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1.
Int J Biol Macromol ; 279(Pt 2): 135293, 2024 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-39233160

RESUMEN

Castor stalk from hemp plants is an attractive lignocellulosic feedstock for biomass refining valorization due to its similar chemical composition to hardwoods. In this study, the castor stalk fibers were pretreated with efficient dual-functional ethanolamine to achieve delignification and swelling of the cellulosic fibers, followed by cellulase enzymatic digestion for biomass conversion. Experimental results showed that ethanolamine pretreatment at 160 °C for 1 h effectively removed 69.20 % of lignin and 43.18 % of hemicellulose. In addition to efficient delignification and removal of hemicellulose, the study also revealed that supramolecular structure of cellulose was another major factor affecting enzymatic hydrolysis performance. The lowered crystallinity (60-70 %) and swelled crystal sizes (2.95-3.04 nm) promoted enzymatic hydrolysis efficiency during the heterogeneous reaction process. Under optimal conditions (160 °C, 1 h; enzyme loading: 15 FPU/g substrate), promoted yields of 100 % glucose and over 90 % xylose were achieved, which were significantly higher than those obtained from untreated castor stalk. These findings highlighted the effectiveness of the dual-functional ethanolamine pretreatment strategy for efficient bioconversion of lignocellulosic feedstocks. Overall, this study provides valuable insights into the development of new strategies for the efficient utilization of biomass resources, which is essential for the sustainable development of our society.


Asunto(s)
Celulasa , Etanolamina , Lignina , Hidrólisis , Lignina/química , Lignina/metabolismo , Etanolamina/química , Etanolamina/metabolismo , Celulasa/metabolismo , Celulasa/química , Biomasa , Ricinus communis/química , Ricinus communis/enzimología , Celulosa/química , Celulosa/metabolismo , Xilosa/química , Xilosa/metabolismo , Polisacáridos/química , Polisacáridos/metabolismo
2.
FEBS J ; 291(19): 4222-4239, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-39185686

RESUMEN

Bacillus circulans xylanase (BcX) from the glycoside hydrolase family 11 degrades xylan through a retaining, double-displacement mechanism. The enzyme is thought to hydrolyze glycosidic bonds in a processive manner and has a large, active site cleft, with six subsites allowing the binding of six xylose units. Such an active site architecture suggests that oligomeric xylose substrates can bind in multiple ways. In the crystal structure of the catalytically inactive variant BcX E78Q, the substrate xylotriose is observed in the active site, as well as bound to the known secondary binding site and a third site on the protein surface. Nuclear magnetic resonance (NMR) titrations with xylose oligomers of different lengths yield nonlinear chemical shift trajectories for active site nuclei resonances, indicative of multiple binding orientations for these substrates for which binding and dissociation are in fast exchange on the NMR timescale, exchanging on the micro- to millisecond timescale. Active site binding can be modeled with a 2 : 1 model with dissociation constants in the low and high millimolar range. Extensive mutagenesis of active site residues indicates that tight binding occurs in the glycon binding site and is stabilized by Trp9 and the thumb region. Mutations F125A and W71A lead to large structural rearrangements. Binding at the glycon site is sensed throughout the active site, whereas the weak binding mostly affects the aglycon site. The interactions with the two active site locations are largely independent of each other and of binding at the secondary binding site.


Asunto(s)
Dominio Catalítico , Especificidad por Sustrato , Cristalografía por Rayos X , Modelos Moleculares , Bacillus/enzimología , Bacillus/genética , Sitios de Unión , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Unión Proteica , Endo-1,4-beta Xilanasas/química , Endo-1,4-beta Xilanasas/genética , Endo-1,4-beta Xilanasas/metabolismo , Glicósido Hidrolasas/metabolismo , Glicósido Hidrolasas/química , Glicósido Hidrolasas/genética , Xilosa/metabolismo , Xilosa/química , Cinética
3.
Int J Biol Macromol ; 277(Pt 3): 134176, 2024 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-39096834

