Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 123
Filtrar
1.
Foods ; 13(13)2024 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-38998486

RESUMO

Dietary fibre (DF) is important for overall health and disease prevention. However, the intake of DF in Westernised countries is below the recommended level, largely due to the excessive consumption of low-fibre foods. Fortifying staple foods, such as bread, with dietary fibre ingredients is one approach to closing the fibre gap in our diet. However, incorporating purified and chemically modified fibre ingredients into food is challenging. This study unveils interactions between soluble-fermentable (arabinoxylan), insoluble-fermentable (resistant starch type IV) and insoluble-unfermentable (cellulose) fibre ingredients and their impact on bread quality using Response Surface Methodology. This resulted in an optimised mixture of these fibre ingredients that can coexist within a bread matrix while maintaining quality characteristics comparable to white wheat bread. The partial replacement of flour with fibre ingredients led to an interference with the gluten network causing a reduction in gluten strength by 12.4% and prolonged gluten network development time by 24.4% compared to the control (no fibre addition). However, the CO2 retention coefficient during dough fermentation was not affected by fibre ingredient inclusion. The fibre content of the white bread was increased by 128%, with only a marginal negative impact on bread quality. Additionally, the fibre-fortified bread showed a lower release of reducing sugars during in vitro starch digestion. This study illustrates the synergy of different types of fibre ingredients in a bread system to advance in closing the fibre gap.

2.
Talanta ; 278: 126416, 2024 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-38924989

RESUMO

The non-thermal and thermal effects on aroma of sea buckthorn juice have rarely been investigated. In this study, 57 odor compounds were identified in fresh sea buckthorn juice (FSBJ), high pressure processing sea buckthorn juice (HSBJ), and pasteurized sea buckthorn juice (PSBJ), including 29 esters, 8 aldehydes, 1 ketone, 5 alcohols, 5 acids, 6 terpenoids, and 3 others. Ethyl 2-methylbutanoate, ethyl 3-methylbutanoate, ethyl hexanoate, and ethyl 2-hydroxy-3-methylbutanoate with flavor dilution factors ranging from 729 to 59,049 contributed to the fruity odors of FSBJ and HSBJ. Besides, the formation of off-odor compounds including hexanal, nonanal, furfural, 3-methylbutanoic acid, and dimethyl disulfide with odor activity values ≥ 1, imparts fatty, roasted, sweaty, and cooked odor in PSBJ. The variations of vitamin C and reducing sugar are significantly associated with changes in odor-active compounds during pasteurized processing. These findings provide new insights that high pressure processing minimizes the adverse effects of pasteurization.

3.
Bioorg Chem ; 150: 107557, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38878754

RESUMO

The limitations of commonly used sodium ascorbate-based catalyst system for copper-catalyzed azide-alkyne cycloaddition (CuAAC) reaction include excess production of reactive oxygen species and rapid catalyst deactivation. In this study instead of using a highly active reducing agent, such as, sodium ascorbate, we chose reducing sugar as a mild reducing agent to build up the catalyst system for CuAAC reaction. Interestingly, the bicinchoninic acid (BCA) assay system containing reducing sugar satisfies the essential elements of the catalyst system for CuAAC reaction. We found that CuSO4/BCA/Reducing sugar system can catalyze the CuAAC reaction but with low yield. Rational analyses of various parameters in CuSO4/BCA/Glucose catalyst system suggested storage at room temperature might enhance the catalytic activity, which was proven to be the case. Importantly, the system remains stable at room temperature and minimal H2O2 was detected. Notably, our study showed that the coordination between the slow reduction of Cu(I) by reducing sugar and the selective chelation of Cu(I) by BCA is key to developing this system. The CuSO4/BCA/Reducing sugar catalyst system was successfully applied to various CuAAC reaction based bioanalyses, and it is suitable for the CuAAC reaction based bioanalyses that are sensitive to ROS or request long reaction time.

