Magnetic field-assisted surface engineering technology for active regulation of Fe3O4 medium to enable the laccase electrochemical biosensing of catechol with visible stripe patterns.

BACKGROUND: Catechol (CC), a prevalent phenolic compound, is a byproduct in various agricultural, chemical, and industrial processes. CC detection is crucial for safeguarding water quality and plays a pivotal role in enhancing the overall quality of life of individuals. Electrochemical biosensors exhibit rapid responses, have small sizes, and can be used for real-time monitoring. Therefore, the development of a fast and sensitive electrochemical biosensor for CC detection is crucial. RESULT: In this study, a laccase-based electrochemical biosensor for detection of CC is successfully developed using Fe3O4 nanoparticles as medium and optimized by applying a magnetic field. This research proposes a unique strategy for biosensor enhancement by actively controlling the distribution of magnetic materials on the electrode surface through the application of a magnetic field, resulting in a visibly alternating stripe pattern. This approach effectively disperses magnetic particles, preventing their aggregation and reducing the boundary layer thickness, enhancing the electrochemical response of the biosensor. After fabrication condition optimization, CC is successfully detected using this biosensor. The fabricated sensor exhibits excellent performance with a wide linear detection range of 10-1000 µM, a low detection limit of 1.25 µM, and a sensitivity of 7.9 µA/mM. The fabricated sensor exhibits good selectivity and reliable detection in real water samples. In addition, the laccase-based sensor has the potential for the fast and accurate monitoring of CC in olive oil. SIGNIFICANCE: The magnetic field optimization in this study significantly improved the performance of the electrochemical biosensor for detecting CC in environmental samples. Overall, the sensor developed in this study has the potential for fast and accurate monitoring of CC in environmental samples, highlighting the potential importance of a magnetic field environment in improving the performance of catechol electrochemical biosensors.

Selenium volatilization in plants, microalgae, and microorganisms.

The augmented prevalence of Se (Se) pollution can be attributed to various human activities, such as mining, coal combustion, oil extraction and refining, and agricultural irrigation. Although Se is vital for animals, humans, and microorganisms, excessive concentrations of this element can give rise to potential hazards. Consequently, numerous approaches have been devised to mitigate Se pollution, encompassing physicochemical techniques and bioremediation. The recognition of Se volatilization as a potential strategy for mitigating Se pollution in contaminated environments is underscored in this review. This study delves into the volatilization mechanisms in various organisms, including plants, microalgae, and microorganisms. By assessing the efficacy of Se removal and identifying the rate-limiting steps associated with volatilization, this paper provides insightful recommendations for Se mitigation. Constructed wetlands are a cost-effective and environmentally friendly alternative in the treatment of Se volatilization. The fate, behavior, bioavailability, and toxicity of Se within complex environmental systems are comprehensively reviewed. This knowledge forms the basis for developing management plans that aimed at mitigating Se contamination in wetlands and protecting the associated ecosystems.

Ultrasound-Assisted Enzymatic Protein Hydrolysis in Food Processing: Mechanism and Parameters.

Ultrasound has been widely used as a green and efficient non-thermal processing technique to assist with enzymatic hydrolysis. Compared with traditional enzymatic hydrolysis, ultrasonic-pretreatment-assisted enzymatic hydrolysis can significantly improve the efficiency of enzymatic hydrolysis and enhance the biological activity of substrates. At present, this technology is mainly used for the extraction of bioactive substances and the degradation of biological macromolecules. This review is focused on the mechanism of enzymatic hydrolysis assisted by ultrasonic pretreatment, including the effects of ultrasonic pretreatment on the enzyme structure, substrate structure, enzymatic hydrolysis kinetics, and thermodynamics and the effects of the ultrasonic conditions on the enzymatic hydrolysis results. The development status of ultrasonic devices and the application of ultrasonic-assisted enzymatic hydrolysis in the food industry are briefly described in this study. In the future, more attention should be paid to research on ultrasound-assisted enzymatic hydrolysis devices to promote the expansion of production and improve production efficiency.

