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Conversion Of Glucose To Starch Hydrolysis

Starch And Sugar

Starch And Sugar

As early as the beginning of the 19th century, theGerman chemist Kirchhoff discovered that by boiling starch with acid, itcould be converted into a sweettasting substance which mainly consistedof glucose. Kirchhoff was looking for a replacementfor cane sugar, which could not be supplied to Europe due to a blockadeduring the Napoleonic wars. However, Kirchhoff's product did not providea complete solution to the shortage of sugar, partly because glucose isonly about twothirds as sweet as cane or beet sugar and partly becausethe yield using his technique was not very high. Nevertheless, since then acid has beenused to a great extent for the breakdown of starch into glucose. This techniquedoes, however, have a number of drawbacks: formation of undesirable byproducts,poor flexibility (the endproduct can only be changed by changing thedegree of hydrolysis) and finally, the necessity for equipment capableof withstanding acid used at temperatures of 140-150C. In all theserespects, enzymes are superior to acid. The DE value (dextrose equivalent)is used as an indication of the degree of hydrolysis of a syrup. The DEvalue of starch is zero and that of dextrose is 100. Syrups with DE valuesfrom 35-43 are still widely produced by acid hydrolysis despite the drawbacksmentioned above. However, due to the formation of byproducts, it isdifficult to produce low and highDE syrups of a high quality. In the last 30 years, as new enzymeshave become available, starch hydrolysis technology has been transformed.There has been a big move away from acid and today the vast majority ofstarch hydrolysis is performed using enzymes. Furthermore, in the 1970s, an enzymetechnique made possible the production of a syrup as sweet as sucrose -high fructose syrup. The production of this syrup has significa Continue reading >>

The Use Of Enzymes In Starch Hydrolysis

The Use Of Enzymes In Starch Hydrolysis

Starch is the commonest storage carbohydrate in plants. It is used by the plants themselves, by microbes and by higher organisms so there is a great diversity of enzymes able to catalyse its hydrolysis. Starch from all plant sources occurs in the form of granules which differ markedly in size and physical characteristics from species to species. Chemical differences are less marked. The major difference is the ratio of amylose to amylopectin; e.g. corn starch from waxy maize contains only 2% amylose but that from amylomaize is about 80% amylose. Some starches, for instance from potato, contain covalently bound phosphate in small amounts (0.2% approximately), which has significant effects on the physical properties of the starch but does not interfere with its hydrolysis. Acid hydrolysis of starch has had widespread use in the past. It is now largely replaced by enzymic processes, as it required the use of corrosion resistant materials, gave rise to high colour and saltash content (after neutralisation), needed more energy for heating and was relatively difficult to control. Figure 4.2. The use of enzymes in processing starch.Typical conditions are given. Of the two components of starch, amylopectin presents thegreat challenge to hydrolytic enzyme systems. This is due to the residuesinvolved in a-1,6-glycosidic branch points which constitute about4 - 6% of theglucose present. Most hydrolytic enzymes are specific for a-1,4-glucosidic linksyet the a-1,6-glucosidic links must also be cleaved for complete hydrolysis ofamylopectin to glucose. Some of the most impressive recent exercises in thedevelopment of new enzymes have concerned debranching enzymes. It is necessary to hydrolyse starch in a wide variety ofprocesses which m be condensed into two basic classes: processes i Continue reading >>

Starch Hydrolysis, Polyphenol Contents, And In Vitro Alpha Amylase Inhibitory Properties Of Some Nigerian Foods As Affected By Cooking

Starch Hydrolysis, Polyphenol Contents, And In Vitro Alpha Amylase Inhibitory Properties Of Some Nigerian Foods As Affected By Cooking

