Carrier Material Research Articles

Formation and non-covalent interactions of binary and ternary complexes based on β-casein, Lentinus edodes mycelia polysaccharide, and taxifolin

Polyphenols, polysaccharides, and proteins are essential nutrients and functional substances present in food, and when present together these components often interact with each other to influence their structure and function. Proteins and polysaccharides are also excellent carrier materials for polyphenols. In this context, this study investigated the non-covalent interactions between taxifolin (TAX), Lentinus edodes mycelia polysaccharide (LMP), and β-casein (β-CN). β-CN and LMP spontaneously formed nanocomplexes by hydrogen bonds and van der Waals forces. The quenching constant and binding constant were (1.94 ± 0.02) × 1013 L mol−1 s−1 and (3.22 ± 0.17) × 105 L mol−1 at 298 K, respectively. The altered conformation of β-CN, resulting from the binding to LMP, affected the interaction with TAX. LMP significantly enhanced the binding affinity of TAX and β-CN, but did not change the static quenching binding mode. The binding constant for β-CN-TAX was (3.96 ± 0.09) × 1013 L mol−1, and that for the interaction between TAX and β-CN-LMP was (32.06 ± 0.05) × 1013 L mol−1. In summary, β-CN-LMP nanocomplexes have great potential as a nanocarrier for polyphenols, and this study provides a theoretical foundation for the rational design of non-covalent complexes involving LMP and β-CN, both in binary and ternary configurations.

Dual single atomic Ni sites constructing Janus hollow graphene for boosting electrochemical sensing of glucose.

Single atom catalysts (SACs) have attracted attention due to their excellent catalysis activity under specific reactions and conditions. However, the low density of SACs greatly limits catalytic performance. The three-dimensional graphene hollow nanospheres (GHSs) with very thin shell structure can be used as excellent carrier materials. Not only can its outer surface be used to anchor metal single atoms, but its inner surface can also provide rich sites. Here, a novel step-by-step assembly strategy is reported to anchor nickel single atoms (Ni SAs) on the inner and outer surfaces of GHSs (Ni SAs/GHSs/Ni SAs), which significantly increases the loading capacity of Ni SAs (4.8 wt%). Compared to conventional materials that only anchor Ni SAs to the outer surface of the carrier (Ni SAs/GHSs), Ni SAs/GHSs/Ni SAs exhibits significantly higher electrocatalytic activity toward glucose oxidation in alkaline media. The sensitivity of Ni SAs/GHSs/Ni SAs/GCE is nearly five times higher than that of Ni SAs/GHSs/GCE. Moreover, the sensor based on Ni SAs/GHSs/Ni SAs can detect glucose in a wide concentrationrange of 0.8µM-1.1244mM with a low detection limit of 0.19µM (S/N = 3). This study not only provides an effective sensing material for glucose detection, but also opens a new avenue to construct high-density metal SACs.

Bio-stimulant based nanodelivery system for pesticides with high adhesion and growth stimulation

Pesticides are important agricultural production materials to ensure global food security, but the low utilization rate during pesticide application has caused a large amount of waste and environmental pollution. The use of pesticide carriers to deliver pesticides can help to prevent rapid release, assist in targeted release, and improve pesticide utilization. However, after completing pesticide delivery, less part of pesticide carriers has more functions and may remain in the environment, leading to material waste and environmental burden. Here, we propose that the environment-friendly carrier materials for pesticide delivery can synergistically enhance control efficacy with pesticides. Based on the bio-stimulant polyglutamic acid, amphiphilic polymers (mPEG-b-PLG) were constructed, and they assembled into nano micelle. After encapsulating prothioconazole (PTC) into the nano micelle through hydrogen bonding, electrostatic interactions and hydrophobic interactions through co-assembly, mPEG-b-PLG-PTC nanospheres with a diameter of approximately 120 nm were prepared. The nanospheres exhibit pH responsiveness for targeted release of pesticides, as well as excellent retention capacity, droplet bounce inhibition ability, and deposition capacity. At the same time, compared with commercial formulations, it has long-term antifungal properties and lower EC50, while its acute toxicity to human cells is lower, which can reduce cell apoptosis by about 63 %. It is also gratifying that the main root length, plant height, and fresh weight of wheat seedlings treated with mPEG-b-PLG have significantly improved, effectively applying carrier materials for synergistic effects. In summary, this work proposes a promising strategy to synergize pesticide carrier materials as active ingredients, providing new ideas for the integration of pesticide and fertilizer, improving pesticide utilization efficiency, and reducing environmental pollution.