Application of Immobilized Enzymes in Juice Clarification.

Immobilized enzymes are currently being rapidly developed and are widely used in juice clarification. Immobilized enzymes have many advantages, and they show great advantages in juice clarification. The commonly used methods for immobilizing enzymes include adsorption, entrapment, covalent bonding, and cross-linking. Different immobilization methods are adopted for different enzymes to accommodate their different characteristics. This article systematically reviews the methods of enzyme immobilization and the use of immobilized supports in juice clarification. In addition, the mechanisms and effects of clarification with immobilized pectinase, immobilized laccase, and immobilized xylanase in fruit juice are elaborated upon. Furthermore, suggestions and prospects are provided for future studies in this area.

Exogenous Betaine Enhances the Protrusion Vigor of Rice Seeds under Heat Stress by Regulating Plant Hormone Signal Transduction and Its Interaction Network.

Rice is an important food crop. Rice seedlings are mainly composed of root, coleoptile, mesocotyl and euphylla. The elongation of coleoptile and mesocotyl promotes the emergence of rice seedlings. Therefore, analyzing the mechanism of coleoptile and mesocotyl elongation is important for the cultivation of rice varieties. Due to global warming, heat stress is threatening rice yields. Betaine plays an important role in plant resistance to heat stress; however, we lack research on its regulation mechanism of rice seed germination under heat stress. Therefore, we explored the effects of soaking seeds with betaine at different concentrations on rice seed germination under heat stress. According to the results, soaking seeds with 10 mM of betaine could effectively improve the seeds' germination potential and rate under heat stress to promote the germination of rice seeds. To clarify the mitigation mechanism of betaine in heat stress, we measured the antioxidant enzyme activity, malondialdehyde content, soluble protein content and endogenous hormone content of seed protrusion under heat stress. We constructed the cDNA library for transcriptome sequencing. According to the results, 10 mM of betaine improved the activities of the superoxide dismutase, peroxidase and catalase of seed protrusion under heat stress to reduce the malondialdehyde content and increase the soluble protein content to alleviate the effect of heat stress on rice seed germination. The detection of the endogenous hormone content showed that soaking seeds with 10 mM of betaine increased the content of gibberellin and decreased the contents of auxin and abscisic acid of seed protrusion under heat stress. According to the transcriptome analysis, betaine can induce the expressions of key genes in the biosynthesis and metabolism of auxin, abscisic acid and gibberellins in the seed coleoptile and mesocotyl elongation stage, regulate the signal transduction of three hormones and promote the germination of rice seeds under heat stress. This study revealed, for the first time, the physiological and molecular regulation mechanism of betaine promotion of seed germination under heat stress.

Magnetic/electric field intervention on oil-rich filamentous algae production in the application of acrylonitrile butadiene styrene based wastewater treatment.

Globally, the release of acrylonitrile-butadienestyrene (ABS) wastewater from numerous industries is a serious concern. Recently, oil-rich filamentous algae Tribonema sp has been grown utilizing toxic but nutrient-rich ABS effluent. Here, Tribonema sp. was cultivated under intervention of different magneto-electric combinatory fields (MCFs) (control, 0.6 V/cm, 1 h/d-1.2 V/cm, 1 h/d-0.6 V/cm, and 1 h/d-1.2 V/cm). Results showed MCF (1 h/d-0.6 V/cm) intervention increased the biomass by 9.7% (2.4 g/L) combined with high removal efficiencies (95% and 99%) of ammonium nitrogen and total phosphorus. The chemical oxygen demand (COD) removal rate increased to 82%, 6% higher than the control. Moreover, MCF of 1 h/d-0.6 V/cm significantly increased lipid and carbohydrate by 7.71% and 4.73% respectively. MCF increased premium fatty acid content such as palmitic acid (C16:0), myristic acid (C14: 0), and hexadecenoic acid (C16:1). MCF intervention also supported a diverse microbial flora, offering a favorable solution for ABS wastewater treatment.

