Extension of the Shelf Life of Sliced Sponge Cake Through a Combination of Modified Atmosphere and Active Packaging with Hydroxytyrosol and Eugenol

The development of bioactive food packaging is an important issue, given its potential to preserve food quality and safety without the use of synthetic preservatives. This study aimed to develop new polystyrene foam (PS) films with hydroxytyrosol (HOxTYR) and eugenol (EUG), alone or in combination, as bioactive molecules to preserve sliced sponge cake during long-term storage. The cake samples were analyzed periodically during storage at 15 °C in terms of quality attributes (pH, water activity, height, volume and weight loss, firmness, CIE Lab color, lipid peroxidation products, microbial spoilage, and overall acceptability) and shelf life. The active film containing the combination of 0.6% HOxTYR and 0.6% EUG showed the strongest antioxidant activity, which was attributed to a potential synergism between the compounds, resulting in lower lipid oxidation rates (TBARS). The combination of HOxTYR and EUG also offered the greatest reduction in bacterial load (62% for <i>S. aureus</i> and 58% for <i>E. coli</i>), suggesting a synergistic effect on microbial inhibition. Likewise, samples packaged in a modified atmosphere (MAP) with the active film containing the combination of HOxTYR and EUG showed the best performance, including a smoother texture and greater volume, more stable color, lower microbial counts, and greater overall acceptability, and, consequently, a longer shelf life of up to 70 days at room temperature. Furthermore, the results of this study could contribute to environmental protection by reducing food waste, and suggest that the developed active packaging technique represents a promising and innovative approach to the preservation of bakery products.