Starch Hydrolysis, Polyphenol Contents, and In Vitro Alpha Amylase Inhibitory Properties of Some Nigerian Foods As Affected by Cooking Find articles by Chinedum Ogbonnaya Eleazu 1Federal University Ndufu-Alike, Ikwo, Nigeria Edited by: Emmanouil Apostolidis, Framingham State University, United States Reviewed by: Sui Kiat Chang, International Medical University, Malaysia; Uma Devi Palanisamy, Monash University, Malaysia *Correspondence: Chinedum Ogbonnaya Eleazu, [email protected] Specialty section: This article was submitted to Food Chemistry, a section of the journal Frontiers in Nutrition Received 2017 Sep 22; Accepted 2017 Nov 20. Copyright 2017 Saidu, Eleazu, Ebuka, Ikechukwu, Blessing, Chibuike and Chukwuma. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. The effect of cooking on starch hydrolysis, polyphenol contents, and in vitro -amylase inhibitory properties of mushrooms (two varieties Russula virescens and Auricularia auricula-judae), sweet potato (Ipomea batatas), and potato (Solanum tuberosum) was investigated. The total, resistant, and digestible starch contents of the raw and cooked food samples (FS) ranged from 6.4 to 64.9; 0 to 10.1; and 6.4 to 62.7 g/100 g, respectively, while their percentages of starch digestibility (DS values expressed as percentages of total starch hydrolyzed) ranged from 45.99 to 100. Raw and boiled unpeeled potato, raw and boiled peeled potato, raw A Continue reading >>

Hydrolysis Of Starch With Immobilized Glucoamylase

Hydrolysis Of Starch With Immobilized Glucoamylase

Hydrolysis of starch with immobilized glucoamylase A comparison between two types of expanded-bed reactors Glucoamylase (E.C.3.2.1.3) covalently immobilized onto chitin particles (dst = 0.37 mm) was examined in two types of continuous bench-scale reactors (180 mL) fed with hydrolyzed manioc starch (15%, w/v): a two-phase reactor (liquid expanded-bed) and a threephase reactor (air expanded-bed). Several conditions of continuous operation were investigated, varying the biocatalyst load (16.7, 37.2, and 54 g/L) into the reactor and the hydraulic residence time. The best results were achieved with the two-phase reactor, which operated continuously for 20 d and showed a decrease of only 6% in conversion (starch to glucose). Conversion levels of 96% were obtained with a hydraulic residence time of about 4 h. A simple mathematical model was able to describe the experimental results of the two types of reactors considering biocatalyst deactivation. Immobilized glucoamylasestarch hydrolysisimmobilized-enzyme bioreactorsenzymatic reactors This is a preview of subscription content, log in to check access Linko, Y. Y., Lindress, A., and Linko, P. (1979),Enzyme Microbiol. Technol. 1, 273278. CrossRef Google Scholar Nakhapetyan, L. A. and Menyalilova, I. I. (1980),Enzyme Engineering: Future Directions, Wingard, L. B. Jr., Berezin, I. V., and Klyosov, A. A., eds., Plenum Press, New York and London. Google Scholar Stanley, W. L., Watters, G. G., Kelly, S. H., and Olson, A. C. (1978),Biotechnol. Bioeng. 20, 135140. CrossRef Google Scholar Toldra, F., Jansen, N. B., and Tsao, G. T. (1986),Biotechnol. Lett. 11, 785790. CrossRef Google Scholar Fiedureck, J., Lobarzewski, J., Wojcik, A., and Wolski, T. (1986),Biotechnol. Bioeng. 28, 744750. Google Scholar Lobarazewski, J., Paszczynski, A., Continue reading >>

Dextrose Equivalent - An Overview | Sciencedirect Topics

Dextrose Equivalent - An Overview | Sciencedirect Topics

W.P. Edwards, in Encyclopedia of Food Sciences and Nutrition (Second Edition) , 2003 Sucrose is insufficiently soluble, at ambient temperatures, to lower the water activity sufficiently to give a microbiologically stable solution. A stable product can only be made by mixing the sucrose with other sugars. The ingredient that is most used as a source of nonsucrose sugars is the starch hydrolysate known variously as glucose syrup or corn syrup. Neither name is entirely accurate as the major ingredient is normally maltose rather than dextrose, but the product can be, and is, manufactured from wheat or potato starch as an alternative to maize starch. The degree of hydrolysis is characterized by the dextrose equivalent (DE), which is a measure of the equivalence of the solids in the syrup to dextrose in the Fehlings titration. The type of syrup normally used is referred to as confectioners' glucose and has a DE of around 40. In this work to avoid confusion between glucose syrup and chemical dextrose, glucose will only be used to refer to the syrup, and the pure sugar will be referred to as dextrose. Originally, the starch was hydrolyzed by using acid, which is a random process. Now, hydrolysis can be carried out by enzymes or a mixture of enzymes and acid. Using enzymes, it is possible to control which bonds are broken to allow the composition of the product to be varied as needed. In principle, the starch could be hydrolyzed to produce any combination of dextrose oligomers from dextrose through maltose and maltotriose to higher oligomers. The proportion of glucose syrup used in different types of sugar confectionery varies for a number of reasons. Commercial pressure would encourage the use of a maximum amount of glucose syrup solids, but technical considerations restrict t Continue reading >>

