pH 1.4, rebu-
dioside A had a stability of 52.3% of initially added compound,
while O-α-D-glucosyl-(1
→6
) rebaudioside A had a stability of
53.3% of initially added compound, indicating a low stability at
low pH (Figure 3C). This suggests that ester and ether bonded
glucose in steviol were chemically degraded at low pH. Regard-
ing thermal stability, rebaudioside A and glucosyl rebaudioside A
were remarkably stable at temperature of 40 °C to 120 °C, indi-
cating that both compounds were highly stable (about 100%) even
at extreme temperature (Figure 3A and 3B).
Stability of O-α-D-glucosyl-(1
→6
) rebaudioside A in
commercial drinks
Rebaudioside A in aqueous solution was chemically degraded
at high temperature (80 °C) and acidic pH conditions. Based
on this information, we observed the stability of rebaudioside A
and O-α-D-glucosyl-(1
→6
) rebaudioside A in two commercial
drinks (Coke and orange juice) at temperatures ranging from 4 °C
to 80 °C. With increasing temperature, the decomposition of
both materials also increased. Most of thermal-induced steviol
glycosides began degradation at 80 °C. At this temperature after
24 hr, the concentration of the remaining rebaudioside A decreased
by 74.5% in Coke (pH 2.49, Table 2). The highest degradation
(92.8%) was seen in Coke after 2 days at 80 °C. In the orange juice
(approximately, pH 3.52), rebaudioside A and O-α-D-glucosyl-
(1
→6
) rebaudioside A were degraded to 33.9% and 22.3% of
their initial amounts, respectively. O-α-D-Glucosyl-(1
→6
) re-
baudioside A was more stable in both commercial drinks than re-
baudioside A for 24 hr at the designated temperature conditions.
After 48 hr, final degradation rate was 88.4% in Coke and 26% in
orange juice. However, O-α-D-glucosyl-(1
→6
) rebaudioside A
Table 3–Box-Behnken design of three independent variables with actual and predicted responses.
Coded level Actual level Product (mM)
Run x1 x2 x3 Dextransucrase (U/mL) Sucrose (mM) Rebaudioside A (mM) Experimental Predicted
1 −1 −1 0 0.2 50 65 4.97 2.64
2 1 −1 0 2.5 50 65 6.70 5.57
3 −1 1 0 0.2 1,200 65 4.31 5.44
4 1 1 0 2.5 1,200 65 25.23 27.57
5 −1 0 −1 0.2 625 10 3.04 1.62
6 1 0 −1 2.5 625 10 4.93 2.31
7 −1 0 1 0.2 625 120 5.69 8.31
8 1 0 1 2.5 625 120 31.26 32.68
9 0 −1 −1 1.35 50 10 3.55 7.30
10 0 1 −1 1.35 1,200 10 6.70 6.99
11 0 −1 1 1.35 50 120 13.40 13.11
12 0 1 1 1.35 1,200 120 41.99 38.24
13 0 0 0 1.35 625 65 30.81 30.33
14 0 0 0 1.35 625 65 25.73 30.33
15 0 0 0 1.35 625 65 33.34 30.33
16 0 0 0 1.35 625 65 33.38 30.33
17 0 0 0 1.35 625 65 26.12 30.33
18 0 0 0 1.35 625 65 32.57 30.33
6 Journal of Food Science r Vol. 0, Iss. 0, 2019
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Production of glucosyl rebaudioside A . . .
Figure 4–Response surface and contour plots of O-α-D-glucosyl-(1→6) rebaudioside A production.
showed higher stability than rebaudioside A in both drinks. After
acidic saponification of glucosyl esters of steviol glycoside and its
glucosylated derivatives, stevioside, rebaudioside A, or O-α-D-
glucosyl-(1
→6
) rebaudioside A, the resulting glucosyl moiety is
usually modified with an alkali and cannot be isolated in an intact
form (Catharino Santos, 2012).
Optimal synthesis of O-α-D-glucosyl-(1
→6
)
rebaudioside A
RSM was used to investigate the interaction of variables im-
portant to the production the O-α-D-glucosyl-(1
→6
) rebau-
dioside A. Through preliminary observations, three important
factors were found to be able to optimize O-α-D-glucosyl-
(1
→6
) rebaudioside A production: rebaudioside A concentra-
tion (10 to 120 mM), sucrose concentration (50 to 1,200 mM),
and enzyme activity (0.2 to 2.5 U/mL). The Box-Behnken de-
sign for O-α-D-glucosyl-(1
→6
) rebaudioside A production is
shown in Table 3. Based on central points of corresponding con-
tour plots (Figure 4), these three important factors for O-α-D-
glucosyl-(1
→6
) rebaudioside A production (that is, rebaudio-
side A, sucrose concentration, and dextransucrase activity) had
optimal values of 2.24 U/mL, 1170.75 mM, and 119.4 mM, re-
spectively. O-α-D-Glucosyl-(1
→6
) rebaudioside A production
was measured to be 43.67 mM under the obtained conditions.
Its production can be expressed with the following regression
equation:
y = 30.33 + 6.26x1 + 6.20x2 + 9.27x3 + 4.80x1x2 + 5.92x1x3
+ 6.36x2x3 − 12.60x2
1 − 7.42x2
2 − 6.49x2
3
where x1, x2, and x3 were values of dextransucrase activity
(U/mL), sucrose concentration (mM), and rebaudioside A con-
centration (mM), respectively. The regression equation yielded a
high R2
value (0.9614) using analysis of variance (ANOVA). This
was an estimate of the fraction of three variations in the data
obtained based on the model. This model was capable of explain-
ing 96% of the variation in the response. The predicted response
for O-α-D-glucosyl-(1
→6
) rebaudioside A production was
43.67 mM, and the real observed experimental production was
39.94 ± 0.48 mM, demonstrating almost identical results between
the predicted and real observed O-α-D-glucosyl-(1
→6
) rebau-
dioside A production.
Conclusions
The glucosylation of rebaudioside A by dextransucrase has
many advantages. First, dextransucrase showed the highest
conversion yield (approximately 86%) of rebaudioside A compared
to another enzymatic synthesis (55% yield, Gerwig et al., 2017).
Second, compared to other applied glucosyl transferases (Gerwig
et al., 2017), dextransucrase yielded a single product with differ-
ent regio-selective glucosyl derivative at the 19-carboxyl group
of rebaudioside A. Third, the transglucosylation product showed
a lower precipitation than rebaudioside A in aqueous solutions
after 15 days of incubation at room temperature. Finally, O-α-
D-glucosyl-(1
→6
) rebaudioside A showed higher stability in
two commercial drinks, Coke and orange juice, than rebaudio-
side A. Thus, O-α-D-glucosyl-(1
→6
) rebaudioside A, a new
steviol glucoside synthesized in this study, could be used as a novel
sweetener. Further studies on the synthesis of various rebaudio-
side A derivatives by glucosyltransferase are ongoing to reveal the
relationship between structure and sweetness.
Acknowledgments
This research was supported by a grant (NRF-
2019R1F1A1058385) of the Basic Science Research Program
through the National Research Foundation of Korea (NRF).
It was also supported by “Cooperative Research Program for
Agriculture Science and Technology Development (Project No.
PJ01256503)” funded by Rural Development Administration,
Republic of Korea.
Author Contributions
YM, JY, and YJ conceived and designed this study. SY, JA, HS,
and MH performed experiments and analyzed data. YM, YJ, and
JY wrote the paper. JA and JS reviewed and edited the manuscript.
All authors read and approved the manuscript.
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Supporting Information
Additional supporting information may be found online in the
Supporting Information section at the end of the article.
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