Tailoring a cellulolytic enzyme cocktail for efficient hydrolysis of mildly pretreated lignocellulosic biomass

Commercially available cellulase cocktails frequently demonstrate high efficiency in hydrolyzing easily digestible pretreated biomass, which often lacks hemicellulose and/or lignin fractions. However, the challenge arises with enzymatic hydrolysis of mildly pretreated lignocellulosic biomasses, which contain cellulose, hemicellulose and lignin in high proportions. This study aimed to address this question by evaluating the supplementation of a commercial cellulolytic cocktail with accessory hemicellulases and two additives (H2O2 and Tween® 80). Statistical optimization methods were employed to enhance the release of glucose and xylose from mildly pretreated sugarcane bagasse. The optimized supplement composition resulted in the production of 304 and 124 mg g-1 DM of glucose and xylose, respectively, significantly increasing glucose release by 84% and xylose release by 94% compared to using only the cellulolytic cocktail. This enhancement might be attributed to a coordinated hemicellulases action degrading hemicellulose, creating more space for cellulase activity, potentially boosted by the presence of H2O2 and Tween® 80. However, the addition of different concentrations of H2O2 in combination with hemicellulase and Tween® 80 did not result a significant difference on sugar release, which could be attributed to the limited range of concentrations studied (5 to 65 µM). The results obtained in this study using the mix of three supplements were also compared to the addition of only hemicellulase and only Tween® 80 to the cellulolytic cocktail. A significant increase in glucose release of 39% and 41%, respectively, was observed when using the optimized combination. For xylose, the increase was 38% and 41%, respectively. This study underscores the substantial potential in optimizing enzyme cocktails for the hydrolysis of mildly pretreated lignocellulosic biomass by using enzymes and additive combinations tailored to the specific biomass composition.

Structural, functional and antioxidant properties of Lentinus edodes protein hydrolysates prepared by five enzymes

The purpose of this study was to investigate structural, functional and antioxidant properties of Lentinus edodes protein hydrolysates (LEPHs) by alcalase, protamex, trypsin, papain and neutrase. Structural and functional properties were determined using gel electrophoresis, Fourier transform infrared spectroscopy, laser scattering, fluorescence spectroscopy, emulsifying properties etc. Antioxidant activities were detected by Fe2+ chelating, hydroxyl and DPPH radical scavenging assays. Enzymatic hydrolysis destroyed secondary and tertiary structures of Lentinus edodes protein, decreased its molecular weight and particle size, particularly hydrolysate prepared by alcalase with the highest hydrolytic degree (32.86 ± 0.98 %), the smallest particle (130.77 ± 1.85 nm) and molecular weight (5.86 kDa). Moreover, alcalase hydrolysate exhibited the highest emulsifying stability, the strongest hydroxyl radical scavenging activity and Fe2+ chelating ability among LEPHs. Whilst trypsin hydrolysate displayed the highest DPPH radical scavenging, foaming and fat absorption capacity. These results provided basis for LEPH as ingredients to be used for food industry.

Efficient preparation of oyster hydrolysate with aroma and umami coexistence derived from ultrasonic pretreatment assisted enzymatic hydrolysis

In the study, an efficient protease Neutrase®-Flavourzyme® (NF) was screened to prepare the umami-aroma flavor oyster hydrolysate. The effect of protease and ultrasonic pretreatment (UP) assisted by the optimal protease on the flavor substances was investigated. The results demonstrated that the optimal UP-NF (450 W) showed a higher amino acid nitrogen content of 0.34 g/100 mL compared to the NF, and 19 major aroma compounds including octanal, decanal, nonanal, benzaldehyde, 2-undecanone, and 1-octen-3-ol were obtained. Additionally, the free amino acid and fatty acid spectrum indicated that the formation of flavor compounds was primarily due to the oxidation of linoleic and linolenic acids and the degradation of amino acids. Furthermore, taste analysis proved that increased umami and saltiness resulted from the accelerated release of Glu, Asp and 5'-IMP. Overall, UP-NF proved to be an effective method for producing umami-aroma flavor, facilitating further processing of oyster products for the application.