RESUMEN

Exploring efficient and comprehensive utilization of agricultural waste to produce high value-added products has been global research hotspot. In this study, a novel process for integrated production of xylose and docosahexaenoic acid (DHA) from hemicellulose and cellulose in corncob was developed. Corncob was treated with dilute H2SO4 at 121 °C for 1 h and xylose was readily produced with a recovery yield of 79.35 %. The corncob residue was then subject to alkali pretreatment under optimized conditions of 0.1 g NaOH/g dry solid, 60 °C for 2 h, and the contents of cellulose, hemicellulose, and lignin in the resulting residue were 87.49 %, 7.58 % and 2.31 %, respectively. The cellulose in the residue was easily hydrolyzed by cellulase, yielding 74.87 g/L glucose with hydrolysis efficiency of 77.02 %. Remarkably, the corncob residue hydrolysate supported cell growth and DHA production in Schizochytrium sp. ATCC 20888 well, and the maximum biomass of 32.71 g/L and DHA yield of 4.63 g/L were obtained, with DHA percentage in total fatty acids of 36.89 %. This study demonstrates that the corncob residue generated during xylose production, rich in cellulose, can be effectively utilized for DHA production by Schizochytrium sp., offering a cost-effective and sustainable alternative to pure glucose.


Asunto(s)
Celulosa , Ácidos Docosahexaenoicos , Polisacáridos , Xilosa , Zea mays , Xilosa/química , Celulosa/química , Zea mays/química , Ácidos Docosahexaenoicos/química , Polisacáridos/química , Polisacáridos/biosíntesis , Hidrólisis , Biomasa , Fermentación
4.
J Agric Food Chem ; 72(33): 18630-18637, 2024 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-39116173

RESUMEN

The formation pathway and mechanism of various pyrazines were investigated during the thermal treatment of the alanine-xylose Amadori compound (Ala-ARP) and exogenous alanine (Ala). 15N-labeled Ala was used to coheated with Ala-ARP to clarify the nitrogen sources and the respective contributions of exogenous Ala and the regenerated Ala released from Ala-ARP to different pyrazine formation. It was found that exogenous Ala exhibited a priority in capturing glyoxal (GO) to form pyrazine during the thermal degradation of ARP. Compared to the Ala-methylglyoxal (MGO) model, a lower activation energy was required for the Ala-GO reaction, where the reaction dynamics of Ala-GO followed a zero-order model. In addition to forming pyrazine, the interaction between existing exogenous Ala and GO would accelerate the thermal degradation of Ala-ARP and retro-aldolization reaction of deoxyxylosones (DXs) to α-dicarbonyls. During this process, the release of regenerated Ala and MGO was promoted. Accordingly, as GO was expended by exogenous Ala during the initial stage of ARP-Ala degradation, the condensation between regenerated Ala and MGO became intensified, leading to the generation of methylpyrazine and 2,5-dimethylpyrazine. As a result, in the thermally treated mixture of Ala-ARP and exogenous Ala, 55% of the formed pyrazine originated from exogenous Ala, while 63% of the formed methylpyrazine and 57% of the formed 2,5-dimethylpyrazine were derived from regenerated Ala (120 °C, 30 min).


Asunto(s)
Alanina , Calor , Pirazinas , Pirazinas/química , Alanina/química , Alanina/análogos & derivados , Marcaje Isotópico , Nitrógeno/química , Xilosa/química , Reacción de Maillard , Cinética
5.
Carbohydr Polym ; 342: 122414, 2024 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-39048204

RESUMEN

This study aims to understand the molecular and supramolecular transformations of wheat endosperm biopolymers during bread-making, and their implications to fabricate self-standing films from stale white bread. A reduction in the Mw of amylopectin (51.8 × 106 vs 425.1 × 106 g/mol) and water extractable arabinoxylans WEAX (1.79 × 105 vs 7.63 × 105 g/mol), and a decrease in amylose length (245 vs 748 glucose units) was observed after bread-baking. The chain length distribution of amylopectin and the arabinose-to-xylose (A/X) ratio of WEAX remained unaffected during bread-making, suggesting that heat- or/and shear-induced chain scission is the mechanism responsible for molecular fragmentation. Bread-making also resulted in more insoluble cell wall residue, featured by water unextractable arabinoxylan of lower A/X and Mw, along with the formation of a gluten network. Flexible and transparent films with good light-blocking performance (<30 % transmittance) and DPPH-radical scavenging capacity (~8.5 %) were successfully developed from bread and flour. Bread films exhibited lower hygroscopicity, tensile strength (2.7 vs 8.5 MPa) and elastic modulus (67 vs 501 MPa) than flour films, while having a 6-fold higher elongation at break (10.0 vs 61.2 %). This study provides insights into the changes in wheat biopolymers during bread-making and sets a precedent for using stale bread as composite polymeric materials.


