Abstract:

Edible films with antioxidant activity were prepared from soy protein isolate (SPI) incorporated with rosemary.
The effect of rosemary addition as an antioxidant on properties of SPI films was investigated. The active protein film was
smooth and transparent with excellent mechanical properties and had a better tensile strength than low-density polyethylene
(LDPE) material of the same thickness. Active protein-based films with different structures were obtained when rosemary
was added in different amounts to SPI, consequently resulting in various interactions between these two materials. The film
with 0.25 g/L rosemary had a relatively loose structure which facilitates the reaction of rosemary with free radicals. Thus
it exhibited significant inhibition against ABTS+ free radical and had the strongest antioxidant activity among the tested
concentrations of rosemary.

Key words: rosemary, soy protein isolate, protein-based film, antioxidant capacity