Optimisation of sugar and solid biofuel co-production from almond tree prunings by acid pretreatment and enzymatic hydrolysis

Almond pruning biomass is an important agricultural residue that has been scarcely studied for the co-production of sugars and solid biofuels. In this work, the production of monosaccharides from almond prunings was optimised by a two-step process scheme: pretreatment with dilute sulphuric acid (0.025 M, at 185.9-214.1 ℃ for 0.8-9.2 min) followed by enzyme saccharification of the pretreated cellulose. The application of a response surface methodology enabled the mathematical modelling of the process, establishing pretreatment conditions to maximise both the amount of sugar in the acid prehydrolysate (23.4 kg/100 kg raw material, at 195.7 ℃ for 3.5 min) and the enzymatic digestibility of the pretreated cellulose (45.4%, at 210.0 ℃ for 8.0 min). The highest overall sugar yield (36.8 kg/100 kg raw material, equivalent to 64.3% of all sugars in the feedstock) was obtained with a pretreatment carried out at 197.0 ℃ for 4.0 min. Under these conditions, moreover, the final solids showed better properties for thermochemical utilisation (22.0 MJ/kg heating value, 0.87% ash content, and 72.1 mg/g moisture adsorption capacity) compared to those of the original prunings.

Bioprocess to valorise fleshing produced in the tanning industry

This study focuses on circular bioeconomy and how to reduce the management of solid by-products in tannery facilities. To achieve this, double enzymatic hydrolysis has been developed, which allows the integrated management of both limed and fresh fleshing that are classified as category 3 animal by-products (ABPs). Fleshing has an average content of 15% fat, 20% protein and 65% water. To process these components independently, the fat fraction is separated from the protein and liquid protein fractions. This bioprocess has been developed from fleshing, yielding up to 78% mass recovery as biostimulants that are suitable for formulation and use in the fertiliser market. The efficacy of the protein fraction as a biostimulant was validated through laboratory tests, specifically by cabbage germination, which exhibited a notable improvement by 25%.

Multi-scale structural disruption induced by radio frequency air cold plasma accelerates enzymatic hydrolysis/ hydroxypropylation of tapioca starch

This study investigated the effects of radio frequency air cold plasma (RFACP) pretreatment on the multi-scale structures, physicochemical properties, enzymatic hydrolysis, and hydroxypropylation of tapioca starch. The results showed that cold plasma (CP) made starch granules rough on the surface and disrupted long- and short-range ordered structures, reducing relative crystallinity from 43.8 % to 37.4 % and R1047/1022 value from 0.992 to 0.934. Meanwhile, the starch molecules were depolymerized and oxidized by CP, reducing weight-average molecular weight from 9.64 × 107 to 2.17 × 107 g/mol, while increasing carbonyl and carboxyl groups by up to 118 % and 53 %. Additionally, CP-treated starches exhibited higher solubility and swelling power, along with lower gelatinization enthalpy. Short-time CP pretreatment (10 min) promoted the hydroxypropylation of starch and increased the molar substitution (0.081-0.112). Also, CP pretreatment accelerated enzymatic hydrolysis of starch, as indicated by the increase in hydrolysis rate (1.846 × 10-3-2.033 × 10-3 min-1) and degree of hydrolysis (51.45 % - 59.92 %). Overall, the multi-scale structural disruption induced by CP treatment facilitated the accessibility of enzymes/chemical reagents into starch granules and glucan chains. This study suggested that RFACP could be used for starch pretreatment to increase production efficiency in modified starch production, as well as in brewing and fermentation industries.

