In this study, the effects of the disulfide bond cleavage induced by peracetic acid oxidation on the surface properties and surface hydrophobicity of soy proteins isolate (SPI) were investigated. The surface hydrophobicity, foaming capacity and emulsifying capacity of oxidized-SPI increased gradually at the initial stage with the increase of peracetic acid concentration. When the concentration of peracetic acid was increased up to 0.4%, compared with that of native SPI, the surface hydrophobicity, foaming capacity, emulsifying capacity and emulsifying stability of oxidized-SPI increased by 114.0, 81.4, 65.2, 49.8%, respectively, and achieved optimal results. However, excessive oxidation led to a decrease in surface hydrophobicity, foaming capacity and emulsifying stability of SPI, but it had no obvious effect on the foaming stability and emulsifying capacity of SPI. The foaming capacity, emulsifying capacity and emulsifying stability of SPI were positively related to the changes of surface hydrophobicity which caused by disulfide bond cleavage. The results of fluorescence spectroscopy, CD spectroscopy, and particle size analysis showed that the disulfide bond cleavage did cause great changes in the molecular structure of SPI, but there was no clear correlation between the molecular structural change and the surface activity of SPI. These suggested that the improvement of foaming capacity, emulsifying capacity and emulsifying stability of SPI could be achieved by changing its surface hydrophobicity via peracetic acid oxidation.
Although various eco-friendly and sustainable biobased polyurethane-coated controlled-release fertilizers (BPCFs) have been developed, their applications were limited by the bio-based coating contained many microscopic holes. In this work, a nano-soy-protein microcapsule-enabled self-healing biopolyurethane-coated controlled-release fertilizer (NSBCF) with enhanced controlled-release performance was fabricated. Nanoscale soy-protein microcapsules (SMCs) were prepared from soy-protein isolate (SPI) and poly (lactic-co-glycolic acid) using the water-oil-water emulsification technology. The self-healing biopolymer coatings of NSBCF with uniformly dispersed SMCs were constructed through self-assembly. The controlled-release longevity of NSBCF was >28 days longer than that of the BPCF with the unmodified coating. The self-healing mechanism of NSBCF was determined by directly observing the restoration area and the 3D pore distribution of coating using fluorescence labeling and X-ray computed tomography . After being released from the SMCs, SPI self-repaired the coating by reacting with glutaraldehyde to form solid resins to clog the microscopic holes. The SMCs-enabled self-healing process successfully reduced the nutrient release rate and extended the nutrient release longevity of NSBCF. This novel biobased controlled-released fertilizer with self-healing function represents a new direction for the development of high efficiency and environmentally friendly fertilizers to improve agriculture and food sustainability .
危险品化学品经营许可证（带存储）