Ultrasound-Assisted Maillard Conjugation of Yeast Protein Hydrolysate with Polysaccharides for Encapsulating the Anthocyanins from Aronia.

Valorisation of food by-products, like spent brewer's yeast and fruit pomaces, represents an important strategy for contributing to sustainable food production. The aims of this study were to obtain Maillard conjugates based on spent yeast protein hydrolysate (SYH) with dextran (D) or maltodextrin (MD) by means of ultrasound treatment and to use them for developing encapsulation systems for the anthocyanins from aronia pomace. The ultrasound-assisted Maillard conjugation promoted the increase of antioxidant activity by about 50% compared to conventional heating and SYH, and was not dependent on the polysaccharide type. The ability of the conjugates to act as wall material for encapsulating various biologically active compounds was tested via a freeze-drying method. The retention efficiency ranged between 58.25 ± 0.38%-65.25 ± 2.21%, while encapsulation efficiency varied from 67.09 ± 2.26% to 88.72 ± 0.33%, indicating the strong effect of the carrier material used for encapsulation. The addition of the hydrolysed yeast cell wall played a positive effect on the encapsulation efficiency of anthocyanins when used in combination with the SYH:MD conjugates. On the other hand, the stability of anthocyanins during storage, as well as their bioavailability during gastrointestinal digestion, were higher when using the SYH:D conjugate. The study showed that hydrolysis combined with the ultrasound-assisted Maillard reaction has a great potential for the valorisation of spent brewer's yeast as delivery material for the encapsulation of bioactive compounds.

Visible Light-Gating Responsive Nanochannel for Controlled Release of the Fungicide.

Fungicides have been widely used to protect crops from the disease of pythium aphanidermatum (PA). However, excessive use of synthetic fungicides can lead to fungal pathogens developing microbicide resistance. Recently, biomimetic nano-delivery systems have been used for controlled release, reducing the overuse of fungicides, and thereby protecting the environment. In this paper, inspired by chloroplast membranes, visible light biomimetic channels are constructed by using retinal, the main component of green pigment on chloroplasts in plants, which can achieve the precise controlled release of the model fungicide methylene blue (MB). The experimental results show that the biomimetic channels have good circularity after and before light conditions. In addition, it is also found that the release of MB in visible light by the retinal-modified channels is 8.78 µmol·m-2·h-1, which is four times higher than that in the before light conditions. Furthermore, MB, a bactericide drug model released under visible light, can effectively inhibit the growth of PA, reaching a 97% inhibition effect. The biomimetic nanochannels can realize the controlled release of the fungicide MB, which provides a new way for the treatment of PA on the leaves surface of cucumber, further expanding the application field of biomimetic nanomembrane carrier materials.

Effects of carriers for oils in compound feeds on growth performance, nutrient digestibility, and gut microbiota in broiler chickens

