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In order to study the correlation between emulsion properties and microencapsulation rates and surface oil contents under different homogenization and sterilization conditions, the effects of emulsion stability, particle size, and particle size distribution on microencapsulation efficiency under different conditions were measured using a LUMiSizer 611 dispersion analyzer, and the morphological properties and storage stability of microcapsules under optimal conditions were analyzed. The results showed that the homogenization pressure and temperature and the sterilization conditions that provided the smallest emulsion stability index and average particle size were 40 MPa, 65 ℃ and 85 ℃/15 min, respectively. Under these conditions, particle size distribution was less scattered, and encapsulation rates of 95.38%, 97.12% and 94.23% were obtained, respectively. The average particle size of walnut oil microcapsules was 6.62 μm, with a surface oil content of 1.03% and an encapsulation rate of 96.41%. The surface and internal structure of the microcapsules were found to be good by scanning electron microscopy (SEM) indicating good encapsulation efficiency. Under accelerated storage conditions, walnut oil microcapsules showed better stability than free walnut oil. After 35 days of storage under different conditions, the reduction in the retention rate of walnut oil microcapsules varied, and the highest retention rate was achieved under the conditions of low temperature, darkness, and no oxygen or low oxygen concentration. This study could provide a theoretical basis for the selection and application of homogenization and sterilization processes for walnut oil emulsion and microcapsule products.

Three walnut peptides with different molecular masses were prepared from walnut meal protein by sequential enzymatic hydrolysis and ultrafiltration, and separately glycosylated with five sugars (glucose, sucrose, lactose, maltodextrin and dextran). The reaction conditions were optimized based on emulsifying properties and anti-lipid oxidation capacity. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier transform infrared (FTIR) spectroscopy and circular dichroism (CD) spectroscopy were used to characterize the glycosylated peptides, their physicochemical properties were studied, and their emulsion stability was determined by laser confocal microscopy (LCM). The results showed that the optimal conditions for the glycosylation reaction between walnut peptide with molecular mass greater than 30 kDa and maltodextrin were as follows: ratio of walnut peptide to maltodextrin 1:2, reaction time 8 h, reaction temperature 80 ℃, and peptide concentration 15 mg/mL. SDS-PAGE confirmed the formation of a covalent complex between the walnut peptide and maltodextrin through glycosylation reaction. FTIR spectroscopy showed that sugar molecules were connected to walnut peptide molecules by covalent bonds. CD spectroscopy showed that the peptide’s structure changed. The proportion of α-helix increased from 4.85% to 6.43%, the proportion of antiparallelism increased from 30.16% to 35.91%, the proportion of parallelism increased from 3.28% to 4.33%, the proportion of β-turn decreased from 23.21% to 20.77%, and the proportion of random coil decreased from 33.59% to 31.22%. The glycosylation modification did not improve the Fe2+ chelating capacity, but increased the solubility, emulsifying capacity to (83.24 ± 1.64) m2/g, emulsion stability to (218.49 ± 3.55) min, water absorption capacity to (3.92 ± 0.36) g/g, oil absorption capacity to (3.17 ± 0.24) g/g, surface hydrophobicity to 251.05 ± 6.91, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging capacity to (86.74 ± 2.14)%, and anti-lipid oxidation capacity to (62.17 ± 3.51)%. The results of LCM showed that the encapsulation capacity of walnut peptides for walnut oil was enhanced after glycosylation, suggesting a potential application for improving the stability of emulsions. The glycosylation modification of walnut peptides provides a new idea for the processing and utilization of walnut meal by-products and provides a reference for the application of glycosylation modification in food development.

Non-dairy creamer is a class of microencapsulated powdered fats and oils that are widely used in the food industry. However, the oils used in it are hydrogenated vegetable oils, which contain large amounts of saturated fatty acids and are extremely harmful to the human body. This study investigated the effects of replacing hydrogenated vegetable oil with walnut oil to prepare walnut non-dairy creamer on lipid levels and intestinal microorganisms in mice. The results show that low-dose walnut non-dairy creamer significantly decreased the contents of TC and TG in serum and increased the content of HDL-C (p < 0.01). The contents of MDA, ALT, and AST were significantly decreased, while the content of SOD was increased (p < 0.01). The abundance of Firmicutes in the walnut non-dairy creamer group decreased, and the abundance of Bacteroidetes/Firmicutes (B/F) increased, which significantly increased the richness of Lactobacillus and Oscillospira (p < 0.01). Allobaculum richness was significantly decreased (p < 0.01). In conclusion, a low dose of walnut non-dairy creamer can effectively promote the metabolism of blood lipids in vivo, alleviate oxidative stress injury and lipid accumulation damage to mouse hepatocytes, and ameliorate the adverse effects of a high-fat diet on the intestinal microbiota of mice. This study provides a theoretical basis for the replacement of traditional non-dairy creamer and the research and development of walnut deep processing. [ABSTRACT FROM AUTHOR]