Characterization and the mechanism underlying the cryoprotective activity of a peptide from large yellow croaker (Pseudosciaena crocea)

Ice crystal-induced protein denaturation is the main cause of the deterioration of fish during frozen storage and transportation. In this study, the ultra-performance liquid chromatography - quadrupole - time of flight (UPLC-Q-TOF) technique was used to identify and screen tryptic peptides Ile-Glu-Glu-Leu-Glu-Glu-Leu-Glu-Ala-Glu-Arg (IEELEEELEAER) from large yellow croaker (Pseudosciaena crocea). The results were used study their cryoprotective effects on turbot fish meat during freeze-thaw cycles at different concentrations, and to investigate their anti-freezing mechanism. The results showed that the I-2.0 group effectively inhibiting the degeneration and structure changes of myofibrillar proteins after three freeze-thaw cycles, and the Ca2+-ATPase activity (1.65 μmolPi/mg/h), increased by 55.86% compared with that of the control group. Additionally, peptide IEELEEELEAER could provide antifreeze protection by binding to the surface of ice crystals and inhibiting their transformation. This peptide acts as a natural cryoprotectant and might be used for the cryogenic storage and transportation of fish products.

p-Toluenesulfonic acid enhanced neutral deep eutectic solvent pretreatment of soybean straw for efficient lignin removal and enzymatic hydrolysis

Deep eutectic solvent (DES) is a newly-emerged green solvent for efficient pretreatment of lignocellulosic feedstock. To improve the component fractionation performance of neutral DES, p-toluenesulfonic acid (p-TsOH) was employed as catalyst to form a novel ternary DES with benzyltriethylammonium chloride (TEBAC) and glycerol (Gly) for pretreatment of soybean straw. Under the optimum reaction conditions (TEBAC:Gly = 1:12, 1.6 wt% p-TsOH and reacted at 90 °C for 160 min), the lignin and hemicellulose removal from soybean straw were amounted to 92.0 % and 88.2 %, respectively. The pretreated substrate showed satisfactory enzymatic hydrolysis performance, as the glucose and reducing sugar concentrations reached 37.3 g/L and 42.3 g/L, respectively, after 72 h saccharification under the action of cellulase with a relatively low enzyme loading of 10 FPU/g cellulose.This method provides an efficient and mild route for utilization of agricultural waste and production of platform monosaccharides.

A green strategy for collagen extraction from tannery raw trimmings using papain enzyme: Process optimization by MW-TOPSIS for enhanced yield

The leather industry poses a significant environmental problem through the extensive discharge of trimming waste, primarily composed of skin matrix rich in proteins. Developing a green approach for utilizing this waste can contribute to the sustainable recovery of proteins, transforming them into valuable bioresources. This study introduces an environmentally friendly and economically viable approach to extract collagen from tannery raw trimming waste using papain enzyme-derived from papaya leaves. The research involved extensive assessments and trials to optimize the enzymatic hydrolysis process. The highest collagen recovery was achieved by hydrolyzing 5 % (w/v) delimed powder with 4 % (w/v) crude papain enzyme from papaya leaf powder, maintaining it at 60 °C for 6 h and at pH 5. Collagen extraction from raw trimming waste using acetic acid was also performed, with the optimized papain enzyme-based hydrolysis process resulting in approximately 91 % yield, while conventional acetic acid method yielded approximately 84 %. To evaluate the performance of the enzymatic hydrolysis process in comparison to acid hydrolysis and hydrothermal hydrolysis, an integrated MW-TOPSIS framework was proposed. This framework determined that enzymatic hydrolysis achieved the highest closeness coefficient value (Ri = 0.40), indicating its superiority as the preferred alternative among the tested methods.

Effect of alkali treatment on enzymatic hydrolysis of p-toluenesulfonic acid pretreated bamboo substrates

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.