Kinetic And Thermodynamic Characterization Of Glucoamylase From Colletotrichum Sp. Kcp1

Kinetic And Thermodynamic Characterization Of Glucoamylase From Colletotrichum Sp. Kcp1

Kinetic and Thermodynamic Characterization of Glucoamylase from Colletotrichum sp. KCP1 Vimal S. Prajapati , Ujjval B. Trivedi , and Kamlesh C. Patel B R D School of Biosciences, Sardar Patel University, Sardar Patel Maidan, Vadtal Road, Satellite Campus, Post Box No. 39, Vallabh Vidyanagar, 388 120 Gujarat India B R D School of Biosciences, Sardar Patel University, Sardar Patel Maidan, Vadtal Road, Satellite Campus, Post Box No. 39, Vallabh Vidyanagar, 388 120 Gujarat India B R D School of Biosciences, Sardar Patel University, Sardar Patel Maidan, Vadtal Road, Satellite Campus, Post Box No. 39, Vallabh Vidyanagar, 388 120 Gujarat India B R D School of Biosciences, Sardar Patel University, Sardar Patel Maidan, Vadtal Road, Satellite Campus, Post Box No. 39, Vallabh Vidyanagar, 388 120 Gujarat India Kamlesh C. Patel, Phone: +91-2692-231041, Fax: +91-2692-231042, Email: [email protected] . Received 2012 Dec 28; Accepted 2013 Apr 16. Copyright Association of Microbiologists of India 2013 Extracellular glucoamylase of Colletotrichum sp. KCP1 produced through solid state fermentation was purified by two steps purification process comprising ammonium sulphate precipitation followed by gel permeation chromatography (GPC). The Recovery of glucoamylase after GPC was 50.40% with 19.3-fold increase in specific activity. The molecular weight of enzyme was found to be 162.18kDa by native-PAGE and was dimeric protein of two sub-units with molecular weight of 94.62 and 67.60kDa as determined by SDS-PAGE. Activation energy for starch hydrolysis was 26.45kJmol1 while temperature quotient (Q10) was found to be 1.9. The enzyme was found to be stable over wide pH range and thermally stable at 4050C up to 120min while exhibited maximum activity at 50C with pH 5.0. The pKa1 and pKa2 of ioni Continue reading >>

Glucose Syrup - Wikipedia

Glucose Syrup - Wikipedia

Glucose syrup, also known as confectioner's glucose, is a syrup made from the hydrolysis of starch . Glucose is a sugar . Maize (corn) is commonly used as the source of the starch in the US, in which case the syrup is called " corn syrup ", but glucose syrup is also made from potatoes and wheat , and less often from barley , rice and cassava . [1] p.21 [2] Glucose syrup containing over 90% glucose is used in industrial fermentation , [3] but syrups used in confectionery contain varying amounts of glucose , maltose and higher oligosaccharides , depending on the grade, and can typically contain 10% to 43% glucose. [4] Glucose syrup is used in foods to sweeten, soften texture and add volume. By converting some of the glucose in corn syrup into fructose (using an enzymatic process), a sweeter product, high fructose corn syrup can be produced. Depending on the method used to hydrolyse the starch and on the extent to which the hydrolysis reaction has been allowed to proceed, different grades of glucose syrup are produced, which have different characteristics and uses. The syrups are broadly categorised according to their dextrose equivalent (DE). The further the hydrolysis process proceeds, the more reducing sugars are produced, and the higher the DE. Depending on the process used, glucose syrups with different compositions, and hence different technical properties, can have the same DE. The original glucose syrups were manufactured by acid hydrolysis of corn starch at high temperature and pressure. The typical product had a DE of 42, but quality was variable due to the difficulty of controlling the reaction. Higher DE syrups made by acid hydrolysis tend to have a bitter taste and a dark colour, due to the production of hydroxymethylfurfural and other byproducts. [1] p.26 Th Continue reading >>

