Biodegradable Duo-functional Active Film: Antioxidant and Antimicrobial Actions for the Conservation of Beef

The mechanical properties as well antioxidant/antimicrobial effects of active packaging for beef produced from cornstarch, linear low-density polyethylene (LLDPE), and citric acid (CA) were evaluated. The addition of starch in the blends influenced the mechanical characteristics of the films, with reduced ultimate tensile strength (TS), elongation at break (E), and modulus of elasticity (ME) parameters for films with a higher starch concentration. Conversely, greater solubility and degree of swelling of the films were observed when the starch content was increased, with gradual release of the CA from the packaging to the product. Characterization by thermogravimetric analysis and Fourier transform infrared spectroscopy showed that the incorporation of starch affected the thermal stability and chemical composition of the blends. The "in vitro" biodegradability was shown by gravimetric evaluation, with weight loss and decrease of TS of the films. Meat samples packed with the active films and stored under refrigeration showed a significant reduction of the levels of thiobarbituric acid reactive substances (TBARSs) and a decrease of about 1 log in the total bacterial count in the beef, compared with the control film (nonactive). The color was also affected, with an increase in the a* (redness) parameter, which characterizes the desirable red color in beef. The biodegradable packaging of starch/LLDPE incorporating CA prevented oxidative and microbial processes, besides providing a more desirable color to the meat during storage. In this study, we hypothesized that the effects were related to CA presence.