Facile synthesis of alcalase-inorganic hybrid nanoflowers used for soy protein isolate hydrolysis to improve its functional properties

Spatially sequential co-immobilization of phosphorylases in tiny environments and its application in the synthesis of glucosyl glycerol

2-O-(α-d-glucopyranosyl)-sn-glycerol (2-αGG) has been applied in the food industry due to its numerous physiological benefits. The synthesis of 2-αGG can be achieved through a cascade catalytic reaction involving sucrose phosphorylase (SP) and 2-O-α-glucosylglycerol phosphorylase (GGP). However, the low substrate transfer rates between free enzymes have hindered the efficiency of 2-αGG synthesis. To address this issue, a novel technology was developed to prepare sequential multi-enzyme nanoflowers via chemical crosslinking and protein assembly, thus overcoming diffusion limitations. Specifically, spatially sequential co-immobilized enzymes, referred to as SP-GGP@Cap, were created through the targeted assembly of Bifidobacterium adolescentis SP and Marinobacter adhaerens GGP on Ca2+. This assembly was facilitated by the spontaneous protein reaction between SpyTag and SpyCatcher. Compared to free SP-GGP, SP-GGP@Cap demonstrated improved thermal and pH stability. Moreover, SP-GGP@Cap enhanced the biosynthesis of 2-αGG, achieving a relative concentration of 98 %. Additionally, it retained the ability to catalyze the substrate to yield 61 % relative concentration of 2-αGG even after ten cycles of recycling. This study presents a strategy for the spatially sequential co-immobilization of multiple enzymes in a confined environment and provides an exceptional biocatalyst for the potential industrial production of 2-αGG.

Enzyme hybrid nanoflowers and enzyme@metal-organic frameworks composites: fascinating hybrid nanobiocatalysts

Hybrid nanomaterials have recently emerged as a new interface of nanobiocatalysis, serving as a host platform for enzyme immobilization. Enzyme immobilization in inorganic crystal nanoflowers and metal-organic frameworks (MOFs) has sparked the bulk of scientific interest due to their superior performances. Many breakthroughs have been achieved recently in the preparation of various types of enzyme@MOF and enzyme-hybrid nanoflower composites. However, it is unfortunate that there are few reviews in the literature related to enzyme@MOF and enzyme-hybrid nanoflower composites and their improved synthesis strategies and their applications in biotechnology. In this review, innovative synthetic strategies for enzyme@MOF composites and enzyme-hybrid nanoflower composites are discussed. Enzyme@MOF composites and enzyme-hybrid nanoflower composites are reviewed in terms of biotechnological applications and potential research directions. We are convinced that a fundamental study and application of enzyme@MOF composites and enzyme-hybrid nanoflower composites will be understood by the reader as a result of this work. The summary of different synthetic strategies for enzyme@MOF composites and enzyme-hybrid nanoflower composites and the improvement of their synthetic strategies will also benefit the readers and provide ideas and thoughts in the future research process.

Immobilizing amyloglucosidase on inorganic hybrid nanoflowers to prepare time-temperature integrators for chilled pork quality monitoring

Time-temperature integrators (TTIs) based on amyloglucosidase@Cu3(PO4)2 nanoflowers (AMG@NFs) were developed to monitor the freshness of chilled pork. AMG@NFs were synthesized through biomineralization, resulting in enhanced activity and stability of amyloglucosidase. The TTI prototypes were constructed by hydrolyzing maltodextrin with AMG@NFs. The hue of the TTIs varied from burgundy to colorless, and the discoloration kinetics were investigated. The deterioration process of chilled pork was explored, and the activation energy (Ea) was calculated as 67.32 ± 5.13 kJ/mol. To optimize costs and match TTIs with food, 6#TTI was selected to predict the quality of chilled pork. The dynamic temperature test revealed that the cumulative effective temperatures of chilled pork and 6#TTI were 289.34 K and 290.05 K, respectively, which indicated that 6#TTI was highly reliable and suitable for monitoring the actual chilled pork system. This study offers a new approach for real-time and accurate visual monitoring of chilled pork quality.

