Optimal Hydrolysis Conditions Research Articles

Integrated biorefinery approach for utilization of wood waste into levulinic acid and 2-Phenylethanol production under mild treatment conditions

In a bid to explore the on-site biorefinery approach for conversion of forestry residues, lignocellulosic biomass into value-added products was studied. The bark white pine wood was subjected to the microwave technique of fast and slow hydrolysis under varying acid and biomass concentrations to produce levulinic acid (LA). The HCl (2% v/v) and plant biomass (1% w/v) were identified as the optimum conditions for fast wood hydrolysis (270 ºC for 12 sec), which led to maximum LA yield of 446.68 g/kgPB. The proposed sustainable approach is mild, quick, and utilized a very low concentration of the HCl for the production of LA. The hydrolysate was used as a medium for Kluyveromyces marxianus growth to produce 2-phenylethanol (2-PE). K. marxianus used 74–95% of furfural from hydrolysate as a co-substrate to grow. The proposed model of the integrated biorefinery is an affordable on-site approach of using forest waste into localized solutions to produce LA and 2-PE.

Preparation of xylooligosaccharides from rice husks and their structural characterization, antioxidant activity, and probiotic properties

Rice husks are rich in xylan, which can be hydrolyzed by xylanase to form xylooligosaccharides (XOS). XOS are a functional oligosaccharide such as improving gut microbiota and antioxidant properties. In this study, the structure and functional characteristics of XOS were studied. The optimal xylanase hydrolysis conditions through response surface methodology (RSM) were: xylanase dosage of 3000 U/g, hydrolysis time of 3 h, hydrolysis temperature of 50 °C. Under this condition, the yield of XOS was 150.9 mg/g. The TG-DTG curve showed that XOS began to decompose at around 200 °C. When the concentration of XOS reached 1.0 g/L, the clearance rate of DPPH reached 65.76 %, and the scavenging rate of OH reached 62.10 %, while the clearance rate of ABTS free radicals reached 97.70 %, which was equivalent to the clearance rate of VC. XOS had a proliferative effect on four probiotics: Lactobacillus plantarum, Lactobacillus brucelli, Lactobacillus acidophilus, and Lactobacillus rhamnosus. However, the further experiments are needed to explore the improvement effect of XOS on human gut microbiota, laying a foundation for the effective utilization of XOS. XOS have a wide range of sources, low price, and broad development prospects. The reasonable utilization of XOS can bring greater economic benefits.

Optimization of hydrolysis conditions of alginate based on high performance liquid chromatography

Alginate is the most abundant polysaccharide compound in brown algae, which is widely used in various fields. At present, the determination of the content of alginate is mostly carried out using sulfuric acid and trifluoroacetic acid hydrolysis followed by the determination of the content, but the results are not satisfactory, and there are problems such as low hydrolysis degree and low recovery rate. Therefore, in this study, based on the optimization of high performance liquid chromatographic conditions for pre-column derivatization of 1-phenyl-3-methyl-5-pyrazolone (PMP), the hydrolysis effects of sulfuric acid, trifluoroacetic acid (TFA), oxalic acid, and formic acid were compared and the hydrolysis conditions were optimized. The results showed that formic acid was the best hydrolyzing acid. The optimal hydrolysis conditions were 95 % formic acid at 110 °C for 10 h. The hydrolysis effect was stable, with high recovery and low destruction of monosaccharides, which made it possible to introduce formic acid into the subsequent polysaccharide hydrolysis. The pre-column derivatization high performance liquid chromatography method established in this study was accurate and reliable, and the hydrolysis acid with better effect was screened, which provided a theoretical basis for the subsequent determination of alginate content.

Exploration and Improvement of Acid Hydrolysis Conditions for Inulin-Type Fructans Monosaccharide Composition Analysis: Monosaccharide Recovery and By-Product Identification.