Asunto(s)
Amilopectina , Pan , Harina , Triticum , Xilanos , Triticum/química , Pan/análisis , Harina/análisis , Biopolímeros/química , Xilanos/química , Amilopectina/química , Resistencia a la Tracción , Arabinosa/química , Xilosa/química , Glútenes/química
6.
Carbohydr Polym ; 342: 122399, 2024 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-39048235

RESUMEN

This work demonstrates that sesame (Sesamum indicum L.) hull, an unexploited food industrial waste, can be used as an efficient source for the extraction of hemicellulose and/or pectin polysaccharides to further obtain functional oligosaccharides. Different polysaccharides extraction methods were surveyed including alkaline and several enzymatic treatments. Based on the enzymatic release of xylose, arabinose, glucose, and galacturonic acid from sesame hull by using different enzymes, Celluclast®1.5 L, Pectinex®Ultra SP-L, and a combination of them were selected for the enzymatic extraction of polysaccharides at 50 °C, pH 5 up to 24 h. Once the polysaccharides were extracted, Ultraflo®L was selected to produce arabinoxylo-oligosaccharides (AXOS) at 40 °C up to 24 h. Apart from oligosaccharides production from extracted polysaccharides, alternative approaches for obtaining oligosaccharides were also explored. These were based on the analysis of the supernatants resulting from the polysaccharide extraction, alongside a sequential hydrolysis performed with Celluclast®1.5 L and Ultraflo®L of the starting raw sesame hull. The different fractions obtained were comprehensively characterized by determining low molecular weight carbohydrates and monomeric compositions, average Mw and dispersity, and oligosaccharide structure by MALDI-TOF-MS. The results indicated that sesame hull can be a useful source for polysaccharides extraction (pectin and hemicellulose) and derived oligosaccharides, especially AXOS.


Asunto(s)
Oligosacáridos , Sesamum , Sesamum/química , Oligosacáridos/química , Hidrólisis , Polisacáridos/química , Xilanos/química , Xilanos/aislamiento & purificación , Pectinas/química , Pectinas/aislamiento & purificación , Residuos Industriales , Arabinosa/química , Xilosa/química
7.
J Agric Food Chem ; 72(28): 16010-16017, 2024 Jul 17.
Artículo en Inglés | MEDLINE | ID: mdl-38965162

RESUMEN

Maillard reaction products (MRPs) of xylose with phenylalanine and xylose with proline exhibit high antibacterial activity. However, the active antibacterial compounds in MRPs have not yet been identified or isolated. This study aimed to isolate the active compounds in the two antibacterial MRPs. The organic layer of the MRP solution was separated and purified using silica gel chromatography and high-performance liquid chromatography. The chemical structures of the isolated compounds were determined by mass spectrometry and nuclear magnetic resonance spectroscopy. The compounds inhibited the growth of Bacillus cereus and Salmonella Typhimurium at 25 °C for 7 days at a concentration of 0.25 mM. Furthermore, the isolated compounds inhibited the growth of naturally occurring microflora of lettuce and chicken thighs at 25 °C for 2 days at a concentration of 0.5-1.0 mM. The antibacterial compounds found in MRPs demonstrated a wide range of effectiveness and indicated their potential as alternative preservatives.


