In-vitro antibacterial and antioxidant properties of starch/chitosan edible composite film incorporated with thyme essential oil

Background/aim
Nowadays, packaging research is receiving considerable attention because of the development of ecofriendly materials made from natural polymers such as starch and chitosan. This study aimed to prepare composite films from starch–chitosan, incorporated with essential oil (S-CH-Th), and to evaluate their antibacterial, antioxidant and optical properties.
Materials and methods
The molecular weight of chitosan was (~400 kDa, 75–85% deacetylated). 27% amylose corn starch, Tween 80, DPPH (2, 2-diphenyl-1-picrylhydrazyl) and Folin–Ciocalteu reagent were used to carry out research. Antibacterial activity testing was performed using the disk method. Antioxidant activity test was performed using a spectrophotometric method with DPPH as the radical source. Essential oil concentrations ranging from 0 to 2%, incorporated into a starch–chitosan composite (S-CH) film, were used.
Results
Antibacterial and antioxidant properties increased significantly with the incorporation of Essential oils (EO) ( < 0.05). On incorporating EO, there was an increase in the total colour differences (Δ), yellowness index and whiteness index, which were significantly higher than those of the control, and the transparency was reduced. Also, the results showed that chitosan edible films incorporated with EO could be used as active films because of their excellent antibacterial and antioxidant activities.
Conclusion
S-CH edible films incorporated with thyme EO as a natural antibacterial and antioxidant agent may potentially be used as an active packaging to enhance the safety of foods and food products.