4.
Int J Biol Macromol ; 265(Pt 1): 130740, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38462117

RESUMO

Enhancing enzyme activity and stability in biomass degradation can improve substrate saccharification and, increases biorefinery efficiency. For the first time, we identified 20 lytic polysaccharide monooxygenases (LPMOs) AA9 genes in the genome of Thermothelomyces fergusii. Our results showed that TfAA9 was categorized into LPMOs1, LPMOs2, and LPMOs3 subgroups based on protein diversity. Protein- 3D structure analysis showed strong interactions between Myceliophthora thermophila AA9 proteins and 17 TfAA9 proteins. Gene ontology analysis indicated a high enrichment of cellulase activity in TfAA9 genes. KEGG pathways analysis revealed the role of TfAA9 proteins in the endohydrolysis of 1,4-beta-D-glucosidic linkages in cellulose. Numerous TfAA9s gene transcripts were up-regulated on avicel, cellobiose, and glucose, with a higher proportion on avicel. Protein concentration, endoglucanase, and cellulase activity were also boosted on avicel. However, limited fungal biomass was observed on avicel, despite the abundance of AA9 LPMOs in the T. fergusii genome. These findings expand our understanding of fungal AA9 genes and their role in lignocellulolytic degradation. The disparity between biomass and enzymatic activity suggests screening TfAA9 genes for highly active enzymes and redundant genes via heterologous expression. In short, functional characterization of these genes could contribute to improving the saccharification process of industrial raw materials.


Assuntos
Celulases , Oxigenases de Função Mista , Oxigenases de Função Mista/química , Polissacarídeos/metabolismo , Celulose/química , Fungos , Genômica
5.
Plants (Basel) ; 13(5)2024 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-38475553

RESUMO

Sugarcane is a significant primitive source of sugar and energy worldwide. The progress in enhancing the sugar content in sugarcane cultivars remains limited due to an insufficient understanding of specific genes related to sucrose production. The present investigation examined the enzyme activities, levels of reducing and non-reducing sugars, and transcript expression using RT-qPCR to assess the gene expression associated with sucrose metabolism in a high-sucrose sugarcane clone (GXB9) in comparison to a low-sucrose sister clone (B9). Sucrose phosphate synthase (SPS), sucrose phosphate phosphatase (SPP), sucrose synthase (SuSy), cell wall invertase (CWI), soluble acid invertase (SAI), and neutral invertase (NI) are essential enzymes involved in sucrose metabolism in sugarcane. The activities of these enzymes were comparatively quantified and analyzed in immature and maturing internodes of the high- and low-sucrose clones. The results showed that the higher-sucrose-accumulating clone had greater sucrose concentrations than the low-sucrose-accumulating clone; however, maturing internodes had higher sucrose levels than immature internodes in both clones. Hexose concentrations were higher in immature internodes than in maturing internodes for both clones. The SPS and SPP enzymes activities were higher in the high-sucrose-storing clone than in the low-sucrose clone. SuSy activity was higher in the low-sucrose clone than in the high-sucrose clone; further, the degree of SuSy activity was higher in immature internodes than in maturing internodes for both clones. The SPS gene expression was considerably higher in mature internodes of the high-sucrose clones than the low-sucrose clone. Conversely, the SuSy gene exhibited up-regulated expression in the low-sucrose clone. The enhanced expression of SPS in the high-sucrose clone compared to the low-sucrose clone suggests that SPS plays a major role in the increased accumulation of sucrose. These findings provide the opportunity to improve sugarcane cultivars by regulating the activity of genes related to sucrose metabolism using transgenic techniques.

6.
Food Chem ; 438: 138045, 2024 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-37992602

RESUMO

High-intensity ultrasound was used as a means to promote maturation of soy sauce. The optimal conditions for ultrasound treatment were 90℃ at an ultrasound intensity of 39.48 W/cm2 for 60 min. The total reducing sugars and soluble salt-free solids content was significantly increased after ultrasound-assisted maturation. The free amino acid content was significantly decreased, mainly due to the Maillard reaction (MR). The promoted MR produced several types of flavor compounds, including esters, pyrazines, and ketones, which imparted an attractive aroma to the maturated soy sauce. The proportion of peptides with a molecular weight of 1-5 kDa provided umami as an important flavor characteristic, and the content in the ultrasound-matured soy sauce (10.19 %) was significantly higher than that in the freshly prepared soy sauce (8.34 %) and the thermally treated sample (8.89 %). Ultrasound-assisted maturation would improve product quality and meanwhile, shorten the duration and reduce the cost for the soy sauce industry.