Efficient biocatalytic removal and algal detoxification of Direct Blue-15 by the hierarchically structured, high-performance, and recyclable laccase@yttrium phosphate hybrid nanostructures

From the environmental point of view, azo dye industrial effluent is a major public health concern due to its toxic, carcinogenic, and teratogenic characteristics. On the other hand, using enzyme-based technologies offers a promising systematic and controllable method for removing synthetic dyes from wastewater. In the present study, yttrium (Y3+) phosphate was applied for the synthesis of hybrid nanoparticles (HNPs) consisting of laccase as the green catalyst. When the association of HNPs was fixed by glutaraldehyde (GA), three-dimensional cubic structures with the regular arrangement were provided. GA increased the reusability of the fabricated hybrid nanostructures (HNSs) up to 32 successive cycles. About 85% of Direct Blue-15 was removed after a 4 h-treatment using laccase@YPO4•HNPs and laccase@GA@YPO4•HNSs. The azo dye removal data were well-fitted with a pseudo-second-order model for both types of the prepared HNSs. For the model freshwater green alga Raphidocelis subcapitata, the half maximal effective concentration (EC50) of the dye decreased 10- and 100-fold after the removal with laccase@YPO4•HNPs and laccase@GA@YPO4•HNSs, respectively. GA-treated HNSs (250 U L-1) inhibited the biofilm formation by approximately 78%, 82%, and 79% for Escherichia coli, Staphylococcus aureus, and Bacillus subtilis, respectively. Thus, the fabricated laccase@GA@YPO4•HNSs could be presented as a novel, efficient, and recyclable heterogeneous biocatalyst for wastewater treatment and clean-up.

Preparation and investigation of novel endopeptidase-exopeptidase co-immobilized nanoflowers with improved cascade hydrolysis

Enzymatic hydrolysis is a promising approach for protein and food processing. However, the efficiency of this approach is constrained by the self-hydrolysis, self-agglomeration of free enzymes and the limited applicability resulted from enzymes' selectivityt. Here, novel organic-inorganic hybrid nanoflowers (AY-10@AXH-HNFs) were prepared by coordinating Cu2+ with both endopeptidase of PROTIN SD-AY10 and exopeptidase of Prote AXH. The results indicate that the AY-10@AXH-HNFs exhibited 4.1 and 9.6 times higher catalytic activity than free Prote AXH and PROTIN SD-AY10, respectively, for the enzymatic hydrolysis of N-benzoyl-L-arginine ethyl ester (BAEE). The kinetic parameters of Km, Vmax and Kcat/Km by AY-10@AXH-HNFs were determined to be 0.6 mg/mL, 6.8 mL·min/mg and 6.1 mL/(min·mg), respectively, surpassing the values obtained from free endopeptidase and exopeptidase. Furthermore, the ability of AY-10@AXH-HNFs to retain 41 % of their initial catalytic activity after undergoing 5 cycles of repeated use confirmed their stability and reusability. This study introduces a novel approach of co-immobilizing endopeptidase and exopeptidase on nanoflowers, resulting in significantly enhanced stability and reusability of the protease in catalytic applications.

Practical and Rapid Membrane-Based Biosensor for Phenol Using Copper/Calcium-Enzyme Hybrid Nanoflowers

