The Addition of Plantain Peel (Musa paradisiaca) to Fermented Milk as a Strategy for Enriching the Product and Reusing Agro-Industrial Waste

The present study investigates the hypothesis that green plantain peel (GPP) could be used as a functional ingredient to enrich fermented milk, thus improving its nutritional profile and bioactive content. The objective of the present study was to develop a fermented milk product with added GPP and to evaluate its physical–chemical, technological, microbiological, and sensory characteristics, as well as the bioaccessibility of bioactive compounds after in vitro digestion (INFOGEST). The methodological strategy involved the formulation of four treatments: one control (Fermented Milk Control, FMC) and three with different concentrations of cooked plantain peel (5%—FM5, 10%—FM10, and 20%—FM20). The results demonstrated that the incorporation of peel had a significant impact on the technological properties, resulting in increased syneresis and color change. In contrast, pH and acidity were more influenced by storage duration. Lactic acid bacteria demonstrated viability at probiotic concentrations (≥106 CFU/mL) for a duration of up to 11 days. The incorporation of GPP resulted in a substantial increase in the phenolic compound content and antioxidant activity of the product, with the FM20 treatment showing the highest antioxidant activity (DPPH: 1555 ± 16 µmol TE/mL, ABTS: 576 ± 29 µmol TE/mL, FRAP: 2427 ± 58 µmol Fe2+/mL) compared to FMC. Sensory analysis revealed that texture and color were the most influential attributes, with formulations FM5 and FM10 being the most accepted, as indicated by an acceptability index above 82%. The simulated in vitro digestion led to an increase in the measurable phenolic content and a corresponding enhancement of antioxidant activity. This suggests that the digestive process enhances the release of these compounds from the food matrix, thereby increasing their bioaccessibility.