Intelligent film based on collagen and anthocyanins from Catharanthus roseus: a new freshness sensor for fish

This study evaluated the impact of different concentrations of anthocyanin extract (CAE) from Catharanthus roseus flowers, an innovative and little-explored source of anthocyanins, on the properties of intelligent films for monitoring the freshness of tilapia fillets. The films were produced from collagen from tilapia skin and pectin, in 4 treatments: FC (control), F10 (10 % CAE), F20 (20 % CAE) and F30 (30 % CAE). The results demonstrated that CAE presented high anthocyanin content, significant antioxidant activity, and phenolic profile composed of phenolic acids, flavonoids and anthocyanins, in addition to color variation sensitive to changes in pH. The incorporation of CAE darkened the films and compromised the elasticity and thermal resistance at the highest concentrations (30 %), without affecting the tensile strength, solubility, and vapor permeability. The higher concentration of CAE also reduced soil film degradation, decreased crystallinity, and increased antioxidant activity. The films demonstrated sensitivity to the presence of different concentrations of ammonia, evidenced by chromatic changes. Among the treatments, the F30 film demonstrated a quick response to pH variations associated with fish spoilage, with a noticeable transition from translucent to an opaque yellowish. These results demonstrate the feasibility of using CAE in intelligent and sustainable systems for monitoring fish freshness.