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    • Studies on Immobilization of β-Galactosidase and Synthesis of Galacto-Oligosaccharide

      Online: May 15,2024 DOI: 10.12301/spxb202300221

      Abstract (120) HTML (0) PDF 1.84 M (257) Comment (0) Favorites

      Abstract:Chitosan, sodium alginate, sodium alginate/gelatin, sodium alginate/carboxymethyl cellulose were used as immobilized carrier materials to investigate the immobilization methods of β-galactosidase, and the synthesis of galacto-oligosaccharide (GOS) by the immobilized enzyme was studied. The results showed that the obtained suitable immobilization carrier was chitosan, and the optimal immobilization conditions were deter mined as follows: chitosan mass concentration 0.03 g/mL, standing time 2 h, glutaraldehyde volume fraction 2%, crosslinking time 3 h, adsorption time 12 h, immobilization temperature 60 ℃, enzyme dosage 0.4 mg/g chitosan microspheres. Compared with the free enzyme, the immobilized enzyme""s stability against acid, alkali and heat was significantly improved. Chitosan immobilized β-galactosidase was further used to synthesize GOS, and the optimal reaction conditions were deter mined: amount of enzyme 2 U/ mL, pH 6.0, 50 ℃, initial lactose mass concentration 500 g/L, and reaction time 14 h. Under these conditions, the GOS yield reached 52.61%, which was higher than those reported. And the content of GOS with DP ≥ 3 in the GOS product was 37.07%. After repeated use of the immobilized enzyme for five times, the GOS production activity remained 97.21% . The chitosan-immobilized β-galactosidase obtained from the study has a promising application in the field of GOS synthesis.

    • Screening Antimicrobial Peptides from Metagenomes Based on Deep Learning and Molecular Simulation

      Online: March 11,2024 DOI: 10.12301/spxb202300710

      Abstract (169) HTML (0) PDF 0.00 Byte (555) Comment (0) Favorites

      Abstract:Antimicrobial peptides are a type of peptide capable of exerting antibacterial functions by interacting with bacterial cell membranes or intracellular biomolecules, thereby disrupting bacterial physiological processes and ultimately leading to bacterial death. Given the challenges posed to food safety and quality, the development of novel food antimicrobials to enhance food safety has become a key direction in current food science research. A novel deep learning model was constructed to screen for antimicrobial peptides from soil metagenomic data, with the screened peptides being validated using techniques such as molecular docking and molecular dynamics simulations. The model demonstrated an outstanding performance with a precision of 98.7%, an accuracy of 96.5%, a recall rate of 91.9%, an F1-score of 95.2%, and a specificity of 99.2%, showcasing excellent efficiency, interpretability, and practical application value alongside robust generalization capabilities. Post-training, the model successfully identified several peptides with significant antimicrobial potential, with a subset chosen for further investigation. The findings revealed that the screened peptide Gly-Thr-Ala-Trp-Arg-Trp-His-Tyr-Arg-Ala-Arg-Ser could effectively attach to the bacterial transcription regulator protein MrkH, exhibiting inhibitory effects on Klebsiella pneumoniae, Escherichia coli, and Staphylococcus aureus. This study aims to provide a theoretical basis for the application of new antimicrobials in the food industry by integrating deep learning with molecular simulation technologies.

    • Effect of thermal sterilization on the physicochemical stability of flaxseed milk

      Online: January 31,2024 DOI: 10.12301/spxb202300523

      Abstract (289) HTML (0) PDF 0.00 Byte (751) Comment (0) Favorites

      Abstract:Flaxseed, as a functional food raw material, was rich in α-linolenic acid, high-quality proteins, soluble polysaccharides, lignans and other active lipid concomitants, thereby possessing high nutritional value and potential for development and utilization. This paper aimed to explore the effect of different thermal sterilization conditions (65 ℃-30 min, 85 ℃-15 min and 95 ℃-15 s) on the physicochemical stability of flaxseed milk, focusing on the changes in interfacial properties of oil bodies. The results showed that the thermal sterilisation treatment resulted in a gradual increase in the mean particle size of flaxseed milk by 95.58% (p<0.05) and a gradual decrease in the absolute value of the zeta potential by 12.26% (p<0.05), which was accompanied by the weakening viscoelastic properties and an increase in the physical stability of the milk. thermal sterilisation, the ratio of protein at the oil bodies interface in flaxseed milk increased by 64.42% (p<0.05) and the ratio of total sugar mass increased by 97.95% (p<0.05). The cryo-scanning electron microscopy imaging further confirmed the adsorption of exogenous storage proteins and soluble polysaccharides at the interface of oil bodies. In addition, the thermal sterilisation treatment increased the total phenolic content of the oil bodies interface in flaxseed milk by 1.42 times (P<0.05), the flavonoid content by 4.94 times (P<0.05), as well as the free radical scavenging capacity of 1,1-Diphenyl-2-picryl-hydrazyl (DPPH) by 4.64 times (P<0.05), and FRAP ferric reducing antioxidant power by 54.05% (P<0.05). In conclusion, suitable thermal sterilization treatment (85 ℃-15 min) could enhance the physical and chemical stability of flaxseed milk based on the interfacial remodeling of oil bodies, which is hoped to provide a certain theoretical basis for further broadening the intake form and application scenarios of flaxseed.

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