Carrier materials for oils in compound feeds may be used in animal nutrition to supply liquid feed additives. However, implications of such carriers for the digestibility of the contained oil are unknown. This study investigated the potential of oil carriers in compound feed and their effect on performance, metabolizable energy, fatty acid (FA) retention, amino acid (AA) digestibility, and gut microbiota in broiler chickens. Six experimental diets were formulated following a 2 × 3 factorial arrangement with 20 g/kg or 40 g/kg of rapeseed oil supplied with no carrier or bound in a silica-based (SC) or lignocellulose-based (LC) carrier in a 1:1 mass ratio. The diets were assigned to 48 metabolism units with 15 animals each based on a randomized complete block design and fed from day 18 to 28 of the trial. Total excreta were collected from day 24 to 27 and used to determine total tract retention (TTR) of FA and MEn. On day 28, AA digestibility both by the distal half of the jejunum and the distal half of the ileum was determined, and microbiota of ileal and cecal digesta was analyzed using 16S ribosomal RNA sequencing. There were significant interactions for ADG, ADFI, the gain:feed ratio (G:F), MEn, and the TTR of crude fat and most fatty acids (P≤0.046) except for C18, C18:2, and C22:0. Addition of SC decreased ADG, ADFI, and G:F (P<0.001), while LC at 40 g/kg oil inclusion increased G:F and MEn (P<0.001) for both inclusion levels. The TTR of crude fat and the FA C18:1, C18:2, C18:3, and C22:0 was increased by the addition of SC (P≤0.016), while LC increased the TTR of the FA C18:1 and C18:2 as well as the TTR of C18:3 at 20 g/kg oil inclusion (P≤0.016). Adding SC and LC increased the digestibility of seven and two AA by the distal half of the jejunum, respectively, and the digestibility of eight and 13 AA by the distal half of the ileum, respectively (P≤0.039). The β-diversity and abundance of some taxa were altered by addition of LC and SC in the ceca while no treatment effect on the ileal microbiota was found. The results give no indication of an incomplete release of the oil from the carriers because the TTR of most FA was increased upon addition of SC and LC. LC may be used to supply liposoluble feed additives without drawbacks for nutrient digestibility and growth while SC requires further examination.

Mini-review of the bi-component nanofibrous scaffolds and drug delivery applications

Drug delivery systems perform to improve the drug's efficacy and heal the affected region. Electrospun nanofibers are strong drug carriers as a scaffold due to their high specific surface area, easy processing, lightweight material. Fibrous scaffolds encapsulating functional bioactive agents are important for drug delivery applications, and they show higher encapsulation efficiency and higher drug loading capacity than various types of carrier materials such as hydrogels, micro/nanobeads, films, conventional fibers, and sponges. In comparison to conventional electrospinning, bi-component electrospinning where drug loading does not occur largely on the surface of the polymer matrix, core-shell nanofibers showed delayed release and a decrease in burst release because the drug was loaded into the core layer. The purpose of this mini-review is to investigate the production and applications of the drug-loaded bi-component nanofibers in structure core-shell, side-by-side, hollow nanofibers, and also emulsion nanofibers using co-axial nozzles. Further, the parameters which influence of these electrospinning process, such as working conditions and polymer properties, as well as drug delivery profile of the resulting nanofibers, have been outlined briefly. The limited clinical studies on the nanofibers have been discussed. Eventually, perspectives on the problems, possibilities, and new approaches for electrospinning advancements have been presented, as well.

Li4SiO4-Based Heat Carrier Derived from Different Silica Sources for Thermochemical Energy Storage

Thermochemical energy storage (TCES) is one of the key technologies facilitating the integration of renewable energy sources and mitigating the climate crisis. Recently, Li4SiO4 has been reported to be a promising heat carrier material for TCES applications, owing to its moderate operation temperature and stability. During the synthetic processes, the properties of the Si source used directly influence the performance of derived Li4SiO4 materials; however, the internal relations and effects are not yet clear. Hence, in this work, six kinds of SiO2 sources with different phases, morphology, particle size, and surface area were selected to synthesize a Li4SiO4-based TCES heat carrier. The physicochemical properties of the SiO2 and the corresponding derived Li4SiO4 were characterized, and the comprehensive performance (e.g., heat storage/releasing capacity, rate, and cyclic stability) of the Li4SiO4 samples was systematically tested. It was found that the silica microspheres (SPs), which possess an amorphous phase, uniform micro-scale structure, and small particle size, could generate Li4SiO4 TCES materials with a highest initial capacity of 777.7 kJ/kg at 720 °C/900 °C under pure CO2. As a result, the SP-L showed an excellent cumulative heat storage amount of 5.84 MJ/kg within 10 heat-releasing/storage cycles, which was nearly 1.5 times greater than the value of Li4SiO4 derived from commonly used silicon dioxide. Furthermore, the effects of the utilized Si source on the performance of as-prepared Li4SiO4 and corresponding mechanisms were discussed, which offers guidance for the future selection of Si sources to produce high-performance Li4SiO4-based TCES heat carriers.