Acid hydrolysis serves as the primary method for determining the monosaccharide composition of polysaccharides. However, inappropriate acid hydrolysis conditions may catalyze the breakdown of monosaccharides such as fructans (Fru), generating non-sugar by-products that affect the accuracy of monosaccharide composition analysis. In this study, we determined the monosaccharide recovery rate and non-sugar by-product formation of inulin-type fructan (ITF) and Fru under varied acid hydrolysis conditions using HPAEC-PAD and UPLC-Triple-TOF/MS, respectively. The results revealed significant variations in the recovery rate of Fru within ITF under different hydrolysis conditions, while glucose remained relatively stable. Optimal hydrolysis conditions for achieving a relatively high monosaccharide recovery rate for ITF entailed 80 °C, 2 h, and 1 M sulfuric acid. Furthermore, we validated the stability of Fru during acid hydrolysis. The results indicated that Fru experienced significant degradation with an increasing temperature and acid concentration, with a pronounced decrease observed when the temperature exceeds 100 °C or the H2SO4 concentration surpasses 2 M. Finally, three common by-products associated with Fru degradation, namely 5-hydroxymethyl-2-furaldehyde, 5-methyl-2-furaldehyde, and furfural, were identified in both Fru and ITF hydrolysis processes. These findings revealed that the degradation of Fru under acidic conditions was a vital factor leading to inaccuracies in determining the Fru content during ITF monosaccharide analysis.

Alcalase-Based Chickpea (Cicer arietinum L.) Protein Hydrolysates Efficiently Reduce Systolic Blood Pressure in Spontaneously Hypertensive Rats.

Studies on antihypertensive chickpea protein hydrolysates have rarely performed in vivo evaluations, limiting the entry of such hydrolysates into functional food development and clinical trials. Thus, our aim was to optimize the hydrolysis conditions to produce an alcalase-based chickpea hydrolysate with a hypotensive effect in vivo at convenient oral doses. The hydrolysis reaction time, temperature, and alcalase/substrate concentration were optimized using a response surface analysis (RSA). ACE-I inhibition was the response variable. The optimized hydrolysis conditions were time = 0.5 h, temperature = 40 °C, and E/S concentration = 0.254 (U/g). The IC50 of the optimized hydrolysate (OCPH) was 0.358 mg/mL. Five hydrolysates from the RSA worksheet (one of them obtained after 5 min of hydrolysis (CPH15)) had an ACE-I inhibitory potential similar to that of OCPH (p > 0.05). At 50 mg/kg doses, OCPH and CPH15 promoted a clinically relevant hypotensive effect in spontaneously hypertensive rats, up to -47.35 mmHg and -28.95 mmHg, respectively (p < 0.05 vs. negative control). Furthermore, the hypotensive effect was sustained for at least 7 h post-supplementation. Overall, OCPH and CPH15 are promising ingredients for functional food development and as test materials for clinical trials.

Determination of Optimum Conditions of pH and Temperature on the Saccharification of Cassava Starch by Amyloglucosidase

Saccharification is the process of breaking complex carbohydrate into its monosaccharide components. The present study however was carried out to determine the optimum conditions of pH and temperature on the saccharification of cassava starch by amyloglucosidase. The optimum conditions of cassava starch hydrolysis was determined by using a pure culture of a thermostable amyloglucosidase for saccharification, and the activities of the enzyme determined at varying pH, temperature and time. Results showed that sample dry weight significantly decreased with respect to increased value of pH, temperature and time, while reducing sugar and dextrose equivalent significantly increased with respect to increased time. The optimal reducing sugar and dextrose equivalent were 74.23% and 96.41 DE, respectively at pH 4.5, 55 °C and 72 h. The glucose obtained from this process may serve as a substrate in fructose syrup production.

Structural Characterization and Immunological Activity of Polysaccharide Degradation Products from Phlebopus portentosus

Phlebopus portentosus is an edible and medicinal mushroom with a delicious taste and high nutritional value. The oligosaccharides derived from P. portentosus may be the material basis for its biological activity. The degradation of polysaccharide and the maintenance of its activity after degradation are key steps in related research. This study applied an acid degradation method to prepare P. portentosus refined polysaccharide (PPRP) with a smaller molecular weight, and the optimal hydrolysis conditions determined were a temperature of 80 °C, an acid concentration of 2 mol/L, and a hydrolysis time of 2 h. The polysaccharide structure and immune activity were then further investigated. The results showed that the PPRP comprised two fractions with approximate weights of 61,600 Da and 5500 Da. The monosaccharide composition of PPRP was mannose, rhamnose, glucose, and galactose, with a molar ratio of 1.00: 22.24: 2.93: 1.03. The major functional groups included O-H, C-H, C-O, and C-O-C. The glycosidic bond types were mainly α- and β-glycosidic bonds. Cell experiments demonstrated that PPRP could significantly increase the proliferation of macrophages and enhance the cytotoxicity of NK cells. Moreover, PPRP also significantly promoted the proliferation of B lymphocytes and T lymphocytes, especially at a concentration of 200 μg/mL. This study furnishes scientific evidence underlining the significant potential of PPRP in immune activity, thereby serving as a material basis and scientific bedrock for further investigations into the mechanism of P. portentosus oligosaccharide activity.