Pullulanase: Role In Starch Hydrolysis And Potential Industrial Applications

Pullulanase: Role In Starch Hydrolysis And Potential Industrial Applications

Pullulanase: Role in Starch Hydrolysis and Potential Industrial Applications We are experimenting with display styles that make it easier to read articles in PMC. The ePub format uses eBook readers, which have several "ease of reading" features already built in. The ePub format is best viewed in the iBooks reader. You may notice problems with the display of certain parts of an article in other eReaders. Generating an ePub file may take a long time, please be patient. Pullulanase: Role in Starch Hydrolysis and Potential Industrial Applications Siew Ling Hii, Joo Shun Tan, [...], and Arbakariya Bin Ariff The use of pullulanase (EC 3.2.1.41) has recently been the subject of increased applications in starch-based industries especially those aimed for glucose production. Pullulanase, an important debranching enzyme, has been widely utilised to hydrolyse the -1,6 glucosidic linkages in starch, amylopectin, pullulan, and related oligosaccharides, which enables a complete and efficient conversion of the branched polysaccharides into small fermentable sugars during saccharification process. The industrial manufacturing of glucose involves two successive enzymatic steps: liquefaction, carried out after gelatinisation by the action of -amylase; saccharification, which results in further transformation of maltodextrins into glucose. During saccharification process, pullulanase has been used to increase the final glucose concentration with reduced amount of glucoamylase. Therefore, the reversion reaction that involves resynthesis of saccharides from glucose molecules is prevented. To date, five groups of pullulanase enzymes have been reported, that is, (i) pullulanase type I, (ii) amylopullulanase, (iii) neopullulanase, (iv) isopullulanase, and (v) pullulan hydrolase type III. The Continue reading >>

Starch-hydrolysis And Required Enzymes - Rebel Wp7: Bioenergy -rebel Wiki

Starch-hydrolysis And Required Enzymes - Rebel Wp7: Bioenergy -rebel Wiki

Structurally, starch can be separated into two polymers, called amylase and amylopectin. Amylose is a linear polymer of D-glucose units linked together by -1,4-glucosidic linkages, whereas amylopectin has branching at -1,6 positions of starch. The concentration of amylase and amylopectin in each plant varies. Waxy starches from maize contain 2 % amylase and 98 % amylopectin, whereas most starches contain 15-30 % amylase. A starch granule exists in a ring structure of amylase and amylopectin extending from the hilum toward the edge of the granule. Enzymes are biological molecules, that catalyze chemical reactions. Nearly all known enzymes are proteins, that function in very specific temperature and pH ranges. Outside these ranges, the enzyme can be inactivated permanently. For starch hydrolysis, several enzymes (starch hydrolases) are known. They act eigher by cleaving -1,4 and -1,6 glucosidic bonds at random positions, releasing oligosaccharides of different chain lengths, called dextrins or from the nonreducing ends of the starch molecules, successively releasing D-glucose. Smaller chain lengths of starch molexules such as disaccharides and oligosaccharides are also substrates for specific enzymes. Microorganisms are the major source for starch hydrolases, generally called amylases. Amylases are classified according to the specific glucosidic bond they cleave as -1,4-glucanases or -1,6-glucanases. Endoglucanases act on interior bonds of starch while exoglucanases cleave the bonds successively from nonreducing ends of starch. Activities of amylases result in smaller molecules called dextrins, disaccharides, and monosaccharides. Glycosyl transferases are enzymes, that synthesize cyclic molecules from starch. -Amylase (1,4- -D-glucan Glucanohydrolase EC 3.2.1.1) -Amylase Continue reading >>

Mammalian Mucosal -glucosidases Coordinate With -amylase In The Initial Starch Hydrolysis Stage To Have A Role In Starch Digestion Beyond Glucogenesis

Mammalian Mucosal -glucosidases Coordinate With -amylase In The Initial Starch Hydrolysis Stage To Have A Role In Starch Digestion Beyond Glucogenesis

Click through the PLOS taxonomy to find articles in your field. For more information about PLOS Subject Areas, click here . Mammalian Mucosal -Glucosidases Coordinate with -Amylase in the Initial Starch Hydrolysis Stage to Have a Role in Starch Digestion beyond Glucogenesis Affiliations Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, West Lafayette, Indiana, United States of America, Centre for Nutrition and Food Sciences and Australian Research Council Centre of Excellence in Plant Cell Walls, The University of Queensland, Brisbane, Queensland, Australia Affiliation Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, West Lafayette, Indiana, United States of America Affiliation Whistler Center for Carbohydrate Research, Department of Food Science, Purdue University, West Lafayette, Indiana, United States of America Affiliation Centre for Nutrition and Food Sciences and Australian Research Council Centre of Excellence in Plant Cell Walls, The University of Queensland, Brisbane, Queensland, Australia Continue reading >>