Phenol, a pollutant frequently found in chemical industries effluents, is highly toxic even in low concentrations. This study reports a green, simple, and rapid method for qualitative phenol biosensing using horseradish peroxidase (HRP) hybrid nanoflowers made with copper (Cu²⁺-hNF) or calcium (Ca²⁺-hNF) ions. The enzyme was immobilized through protein-inorganic self-assembly into hybrid structures and subsequently supported onto a polyvinylidene fluoride (PVDF) membrane. SEM, EDS, FTIR, and XRD techniques sustained the effective enzyme encapsulation into hybrid structures. The protein concentration in the structures was 0.25 mg.mL^-1 for both ions. The best temperature and pH were 60 °C and 7.4, respectively, for both hybrids and the free enzyme, suggesting that the immobilization did not affect the optimal conditions of the free HRP. Thermal stability from 25 to 70 °C and pH stability from 4.0 to 9.0 of the hybrids were also determined. Finally, using copper and calcium hybrids, both biosensors produced onto a PVDF membrane could detect phenol in concentrations ranging from 0.72 to 24.00 µmol.mL^-1 in 1 min. In contrast, control biosensors produced with free enzyme have not presented a visible color change in the same conditions. The findings suggest a promising application of the developed biosensors in functional phenol detection.

Versatility of subtilisin: A review on structure, characteristics, and applications

Due to its thermostability and high pH compatibility, subtilisin is most known for its role as an additive for detergents in which it is categorized as a serine protease according to MEROPS database. Subtilisin is typically isolated from various bacterial species of the Bacillus genus such as Bacillus subtilis, B. amyloliquefaciens, B. licheniformis, and various other organisms. It is composed of 268-275 amino acid residues and is initially secreted in the precursor form, preprosubtilisin, which is composed of 29-residues signal peptide, 77-residues propeptide, and 275-residues active subtilisin. Subtilisin is known for the presence of high and low affinity calcium binding sites in its structure. Native subtilisin has general properties of thermostability, tolerance to neutral to high pH, broad specificity, and calcium-dependent stability, which contribute to the versatility of subtilisin applicability. Through protein engineering and immobilization technologies, many variants of subtilisin have been generated, which increase the applicability of subtilisin in various industries including detergent, food processing and packaging, synthesis of inhibitory peptides, therapeutic, and waste management applications.

Physicochemical Antioxidative and Emulsifying Properties of Soybean Protein Hydrolysates Obtained with Dissimilar Hybrid Nanoflowers

This study investigated the changes in the structure and properties of soybean protein after hydrolysis using two types of hybrid nanoflowers (alcalase@Cu3(PO4)2•3H2O (ACHNs) and dispase@Cu3(PO4)2•3H2O (DCHNs)) and examined the basic properties and oxidative stability of hydrolyzed soybean protein emulsions. The formations of the two hybrid nanoflowers were first determined using a scanning electron microscope, transmission electron microscope, and Fourier infrared spectroscopy. The structure and functional properties of soybean protein treated with hybrid nanoflowers were then characterized. The results indicated that the degree of hydrolysis (DH) of the ACHNs hydrolysates was higher than that of the DCHNs for an identical reaction time. Soybean protein hydrolysates treated with two hybrid nanoflowers showed different fluorescence and circular dichroism spectra. The solubility of the hydrolysates was significantly higher (p < 0.05) than that of the soybean protein (SPI) at all pH values tested (2.0−10.0)*: at the same pH value, the maximum solubility of ACHNs hydrolysates and DCHNs hydrolysates was increased by 46.2% and 42.2%, respectively. In addition, the ACHNs hydrolysates showed the highest antioxidant activity (DPPH IC50 = 0.553 ± 0.009 mg/mL, ABTS IC50 = 0.219 ± 0.019 mg/mL, and Fe2+ chelating activity IC50 = 40.947 ± 3.685 μg/mL). The emulsifying activity index of ACHNs and DCHNs hydrolysates reached its maximum after hydrolysis for 120 min at 61.38 ± 0.025 m2/g and 54.73 ± 0.75 m2/g, respectively. It was concluded that the two hydrolysates have better solubility and antioxidant properties, which provides a theoretical basis for SPI product development. More importantly, the basic properties and oxidative stability of the soybean-protein-hydrolysates oil-in-water emulsions were improved. These results show the importance of proteins hydrolyzed by hybrid nanoflowers as emulsifiers and antioxidants in the food and pharmaceutical industry.