Bioethanol production from dilute acid hydrolysis of cassava peels, sugar beet pulp, and green macroalgae (Ulva lactuca)

This study presents the characterization and application of different pretreatment possibilities to optimize simple carbohydrate production from representative feedstock, followed by ethanol production through optimized saccharification steps using suitable microorganisms. Total soluble carbohydrates and carbohydrate yield were evaluated using dilute acid hydrolysis of biomass and reference materials (starch and cellulose) under different conditions. To explore two-factor interactions, the Plackett-Burman design of experiments was used in the statistical screening of variables and then transformed to a full-factorial design based on the significant variables. According to the experimental findings, dilute acid hydrolysis can yield a considerable amount of soluble carbohydrates. The goodness of fit of the model was evaluated using the coefficient of determination. The optimized carbohydrate yields of the biomass were 0.76 g/g cassava peels, 0.35 g/g sugar beet pulp, and 0.36 g/g green macroalgae. Bioethanol production from optimized hydrolysis conditions using Saccharomyces cerevisiae and Scheffersomyces stipitis DSM 3651, led to a maximum ethanol yield of 0.286 g/g from cassava peels and 0.033 g/g from sugar beet pulp, while using Neurospora intermedia DSM 1265 led to a maximum ethanol yield of 0.076 g/g from green macroalgae. Hence, these biomasses are considered valuable feedstock for bioethanol production with cassava peels having the highest potential.

Extraction, identification, and molecular mechanisms of α-glucosidase inhibitory peptides from defatted Antarctic krill (Euphausia superba) powder hydrolysates

The objective of this study was to explore the potential of Antarctic krill-derived peptides as α-glucosidase inhibitors for the treatment of type 2 diabetes. The enzymolysis conditions of α-glucosidase inhibitory peptides were optimized by response surface methodology (RSM), a statistical method that efficiently determines optimal conditions with a limited number of experiments. Gel chromatography and LC-MS/MS techniques were utilized to determine the molecular weight (Mw) distribution and sequences of the hydrolysates. The identification and analysis of the mechanism behind α-glucosidase inhibitory peptides were conducted through conventional and computer-assisted techniques. The binding affinities between peptides and α-glucosidase were further validated using BLI (biolayer interferometry) assay. The results revealed that hydrolysates generated by neutrase exhibited the highest α-glucosidase inhibition rate. Optimal conditions for hydrolysis were determined to be an enzyme concentration of 6 × 103 U/g, hydrolysis time of 5.4 h, and hydrolysis temperature of 45 °C. Four peptides (LPFQR, PSFD, PSFDF, VPFPR) with strong binding affinities to the active site of α-glucosidase, primarily through hydrogen bonding and hydrophobic interactions. This study highlights the prospective utility of Antarctic krill-derived peptides in curtailing α-glucosidase activity, offering a theoretical foundation for the development of novel α-glucosidase inhibitors and related functional foods to enhance diabetes management.

Optimization of Hydrolysis Conditions, Isolation, and Identification of Biologically Active Peptides Derived from Acheta domesticus for Antioxidant and Collagenase Inhibition.

