Abstract:

Microcapsules of rice antioxidant peptide with enhanced stability were prepared by piercing method using
sodium alginate as the wall material. Operating parameters such as mass ratio of core to wall material, sodium alginate
concentration, temperature, calcium chloride concentration, and sucrose fatty acid ester concentration were optimized
by response surface methodology based on the microencapsulation efficiency of rice antioxidant peptide. The prepared
microcapsules were subjected to storage tests and electron microscopic observation. The results showed that the optimal
experimental conditions were 0.3:1, 1.4%, 50 ℃, 1.8%, and 0.26% for mass ratio of core to wall material, sodium alginate
concentration, temperature, calcium chloride concentration, and sucrose fatty acid ester concentration, respectively.
Experiments under these optimal conditions led to a microencapsulation efficiency of 81.24%, showing a relative error
of only 0.6% compared to the expected value (81.75%). Storage test revealed that the stability of microencapsulated rice
antioxidant peptide was improved obviously. Scanning electron microscopy images showed that the surface morphology and
structure of microencapsulated rice antioxidant peptide were intact. Therefore, microencapsulation is a good way to protect
the activity of antioxidant peptide. These results could provide references for actual production of rice antioxidant peptide
microcapsules.

Key words: piercing method, rice antioxidant peptide, microcapsules, microencapsulation efficiency