Chitosan-regulated biomimetic hybrid nanoflower for efficiently immobilizing enzymes to enhance stability and by-product tolerance

Organic-inorganic hybrid nano-materials have been considered to be promising immobilization matrixes for enzymes due to their significantly enhanced reusability and stability of enzymes. Herein, we constructed a novel organic-inorganic hybrid nanoflower via biomacromolecule-regulated biomimetic mineralization to immobilize sucrose phosphorylase (SPase). It was found that chitosan (CS) effectively regulated the biomimetic mineralization of calcium phosphate (CaP), leading to the formation of flower-like hybrid materials for the entrapment of SPase via self-assembly to establish a nano-biocatalyst (CS-CaP@SPase). Upon immobilization, the obtained CS-CaP@SPase exhibited excellent pH, by-product and organic solvents tolerance, and storage stability. Specifically, at acidic condition (pH 4), CS-CaP@SPase performed over 80 % of initial activity, which was 2.42-folds higher than that of free SPase. The catalytic activity of free SPase was severely inhibited about 30 % in the presence of fructose (1.2 M), but CS-CaP@SPase only lost 5 % relative activity. The CS-CaP@SPase retained over 80 % of its relative activity, while the free SPase maintained <20 % of its relative activity in acetonitrile. The relative activity of CS-CaP@SPase was still retained about 80 % after 10 cycles and maintained 75 % after 15 days. Based on Raman spectra analysis, it was also found that the increased β-folding component of SPase in the secondary structure after immobilization was the main factor for its enhanced stability. It is reasonable to believe that biomacromolecule-regulated biomimetic mineralization could be potentially used as a promising method to immobilize enzymes with excellent stability and recyclability, thereby facilitating the preparation of highly efficient catalysts for industrial biocatalysts, biosensing, and biomedicine.

An updated review of functional properties, debittering methods, and applications of soybean functional peptides

Soybean functional peptides (SFPs) are obtained via the hydrolysis of soybean protein into polypeptides, oligopeptides, and a small amount of amino acids. They have nutritional value and a variety of functional properties, including regulating blood lipids, lowering blood pressure, anti-diabetes, anti-oxidant, preventing COVID-19, etc. SFPs have potential application prospects in food processing, functional food development, clinical medicine, infant milk powder, special medical formulations, among others. However, bitter peptides containing relatively more hydrophobic amino acids can be formed during the production of SFPs, seriously restricting the application of SFPs. High-quality confirmatory human trials are needed to determine effective doses, potential risks, and mechanisms of action, especially as dietary supplements and special medical formulations. Therefore, the physiological activities and potential risks of soybean polypeptides are summarized, and the existing debitterness technologies and their applicability are reviewed. The technical challenges and research areas to be addressed in optimizing debittering process parameters and improving the applicability of SFPs are discussed, including integrating various technologies to obtain higher quality functional peptides, which will facilitate further exploration of physiological mechanism, metabolic pathway, tolerance, bioavailability, and potential hazards of SFPs. This review can help promote the value of SFPs and the development of the soybean industry.

Assessment of obtaining sunflower oil from enzymatic aqueous extraction using protease enzymes

The aim of this work was to maximize the enzymatic aqueous extraction (EAE) of sunflower seed oil using protease enzymes from the evaluation of various temperatures, pH and enzyme concentrations, using a Box-Behnken experimental design. The effect of a thermal pre-treatment of sunflower seeds on free oil yield (FOY) and oil quality was also determined. In the experimental range adopted, a lower temperature (40 °C) provided higher FOY values, as well as the intermediate pH (8.00) and maximum enzyme concentration (9% v/v). Thermal pre-treatment provided an increase in FOY in the initial extraction times (60 to 180 min) and decreased of the extraction time of 4 to 3 h to obtain the highest FOY value (~16%). The fatty acid composition of the oils obtained showed a predominance of oleic (~47.5%) and linoleic acids (~39.5%). The total phytosterol content in the samples was hardly affected by the heat pre-treatment of the seeds, while the fatty acid profile, tocopherol content and oxidative stability were not altered.