Prebiotic potential of pectin and cello-oligosaccharides from apple bagasse and orange peel produced by high-pressure homogenization and enzymatic hydrolysis

Apple bagasse and orange peel were subjected to high-pressure homogenization (HPH), enzymatic hydrolysis (EH) and their combination (HPHE) to study their effect on oligosaccharide production and in vitro fermentability. The application of a cellulase-pectinase mixture on the by-products generated significant quantities of cellobiose (COS-2) and pectin derived oligosaccharides (POS) which were identified as mainly methylated and acetylated oligogalacturonides with DP 2-5 (POS 2-5). When pre-treating the substrates with HPH, the release in orange peel was enhanced significantly leading to a POS content of 44.51 g/100 g peel, whereas oligosaccharide solubilization in apple bagasse was not affected. In vitro fermentation of the hydrolysates containing COS-2 and POS showed faster fermentation rates, between 6 and 10 h, and enhanced gas production, compared to those samples not subjected to enzymatic hydrolysis. Short chain fatty acid (SCFA) production was not impacted by the presence of POS and COS-2 in the induced quantities.

Upcycling mango peels into a functional ingredient by combining fermentation and enzymatic-assisted extraction

This study aims at upcycling mango peels by a sequential application of enzymatic hydrolysis, using Viscozyme and Pectinex at 50 °C for 2 h; and fermentation, using L. plantarum and B. animalis at 48 h for 37 °C. The use of Viscozyme led to a considerable increase in the concentration of galacturonic and glucuronic acids in the unfermented samples (308.96 and 12.97 mg/100 ml higher than control, respectively), whereas the use of Pectinex resulted in higher oligosaccharide solubilization (5.3 % more than control). None of the enzymes influenced microbiological growth. The recovery of gallic acid aglycone increased 17-fold over the control when Pectinex and B. animalis were used. Similarly, the recovery of mangiferin aglycone increased by 60 % after fermentation by either bacteria. The results indicate that this sequential processing strategy might be utilized to extract phenolic aglycones and produce functional ingredients from mango peels.

Sustainable structural polysaccharides conversion: How does DES pretreatment affect cellulase adsorption, thereby improving enzymatic digestion of lignocellulose?

Biomass conversion aims at degrading the structural polysaccharides of lignocellulose into reducing sugars. Pretreatment is necessary to overcome the recalcitrance of lignocellulose. The DES La/ChCl in this paper was selected based on our previous study. To examine cellulase adsorption of lignocellulose after DES pretreatment, sorghum straw was pretreated with DES under different condition. The adsorption improvement of cellulase on lignocellulose after DES pretreatment has positive impact on reducing sugar production of biomass. After DES pretreatment, 1. pore corrosion caused the upward trend of pore radius and the downward trend of SSA. 2. the hydrogen bounding force of pretreated sorghum straw and MCC decreased, the hydrogen bounding force of pretreated lignin increased. 3. although the unsaturation of pretreated lignin increased, DES pretreatment is helpful for the removal of lignin. 4. The decrease in the hydrophobicity of sorghum straw make it easier to disperse. 5. the Zeta potential of pretreated sorghum straw shifted towards the positively charged region, while pretreated lignin shifted towards the negatively charged region. 6. different adsorption behaviors were observed in specific components of cellulase mixtures (BGs, CBHs, EGs and xlylanase). These results revealing the mechanism of enzyme adsorption are conductive for understanding the role of pretreatment in biomass conversion.

Potential of ionic liquids as emerging green solvent for the pretreatment of lignocellulosic biomass

Lignocellulosic biomass is available in abundance as a renewable resource, but the major portion of it is often discarded as waste without utilizing its immense potential as an alternative renewable energy resource. To overcome recalcitrance of lignocellulosic biomass, various pretreatment methods are applied to it, so that the complex and rigid polymeric structure can be broken down into fractions susceptible for enzymatic hydrolysis. Effective and efficient biomass processing is the goal of pretreatment methods, but none of the explored pretreatment methods are versatile enough to fulfil the requirement of biomass processing with greater flexibility in terms of operational cost and desired output efficiency. Deployment of green solvents such as ionic liquids for the pretreatment of lignocellulosic biomass has been a topic of discussion amongst the scientific community in recent times. The presented work provides a detailed overview on the deployment of ionic liquid for the pretreatment of lignocellulosic biomass coupled with a brief discussion on other pretreatments methods. The recyclability and reusability along with other unique properties makes an ionic liquid pretreatment different from the other traditional pretreatment methods. Also, this study explores diverse critical parameters that governs the dissolution process of biomass. Hazardous properties of ionic liquids have also been explored. Future perspective and recommendations have been given for an efficient, effective, and eco-friendly deployment of ionic liquid in biomass pretreatment process.

