The study evaluated the potential use of acerola (Malpighia emarginata) concentrate, either raw or maltodextrin-encapsulated, in starch-based biodegradable active packaging films to extend the shelf life of lamb meat. The concentrate was used at two stages of maturity and three levels of concentrate inclusion (1.5%, 3.0%, and 4.5%). Packaged meat samples were stored at 4 °C for 15 days. The pH, colour, and lipid oxidation (TBARs) were measured at 0, 5, 10 and 15 days of storage. The results showed that ripeness increased total phenolic content and antioxidant activity, while microencapsulation reduced these values. A total of 24 phenolic compounds with potential antioxidant activity were detected. Flavonoids were the main contributors to total antioxidant activity, with the major compounds being hesperidin, kaempferol and kaempferol 3-glucoside, representing 22%, 19.3%, and 18.2% of the total, respectively. Although acerola-based films were successfully produced using a polysaccharide matrix, they exhibited no antimicrobial activity and did not extend the shelf life of packaged lamb meat since they provided no protection against either lipid oxidation or color degradation. These findings highlight the challenges of preserving bioactive functionality after encapsulation and suggest limitations in the effectiveness of the packaging under the tested conditions.