Nanoflowers: A New Approach of Enzyme Immobilization

Enzymes are biocatalysts known for versatility, selectivity, and brand operating conditions compared to chemical catalysts. However, there are limitations to their large-scale application, such as the high costs of enzymes and their low stability under extreme reaction conditions. Immobilization techniques can efficiently solve these problems; nevertheless, most current methods lead to a significant loss of enzymatic activity and require several steps of activation and functionalization of the supports. In this context, a new form of immobilization has been studied: forming organic-inorganic hybrids between metal phosphates as inorganic parts and enzymes as organic parts. Compared to traditional immobilization methods, the advantages of these nanomaterials are high surface area, simplicity of synthesis, high stability, and catalytic activity. The current study presents an overview of organic-inorganic hybrid nanoflowers and their applications in enzymatic catalysis.

Self-assembled κ-carrageenase-inorganic hybrid nanoflowers exerting high catalytic efficiency with stable and recyclable properties

κ-Carrageenan oligosaccharides from κ-carrageenan hydrolysis are important biochemicals with more bioactivity. Enzyme engineering plays a key role in improving κ-carrageenase catalytic efficiency for production of κ-carrageenan oligosaccharides. Effect of metal ions on enzyme activity, especially stability and efficiency, is main factor in catalytic process, but metal ions addition leads to gelation of κ-carrageenan solution. In this study, molecular dynamics simulation was used to explore the interaction between κ-carrageenase CgkPZ and Ca²⁺, and Ca²⁺ bonded to D164 and E167 in the catalytic center resulting in the catalytic efficiency increase. Circular dichroism analysis indicated that the secondary structure of κ-carrageenase could change in the presence of Ca²⁺. Therefore, a novel self-assembly κ-carrageenase-inorganic hybrid nanoflowers CaNF@CgkPZ was synthesized and systematically characterized. The catalytic efficiency (k_cat/K_m) of CaNF@CgkPZ was 382.1 mL·mg^-1·s^-1, increased by 292% compared with free κ-carrageenase. Notably, the enzyme activity of CaNF@CgkPZ was not reduced significantly after 19 cycles use, and 70-100% relative activity was still retained when stored at 4-25 ℃ for 15 days. This work provides an efficient approach for κ-carrageenase immobilization with good storage stability, reusability and enhanced catalytic efficiency, which is of great significance in practical applications.

Organic-inorganic epoxide hydrolase hybrid nanoflowers with enhanced catalytic activity: Hydrolysis of styrene oxide to 1-phenyl-1,2-ethanediol

Epoxide hydrolases are ubiquitous in nature and are utilized to catalyze the cofactor-independent hydrolysis of epoxides to their corresponding diols. These enzymes have tremendous potential and have been applied in the synthesis of bulk and fine chemical industry and utilized as chiral building blocks. Herein, we report a green, facile, and economical method for immobilization of epoxide hydrolase based on biomimetic mineralization. The organic-inorganic hybrid nanoflowers have received tremendous attention due to their higher catalytic activity and stability. The nanoflowers were synthesized, with the organic component being enzyme epoxide hydrolase and the inorganic component being Ca²⁺ ions. A unique hierarchical flower-like spherical structure with hundreds of spiked petals was observed. The synthesized nanoflowers were applied for styrene oxide hydrolysis, producing 1-phenyl-1,2-ethanediol. Further, the factors influencing the morphology, catalytic activity, and stability studies were performed to study the activity recovery of the synthesized organic-inorganic hybrid epoxide hydrolase nanoflowers. The findings will have interesting applications.