The study aimed to optimize hydrolysis conditions and isolate and identify bioactive peptides with anti-skin aging effects from Acheta domesticus (house cricket). A. domesticus proteins underwent hydrolysis using Alcalase® and optimized conditions using response surface methodology through a face-centered central composite design. Variable controls (enzyme-substrate concentration (E/S), time, and temperature) were assessed for their impact on activities against collagenase, 2,2-diphenyl-1-picrylhydrazyl radical (DPPH●), and degree of hydrolysis of protein hydrolysate (PH). PH was also investigated for composition, anti-skin aging, and anti-inflammatory effects. Amino acid sequences with potent anti-skin aging activity were isolated and identified using ultrafiltration, gel filtration chromatography, and liquid chromatography coupled with tandem mass spectrometry, employing de novo sequencing. Optimal conditions for producing PH with maximum anti-skin aging activity were an E/S concentration of 2.1% (w/w), 227 min, and 61.5 °C. Glutamic acid was a predominant amino acid and PH exhibited a molecular weight below 15 kDa. Additionally, PH displayed significant activities against collagenase, hyaluronidase, DPPH●, lipid peroxidation, and NF-κB-mediated inflammation (p < 0.05). Three novel anti-skin aging peptides were identified-Ala-Val-Thr-Lys-Ala-Asp-Pro-Tyr-Thr-Asp-Gln, Thr-Val-Met-Glu-Leu-Asn-Asp-Leu-Val-Lys-Ala-Phe, and Val-Pro-Leu-Leu-Glu-Pro-Trp-exhibiting the most potent collagenase and DPPH● inhibition. Therefore, this study proposed that PH, produced with Alcalase® under optimal conditions, emerges as a promising substance with potent anti-skin aging activity for the cosmeceutical industry.

Alkali hydrolysis of wool fibres using microwave irradiation as a recycling approach for handling wool-waste

The aim of the present work is to investigate the influence of microwave irradiation on alkali hydrolysis, under various thermochemical conditions, of wool fibres. This perspective seems to be a promising alternative for the valorization of wool waste. The reaction yield is calculated in every case in order to determine the optimum hydrolysis conditions. The solid residue, as well as the filtrate, are subjected to instrumental chemical analysis in order to identify and isolate useful products. The optimal conditions for the hydrolysis of wool resulted to be the use of 5% w/v NaOH, microwave treatment for 10 min in absence of phase-transfer catalyst. In addition, the analysis in the Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) allowed the identification of certain small molecules like N2, H2S, NH3, C6H5OH, C4H9NO and larger ones like amino acids, such as alanine, cystine, proline, valine and leucine. Additionally, the content of wool hydrolysate was specified upon identifying several substituted products of tyrosine, proline and alanine amino acids. Liquid Chromatography–Orbitrap High-Resolution Mass Spectrometry (LC–Orbitrap HRMS) was also employed to identify the components present in the wool hydrolysate, detecting mainly various dipeptides as well as leucylproline and cysteic acid. In this light, the amino acids produced by wool alkali hydrolysis degradation could valorise the wool waste once inserted in industrial chemistry, as a prominent alternative for “greener” adhesives of two components, outlining by these means the feasibility of a practically sustainable circular economy.

Monosaccharide composition of lignocellulosic matrix—Optimization of microwave-assisted acid hydrolysis condition

Compositional analysis of polysaccharides is crucial in many applications of analytical chemistry, and typically involves hydrolysis as initial step, to break glycosidic bonds and release individual monosaccharide units. We developed a new method for the microwave-assisted acid hydrolysis of polysaccharides, here applied for determining the composition of the polysaccharide fraction within the lignocellulosic matrix of Pinus sylvestris. The optimisation of reaction conditions was carried out using a GC–MS method after a double-step sugar derivatization process.Under the optimized conditions, specifically, employing 2 M TFA, 40 min, and 120 °C, a high depolymerisation yield was achieved with minimal degradation. Furthermore, the amount of polysaccharides detected in pine wood aligns with the results in existing literature, substantiating the determined chemical composition.The synergy of microwave-assisted acid hydrolysis and full factorial design not only facilitated the determination of the optimal hydrolysis conditions but also enabled the assessment of the parameters influencing the polysaccharide hydrolysis process and their relationships. This approach made it feasible to achieve maximum hydrolysis efficiency while minimizing analyte degradation, employing a method that reduces environmental impact through the use of microwave energy. This strategy effectively reduced the required reaction temperature, time, and reagent quantities.