Study of shelf life of Trichoderma viride on different carrier materials by using coconut husk, groundnut shell, charcoal powder

Study of shelf life of Trichoderma viride on different carrier materials by using coconut husk, groundnut shell, charcoal powder

Improving anaerobic digestion performance after severe acidification: Unveiling the impacts of Fe3O4-bentonite composites in co-digestion of waste activated sludge and food waste

Acidification recovery in anaerobic digestion of food waste is challenging. This study explored its in-situ recovery using a co-substrate of food waste and waste activated sludge. Fe3O4 and bentonite were used as conductor and carrier, respectively, to enhance AD performance under severe acidification. The application of Fe3O4-bentonite resulted in a 152% increase in cumulative methane in the Fe3O4-bentonite 10 digester, demonstrating its effectiveness in restoring the acidified AD system. In acidified systems, bentonite enhanced the diversity and richness of microbial communities due to its buffering capacity. The excessive non-conductive polysaccharides excreted by bacteria in extracellular polymeric substances reduced the possibility of electron transfer by Fe3O4. However, in the synergistic application of Fe3O4 and bentonite, this resistance was alleviated, increasing the possibility of direct interspecies electron transfer, and accelerating the consumption of volatile fatty acids. This approach of integrating carrier and conductive materials is significant for in-situ restoration of acidified systems.

Preparation and characterization of self-aggregating micelles from stearic acid-modified burdock root polysaccharide

In order to obtain amphiphilic polysaccharide self-assembly micelles, the hydrophobic modification by grafting stearic acid (SA) onto the backbone of burdock root polysaccharide (BRP) was carried out and its main physicochemical properties were characterized. The results showed that the optimal esterification conditions were as follows: reaction time of 2 h, reaction temperature of 55 ℃, system pH of 8.0 and the SA addition of 4 mmol, a maximum substitution degree (DS) of the esterification products was obtained as 0.1012. The FTIR analysis verified that the modified polysaccharide successfully introduced the ester carbonyl group. 1H NMR spectra further confirmed that the esterification reaction occurred. The SA-modified BRP micelles were roughly spherical with uniform dispersion and the particle size was in the range of 259–352 nm, which showed a negative correlation with the DS. The solubility of the esterification products also decreased. The smaller critical micelle concentration (CMC) led to easier formation of self-aggregating micelles and stronger solubilization effect. The above results indicated that SA-modified BRP as a novel carrier material possessed potential to deliver hydrophobic active substances.Graphical

Evaluating hydrogen storage potential of NaNbO3-xHx: DFT-based approach

Alternative energy carrier materials are needed since non-renewable energy resources are diminishing at a fast rate. Increasingly, hydrogen storage has gained popularity as a clean energy source. For the first time, NaNbO3-xHx has been explored computationally as a potential material for hydrogen storage using the GGA-PBE approach as implemented in the CASTEP code. Structural, elastic, mechanical, electronic, and optical characteristics have been investigated to evaluate the suitability of the proposed material for hydrogen storage applications. All H-incorporated concentrations are thermodynamical and energetically stable and can be synthesized. Structural parameters vary with varying hydrogen concentrations; however, against each hydrogen concentration, the material maintains cubical geometry. The NaNbO2.7H0.3 show the highest (742.92 GPa) bulk modulus, while NaNbH3 stands with the lowest (52.48 GPa) among all. Standardizing the Poisson ratio reveals a brittle nature except for the X=0.3 composition. With increasing H-incorporation in the structure, the band gap increases (1.624 eV » 2.505 eV) and also causes electronic nature shifting (p-type → n-type); however, the band gap remains indirect over different symmetry points in BZ. Hence, have the potential for numerous optoelectronic applications. Furthermore, optical parameters, dielectric constant, refractive index, extinction coefficient, reflectivity, absorption coefficients, and loss functions are analyzed, which reveal the potential for numerous optoelectronic applications. Hydrogen storage capacity achieved up to 2.48 %, allowing this material to be utilized in energy storage systems.