Optimization of the nutritional constituents for ergosterol peroxide production by Paecilomyces cicadae based on the uniform design and mathematical model.

we optimized medium components for the production of ergosterol peroxide (EP) by Paecilomyces cicadae based on a mono-factor experiment, a uniform design, and a non-linear regression analysis. The maximum EP yield achieved was 256 µg/L, which was increased by 5 folds compared with that before the optimization. Structured Monod model, Andrews model, Contois model, and Aibe model were developed to describe the effects of viscosity inhibition, substrate, and production on biomass growth. The results showed that the Monod model could predict biomass growth, and the effects of viscosity and substrate on the EP concentration were significantly higher compared with the effect of production. The addition of water and glycerol could decrease the viscosity inhibition and glycerol inhibition, and further increase the EP yield. The newly developed structured model was demonstrated for batch growth of P. cicadae.

Weak magnetic field intervention on outdoor production of oil-rich filamentous microalgae: Influence of seasonal changes.

The weak magnetic field (MF) intervention on the semi-continuous system of filamentous algae Tribonema sp. during outdoor cultivation was investigated using starch wastewater. Results show that except for winter, MF in other seasons can effectively improve the algal biomass yield and oil productivity. In summer, the biomass concentration and oil productivity of Tribonema sp. could reach up to 14.7 g/L and 0.216 g/(L d) (130 mT), which increased by 9.8% and 35.8% respectively compared with the control group without MF intervention. By continuously shortening HRT to increase the nutrient load, the removal rate of COD, total nitrogen and total phosphorus all reached more than 87.9%. MF intervention not only weakened the bacterial diversity in open-photobioreactors system but also proved to be beneficial to the establishment of bacteria-algae symbiotic system. As a non-transgenic method, MF effectively up-regulated the growth of filamentous microalgae and promoted the biosynthesis productivity of high value-added compounds.

Impact of pulsed magnetic field treatment on enzymatic inactivation and quality of cloudy apple juice.

The effects of PMF (5-7 T, 5-30 pulses) on enzyme activity, pH, titratable acidity, soluble solids, color, ascorbic acid, total phenols and antioxidant activity (DPPH radical scavenging activity) of cloudy apple juice were evaluated. PMF inhibited activities of polyphenoloxidase (PPO), peroxidase (POD) and pectinmethylesterase (PME), but PPO was more sensitive to PMF than POD and PME. At the intensity of 6 T with 15 pulses, PPO and POD both exhibited the lowest residual activity (53.22 and 92.96%), while PME showed the lowest residual activity (83.01%) at 7 T with 30 pulses. No significant effect on soluble solids was found under all processing parameters, whereas significant decreases of ascorbic acid were observed at the intensity of 7 T with 5-30 pulses. PMF did not change pH, titratable acidity, color, total phenols and DPPH radical scavenging activity severely. These results suggest PMF can be a potential technology for enzymatic inactivation in apple juice with high retention of quality.

Transcriptomic analysis of Listeria monocytogenes under pulsed magnetic field treatment.

Pulsed magnetic field (PMF) is an emerging non-thermal decontamination technology. The lack of research on microbial inactivation mechanisms restricts the wide application of PMF. In this study the effect of PMF on the gene expression level of Listeria monocytogenes (L. monocytogenes) was evaluated to explore the inactivation mechanism of PMF. Transcriptomics was applied to study the gene expression level of Listeria monocytogenes and 588 differentially expressed genes (DEGs) including 307 up-regulated and 281 down-regulated genes were identified after PMF treatment (8 T, 20 pulses). Gene Ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways analysis have demonstrated significant changes in mobility, carbohydrate metabolism, energy metabolism, amino acid metabolism, phosphorylation and dephosphorylation, membrane, quorum sensing, two-component regulatory system and ATP-binding cassette (ABC) transporters. The expression level of 5 relevant genes was subsequently confirmed by quantitative real-time PCR assay.

Effect of high-humidity hot air impingement blanching (HHAIB) on drying and quality of red pepper (Capsicum annuum L.).