Fabrication of carbon black nanoparticles from green algae and sugarcane bagasse

There are several industrial uses for carbon black (CB), an extremely fine powdered form of elemental carbon that is made up of coalesced particle aggregates and almost spherical colloidal particles. Most carbon black is produced from petroleum-derived feedstock, so there is a need to find an alternative method to produce CB, which relies on renewable resources such as algae and agricultural waste. A process involving hydrolysis, carbonization, and pyrolysis of green algae and sugarcane bagasse was developed, as the optimal hydrolysis conditions (16N sulfuric acid, 70 °C, 1 h, 1:30 g/ml GA or SC to sulfuric acid ratio), a hydrolysis ratio of 62% for SC and 85% for GA were achieved. The acidic solution was carbonized using a water bath, and the solid carbon was then further pyrolyzed at 900 °C. The obtained carbon black has a high carbon content of about 90% which is confirmed by EDX, XRD, and XPS analysis. By comparison carbon black from sugar cane bagasse (CBB) and carbon black from green algae Ulva lactuca (CBG) with commercial carbon black (CCB) it showed the same morphology which was confirmed by SEM analysis. The BET data, showed the high specific surface area of prepared CB, which was 605 (m2/g) for CBB and 424 (m2/g) for CBG compared with commercial carbon black (CBB) was 50 (m2/g), also the mean pore diameter of CBB, CBG and CCB indicated that CBB and CBG were rich in micropores, but CCB was rich in mesoporous according to IUPAC classification. This study might have created a technique that can be used to make carbon black from different kinds of biomass.

The Effect of Fermentation Time, pH and Saccharomyces Cerevisiae Concentration for Bioethanol Production from Ulva Reticulata Macroalgae

Research has been carried out on the effect of pH, fermentation time and yeast concentration on bioethanol production through hydrolysis using a CEM (Ceramic Elekctromagnetic Microwave) synthesizer and bioethanol production from Ulva reticulata seaweed. Ulva reticulata seaweed contains carbohydrates in the form of heteropolysaccharides such as glucose, arabinose, ramnose and xylose which are very abundant and suitable for conversion into bioethanol because the people of Timor Island do not use them as food. The carbohydrate content of Ulva reticulata seaweed can be converted into hexose and pentose sugars (glucose, arabinose, ramnose and xylose) through hydrolysis using 3 types of acid catalysts, namely hydrochloric acid (HCl), sulfuric acid (H2SO4) and nitric acid (HNO3). Fermentation was carried out with S. cerevisiae concentration variation of 6; 8; 10; 12 % (v/v) and fermentation time variation of 3; 5; 7; 9 days and a pH variation of 4; 4.5; 5; 5.5 at a temperature of 30 °C. Reducing sugar characterization used the Dinitrosalicylic acid (DNS) reagent, sample surface texture analysis was carried out using Scanning Electron Microscopy (SEM) and ethanol characterization used Gas Chromatography-Flame Ionization Detector (GC-FID). The results of surface texture analysis before and after hydrolysis experienced significant changes. Optimal conditions for hydrolysis of Ulva reticulata seaweed using sulfuric acid (H2SO4) combined with a CEM synthesizer at an acid concentration of 3 % (v/v) with irradiation power of 200 watts for 50 min at a temperature of 150 °C, produced reducing sugar of 97.06 g/L. The results of GC-FID analysis indicated that bioethanol concentration obtained at optimal conditions of pH 4.5 was 42.32 %, S. cerevisiae concentration was 12 % with a bioethanol content of 42.53 % at a fermentation time of 5 days. This research is expected to provide information for researchers and industry to overcome world energy problems and environmental pollution through Ulva reticulata waste. HIGHLIGHTS The results of surface texture analysis before and after hydrolysis experienced significant changes. Optimum conditions for hydrolysis of Ulva reticulata seaweed using sulfuric acid (H2SO4) combined with a CEM synthesizer at an acid concentration of 3 % (v/v) with irradiation power of 200 watts for 50 min at a temperature of 150 °C, producing reducing sugar of 97.06 g /L. GRAPHICAL ABSTRACT

Identification and anti-oxidative potential of milk fat globule membrane (MFGM)-derived bioactive peptides released through in vitro gastrointestinal digestion