Catalytic Cracking of Oily Sludge using Nickel Metal Catalyst Embedded in Silica Derived from Adsorbent in a Gas Process Plant

Abstract. One of the Oily Sludge (OS) recycling methods is through catalytic cracking. This process involves the reaction breaking down large molecules into smaller ones with the help of a catalyst. Nickel (Ni) metal is often used as a catalyst because it can increase fuel liquid yield while reducing the coke formation. To enhance its performance, Ni metal can be embedded in a carrier material like Silica to form the Ni-Silica catalyst. In this research, OS sourced from a Gas Process Plant is treated with catalytic cracking using Ni-Silica, where the Silica used is derived from an Adsorbent activated with NaOH. Optimization of the cracking conditions is carried out using Response Surface Methodology (RSM) with a Box-Behnken design. The optimized cracking reaction conditions include temperature (713 K, 723 K, and 733 K), time (50 min, 60 min, and 70 min), and catalyst-to-OS ratio of 1:5, 1:6, and 1:7. Statistical analysis indicates that the relationship between the reaction condition variables and the Oil Liquid Product (OLP) falls into the moderate category, as shown by the coefficient of determination (R²) of 0.5. The calculated F-value for the deviation from the mathematical model is smaller than the F-Table value (9.2) at both 5% and 1% significance levels, with a value of 0.6. This indicates that the mathematical model generated can be accepted as the mathematical model within the range of reaction conditions in this study. Calculus analysis reveals that the optimum reaction conditions are a temperature of 717.34 K, a time of 58.58 min, and a catalyst-to-OS ratio of 1:6, 15. Canonical analysis indicates that for OLP, λ1= [-12.38], λ2= [-2.27], and λ3= [4.50], where lambda values indicate that the most sensitive response surface parameter for OLP is temperature, followed by the catalyst-to-sample ratio, and the least sensitive is reaction time. Keywords: Catalytic Cracking, Ni Metal, OS, RSM, Silica

Facile construction of pectin-based hesperidin microcapsules: Solubilization, stability, loading process, and release mechanism

Constructing carrier materials with polysaccharides to enhance the solubility of insoluble active ingredients is a crucial strategy for improving bioavailability. This research constructed pectin-based hesperidin microcapsules (PHM) through self-assembly processes in the deep eutectic solvent, improving the solubility, storage stability, and bioavailability of hesperidin (HES). PHM exhibited high encapsulation efficiency (91.7%) and loading capacity (11.5%), with a small particle size (1.73 μm). The interaction mechanism was clarified through physical characterization and density functional theory (DFT) calculations. The vitro release demonstrated that the release ratio of PHM was only 6.4% in simulated gastric fluid (SGF), but reached 80.9% in simulated intestinal fluid (SIF). The release mechanism of PHM in SGF followed Fickian diffusion, while in SIF followed skeleton dissolution diffusion with a stable rate. Furthermore, the cell cytotoxicity experiments confirmed the remarkable biocompatibility of PHM toward human colon cells, which suggested its potential application in food and pharmaceutical fields.

Folic Acid-Decorated Nanocrystals as Highly Loaded Trojan Horses to Target Cancer Cells.