Assuntos
Alimentos de Soja , Alimentos de Soja/análise , Aminoácidos , Reação de Maillard , Odorantes , Peso Molecular
7.
Cryobiology ; 114: 104793, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37979827

RESUMO

One of the most common life-saving medical procedures is a red blood cell (RBC) transfusion. Unfortunately, RBCs for transfusion have a limited shelf life after donation due to detrimental storage effects on their morphological and biochemical properties. Inspired by nature, a biomimetics approach was developed to preserve RBCs for long-term storage using compounds found in animals with a natural propensity to survive in a frozen or desiccated state for decades. Trehalose was employed as a cryoprotective agent and added to the extracellular freezing solution of porcine RBCs. Slow cooling (-1 °C min-1) resulted in almost complete hemolysis (1 ± 1 % RBC recovery), and rapid cooling rates had to be used to achieve satisfactory cryopreservation outcomes. After rapid cooling, the highest percentage of RBC recovery was obtained by plunging in liquid nitrogen and thawing at 55 °C, using a cryopreservation solution containing 300 mM trehalose. Under these conditions, 88 ± 8 % of processed RBCs were recovered and retained hemoglobin (14 ± 2 % hemolysis). Hemoglobin's oxygen-binding properties of cryopreserved RBCs were not significantly different to unfrozen controls and was allosterically regulated by 2,3-bisphosphoglycerate. These data indicate the feasibility of using trehalose instead of glycerol as a cryoprotective compound for RBCs. In contrast to glycerol, trehalose-preserved RBCs can potentially be transfused without time-consuming washing steps, which significantly facilitates the usage of cryopreserved transfusible units in trauma situations when time is of the essence.


Assuntos
Criopreservação , Crioprotetores , Animais , Suínos , Crioprotetores/química , Criopreservação/métodos , Trealose/farmacologia , Trealose/metabolismo , Glicerol/farmacologia , Glicerol/metabolismo , Hemólise , Preservação de Sangue/métodos , Eritrócitos/metabolismo , Hemoglobinas/metabolismo , Hemoglobinas/farmacologia , Oxigênio/metabolismo
8.
Int J Biol Macromol ; 258(Pt 1): 128888, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38141701

RESUMO

The microwave assisted pretreatment on sugarcane leaf (SCL) biomass for delignification was studied to enhance cellulose digestibility. In this work, microwave assisted with additives were used to delignification SCL for maximize sugar yield recovery. Single factorial and Central composite design (CCD) were employed to optimize the microwave assisted pretreatment conditions for improve delignification efficiency and the sugar yield recovery. The optimized pretreatment conditions were determined to be 4 min pre-treatment time, 500 W microwave power, 1.0 M Na2CO3 and 10 % biomass loading condition produce maximum reducing sugar yield (601 mg g-1) and glucose sugar yield (231 mg g-1) were achieved during saccharification. Pretreated biomass produced reducing sugar and glucose yields that were 4.5 and 4.1 times higher than those of untreated (native) SCL-N biomass, respectively. Additionally, the recyclability study of black liquor, obtained from optimized conditioned treatment of SCL-MSC (Microwave-assisted sodium carbonate pretreated SCL) resulted in considerable saccharification yield up to three pretreatment cycles. The 1H NMR and 13C NMR spectra studies illustrate that aromatic units present in SCL fractionated lignin samples. The variations of structure features and chemical compositions of the raw and pretreated SCL biomass were analyzed by SEM, XRD and XPS analysis. Overall, SCL-MSC pretreatment condition significantly delignification of SCL and led to the maximum sugar production optimized strategies pretreatment conditions was produced maximum amount of sugar, which is great potential for bio-refinery product development.