This study investigated the stability of milk fat globule membrane (MFGM) protein under simulated gastrointestinal conditions using an in vitro enzymatic digestion method. The optimal hydrolysis conditions were determined by monitoring the changes in particle size and zeta-potential of MFGM protein hydrolysates over time. Furthermore, the distribution of small molecular weight peptides with antioxidant activity was explored through DEAE-52 combined with in vitro cell experiments. Two novel antioxidant peptides (TGIIT and IITQ) were identified based on molecular docking technology and evaluated their potential scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2′-Azinobis-(3-ethylbenzthiazoline-6-sulphonate) (ABTS+) radicals. TGIIT and IITQ also demonstrated remarkable abilities in promoting mitochondrial biogenesis and activating Keap1/Nrf2 signaling pathway, which can effectively counteract skeletal muscle dysfunction induced by oxidative stress. Thus, MFGM-derived antioxidant peptides have the potential to be employed in food to regulate muscle protein metabolism and alleviate sarcopenia.

Ethanol production from sugarcane bagasse by modified PDMS membrane in a membrane bioreactor: pervaporation technique

AbstractBACKGROUNDBioethanol is considered a highly promising alternative to fossil fuels due to its derivation from renewable sources. Reducing the disadvantages of conventional fermentation requires removing the product from the fermentation broth after its formation. Therefore, coupling the membrane separation with a biological process in a single unit leads a reduction of substrate and product inhibitions.RESULTSIn this work, bioethanol production was investigated in a membrane bioreactor (MBR) with sugarcane bagasse (lignocellulose waste) as a renewable source by the sulfuric acid hydrolysis process. Firstly, the optimum conditions to produce the maximum amount of sugar by acid hydrolysis were determined. Second, the membrane bioreactor and pervaporation unit equipped with poly(dimethyl siloxane) carbon nanotube/Tetrazole membrane (PDMS‐CNT/Tetrazole) was fabricated. Third, bioethanol production in a conventional batch reactor (CBR) and the novel MBR was implemented. The outcomes of the two kinds of reactors were then compared. The results illustrated that the optimum conditions for acid hydrolysis are at a temperature of 199.4 °C, an operation time of 30.77 min, and an acid concentration of 1.12%. The obtained data shows that the ethanol production in MBR was increased by 103.6% over conventional fermentation. Furthermore, the pervaporated ethanol concentration was higher than that of the broth because of the high membrane selectivity, where a maximum ethanol concentration of 165.7 g L−1 in the cold trap was achieved.CONCLUSIONFinally, the results illustrate that the MBR can decrease the cell density growth rate and dominate any substrate and product inhibitions, while keeping process productivity for ethanol quite high. © 2024 Society of Chemical Industry (SCI).

Optimizing bioconversion processes of rice husk into value-added products: D-psicose, bioethanol, and lactic acid

Rice husk, rich carbon content, is an agricultural waste produced globally at an amount of 120 million tons annually, and it has high potential as a biorefinery feedstock. Herein, we investigated the feasibility of producing various products as D-psicose, bioethanol and lactic acid from rice husk (RH) through a biorefinery process. Alkali-hydrogen peroxide-acetic acid pretreatment of RH effectively removed lignin and silica, resulting in enzymatic hydrolysis yield of approximately 86.3% under optimal hydrolysis conditions. By using xylose isomerase as well as D-psicose-3-epimerase with borate, glucose present in the RH hydrolysate was converted into D-psicose with a 40.6% conversion yield in the presence of borate. Furthermore, bioethanol (85.4%) and lactic acid (92.5%) were successfully produced from the RH hydrolysate. This study confirmed the high potential of RH as a biorefinery feedstock, and it is expected that various platform chemicals and value-added products can be produced using RH.

Dynamic changes of zinc chemical speciation and zinc-containing peptides release in oysters (Crassostrea hongkongensis) during enzymatic hydrolysis

Oyster hydrolysates exhibit promising potential as a zinc supplement for its significant amounts of zinc, however, the zinc chemical speciation which determines zinc nutrition in oyster hydrolysates has not been investigated. This study optimized the oyster hydrolysis conditions using the Response surface methodology (RSM) method, and the zinc chemical speciation, the sequence of zinc-containing peptides, and the binding sites of zinc and peptides were further investigated. Results showed that inorganic and organic zinc in oysters were 60.15% and 36.53% of total zinc respectively, while organic zinc in oysters aqueous extract was 4.54% of which 3.56% was present in the polysaccharide fraction. The zinc yield was 84.20% of total zinc under optimal hydrolysis conditions, while the organic zinc increased to 52.93% of which 38.14% existed in the protein/peptides fraction. Zinc in protein/peptide fraction primarily was bound to low-molecular-weight peptides (Mw < 1000 Da). Further, 42 shared zinc-containing peptides (mainly 3–4 peptides) were identified. Molecular docking indicated that Glu, Leu, and Tyr might be the binding sites for zinc and peptides. These findings provided a theoretical basis for the development of novel and safe zinc dietary supplements.