Effects of high-humidity hot air impingement blanching (HHAIB) under different times (30, 60, 90, 120, 150, 180, 210, and 240s) on drying characteristics and quality attributes of red peppers in terms of surface colour, red pigment content, microstructure and texture were investigated. Results showed that polyphenol oxidase (PPO) residual activity of the samples decreased with increasing blanching time; it was decreased to 7% after 120s. A first-order fraction model described PPO inactivation well. Suitable HHAIB time can reduce drying time extensively. Pepper surface colour was influenced by different treatments. In terms of red pigment content, there was no significant difference for blanching time under 120s, whereas over blanching (blanching time ⩾150s) can significantly reduce the red pigment content. Microstructure observations indicate that superficial micro-cracks occur, which explain, why HHAIB enhances drying rate. The firmness, hardness, and gumminess of the samples decreased with increase of HHAIB time.

Phytic Acid Enhances Biocontrol Activity of Rhodotorula mucilaginosa against Penicillium expansum Contamination and Patulin Production in Apples.

The effect of Rhodotorula mucilaginosa in combination with phytic acid (PA) on blue mold decay and patulin contamination of apples was investigated. Results from this study show that different concentrations of PA were effective in reducing the disease incidence of apples and that PA at concentration of 4 µmol/mL, decreased the incidence of blue mold decay in apples from 86.1 to 62.5%, and showed higher control efficacy compared to untreated, control fruit during storage at 20°C. However, R. mucilaginosa combined with PA (4 µmol/mL) showed better control efficacy of blue mold decay than R. mucilaginosa used as single treatment, the disease incidence was reduced to 62.5% and lesion diameter on apples was reduced to 16.59 cm. In in vitro experiments, the addition of PA enhanced the biocontrol effect of R. mucilaginosa against the growth of Penicillium expansum and reduced patulin level when compared with either R. mucilaginosa or PA used separately. R. mucilaginosa together with PA, improved the inhibition of patulin production in wounded apples, decreasing the content of patulin by 89.6% compared to the control, under experimental conditions. Both R. mucilaginosa and R. mucilaginosa in combination with PA degraded patulin in vitro. In conclusion, the appropriate combination of R. mucilaginosa and PA may provide an effective biocontrol method for reducing postharvest decay of apples.

D-isoascorbyl palmitate: lipase-catalyzed synthesis, structural characterization and process optimization using response surface methodology.

BACKGROUND: Isoascorbic acid is a stereoisomer of L-ascorbic acid, and widely used as a food antioxidant. However, its highly hydrophilic behavior prevents its application in cosmetics or fats and oils-based foods. To overcome this problem, D-isoascorbyl palmitate was synthesized in the present study for improving the isoascorbic acid's oil solubility with an immobilized lipase in organic media. The structural information of synthesized product was clarified using LC-ESI-MS, FT-IR, 1H and 13C NMR analysis, and process parameters for high yield of D-isoascorbyl palmitate were optimized by using One-factor-at-a-time experiments and response surface methodology (RSM). RESULTS: The synthesized product had the purity of 95% and its structural characteristics were confirmed as isoascorbyl palmitate by LC-ESI-MS, FT-IR, 1H, and 13C NMR analysis. Results from "one-factor-at-a-time" experiments indicated that the enzyme load, reaction temperature and D-isoascorbic-to-palmitic acid molar ratio had a significant effect on the D-isoascorbyl palmitate conversion rate. 95.32% of conversion rate was obtained by using response surface methodology (RSM) under the the optimized condition: enzyme load of 20% (w/w), reaction temperature of 53°C and D- isoascorbic-to-palmitic acid molar ratio of 1:4 when the reaction parameters were set as: acetone 20 mL, 40 g/L of molecular sieves content, 200 rpm speed for 24-h reaction time. CONCLUSION: The findings of this study can become a reference for developing industrial processes for the preparation of isoascorbic acid ester, which might be used in food additives, cosmetic formulations and for the synthesis of other isoascorbic acid derivatives.