Asunto(s)
Antibacterianos , Pollos , Reacción de Maillard , Fenilalanina , Prolina , Salmonella typhimurium , Xilosa , Antibacterianos/farmacología , Antibacterianos/química , Prolina/química , Fenilalanina/química , Xilosa/química , Salmonella typhimurium/efectos de los fármacos , Animales , Bacillus cereus/efectos de los fármacos , Bacillus cereus/crecimiento & desarrollo , Cromatografía Líquida de Alta Presión
8.
J Agric Food Chem ; 72(30): 16930-16940, 2024 Jul 31.
Artículo en Inglés | MEDLINE | ID: mdl-39038222

RESUMEN

Lysine (Lys) is capable of forming a di-substituted Amadori rearrangement product (ARP) with xylose (Xyl), designated as diXyl-α,ε-Lys-ARP. DiXyl-α,ε-Lys-ARP degradation was characterized by two steps: Initially, Xyl-α- and Xyl-ε-Lys-ARP were formed through elimination or hydrolysis at specific Nα/Nε positions of the corresponding enol and imine intermediates, which were then further degraded to dicarbonyl compounds and regenerated Lys. Xyl-α- or Xyl-ε-Lys-ARP had a reactive free amino group (ε-NH2 or α-NH2), both of which were still highly reactive and able to undergo further reactions with Xyl. Therefore, the diXyl-α,ε-Lys-ARP/Xyl model system was established to explore the impact of extra-added Xyl on diXyl-α,ε-Lys-ARP degradation behavior. Extra-added Xyl remarkably affected the degradation pathway of diXyl-α,ε-Lys-ARP by capturing the Xyl-α- and Xyl-ε-Lys-ARP to regenerate diXyl-α,ε-Lys-ARP. This interaction between Xyl and mono-substituted Lys-ARPs promoted the shift of chemical equilibrium toward the degradation of diXyl-α,ε-Lys-ARP, thereby accelerating its degradation rate. This degradation was markedly facilitated by the elevated temperature and pH values. Interestingly, the yield of Xyl-α- and Xyl-ε-Lys-ARP was particularly dependent on the pH during diXyl-α,ε-Lys-ARP degradation. Xyl-ε-Lys-ARP was the dominant product at pH 5.5-7.5 while Xyl-α-Lys-ARP possessed a relatively higher content under weak alkaline conditions, which was related to the reactivities of the Nα/Nε positions under various reaction conditions.


Asunto(s)
Lisina , Reacción de Maillard , Xilosa , Xilosa/química , Lisina/química , Hidrólisis , Cinética , Calor
9.
Int J Biol Macromol ; 276(Pt 1): 133739, 2024 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-39002907

RESUMEN

Xylose plants (produce xylose from corncob through dilute acid treatment) generate a large amount of corncob residue (CCR), most of which are burned and lacked of valorization. Herein, to address this issue, CCR was directly used as starting material for high-solid loading enzymatic hydrolysis via a simple strategy by combining PFI homogenization (for sufficient mixing) with batch-feeding. A maximum glucose concentration of 187.1 g/L was achieved after the saccharification with a solid loading of 25 wt% and enzyme dosage of 10 FPU/g-CCR. Furthermore, the residue of enzymatic hydrolysis (REH) was directly used as a bio-adhesive for plywood production with both high dry (1.7 MPa) and wet (1.1 MPa) surface bonding strength (higher than the standard (0.7 MPa)), and the excellent adhesion was due to the interfacial crosslinking between the REH adhesive (containing lignin, free glucose, and nanosized fibers) and cell wall of woods. Compared with traditional reported adhesives, the REH bio-adhesive has advantages of formaldehyde-free, good moisture resistance, green process, relatively low cost and easy realization. This study presents a simple and effective strategy for better utilization of CCR, which also provides beneficial reference for the valorization of other kinds of lignocellulosic biomass.


Asunto(s)
Adhesivos , Fermentación , Lignina , Zea mays , Lignina/química , Hidrólisis , Zea mays/química , Adhesivos/química , Glucosa/metabolismo , Glucosa/química , Xilosa/química , Madera/química , Azúcares/química , Azúcares/metabolismo
10.
Bioresour Technol ; 406: 131030, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38917911

RESUMEN

This study investigates the efficacy of pyrite in enhancing biohydrogen production from xylose at low temperature (20 °C). Higher hydrogen yield rates (Rm) and reduced lag time (λ) were achieved across initial xylose concentrations ranging from 2-10 g/L. At an optimal xylose concentration of 5 g/L, pyrite reduced λ by 2.5 h and increased Rm from 1.3 to 2.7 mL h-1. These improvements are attributed to pyrite's ability to enhance the secretion of extracellular polymeric substance and flavins, facilitate NADH and NAD+ generation and transition, and favor biohydrogen production. Thermodynamic analyses and Gibbs free energy calculations further elucidated pyrite's role in the full reaction process and rate-limiting steps at low temperature. This study offers valuable insights into improving the efficiency of biohydrogen production at low temperature, with significant implications for energy conservation.