Bioconversion of spray corn husks into L-lactic acid with liquid hot water pretreatment

Agricultural by-products like rice husk, bran, and spray corn husks, often utilized as feed, are considered less desirable. This study aims to enhance the utilization rate of these materials by subjecting then to liquid hot water (LHW) pretreatment, followed by enzymatic hydrolysis to produce fermentable sugars. We investigated the production of L-lactic acid using two methods: simultaneous saccharification fermentation (SSF) and separate hydrolysis fermentation (SHF), following varying intensities of LHW pretreatment. The results showed that the optimal enzymatic hydrolysis efficiency was achieved from spray corn husks under the pretreatment conditions of 155 °C and 15 min. SHF was generally more effective than SSF. The glucose L-lactic acid conversion rate in SHF using spray corn husks can reach more than 90 %. Overall, this work proposed a novel, environmental-friendly strategy for efficient and for L- lactic acid production from spray corn husks.

1-Ethyl-3-methylimidazolium acetate pretreatment for maximizing reducing sugar recovery from mixed cabbage residue

Vegetable waste, including mixed cabbage residue (MCR), is considered a promising raw material for bioenergy production because of its high lignocellulosic component. In this study, the pretreatment of MCR by ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) was optimized based on response surface methodology. The optimal condition for MCR pretreatment was determined at 55.8 °C, with a reaction of 2.65 h and liquid-solid ratio of 4.60:1 v/w. Hydrolysis of pretreated MCR from optimal pretreatment conditions generated a maximum glucose yield of 156.65 ± 7.66 mg/g MCR. Untreated and pretreated MCRs were successfully characterized by scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The pretreated MCR exhibited increased clear pores and incomplete structure. Moreover, compared with untreated biomass, decreased lignin, decreased hemicellulose, increased surface area, and cellulose crystallinity were observed. Thus, [Emim][OAc] pretreatment is a promising alternative approach for higher glucose production from MCR.

Treatment and mechanism for hot melting starch by reducing the molecular chain winding and crystallinity

Unlike thermoplastic petroleum-based materials, starch-based materials rely on aqueous systems but are incapable of hot melting, resulting in low processing efficiency and limited large-scale industrial applications. In this study, the combination of α-amylase liquefaction and urea plasticization was used for the first time to obtain enzymatic thermoplastic starch (ETPS) for hot melting by changing the molecular chain of starch. ETPS showed an apparent hot melting phenomenon when heated below 200 °C. Differential scanning calorimetry revealed that heat absorption peaks were obviously reduced, and the hot melting phenomenon occurred easily depending on the combination of enzymatic hydrolysis and plasticization. Dynamic mechanical analysis indicated that the combined modification effectively increased the number of freely movable chains. The red shift of -OH stretching vibration peaks indicated the formation of strengthened hydrogen bonds in ETPS. X-ray diffraction showed that the crystallinity of ETPS was reduced to 5.68 %, effectively reducing the regenerative phenomenon. Gel permeation chromatography revealed that the molecular weight of ETPS decreased, and the entanglements between molecular chains were reduced. A tensile test showed that the elongation at break of ETPS was as high as 235.29 %, which was much higher than those of enzymatic hydrolysis starch and thermoplastic starch.