Pretreatment and enzymatic hydrolysis optimization of lignocellulosic biomass for ethanol, xylitol, and phenylacetylcarbinol co-production using Candida magnoliae.

Cellulosic bioethanol production generally has a higher operating cost due to relatively expensive pretreatment strategies and low efficiency of enzymatic hydrolysis. The production of other high-value chemicals such as xylitol and phenylacetylcarbinol (PAC) is, thus, necessary to offset the cost and promote economic viability. The optimal conditions of diluted sulfuric acid pretreatment under boiling water at 95°C and subsequent enzymatic hydrolysis steps for sugarcane bagasse (SCB), rice straw (RS), and corn cob (CC) were optimized using the response surface methodology via a central composite design to simplify the process on the large-scale production. The optimal pretreatment conditions (diluted sulfuric acid concentration (% w/v), treatment time (min)) for SCB (3.36, 113), RS (3.77, 109), and CC (3.89, 112) and the optimal enzymatic hydrolysis conditions (pretreated solid concentration (% w/v), hydrolysis time (h)) for SCB (12.1, 93), RS (10.9, 61), and CC (12.0, 90) were achieved. CC xylose-rich and CC glucose-rich hydrolysates obtained from the respective optimal condition of pretreatment and enzymatic hydrolysis steps were used for xylitol and ethanol production. The statistically significant highest (p ≤ 0.05) xylitol and ethanol yields were 65% ± 1% and 86% ± 2% using Candida magnoliae TISTR 5664. C. magnoliae could statistically significantly degrade (p ≤ 0.05) the inhibitors previously formed during the pretreatment step, including up to 97% w/w hydroxymethylfurfural, 76% w/w furfural, and completely degraded acetic acid during the xylitol production. This study was the first report using the mixed whole cells harvested from xylitol and ethanol production as a biocatalyst in PAC biotransformation under a two-phase emulsion system (vegetable oil/1M phosphate (Pi) buffer). PAC concentration could be improved by 2-fold compared to a single-phase emulsion system using only 1M Pi buffer.

Optimization of welan gum extraction and purification using lysozyme and alkaline protease.

Welan gum, a natural polysaccharide produced by Sphingomonas sp. ATCC 31555, has attracted considerable attention in the scientific community due to its desirable properties. However, challenges, such as high viscosity, residual bacterial cells, carotenoids, and protein complexation, hinder the widespread application of welan gum. In this study, we established a method for the extraction and purification of welan gum using a synergistic approach with lysozyme and alkaline protease. Lysozyme hydrolysis conditions were optimized by applying response surface methodology, and the best results for bacterial cell removal were achieved at 11 000 U/g, 44°C, and pH 9 after 3h of treatment. Subsequently, we evaluated protein hydrolysis through computer simulation and identified alkaline protease as the most suitable enzyme. Through experimental investigations, we found that the optimal conditions for alkaline protease hydrolysis were 7500 U/g, 50°C, pH 10, and 600rpm. These conditions resulted in a sugar recovery rate of 76.1%, carotenoid removal rate of 89.5%, bacterial removal rate of 95.2%, and protein removal rate of 87.3% after 3h of hydrolysis. The purified welan gum exhibited high transparency and purity. Structural characterization and antioxidant activity evaluation revealed that enzymatically purified welan gum has potential application prospects. Our study provides valuable insights into the optimal method for the enzymatic extraction and purification of welan gum. Such a method is conducive to the development of the multiple potential applications of welan gum. KEY POINTS: • A novel process for the synergistic purification of welan gum using lysozyme and alkaline protease was established. • In silico virtual digestion was employed to select the purification enzyme. • Welan gum with high transparency and purity was obtained.