Asunto(s)
Hidrógeno , Sulfuros , Termodinámica , Xilosa , Hidrógeno/metabolismo , Xilosa/química , Sulfuros/química , Hierro/química , Frío , NAD/metabolismo , Temperatura
11.
Chemosphere ; 362: 142660, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38901700

RESUMEN

This study proposed a two-stage pressurized microwave hydrothermal treatment with a catalyst, followed by enzymatic saccharification, as a pretreatment method for efficiently converting cellulose and hemicellulose from rice straw into glucose and xylose. The use of various inorganic salts and dilute sulfuric acid as catalysts enhances sugar production. Using 1 wt% sulfuric acid as a catalyst at 150 °C for 5 min for the first-stage and then 180 °C for 5 min for the second-stage yielded the highest sugar production from rice straw compared with other inorganic salts tested. The filtrate and enzymatic saccharification solution contained a total sugar of 0.434 g/g-untreated rice straw (i.e. 0.302 g-glucose/g-untreated rice straw and 0.132 g-xylose/g-untreated rice straw). When inorganic salts such as NaCl, MgCl2, CaCl2, and FeCl3 were used as catalysts, the highest sugar yield of 0.414 g/g-untreated rice straw (i.e. 0.310 g-glucose/g-untreated rice straw and 0.104 g-xylose/g-untreated rice straw) was obtained when using 1 wt% FeCl3 at 170 °C for 5 min in the first-stage and 190 °C for 5 min in the second-stage, with a value close to that of 1 wt% sulfuric acid. These findings suggest that two-stage treatment with a catalyst is a suitable pretreatment method for the production of glucose and xylose from rice straw owing to the different hydrolysis temperatures of cellulose and hemicellulose.


Asunto(s)
Microondas , Monosacáridos , Oryza , Sales (Química) , Oryza/química , Monosacáridos/química , Sales (Química)/química , Xilosa/química , Celulosa/química , Glucosa/química , Ácidos Sulfúricos/química , Polisacáridos/química , Catálisis
12.
Nature ; 630(8016): 381-386, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38811733

RESUMEN

Lignocellulose is mainly composed of hydrophobic lignin and hydrophilic polysaccharide polymers, contributing to an indispensable carbon resource for green biorefineries1,2. When chemically treated, lignin is compromised owing to detrimental intra- and intermolecular crosslinking that hampers downstream process3,4. The current valorization paradigms aim to avoid the formation of new C-C bonds, referred to as condensation, by blocking or stabilizing the vulnerable moieties of lignin5-7. Although there have been efforts to enhance biomass utilization through the incorporation of phenolic additives8,9, exploiting lignin's proclivity towards condensation remains unproven for valorizing both lignin and carbohydrates to high-value products. Here we leverage the proclivity by directing the C-C bond formation in a catalytic arylation pathway using lignin-derived phenols with high nucleophilicity. The selectively condensed lignin, isolated in near-quantitative yields while preserving its prominent cleavable ß-ether units, can be unlocked in a tandem catalytic process involving aryl migration and transfer hydrogenation. Lignin in wood is thereby converted to benign bisphenols (34-48 wt%) that represent performance-advantaged replacements for their fossil-based counterparts. Delignified pulp from cellulose and xylose from xylan are co-produced for textile fibres and renewable chemicals. This condensation-driven strategy represents a key advancement complementary to other promising monophenol-oriented approaches targeting valuable platform chemicals and materials, thereby contributing to holistic biomass valorization.


