Development of Antioxidant Composites Based on Reprocessed PLA Reinforced with Bacterial Cellulose Obtained from Kombucha Fermentation in an Infusion of Cauliflower Stems

In this study, cauliflower stems were used as an infusion medium for kombucha fermentation to produce kombucha bacterial cellulose (KBC). The obtained KBC was incorporated into reprocessed poly(lactic acid) (rPLA) films as a reinforcing filler. Cauliflower stem powder (CS) was also evaluated for comparison. Films containing 1 and 3 wt.% of each filler were characterized in terms of their mechanical, thermal, physicochemical, and morphological properties, surface wettability, water vapor barrier properties, antioxidant activity using a fatty food simulant, and disintegration under laboratory-scale composting conditions. The results showed that both fillers reduced the mechanical strength of the films without significantly affecting their thermal transitions, chemical structure, or surface wettability. rPLA-KBC-reinforced films exhibited the best overall performance for the intended use, with lower reductions in mechanical and barrier properties and providing antioxidant activity to rPLA-based systems, reaching radical scavenging activities of approximately 15% and 26% for films containing 1 and 3 wt.% of KBC, respectively. In addition, all formulations completely disintegrated under composting conditions within approximately 21 days. These findings demonstrate the potential of combining agricultural and industrial waste to develop sustainable antioxidant rPLA-based materials for food packaging applications.