From feed to functionality: Unravelling the nutritional composition and techno-functional properties of insect-based ingredients

In recent years, there has been a growing interest in using insects as a sustainable resource for biorefinery processes. This emerging field aims to convert insect biomass into valuable products while minimizing waste. The integration of emerging green technologies and the efficient extraction of high-value compounds from insects offer promising avenues for addressing the growing demand for sustainable food production and resource utilization. The review examines the impact of dietary modifications on the nutritional profile of insects. It highlights the potential for manipulating insect feed to optimize protein quality, amino acid profile, lipid content and fatty acid composition. Additionally, innovative green processing technologies such as ultrasound, high pressure processing, pulsed electric fields, cold plasma and enzymatic hydrolysis are discussed for their ability to enhance the extraction and techno-functional properties of insect-based ingredients. The review finds that dietary modifications can impact the nutritional composition of insects, allowing the customization of their nutrient content. By optimizing the insect feed, it is possible to increase the quantity and improve the quality of essential nutrients like proteins or lipids in the derived ingredients. Moreover, alternative processing technologies can improve the techno-functional properties (e.g., solubility, water and oil holding capacities, among others) of insect-based ingredients by modifying proteins' conformation. By harnessing these strategies, researchers and industry professionals can unlock the full potential of insects as a sustainable and nutritional food source, paving the way for innovative insect-based food products.

Integrated acetic acid and deep eutectic solvent pretreatment on poplar for co-production of xylo-oligosaccharides, fermentable sugars and lignin antioxidants/adsorbents

Efficient fractionation of lignocellulosic biomass in usable forms of hemicellulose, cellulose and lignin is very important for the sustainable lignocellulosic biorefinery. Herein, poplar sawdust was pretreated with an integrated process composed of acetic acid pre-hydrolysis (170 °C, 60 min) for xylo-oligosaccharides (XOS) production and mild deep eutectic solvent (90-130 °C, 60 min) post-delignification for recovering lignin fractions, resulting in easily hydrolyzed cellulose fraction. Results showed that, after integrated pretreatment and enzymatic hydrolysis, 51 % of xylan and 92 % of glucan in raw biomass could be converted to XOS (DP 2-6) and glucose, respectively, while 71 % of the original lignin could be recovered in DES solvent. The resulting XOS were proven to ensure the growth of probiotics, Bifidobacterium adolescentis. Besides, the lignin macromolecules recovered from DES solvent showed high-purity (around 95 %), low-molecular weight (Mw around 2000), small particle size (270-170 nm) and high-PhOH (3.08 mmol/g) content, which were likely relevant to the excellent antioxidant activity (RSI = 15.16) and adsorbent activity (Pb(II) 461.89 mg/g lignin). Finally, mass balance and energy analysis revealed that the integrated pretreatment could be used as a promising approach for the production of bio-based chemicals and materials from woody biomass.

Unveiling the potential of novel recyclable deep eutectic solvent pretreatment: Effective separation of lignin from poplar hydrolyzed residue

To effectively convert the fermentable sugars present in lignocellulosic biomass into biofuels and additional value-added products, it is crucial to remove lignin from the biomass. With the intention of expeditiously remove lignin from poplar wood and improve cellulose saccharification, an innovative ternary deep eutectic solvent (DES) benzyl triethyl ammonium chloride-ethylene glycol-FeCl3 (T-EG-F) was studied for the pretreatment of poplar hydrolyzed residue (PHR). The results revealed that following T-EG-F DES pretreatment at 130 °C for 4 h, the lignin removal rate reached 91.88 %. The effect of DES on PHR and regenerated lignin was comprehensively investigated using X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), Thermogravimetric (TG) and other characterization methods, providing valuable insights into the mechanism of this innovative biomass pretreatment. Moreover, there was a significant improvement in the enzyme digestibility of the DES pretreatment residue. At 48 h, the enzyme load of 30 FPU/g cellulose achieved a remarkable enzyme digestibility of 97.31 %, and this value exhibited a notable increase of 6.56 times compared to the untreated poplar sample. In addition, the T-EG-F could be recycled and reused. This study demonstrates that the potential of T-EG-F DES pretreatment as a green and efficient method for lignin dissociation from lignocellulosic biomass, offering a promising approach for biomass component separation.