Asunto(s)
Compuestos de Bencidrilo , Biomasa , Fraccionamiento Químico , Lignina , Fenoles , Compuestos de Bencidrilo/química , Compuestos de Bencidrilo/metabolismo , Catálisis , Celulosa/química , Celulosa/metabolismo , Fraccionamiento Químico/métodos , Hidrogenación , Lignina/química , Lignina/metabolismo , Fenoles/química , Fenoles/metabolismo , Madera/química , Xilanos/química , Xilanos/metabolismo , Xilosa/química , Xilosa/metabolismo , Combustibles Fósiles , Textiles
13.
Carbohydr Res ; 540: 109145, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38759341

RESUMEN

The cell wall of endophytic strain Rathayibacter oskolensis VKM Ac-2121T (family Microbacteriaceae, class Actinomycetes) was found to contain neutral and acidic glycopolymers. The neutral polymer is a block-type rhamnomannan partially should be substitutied by xylose residues, [→2)-α-[ß-D-Xylp-(1 â†’ 3)]-D-Manp-(1 â†’ 3)-α-D-Rhap-(1→]∼30 [→2)-α-D-Manp-(1 â†’ 3)-α-D-Rhap-(1→]∼45. The acidic polymer has branched chain, bearing lactate and pyruvate residues, →4)-α-D-[S-Lac-(2-3)-α-L-Rhap-(1 â†’ 3)]-D-Manp-(1 â†’ 3)-α-D-[4,6-R-Pyr]-D-Galp-(1 â†’ 3)-ß-D-Glcp-(1 â†’. The structures of both glycopolymers were not described in the Gram-positive bacteria to date. The glycopolymers were studied by chemical and NMR spectroscopic methods. The results of this study provide new data on diversity of bacterial glycopolymers and may prove useful in the taxonomy of the genus Rathayibacter and for understanding the molecular mechanisms of interaction between plants and plant endophytes.


Asunto(s)
Pared Celular , Xilosa , Pared Celular/química , Pared Celular/metabolismo , Xilosa/química , Xilosa/metabolismo , Ácido Láctico/química , Ácido Láctico/metabolismo , Ácido Pirúvico/química , Ácido Pirúvico/metabolismo , Mananos/química , Secuencia de Carbohidratos , Actinobacteria/química , Actinobacteria/metabolismo , Ramnosa/química , Polisacáridos Bacterianos/química , Polisacáridos/química , Actinomycetales/química , Actinomycetales/metabolismo
14.
Int J Biol Macromol ; 266(Pt 2): 131290, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38569993

RESUMEN

Lignocellulosic biomass (LCB) has been a lucrative feedstock for developing biochemical products due to its rich organic content, low carbon footprint and abundant accessibility. The recalcitrant nature of this feedstock is a foremost bottleneck. It needs suitable pretreatment techniques to achieve a high yield of sugar fractions such as glucose and xylose with low inhibitory components. Cellulosic sugars are commonly used for the bio-manufacturing process, and the xylose sugar, which is predominant in the hemicellulosic fraction, is rejected as most cell factories lack the five­carbon metabolic pathways. In the present review, more emphasis was placed on the efficient pretreatment techniques developed for disintegrating LCB and enhancing xylose sugars. Further, the transformation of the xylose to value-added products through chemo-catalytic routes was highlighted. In addition, the review also recapitulates the sustainable production of biochemicals by native xylose assimilating microbes and engineering the metabolic pathway to ameliorate biomanufacturing using xylose as the sole carbon source. Overall, this review will give an edge on the bioprocessing of microbial metabolism for the efficient utilization of xylose in the LCB.


Asunto(s)
Biomasa , Lignina , Xilosa , Xilosa/metabolismo , Xilosa/química , Lignina/química , Lignina/metabolismo
15.
J Agric Food Chem ; 72(12): 6554-6564, 2024 Mar 27.
Artículo en Inglés | MEDLINE | ID: mdl-38498924