Assuntos
Lignina , Saccharum , Lignina/química , Saccharum/química , Micro-Ondas , Hidrólise , Carboidratos , Glucose , Biomassa
9.
Indian J Microbiol ; 63(4): 693-701, 2023 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-38031602

RESUMO

Lignocellulosic biomass (LCB) from agriculture residues has gained a lot of attention in recent years for its conversion to useful by-products. The one drawback that the conversion of biomass faces is its recalcitrant nature which can be overcome by effective pretreatment technology. One such process is the EnZolv, a novel pretreatment technique used for delignification of biomass and it was recognized as an eco-friendly approach. The main objective of our present study is to optimize the novel EnZolv process parameters for enhanced release of reducing sugar from banana fiber. Banana fiber pre-optimization for EnZolv pretreated at 100% moisture content, incubated at 40 °C temperature, with an enzyme load of 50 U·g-1 of biomass for an incubation time of 5 h at a shaking speed of 100 rpm yielded enhanced sugar release of 1.7 mg·mL-1. The effect of pretreatment on proximate composition results in a decrease in the volatile matter (53%) and moisture percentage (1.07%) and an increase in the other parameters such as ash content (12%) and fixed carbon content (34%) under the optimized condition. A significantly higher release of phenol content 1264 µg·mL-1 equivalent to gallic acid suggests that EnZolv pretreatment confirms the degradation of lignin content in the biomass. Supplementary Information: The online version contains supplementary material available at 10.1007/s12088-023-01130-4.

10.
Food Res Int ; 174(Pt 1): 113523, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37986512

RESUMO

This study aimed to evaluate the fate in digestive steps, bioaccessibility and diffusion of acrylamide (AA) and 5-Hydroxymethylfurfural (5-HMF) in bread samples produced under different processing parameters. AA and 5-HMF were determined in every sample ready-to-eat, after every digestion step and in the digested after crossing the dialysis membrane. The contaminants were extracted by QuEChERS method and determined by HPLC-PDA. Doubling fermentation time (from 60 to 120 min) increased the level of AA by 1.2-fold, and it decreased the level of 5-HMF by 1.4-fold. A combination of 60 min fermentation and 20 min baking led to the lowest levels of AA (1.71 mg/kg) and 5-HMF (0.50 mg/kg). There was no increase in AA level in the gastric stage however, the 5-HMF level increased. Both contaminant levels had increased in the intestinal stage. This fact showed that the determination of the contaminants in the ready-to-eat product did not reflect their actual bioaccessibility because the digestive enzymes and pH variation may affect the release and detection of AA and 5-HMF accumulated in the baking stage. The initial levels of 5-HMF were correlated to the baking time, and initial levels of AA were correlated to the fermentation time. From the bioaccessible levels of AA and 5-HMF, approximately 90 % (5 mg/kg) and 100 % (6.5 mg/kg) crossed the dialysis membrane respectively. Initial and bioaccessible levels of AA were above the security recommendations for bread (50 µg/kg), which is a concern considering the daily consumption of this food. This study showed that focusing on a combination of processing parameters could be a promising strategy to decrease the bioaccessibility of both contaminants in bread.


Assuntos
Acrilamida , Furaldeído , Cromatografia Líquida de Alta Pressão
11.
Bioresour Technol ; 388: 129721, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37730140

RESUMO

The biological invasion caused by the invasive macroalga Rugulopteryx okamurae is causing increasing concern in southern Europe. To reduce its impact, this brown alga can be treated from a biorefinery approach. In this study, the macroalga is used as raw material to obtain fermentable sugars, which can be converted into high value-added products. The alga was exposed to hydrothermal and hydrothermal acid pretreatment and the pretreated biomass was used for enzymatic hydrolysis, achieving a hydrolysate with a reducing sugar concentration of almost 25 g/L (49.2% more than with non-pretreated alga). In addition, the combined severity factor was calculated to identify the best pretreatment conditions, finding the optimum in those pretreatments performed with 0.2 N HCl concentration and 15 min reaction time. Based on the results, it would be interesting to carry out new studies using the saccharified medium obtained under optimal conditions to obtain value-added compounds by fermentation.