The nanocrystal (NC) technology has become one of the most commonly used strategies for the formulation of poorly soluble actives. Given their large specific surface, NCs are mainly used to enhance the oral absorption of poorly soluble actives. Differently from conventional nanoparticles, which require the use of carrier materials and have limited drug loadings, NCs' drug loading approaches 100% since they are formed of the pure drug and surrounded by a thin layer of a stabilizer. In this work, we report the covalent decoration of curcumin NCs with folic acid (FA) using EDC/NHS chemistry and explore the novel systems as highly loaded "Trojan horses" to target cancer cells. The decorated NCs demonstrated a remarkable improvement in curcumin uptake, exhibiting enhanced growth inhibition in cancer cells (HeLa and MCF7) while sparing healthy cells (J774A.1). Cellular uptake studies revealed significantly heightened entry of FA-decorated NCs into cancer cells compared to unmodified NCs while also showing reduced uptake by macrophages, indicating a potential for prolonged circulation in vivo. These findings underline the potential of NC highly loaded nanovectors for drug delivery and, in particular, for cancer therapies, effectively targeting folate receptor-overexpressing cells while evading interception by macrophages, thus preserving their viability and offering a promising avenue for precise and effective treatments.

A urea-based approach to synthesize single atom iron catalysts for catalyzing peroxymonosulfate to degrade antibiotics

Understanding the role and catalytic mechanism of single atomic catalysts (SACs) in activating peroxymonosulfate (PMS) and subsequently eliminating antibiotics in environmental water is crucial for designing more efficient catalysts. Despite C-N-metal SACs exhibiting excellent performance, their application is constrained by the intricate N-doped pretreatment process and the high cost of carrier materials. To handle these challenges effectively, a new approach, by using molten urea as both solvent and nitrogen source and polyethylene glycol as carbon source, was employed to synthesize the u-Fex-N-C (x = 1, 2, 3) catalysts. In which, u-Fe1-N-C had achieved an impressive 92 % degradation ratio for oxytetracycline (OTC) and remains unaffected by pH in the range of 3–11. It further exhibited catalytic degradation activity towards a broad spectrum of environmental pollutants, including sulfamethoxazole (SMZ), naproxen (NPX), ofloxacin (OFL), rhodamine B (RhB), and bisphenol A (BPA), and the degradation efficiencies reached 67 %, 83 %, 77 %, 99 %, and 93 %, respectively. According to a series of the characterization, the prepared u-Fe1-N-C possessed a unique FeN4 structure. Electron paramagnetic resonance (EPR) and radical quenching experiments proved that 1O2 and Fe (Ⅳ) played a key role in the current reaction system. In-situ Raman and electrically coupled oxidation systems also proved that the non-radical degradation pathway involving electron transfer in the u-Fe1-N-C/PMS system was the primary way for activating PMS. The degradation efficiency of OTC from real water samples still reached 84 %. This work provides a simple and cost-effective strategy for synthesizing SACs, offering promising applied prospects in the field of water treatment and environmental remediation.

Studies on different polysaccharides used as carrier material for spray-drying of synbiotics and its viability under different storage conditions

The objective of this study was to investigate the different polysaccharides as carrier material for spray-drying synbiotics and to study the physicochemical characteristics of synbiotics at different storage conditions. The thermally acclimatized probiotic strains, Lactobacillus helveticus (H-45) and Lacticaseibacillus casei (N-45) with enhanced probiotic properties were spray-dried using these polysaccharides along with galactooligosaccharides (GOS) as prebiotic. The studied plant-based polysaccharides are maltodextrin (MDX), corn starch (CS), and gum acacia (GA). After spray-drying, the survivability of all synbiotic combinations was higher in the presence of corn starch as carrier material. The synbiotic combination N45 + GOS + CS showed better survivability during spray-drying, under simulated intestinal (8.43 ± 0.17 log CFU/g), acid (5.51 ± 0.12 log CFU/g), and bile (7.31 ± 0.04 log CFU/g) conditions. The spray-dried powders had good to moderate flow properties with moisture content and water activity (aw) at the optimal range for the survival of probiotics. Among the spray-dried powders, synbiotic-N45 + GOS + CS showed improved storage survivability during shelf-life studies at three different temperatures (4 °C, 30 °C, and 37 °C) for eight weeks. However, all spray-dried probiotic and synbiotic powders had higher viability when stored at 4 °C. Hence, the study suggests that cornstarch as a polysaccharide in the synbiotics formulation (N45 + GOS + CS) may have a potential application in functional foods.