Modulating digestibility and stability of Pickering emulsions based on cellulose nanofibers

Cellulose nanofibers (CNF) have been widely studied for their biodegradability and for their unique advantages as a stabilizer in Pickering-type emulsions. However, it is challenging to produce cellulose nanofibers from agroindustry waste with good techno-functional properties, without the use of harsh process conditions. Green alternatives (eco-friendly) have been studied to obtain nanofibers, such as enzymatic hydrolysis and/or application of mechanical processes. In this work, we used acid hydrolysis (as a control and example of an efficient method), enzymatic hydrolysis and a mechanical process (ultrasound) to obtain cellulose nanofibers. We also evaluated the effect of the presence of ethyl groups in the cellulosic matrix (ethylcellulose) on the stabilizing mechanism of emulsions. All cellulose nanofibers were able to produce Pickering emulsions at concentrations of 0.01-0.05% (w/w), although showing differences in emulsion stability and digestibility. Morphology of the different cellulose nanofibers affected the viscosity of the aqueous suspensions used as continuous phase. Emulsions with nanofibers obtained from cassava peel (without the presence of ethyl groups) were stabilized only by the Pickering-type mechanism, while ethylcellulose nanofibers also showed surface activity that contributed to the stability of the emulsion. Furthermore, these latter emulsions showed greater release of free fatty acids in in vitro digestion compared to emulsions stabilized by cellulose nanofibers. Despite these differences, in vitro digestion showed the potential of applying cellulose-stabilized emulsions to control the rate of lipid digestion, due to the low amount of free fatty acids released (<20%).

Production of Rhamnosyl Icariside II by snailase hydrolysis of Epimedium wushanense extracts

Rhamnosyl Icariside II is a rare secondary flavonoid glycoside isolated from Epimedium L. plants. It has better stability and physiological activity than the primary flavonoid glycosides of Epimedium L., therefore, conversion of the primary flavonoid glycoside into Rhamnosyl Icariside II would be desirable. In this study, a method for the enzymatic production of Rhamnosyl Icariside II from the total flavonoids of Epimedium wushanense was established, and the conditions were optimized. Six commercial enzymes were screened, and the reaction conditions for the best enzyme were optimized. Snailase was the most effective hydrolase, and the highest yield was obtained under the optimized conditions. To facilitate industrial production of Rhamnosyl Icariside II, a scaled-up pilot test was performed. The reaction solution was extracted with n-butanol to obtain the Rhamnosyl Icariside II crude product, which was then subjected to silica gel column chromatography and preparative chromatography. Finally, a product of Rhamnosyl Icariside II with purity of 99.1 % was achieved, in a total yield of 46.8 %. Compared to direct extraction and acid hydrolysis, this method improves the product yield and purity, which is of great significance for the large-scale production of Rhamnosyl Icariside II. This study provides a basis for the physiological activity study of Rhamnosyl Icariside II, and offers possibilities for future applications in the healthcare sector.

Covalent connectivity of glycogen in brewer's spent yeast cell walls revealed by enzymatic approaches and dynamic nuclear polarization NMR

Yeast cell walls undergo modifications during the brewing process, leading to a remodelling of their architecture. One significant change is the increased insolubility of the cell wall glycogen pool, likely due to the formation of covalent bonds between glycogen and cell wall polysaccharides. To verify this hypothesis, we extracted the brewer's spent yeast with 4 M KOH, obtaining an insoluble glucan fraction (AE.4 M) primarily composed of (α1 → 4)- and (1 → 3)-linked Glc residues. Dynamic nuclear polarization solid-state NMR of AE.4 M revealed distinct glucan resonances that helped to differentiate between α- and β glucosyl (1 → 4)-linked residues, and confirm covalent linkages between (β1 → 3)-glucans and glycogen through a (β1 → 4)-linkage. The hydrolysis with different endo-glucanases (zymolyase, cellulase, and lichenase) was used to obtain solubilized high molecular weight glycogen fractions. NMR analysis showed that covalent links between glycogen and (β1 → 6)-glucans through (α1 → 6) glycosidic linkage, with branching at the C6 position involving (β1 → 3), and (β1 → 6)-glucans. HPAEC-PAD analysis of the enzymatically released oligosaccharides confirmed covalent linkages of (β1 → 3), (β1 → 6)-, and (β1 → 4)-glucan motifs with (α1 → 4)-glucans. This combination of multiple enzymatic approaches and NMR methods shed light into the role of yeast cell wall glycogen as a structural core covalently linked to other cell wall components during the brewing process.

