Preparation and Characterization of Silkworm Pupa SourcePeptide-zinc Nanoparticles

Silkworm pupa peptide (SCP) was prepared by enzymatic hydrolysis and then chelated with soluble zinc ions to obtain silkworm pupa peptide-zinc chelates (SCP-Zn), so as to develop safe and easily absorbable zinc supplements and improve the utilization value of silkworm pupa. Taking the zinc chelating capacity as an index, the optimum preparation process of SCP-Zn was determined, and the structure of both SCP and SCP-Zn were characterized by ultraviolet spectrum, fluorescence spectra, scanning electron microscopy, elemental analysis, particle size analysis and Fourier transform infrared spectrum. The results showed that the chelation rate of silkworm chrysalis peptide was 58.05% under the conditions of 1% alkaline protease plus enzyme, pH8.0, temperature 50 ℃ and enzymatic hydrolysis time 6 h. The optimum preparation conditions for preparation of SCP-Zn nanoparticles were as follows: Mass ratio of zinc peptide 1:0.5, pH6.5, 55 ℃, time 20 min, and the chelation rate of zinc reached 72.63%. The results of ultraviolet spectrum and fluorescence spectrum showed that zinc ions successfully combined with SCP. The obtained chrysalis SCP-Zn belongs to nanoparticles with an average particle size of 71.99 nm, with uniform granular structure on the surface, and the relative content of zinc reached 37.46%. The -COOH, -NH₂ and -C=O in the peptide chain were the main binding sites of Zn²⁺ and SCP. The results indicated that silkworm pupa was a good raw material for preparation of zinc chelates. The study provides a theoretical basis for enriching organic zinc supplement resources and the high value utilization of silkworm pupa.