Immobilized enzymes in inorganic hybrid nanoflowers for biocatalytic and biosensing applications

Enzyme immobilization has been accepted as a powerful technique to solve the drawbacks of free enzymes such as limited activity, stability and recyclability under harsh conditions. Different from the conventional immobilization methods, enzyme immobilization in inorganic hybrid nanoflowers was executed in a biomimetic mineralization manner with the advantages of mild reaction conditions, and thus it was beneficial to obtain ideal biocatalysts with superior characteristics. The key factors influencing the formation of enzyme-based inorganic hybrid nanoflowers were elucidated to obtain a deeper insight into the mechanism for achieving unique morphology and improved properties of immobilized enzymes. To date, immobilized enzymes in inorganic hybrid nanoflowers have been successfully applied in biocatalysis for preparing medical intermediates, biodiesel and biomedical polymers, and solving the environmental or food industrial issues such as the degradation of toxic dyes, pollutants and allergenic proteins. Moreover, they could be used in the development of various biosensors, which provide a promising platform to detect toxic substances in the environment or biomarkers associated with various diseases. We hope that this review will promote the fundamental research and wide applications of immobilized enzymes in inorganic hybrid nanoflowers for expanding biocatalysis and biosensing.

Understanding intricacies of bioinspired organic-inorganic hybrid nanoflowers: A quest to achieve enhanced biomolecules immobilization for biocatalytic, biosensing and bioremediation applications

The immobilization of biomolecules has been a subject of interest for scientists for a long time. The organic-inorganic hybrid nanoflowers are a new class of nanostructures that act as a host platform for the immobilization of such biomolecules. It provides better practical applicability to these functional biomolecules while also providing superior activity and reusability when catalysis is involved. These nanostructures have a versatile and straightforward synthesis process and also exhibit enzyme mimicking activity in many cases. However, this facile synthesis involves many intricacies that require in-depth analysis to fully attain its potential as an immobilization technique. A complete account of all the factors involving the synthesis process optimisation is essential to be studied to make it commercially viable. This paper explores all the different aspects of hybrid nanoflowers which sets them apart from the conventional immobilization techniques while also giving an overview of its wide range of applications in industries.

Facile synthesis of recyclable laccase-mineral hybrid complexes with enhanced activity and stability for biodegradation of Evans Blue dye

Two morphologies of laccase-mineral hybrid complexes, i.e., laccase-mineral hybrid nanoflowers (La-HNF) and nanopetals (La-HNP), were synthesized via biomineralization using Cu₃ (PO₄)₂·3H₂O as the mineral for Evans Blue (EB) dye biodegradation. XRD patterns and FT-IR spectra results revealed the successful immobilization of laccase via in-situ formed Cu₃(PO₄)₂·3H₂O crystals. Compared with free laccase, laccase-mineral hybrid complexes showed higher enzymatic activity due to the activation effect induced by copper ions of Cu₃(PO₄)₂·3H₂O, further, the improved kinetic parameters of laccase-mineral hybrid complexes could be ascribed to nanoscale-dispersed laccase molecules within hybrid complexes. For EB dye biodegradation, the reason why the biodegradation efficiency (94.9%) of La-HNF was higher than that (86.8%) of La-HNP could be synergistic effect of immobilized laccase within 3D hierarchical structure of La-HNF. In addition, the optimized biodegradation conditions (pH 4.6 and 40 °C) of La-HNF were obtained, moreover, 93.2% and 48.1% of EB dye were biodegraded by La-HNF after stored for 30 days and reused for 10 cycles, respectively, demonstrating La-HNF have good practicability.