12.
Environ Technol ; : 1-9, 2023 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-37395350

RESUMO

ABSTRACTDeep eutectic solvent (DES) has been identified as a potential green solvent in biomass processing. In the present investigation, a deep eutectic solvent i.e. choline chloride: urea (ChCl/U) was synthesized and employed to pretreat rice husks. Plackett- Burman response surface methodology was used to optimize the factors which are DES molar ratio, residence time, temperature, and biomass concentration. A total of 11 experimental conditions were evaluated and the highest amount of reducing sugar was obtained when 2 g rice husk was pretreated with 1:2 ChCl/U at 80°C for 6 h i.e. 0.67 ± 0.05 mg/mL. Furthermore, scanning electron microscopy (SEM), Fourier transforms infrared (FTIR), and X-ray diffraction (XRD) studies were used to characterize the structural and compositional changes in which DES demonstrates a great performance in the pretreatment of rice husk by eliminating amorphous lignin and hemicellulose content. Therefore, the facile process used in this study has the potential to be used on a massive scale to produce fermentable sugars and other compounds.

13.
Biosci Biotechnol Biochem ; 87(10): 1249-1253, 2023 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-37475702

RESUMO

YcjT is a kojibiose phosphorylase found in Escherichia coli. We found that sucrose was a good acceptor of YcjT in reverse phosphorolysis using ß-d-glucose 1-phosphate as a donor. The product was identified as ß-d-fructofuranosyl α-d-glucopyranosyl-(1→2)-α-d-glucopyranoside. This sugar was also synthesized from sucrose and maltose using YcjT and maltose phosphorylase and promoted the growth of the probiotic Bifidobacterium breve.


Assuntos
Escherichia coli , Glicosídeos , Fosforilases , Glucosiltransferases , Maltose , Sacarose/farmacologia
14.
Int J Mol Sci ; 24(11)2023 Jun 03.
Artigo em Inglês | MEDLINE | ID: mdl-37298661

RESUMO

Lytic polysaccharide monooxygenases (LPMOs) can oxidatively break the glycosidic bonds of crystalline cellulose, providing more actionable sites for cellulase to facilitate the conversion of cellulose to cello-oligosaccharides, cellobiose and glucose. In this work, a bioinformatics analysis of BaLPMO10 revealed that it is a hydrophobic, stable and secreted protein. By optimizing the fermentation conditions, the highest protein secretion level was found at a IPTG concentration of 0.5 mM and 20 h of fermentation at 37 °C, with a yield of 20 mg/L and purity > 95%. The effect of metal ions on the enzyme activity of BaLPMO10 was measured, and it was found that 10 mM Ca2+ and Na+ increased the enzyme activity by 47.8% and 98.0%, respectively. However, DTT, EDTA and five organic reagents inhibited the enzyme activity of BaLPMO10. Finally, BaLPMO10 was applied in biomass conversion. The degradation of corn stover pretreated with different steam explosions was performed. BaLPMO10 and cellulase had the best synergistic degradation effect on corn stover pretreated at 200 °C for 12 min, improving reducing sugars by 9.2% compared to cellulase alone. BaLPMO10 was found to be the most efficient for ethylenediamine-pretreated Caragana korshinskii by degrading three different biomasses, increasing the content of reducing sugars by 40.5% compared to cellulase alone following co-degradation with cellulase for 48 h. The results of scanning electron microscopy revealed that BaLPMO10 disrupted the structure of Caragana korshinskii, making its surface coarse and poriferous, which increased the accessibility of other enzymes and thus promoted the process of conversion. These findings provide guidance for improving the efficiency of enzymatic digestion of lignocellulosic biomass.