Fusion of cellulose microspheres with pulp fibers: Creating an unconventional type of paper

Cellulose microspheres (CMS) are a type of spherical regenerated cellulose particles with versatile properties which have been used as carrier materials in medical and technical applications. The integration of CMS into paper products opens up novel application scenarios for paper products in a wide range of fields. However, the incorporation of CMS carriers into paper products is challenging and hitherto no reports do exist in literature. Here, we present a feasibility study to incorporate up to 50 w.% CMS in paper hand sheets using retention aids. Our primary observations highlight the successful formation of uniform paper hand sheets retaining its tensile strengths at elevated CMS concentrations. Sheets with high CMS contents exhibit an increase in density and display enhanced surface smoothness — an outcome of a CMS layer forming atop the fiber base — which effectively bridges voids and rectifies surface irregularities as supported by Gurley testing, infinite focus microscopy and scanning electron microscopy. While our primary objective centered on the general feasibility to manufacture CMS-containing papers, the resulting composite scaffold carries significant potential as a platform for innovative, functional paper-based materials.

Magnetic biocatalytic nanoreactors based on graphene oxide with graded reduction degrees for the enzymatic synthesis of phytosterol esters

As we know, the carriers of enzymatic nanoreactors with different amphipathy have significant influence on the interfacial enzyme activities and its performance. In this study, the magnetic graphene oxide (GO) enzyme carriers were constructed by assembling graphene oxide with different reduction degrees (rGO(x)) and polyethyleneimine (PEI) modified nano-flowery Fe3O4 into composite materials through electrostatic interactions, and x here represents the reduction reaction hours of GO. The SEM, TEM, contact angles and BET tests qualified the ideal enzyme carrier, PEI-Fe3O4-rGO(12), by adsorption-crosslinking method, the Candida rugosa lipase (CRL) was immobilized to obtain the lipase nanoreactor, PEI-Fe3O4-rGO(12)@CRL. The nano-sheet and nano-flower structures provided a larger specific surface area and suitable pore size, and the CRL had higher protein load on the carrier material (163.11 mg/g). In addition, using hydrolyzed p-nitrophenol palmitate as the model, the PEI-Fe3O4-rGO(12)@CRL can still show 76.5 % residual activity after 8 repeated uses. At the same time, the immobilized lipase showed good catalytic performance in the biosynthesis of phytosterol esters. The optimal esterification conditions were determined by single factor experiment (isooctane, sterol concentration 150 μmol/mL, alkyd molar ratio 1:2, enzyme dosage 120 mg, 26 h, 55 °C, the esterification rate was 76.24 %). Therefore, the optimal biocatalyst PEI-Fe3O4-rGO(12)@CRL may has good performance in the biosynthesis of other novel foods.

Fabrication and characterization of pullulan/tapioca starch-based antibacterial films incorporated with Litsea cubeba essential oil for meat preservation

Active packaging is a novel technology that utilizes active materials to interact with products and the environment, improving food shelf life. The purpose of this work was to fabricate a multifunctional film using Litsea cubeba essential oil (LC-EO) (1 %, 3 %, 5 %, and 7 %) as the active ingredient and pullulan(P)/tapioca starch (TS) as the carrier material. Adding essential oil improves the films properties, such as barrier ability, anti-oxidant, and antibacterial activity. However, tensile strength (TS) and elongation at break (EAB) were slightly reduced from 28.94 MPa to 11.29 MPa and 15.36 % to 12.19 %. The developed PTS3% films showed the best performance in mechanical properties, especially EAB (14.26 %), WVP (3.26 %) and OP (3.13 %), respectively. The inhibitory zone diameters in the agar-well diffusion test were 18.59 mm for Staphylococcus aureus and 17.32 mm for Escherichia coli. Further study was conducted to compare the preservation effects of film with low-density polyethylene bag (LDPE) on chilled beef. Remarkably, PTS3% film decreased the bacterial population in beef meat while maintaining the pH, color, texture, and TBARS levels within an acceptable range for ten days of storage at 4 °C rather than in a low-density polyethylene bag. The outcomes indicated the potential of PTS3% films in food packaging applications.