Us3922199a - Enzymatic Hydrolysis Of Granular Starch - Google Patents

Us3922199a - Enzymatic Hydrolysis Of Granular Starch - Google Patents

US3922199A - Enzymatic hydrolysis of granular starch - Google Patents US3922199A US43745274A US3922199A US 3922199 A US3922199 A US 3922199A US 43745274 A US43745274 A US 43745274A US 3922199 A US3922199 A US 3922199A Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.) Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.) Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.) C13KSACCHARIDES, OTHER THAN SUCROSE, OBTAINED FROM NATURAL SOURCES OR BY HYDROLYSIS OF NATURALLY OCCURRING DI-, OLIGO- OR POLYSACCHARIDES C08ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON C08BPOLYSACCHARIDES; DERIVATIVES THEREOF C08B30/00Preparation of starch, degraded or non-chemically modified starch, amylose, or amylopectin C08B30/12Degraded, destructured or non-chemically modified starch, e.g. mechanically, enzymatically or by irradiation; Bleaching of starch C12BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING C12PFERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE C12P19/00Preparation of compounds containing saccharide radicals C12P19/14Preparation of compounds containing saccharide radicals produced by the action of a carbohydrase (EC 3.2.x), e.g. by alpha-amylase, e.g. by cellulase, hemicellulase C12B

Maps Enzymes

Maps Enzymes

In the early 19th century, it was discovered that by boiling starch with acid it could be converted into a sweettasting substance, which consisted mainly of glucose. Since then acids have been used widely for breaking down starch into glucose. This technique does have a number of drawbacks. The DE (dextrose equivalent) value is used as an indication of the degree of hydrolysis of syrup. The DE value of starch is zero and that of dextrose is 100. In the last 25 years, as new enzymes are available, starch hydrolysis technology has move away from acids to enzymes. Enzymatic starch conversion, depending on the enzymes used, syrups with different compositions and physical properties of starch. There are three basic steps in enzymatic starch conversion: liquefaction, saccharification and isomerisation. Firstly, there is a liquefaction process. A starch suspension containing 30-40% dry matter is first gelatinised and liquefied. By using heat-stable bacterial alpha amylase, 'maltodextrin' is obtained which contains mainly different oligosaccharides and dextrins. Maltodextrins are only slightly sweet and they usually undergo further conversion. In most starch conversion plants, starch liquefaction takes place in a jet-cooking process. The heat stable alpha amylase is added to the starch slurry after pH adjustment, and the slurry is pumped through a jet cooker. Live steam is injected here to raise the temperature to 105?C, and the slurry is then passed through a series of holding tubes for 5-7 minutes, which is necessary to gelatinise the starch fully. Then the temperature of the partially liquefied starch is reduced to 90-100?C by flashing, and the enzyme is allowed to react further at this temperature for 1-2 hours until the required DE (Dextrose Equivalent) is obtained. Continue reading >>

Raw Starch Conversion By Saccharomyces Cerevisiae Expressing Aspergillus Tubingensis Amylases

Raw Starch Conversion By Saccharomyces Cerevisiae Expressing Aspergillus Tubingensis Amylases

Raw starch conversion by Saccharomyces cerevisiae expressing Aspergillus tubingensis amylases 1Department of Microbiology, Stellenbosch University, Private Bag 1, Stellenbosch, Matieland 7602, South Africa Received 2013 Jun 10; Accepted 2013 Oct 9. Copyright 2013 Viktor et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License ( ), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. This article has been cited by other articles in PMC. Starch is one of the most abundant organic polysaccharides available for the production of bio-ethanol as an alternative transport fuel. Cost-effective utilisation of starch requires consolidated bioprocessing (CBP) where a single microorganism can produce the enzymes required for hydrolysis of starch, and also convert the glucose monomers to ethanol. The Aspergillus tubingensis T8.4 -amylase (amyA) and glucoamylase (glaA) genes were cloned and expressed in the laboratory strain Saccharomyces cerevisiae Y294 and the semi-industrial strain, S. cerevisiae Mnu1. The recombinant AmyA and GlaA displayed protein sizes of 110150kDa and 90kDa, respectively, suggesting significant glycosylation in S. cerevisiae. The Mnu1[AmyA-GlaA] and Y294[AmyA-GlaA] strains were able to utilise 20gl-1 raw corn starch as sole carbohydrate source, with ethanol titers of 9.03 and 6.67gl-1 (0.038 and 0.028gl-1h-1), respectively, after 10days. With a substrate load of 200gl-1 raw corn starch, Mnu1[AmyA-GlaA] yielded 70.07gl-1 ethanol (0.58gl-1h-1) after 120h of fermentation, whereas Y294[AmyA-GlaA] was less efficient at 43.33gl-1 ethanol (0.36gl-1h-1). In a semi-industrial amylolytic S. cerevisiae strain expressing Continue reading >>