RESUMEN

Dihydromyricetin (DMY) was employed to reduce the yield of furfural derived from the Amadori rearrangement product of l-threonine and d-xylose (Thr-ARP) by trapping Thr-ARP, 3-deoxyxyosone (3-DX), and furfural to form adducts. The effect of different concentrations of DMY at different pH values and temperatures on the reduction of furfural production was studied, and the results showed that DMY could significantly reduce furfural production at higher pH (pH 5-7) and lower temperature (110 °C). Through the surface electrostatic potential analysis by Gaussian, a significant enhancement of the C6 nucleophilic ability at higher pH (pH ≥ 5) was observed on DMY with hydrogen-dissociated phenol hydroxyl. The nucleophilic ability of DMY led to its trapping of Thr-ARP, 3-DX, and furfural with the generation of the adducts DMY-Thr-ARP, DMY-3-DX, and DMY-furfural. The formation of the DMY-Thr-ARP adduct slowed the degradation of Thr-ARP, caused the decrease of the 3-DX yield, and thereby inhibited the conversion of 3-DX to furfural. Therefore, DMY-Thr-ARP was purified, and the structure was identified by nuclear magnetic resonance (NMR). The results confirmed that C6 or C8 of DMY and carbonyl carbon in Thr-ARP underwent a nucleophilic addition reaction to form the DMY-Thr-ARP adduct. In combination with the analysis results of Gaussian, most of the DMY-Thr-ARP adducts were calculated to be C6-DMY-Thr-ARP. Furthermore, the formation of DMY-furfural caused furfural consumption. The formation of the adducts also shunted the pathway of both Thr-ARP and 3-DX conversion to furfural, resulting in a decrease in the level of furfural production.


Asunto(s)
Furaldehído , Xilosa , Xilosa/química , Temperatura , Flavonoles/química
16.
Bioresour Technol ; 399: 130535, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38492653

RESUMEN

For a sustainable economy, biorefineries that use second-generation feedstocks to produce biochemicals and biofuels are essential. However, the exact composition of renewable feedstocks depends on the natural raw materials used and is therefore highly variable. In this contribution, a process analytical technique (PAT) strategy for determining the sugar composition of lignocellulosic process streams in real-time to enable better control of bioprocesses is presented. An in-line mid-IR probe was used to acquire spectra of ultra-filtered spent sulfite liquor (UF-SSL). Independent partial least squares models were developed for the most abundant sugars in the UF-SSL. Up to 5 sugars were quantified simultaneously to determine the sugar concentration and composition of the UF-SSL. The lowest root mean square errors of the predicted values obtained per analyte were 1.02 g/L arabinose, 1.25 g/L galactose, 0.50 g/L glucose, 1.60 g/L mannose, and 0.85 g/L xylose. Equipped with this novel PAT tool, new bioprocessing strategies can be developed for UF-SSL.


Asunto(s)
Glucosa , Azúcares , Fermentación , Espectroscopía Infrarroja por Transformada de Fourier , Glucosa/química , Xilosa/química , Sulfitos
17.
Food Chem ; 445: 138398, 2024 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-38394903

RESUMEN

A protein hydrolysate of goat viscera added with xylose, cysteine, and thiamine under different pH was used to prepare a meat flavoring. Goat viscera hydrolysate and flavoring were subjected to analysis of physicochemical characteristics, amino acid profile, sugars, fatty acids, and volatile profile. Meat aroma characteristics were initiated in the hydrolysate, in which Strecker's pyrazines and aldehydes were identified, which also had fatty acids and amino acids available for the formation of 96 volatile compounds in the flavorings via lipid manipulation, Maillard occurrence, Strecker manipulation and interactions among these means. Maillard reaction products with intense meat aroma, such as 2-methyl-3-furanthiol, 2-furfurylthiol and, bis(2-methyl-3-furyl) disulfide were isolated only in the flavoring at pH 4. In contrast, the flavoring at pH 6 showed a higher concentration than all the other compounds, providing a lower meat characteristic, but an intense sweet, fatty and goat aroma.