Bioprospecting CAZymes repertoire of Aspergillus fumigatus for eco-friendly value-added transformations of agro-forest biomass

BACKGROUND

Valorizing waste residues is crucial to reaching sustainable development goals and shifting from a linear fossil-based economy to a circular economy. Fungal cell factories, due to their versatility and robustness, are instrumental in driving the bio-transformation of waste residues. The present work isolated a potent strain, i.e., Aspergillus fumigatus (ZS_AF), from an ancient Złoty Stok gold mine, which showcased distinctive capabilities for efficient hydrolytic enzyme production from lignocellulosic wastes.

RESULTS

The present study optimized hydrolytic enzyme production (cellulases, xylanases, and β-glucosidases) from pine sawdust (PSD) via solid-state fermentation using Aspergillus fumigatus (ZS_AF). The optimization, using response surface methodology (RSM), produced a twofold increase with maximal yields of 119.41 IU/gds for CMCase, 1232.23 IU/gds for xylanase, 63.19 IU/gds for β-glucosidase, and 31.08 IU/gds for FPase. The secretome profiling validated the pivotal role of carbohydrate-active enzymes (CAZymes) and auxiliary enzymes in biomass valorization. A total of 77% of carbohydrate-active enzymes (CAZymes) were constituted by glycoside hydrolases (66%), carbohydrate esterases (9%), auxiliary activities (3%), and polysaccharide lyases (3%). The saccharification of pretreated wheat straw and PSD generated high reducing sugar yields of 675.36 mg/g and 410.15 mg/g, respectively.

CONCLUSION

These findings highlight the significance of an efficient, synergistic, and cost-effective arsenal of fungal enzymes for lignocellulosic waste valorization and their potential to contribute to waste-to-wealth creation through solid-waste management. The utilization of Aspergillus fumigatus (ZS_AF) from an unconventional origin and optimization strategies embodies an innovative approach that holds the potential to propel current waste valorization methods forward, directing the paradigm toward improved efficiency and sustainability.

Comprehensive structural characterization of water-soluble and water-insoluble homoexopolysaccharides from seven lactic acid bacteria

Several lactic acid bacteria are able to produce water-soluble and water-insoluble homoexopolysaccharides (HoEPS) from sucrose. In this study, structures of all HoEPS which were fermentatively produced by Leuconostoc mesenteroides subsp. dextranicum NRRL B-1121 and B-1144, Leuconostoc mesenteroides subsp. mesenteroides NRRL B-1149, B-1438 and B-1118, Leuconostoc suionicum DSM 20241, and Liquorilactobacillus satsumensis DSM 16230 were systematically analyzed. Monosaccharide analysis, methylation analysis, NMR spectroscopy, size-exclusion chromatography, and different enzymatic fingerprinting methods were used to obtain detailed structural information. All strains produced water-soluble dextrans and/or levans as well as water-insoluble glucans. Levans showed different degrees of branching and high molecular weights, whereas dextrans had comparable structures and broader size distributions. Fine structures of water-soluble HoEPS were analyzed after endo-dextranase and endo-levanase hydrolysis. Water-insoluble glucans were composed of different portions of 1,3-linkages (5 to 40 %). Hydrolysis with endo-dextranase and endo-mutanase yielded further information on block sizes and varying fine structures. Overall, clear differences between HoEPS yields and structures were observed.