Enzyme-Loaded Flower-Shaped Nanomaterials: A Versatile Platform with Biosensing, Biocatalytic, and Environmental Promise

As a result of their unique structural and multifunctional characteristics, organic-inorganic hybrid nanoflowers (hNFs), a newly developed class of flower-like, well-structured and well-oriented materials has gained significant attention. The structural attributes along with the surface-engineered functional entities of hNFs, e.g., their size, shape, surface orientation, structural integrity, stability under reactive environments, enzyme stabilizing capability, and organic-inorganic ratio, all significantly contribute to and determine their applications. Although hNFs are still in their infancy and in the early stage of robust development, the recent hike in biotechnology at large and nanotechnology in particular is making hNFs a versatile platform for constructing enzyme-loaded/immobilized structures for different applications. For instance, detection- and sensing-based applications, environmental- and sustainability-based applications, and biocatalytic and biotransformation applications are of supreme interest. Considering the above points, herein we reviewed current advances in multifunctional hNFs, with particular emphasis on (1) critical factors, (2) different metal/non-metal-based synthesizing processes (i.e., (i) copper-based hNFs, (ii) calcium-based hNFs, (iii) manganese-based hNFs, (iv) zinc-based hNFs, (v) cobalt-based hNFs, (vi) iron-based hNFs, (vii) multi-metal-based hNFs, and (viii) non-metal-based hNFs), and (3) their applications. Moreover, the interfacial mechanism involved in hNF development is also discussed considering the following three critical points: (1) the combination of metal ions and organic matter, (2) petal formation, and (3) the generation of hNFs. In summary, the literature given herein could be used to engineer hNFs for multipurpose applications in the biosensing, biocatalysis, and other environmental sectors.

Influence of ultrasound-assisted ionic liquid pretreatments on the functional properties of soy protein hydrolysates

In this work, the effect of dual-frequency ultrasound-assisted ionic liquids (ILs) pretreatment on the functional properties of soy protein isolate (SPI) hydrolysates was investigated. The degree of hydrolysis (DH) of SPI pretreated by ultrasound and [BMIM][PF₆] increased by 12.53% as compared to control (P < 0.05). More peptides with low molecular weight were obtained, providing support for the changes in DH. The trichloroacetic acid-nitrogen soluble index presented an increase, suggesting a better protein hydrolysate property. The increase in the calcium-binding activity showed the ultrasound-assisted ILs pretreatment could potentially improve bone health. The foaming capacity and stability of SPI hydrolysates pretreated by ultrasound-assisted [BMIM][PF₆] always increased remarkably as compared to ultrasound-assisted [BDMIM][Cl] pretreatment. However, the synergistic effect of ultrasound-assisted [BMIM][PF₆] on the emulsifying activity and antioxidant activities (DPPH and hydroxyl radical scavenging activity) was not as ideal as ultrasound-assisted [BDMIM][Cl] pretreatment, which may be affected by the structure of peptide. In conclusion, these results indicated the combination of dual-frequency ultrasound and ionic liquids would be a promising method to improve the functional properties of SPI hydrolysates and broaden the application scope of compound modification in proteolysis industry.

Interaction of Soy Protein Isolate Hydrolysates with Cyanidin-3-O-Glucoside and Its Effect on the In Vitro Antioxidant Capacity of the Complexes under Neutral Condition

The interaction of soy protein isolate (SPI) and its hydrolysates (SPIHs) with cyanidin-3-O-glucoside (C3G) at pH 7.0 were investigated to clarify the changes in the antioxidant capacity of their complexes. The results of intrinsic fluorescence revealed that C3G binds to SPI/SPIHs mainly through hydrophobic interaction, and the binding affinity of SPI was stronger than that of SPIHs. Circular dichroism and Fourier-transform infrared spectroscopy analyses revealed that the interaction with C3G did not significantly change the secondary structures of SPI/SPIHs, while the surface hydrophobicity and average particle size of proteins decreased. Furthermore, the SPI/SPIHs-C3G interaction induced an antagonistic effect on the antioxidant capacity (ABTS and DPPH) of the complex system, with the masking effect on the ABTS scavenging capacity of the SPIHs-C3G complexes being lower than that of the SPI-C3G complexes. This study contributes to the design and development of functional beverages that are rich in hydrolysates and anthocyanins.