Asunto(s)
Cisteína , Reacción de Maillard , Animales , Cisteína/química , Tiamina/análisis , Xilosa/química , Hidrolisados de Proteína , Cabras , Aromatizantes/análisis , Carne/análisis , Ácidos Grasos , Odorantes/análisis
18.
Bioresour Technol ; 396: 130454, 2024 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-38360218

RESUMEN

The comprehensive separation and utilization of whole components of lignocellulosic materials has received extensive attention in present research. This study focused on the efficacy of alkali treatment for enzymatic saccharification of cellulose based on p-toluenesulfonic acid (p-TsOH) pretreated bamboo substrate. The results showed that the cellulose to glucose conversion yield was 94.69 % under optimized conditions of 0.4 g NaOH/g, 160 °C and 4 h (soaked), which after only 6 h enzymatic hydrolysis time. Alkali lignin recovery was 88.51 %, with potential for conversion to lignin derivatives. The yield of hemicellulose in the pretreated filtrate was 51.85 % after the 4th cycling reuse of p-TsOH. This work has borrowed the advantages of p-TsOH pretreatment of depolymerized hemicellulose from bamboo, combined with a low-priced weak alkali secondary treatment method, which can be effectively applied to the co-production of lignin, xylooligosaccharide, xylose and glucose, and the whole process is green and economically sustainable.


Asunto(s)
Álcalis , Bencenosulfonatos , Lignina , Biomasa , Celulosa , Glucosa , Hidrólisis , Xilosa/química , Oligosacáridos/química
19.
J Sci Food Agric ; 104(7): 4128-4135, 2024 May.
Artículo en Inglés | MEDLINE | ID: mdl-38308538

RESUMEN

BACKGROUND: Glycation is a green processing technology. Based on our previous studies, glycation with l-arabinose and xylose was beneficial to enhance the texture properties of silver carp mince (SCM) gels. However, the possible enhancement mechanism remained unclear. Therefore, in this study, SCM gels with different types of reducing sugar (glucose, l-arabinose, and xylose) were prepared based on our previous study. The possible mechanism of texture enhancement of SCM gels was analyzed by investigating the changes in water distribution, protein structures, and microstructure in the gel system. RESULTS: The glycation of l-arabinose and xylose enhanced the hardness, cohesiveness, chewiness, and resilience of SCM gels. Hardness increased from 1883.04 (control group) to 3624.54 (l-arabinose group) and 4348.18 (xylose group). Low-field nuclear magnetic resonance (LF-NMR) showed that glycation promoted the tight binding of immobilized water to proteins. Raman spectroscopic analysis showed that glycation increased the surface hydrophobicity and promoted the formation of disulfide bonds. Scanning electron microscopy (SEM) showed that glycation promoted the formation of uniform and dense three-dimensional network structure in SCM gels. CONCLUSION: In summary, glycation enhanced the binding ability of immobilized water to proteins, improved the surface hydrophobicity, promoted the formation of disulfide bonds, and led to a more uniform and dense gel network structure of proteins, thus enhancing the texture properties of SCM gels. This research provided a theoretical basis for a better understanding of the mechanism of the effect of glycation on the quality of gel products and also provided technical support for the application of l-arabinose and xylose in new functional gel foods. © 2024 Society of Chemical Industry.


Asunto(s)
Carpas , Reacción de Maillard , Animales , Xilosa/química , Arabinosa/química , Carpas/metabolismo , Geles/química , Proteínas , Agua , Disulfuros
20.
Food Chem ; 442: 138421, 2024 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-38244443

RESUMEN

A systematic kinetic study was conducted in subcritical water medium in the temperature range from 150 to 200 °C for pure glucose, xylose, proline and aspartic acid as well as binary mixtures of sugars + amino acids to understand the reaction kinetics and interactions among biomass components and to discern the influence of Maillard reaction (MR) on the overall reaction kinetics. The main degradation products identified for glucose and xylose were the respective dehydration products, hydroxymethyl furfural and furfural, yielding an increasing solid residue with temperature (15.9 wt% at 200 °C) with an augmented heating value. The degradation of sugars and amino acids in binary systems was faster compared to pure compounds due to MR and the production of dehydration products was delayed when considering total sugar conversion. Higher relative reactivity in MR was observed for xylose over glucose showing also higher antioxidant activity.


Asunto(s)
Aminoácidos , Xilosa , Humanos , Xilosa/química , Glucosa/química , Azúcares , Ácido Aspártico/química , Prolina , Agua/química , Furaldehído/química , Reacción de Maillard , Deshidratación , Cinética
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