Assuntos
Celulase , Oxigenases de Função Mista , Oxigenases de Função Mista/metabolismo , Biomassa , Polissacarídeos/metabolismo , Celulose/metabolismo , Celulase/metabolismo , Celobiose , Hidrólise
15.
Bioresour Technol ; 385: 129279, 2023 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-37321308

RESUMO

Sunflower straw, a usually neglected and abundant agricultural waste, has great potential for contributing to environmental protection realizing its high-value of valorization if utilizing properly. Because hemicellulose contains amorphous polysaccharide chains, relatively mild organic acid pretreatment can effectively reduce its resistance. Through hydrothermal pretreatment, sunflower straw was pretreated in tartaric acid (1 wt%) at 180 °C for 60 min to enhance its reducing sugar recovery. After tartaric acid-assisted hydrothermal pretreatment, 39.9% of lignin and 90.2% of xylan were eliminated. The reducing sugar recovery increased threefold, while the solution could be effectively reused for four cycles. The properties of more porous surface, improved accessibility, and decreased surface lignin area of sunflower straw were observed through various characterizations, which explained the improved saccharide recovery and provided a basis for the mechanism of tartaric acid-assisted hydrothermal pretreatment. Overall, this tartaric acid hydrothermal pretreatment strategy greatly provided new impetus for the biomass refinery.


Assuntos
Helianthus , Lignina , Celulose , Hidrólise , Açúcares
16.
Methods Mol Biol ; 2657: 3-14, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37149519

RESUMO

The quantitation of liberated reducing sugars by the copper-bicinchoninic acid (BCA) assay provides a highly sensitive method for the measurement of glycoside hydrolase (GH) activity, particularly on soluble polysaccharide substrates. Here we describe a straightforward method adapted to low-volume polymerase chain reaction (PCR) tubes that enables the rapid, parallel determination of GH kinetics in applications ranging from initial activity screening and assay optimization to precise Michaelis-Menten analysis.


Assuntos
Glicosídeo Hidrolases , Quinolinas , Cobre , Polissacarídeos
17.
Front Plant Sci ; 14: 1133029, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-36875591

RESUMO

Cold-induced sweetening (CIS) is an unwanted physiological phenomenon in which reducing sugars (RS) get accumulated in potato (Solanum tuberosum) upon cold storage. High RS content makes potato commercially unsuitable for processing due to the unacceptable brown color in processed products like chips, fries, etc., and the production of a potential carcinogen, acrylamide. UDP-glucose pyrophosphorylase (UGPase) catalyzes the synthesis of UDP-glucose towards the synthesis of sucrose and is also involved in the regulation of CIS in potato. The objective of the present work was RNAi-mediated downregulation of the StUGPase expression level in potato for the development of CIS tolerant potato. Hairpin RNA (hpRNA) gene construct was developed by placing UGPase cDNA fragment in sense and antisense orientation intervened by GBSS intron. Internodal stem explants (cv. Kufri Chipsona-4) were transformed with hpRNA gene construct, and 22 transgenic lines were obtained by PCR screening of putative transformants. Four transgenic lines showed the highest level of RS content reduction following 30 days of cold storage, with reductions in sucrose and RS (glucose & fructose) levels of up to 46% and 57.5%, respectively. Cold stored transgenic potato of these four lines produced acceptable chip colour upon processing. The selected transgenic lines carried two to five copies of the transgene. Northern hybridization revealed an accumulation of siRNA with a concomitant decrease in the StUGPase transcript level in these selected transgenic lines. The present work demonstrates the efficacy of StUGPase silencing in controlling CIS in potato, and the strategy can be employed for the development of CIS tolerant potato varieties.