Chemical Equation For Conversion Of Starch To Glucose And Glucose To...

Chemical Equation For Conversion Of Starch To Glucose And Glucose To...

Sugar is converted to ethanol, carbon dioxide and yeast/bacterial biomass as well as much smaller quantities of minor end products such as glycerol, fusel oils, aldehydes and ketones (Laopaiboon et al ., 2007; Jacques et al ., 1999). In the distillation section, alcohol from fermented mash is concentrated up to 95% v/v. This is further concentrated to produce ethanol with 99.6% v/v (minimum) concentration. The treatment of vinasse generated in the distillation section can be done using the following option: concentration of part of vinasse to 20 to 25% solids followed by composting using press mud available and concentration of the rest of the vinasse to 55% solids and can be used as liquid fertilizer. The schematic representation of ethanol fermentation from sweet sorghum stalk is given in Figure 2. The ethanol production processing from sweet sorghum grain and bagasse is similar to other starchy crops like corn and cassava (Quintero et al ., 2008). Chemically starch is a polymer of glucose (Peterson, 1995). Yeast cannot use starch directly for ethanol production. Therefore, grain starch has to be completely broken down to glucose by a combination of two enzymes, viz., amylase and amyloglucosidase, before it is fermented by yeast to produce ethanol (Figures 2 and 3). After washing, crushing and milling the sweet sorghum grains, the starch is gelatinized, liquefied and saccharified using -amylase and amyloglucosidase. Fermentation, distillation and dehydration processing of grain sorghum are similar to the sweet sorghum stalk. However, the by-products of grain are not similar to the stalk because DDGS (dried distillers grains with solubles) as a co-product of the ethanol production process from grain is a high nutrient valued feed which is used by the livestock industr Continue reading >>

Enhancing Saccharification Of Cassava Stems By Starch Hydrolysis Prior To Pretreatment

Enhancing Saccharification Of Cassava Stems By Starch Hydrolysis Prior To Pretreatment

Enhancing saccharification of cassava stems by starch hydrolysis prior to pretreatment Author links open overlay panel CarlosMartna Cassava stems are a glucan-rich feedstock with a high starch share (up to 42%). Starch hydrolysis prior to pretreatment improves saccharification of cassava stems. The hydrolysis of starch minimizes sugar degradation in acid pretreatment. The starch hydrolysis leads to a two-fold increase of the overall hydrolyzed glucan. Pretreating cassava stems with [Emim]OAc is more effective than with sulfuric acid. Chemical characterization of cassava stems from different origin revealed that glucans accounted for 5463% of the dry weight, whereas 3567% of these glucans consisted of starch. The cassava stems were subjected to a saccharification study including starch hydrolysis, pretreatment with either sulfuric acid or 1-ethyl-3-methylimidazolium acetate ([Emim]OAc), and enzymatic hydrolysis of cellulose. Starch hydrolysis prior to pretreatment decreased sugar degradation, improved enzymatic convertibility of cellulose, and increased overall glucan conversion. Glucan recovery after pretreatment of starch-free cassava stems (SFCS) was around 85%, but below 52% when the stems were pretreated under the same conditions without preparatory starch hydrolysis. The total amount of hydrolyzed glucan after cellulose hydrolysis was two-fold higher for pretreated SFCS than for directly pretreated stems. Pretreatment with [Emim]OAc resulted in 20% higher glucan conversion than pretreatment with acid. Pyrolysis-GC/MS, X-ray diffraction, CP/MAS 13C NMR and FTIR analyses revealed major differences between H2SO4- and [Emim]OAc-pretreated material. Continue reading >>

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