Novel Zn-Binding Peptide Isolated from Soy Protein Hydrolysates: Purification, Structure, and Digestion

In this study, a novel Zn-binding peptide, Lys-Tyr-Lys-Arg-Gln-Arg-Trp (KYKRQRW), was purified and identified from soy protein isolate hydrolysates (SPIHs). The Zn-binding peptide exhibited improved Zn-binding capacity (83.21 ± 2.65%) than SPIH solutions. CD, NMR, and Fourier transform infrared spectroscopy were used to confirm the complexation between Zn and the peptide. The results showed that the Zn-binding peptide formed a folding structure with part of the β-sheet (29.3-13.4%) turning into random coils (41.7-57.6%) during complexation. It was further proved that the binding sites were located at the oxygen atoms on the carboxyl group of the Trp side chain and nitrogen atoms on the amino group of the Lys side chain. Moreover, the Zn-peptide complex exhibited increased solubility than ZnSO₄ during simulated gastrointestinal digestion. This study highlighted that the novel soy peptide possessed a strong zinc chelate rate and had a positive effect on the gastrointestinal stability of Zn which could be utilized as a functional ingredient in future.

Use of Alcalase in the production of bioactive peptides: A review

This review aims to cover the uses of the commercially available protease Alcalase in the production of biologically active peptides since 2010. Immobilization of Alcalase has also been reviewed, as immobilization of the enzyme may improve the final reaction design enabling the use of more drastic conditions and the reuse of the biocatalyst. That way, this review presents the production, via Alcalase hydrolysis of different proteins, of peptides with antioxidant, angiotensin I-converting enzyme inhibitory, metal binding, antidiabetic, anti-inflammatory and antimicrobial activities (among other bioactivities) and peptides that improve the functional, sensory and nutritional properties of foods. Alcalase has proved to be among the most efficient proteases for this goal, using different protein sources, being especially interesting the use of the protein residues from food industry as feedstock, as this also solves nature pollution problems. Very interestingly, the bioactivities of the protein hydrolysates further improved when Alcalase is used in a combined way with other proteases both in a sequential way or in a simultaneous hydrolysis (something that could be related to the concept of combi-enzymes), as the combination of proteases with different selectivities and specificities enable the production of a larger amount of peptides and of a smaller size.

A novel Pickering emulsion system as the carrier of tocopheryl acetate for its application in cosmetics

Pickering emulsion (PE) stabilized by bio-compatible polymer nanoparticles (NPs) was first developed for the encapsulation of lipophilic tocopheryl acetate (TA) for its application in cosmetics. The poly(lactide-co-glycolide) (PLGA)/poly(styrene-co-4-styrene-sulfonate) (PSS) NPs were prepared by solvent displacement, and then they were used as emulsifier particles to fabricate TA-encapsulated PE. It was found that the TA encapsulation efficiency was >98%. Scanning electron microscope analysis showed that the obtained PE exhibited 'shell' structure. The PE droplets had spherical shape with diameter around 2 μm and good dispersibility as evidenced by laser scanning confocal microscope. In addition, the PE was stable at the pH range of 4.29-7.07 which was compatible to skin pH. Meanwhile, the PE also showed good storage stability since there was no obvious change in its diameter, PDI and TA retention after storage at 4 °C for 30 days. The DPPH method confirmed that TA retained its antioxidation in the PE preparation process. Moreover, an improved UV irradiation stability was observed for the TA after being encapsulated in the PE. The results of cytotoxicity test suggested that the PE was compatible to the Hacat cell line (human immortalized keratinocytes). And there is negligible influence in the cellular uptake of TA after its encapsulation in the PE. However, the cellular antioxidant activity (CAA) of encapsulated TA presented a significant increase from 1.32 to 1.56 μM quercetin equivalent/mg·mL^-1. Hence, the prepared PE was promising as the carrier of TA for its cosmetic application.