Preparation and characterization of soy protein isolate/SiO2 nanocomposite films and their walnut oil microcapsules

In this study, nano-SiO2/soy protein isolate composite film was prepared by casting method. The effects of (adding 0%, 1%, 3%, 5%, 7%, and 9% w/w) nano-SiO2 on the properties of the resulting blend films were investigated. Results showed that the addition of 5% nano-SiO2 exhibited good barrier properties. The mechanical properties including tensile strength and elongation at break of the film with 7% nano-SiO2 is increased by 82.6% and 31.49% correspondingly. Differential scanning calorimetry indicated that the melting temperature of the composite film is increased by 56.6 degrees C compared with the pure film. The wall material modified by nano-SiO2 (adding 1%, 3%, 5%, 7%, and 9% w/w) was used for encapsulating walnut oil by spray drying. After accelerating oxidation test at 63 degrees C for 12 days, we found that the encapsulation efficiency value of walnut oil microcapsules with 0%, 1%, 3%, 5%, 7%, and 9% nano-SiO2 decreased by 64.23%, 48%, 21%, 22%, 21.00%, and 31% respectively. The results suggested that the stability of the core material was improved by adding nano-SiO2 to the wall material.

Automated summary

The study demonstrated that adding 5% nano-SiO2 improved the barrier properties of the composite film, while adding 7% nano-SiO2 significantly enhanced the mechanical properties of the film. Nano-SiO2 also increased the melting temperature of the composite film, and through spray drying encapsulation, the stability of walnut oil microcapsules was improved by incorporating nano-SiO2 into the wall material.