18.
Polymers (Basel) ; 15(5)2023 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-36904327

RESUMO

The evolution of green technology for the simple and ecological formation of silver nanoparticles (AgNPs) inspired the present work for simple and efficient detection of reducing sugars (RS) in foods. The proposed method relies on gelatin as the capping and stabilizing agent and the analyte (RS) as the reducing agent. This work may attract significant attention, especially in the industry, for testing the sugar content using gelatin-capped silver nanoparticles as it not only detects the sugar in food, but also determines the content (%), which could be an alternative technique to the conventionally used DNS colorimetric method. For this purpose, a certain amount of maltose was mixed with a gelatin-silver nitrate. Different conditions that may affect the color changes at 434 nm owing to the in situ formed AgNPs, such as gelatin-silver nitrate ratio, PH, time, and temperature, have been investigated. The 1:3 mg/mg ratio of gelatin-silver nitrate dissolved in 10 mL distilled water was most effective in color formation. The development of AgNPs color increases within 8-10 min at PH 8.5 as the selected optimum value and at the optimum temperature of 90 °C for the evolution of the gelatin-silver reagent's redox reaction. The gelatin-silver reagent showed a fast response (less than 10 min) with a detection limit for maltose at 46.67 µM. In addition, the selectivity of maltose was checked in the presence of starch and after its hydrolysis with α-amylase. Compared with the conventionally used dinitrosalicylic acid (DNS) colorimetric method, the proposed method could be applied to commercial fresh apple juice, watermelon, and honey to prove its viability for detecting RS in fruits; the total reducing sugar content was 287, 165, and 751 mg/g, respectively.

19.
J Agric Food Chem ; 71(14): 5796-5803, 2023 Apr 12.
Artigo em Inglês | MEDLINE | ID: mdl-37000938

RESUMO

The reaction of proteins with reducing sugars results in the formation of Amadori products, which involves the N-terminal group and/or ε-amino group of the lysine side chain. However, less attention has been given to the reactivity of the N-terminus of a peptide chain under similar conditions. In our work, we focused on the reaction of the α-amino group of peptides in the presence of a reducing sugar, specifically lactose. We optimized the reaction conditions of model peptides with lactose in the solid phase and showed that temperatures above 120 °C lead to the deamination of the N-terminal amino acid moiety, ultimately resulting in α-ketoacids. We carried out detailed studies to confirm the structure of the deaminated product using analytical methods such as ESI-MS and LC-MS/MS, as well as chemical methods that involved the reduction of the carbonyl group combined with isotopic exchange and the reactivity of the carbonyl group with the hydroxylamine derivative. The structure of the reaction product was also confirmed by chemical synthesis. We suggested plausible mechanisms for the formation of the deaminated product and considered the probable path of its formation. Our aim was to determine whether the reaction proceeds according to the Strecker-based mechanism and direct imine isomerization by carrying out reactions of model peptides in the presence of lactose under aerobic and anaerobic conditions and comparing the results obtained.


Assuntos
Glucose , Lactose , Cromatografia Líquida , Temperatura , Espectrometria de Massas em Tandem , Peptídeos
20.
Prep Biochem Biotechnol ; 53(3): 279-287, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-35635302

RESUMO

Excessive use of fossil fuels has accelerated climate change and global warming necessitates the need for renewable energy sources that have a lower environmental impact. In the recent decade, lignocellulosic biomass has become a prominent alternative to renewable energy resources for the production of bioenergy. The pretreatment procedure is considered a pivotal step for transforming biomass into value-added products such as sugars, biofuels, etc. Therefore, the present work aims to study the effect of different pretreatment approaches on rice husk with acids (H2SO4 and HCl), alkalis (NaOH and KOH), and organic solvents (ethanol and methanol) utilizing different concentrations like (2, 4 and 6% in case of acids), (2,4 and 6% for alkalis) and (50% and 70% for organic solvents) with different residence time (1, 3, 6, and 24 h). The most effective results obtained from the aforementioned steps were further adopted for enzymatic hydrolysis. Further, the changes in structural properties of biomass were assessed in relation to the pretreatment process employing scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier Transform Infrared (FTIR) analyses. This paper also highlights the techno-economic analysis of alkali pretreatment. Additionally, the operational targets for the process were identified by using a modeling software-SuperPro Designer. Results obtained from the study showed a maximum yield of reducing sugar i.e., 1.906 ± 0.2 mg/ml (4% NaOH with 6 h of incubation). This study demonstrates that 4% NaOH pretreatment effectively disintegrates the biomass and yields high sugar recovery which can be used further for the production of biofuels and value-added products.


Assuntos
Oryza , Açúcares , Lignina/química , Biocombustíveis , Álcalis , Hidróxido de Sódio , Solventes , Biomassa , Hidrólise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA