Tannin-Rich Chestnut and Persimmon Extracts in Puddings: Gelation, Proteins, and Antioxidant Activity

To promote sustainable food production, the effective valorization of agricultural byproducts is essential. This study investigated the potential of underutilized chestnut inner skin (CIS) and thinned young persimmon fruit (YPF) extracts as functional ingredients in pudding gels, selected as a complex model system utilizing heat-induced egg gelation with milk and sugar. Puddings were prepared by replacing water with 10% or 50% CIS or YPF extracts. We comprehensively evaluated the physicochemical properties (texture, color, viscosity), microstructure (SEM), and sensory quality. Additionally, immunoreactive allergenic proteins (ovalbumin, casein, β-lactoglobulin) were quantified using ELISA, and antioxidant activity was measured via DPPH and H-ORAC assays. Results indicated that while high extract concentrations (50%) negatively impacted texture by increasing hardness and forming air pockets, the 10% YPF treatment yielded a smooth, homogeneous microstructure comparable to the control. Crucially, the 10% YPF extract significantly reduced the concentration of detectable allergenic proteins, attributed to the formation of insoluble tannin–protein complexes, without compromising sensory acceptance. Furthermore, the addition of these extracts significantly enhanced the antioxidant activity of the puddings in a concentration-dependent manner. These findings demonstrate that 10% YPF is a promising candidate for developing sustainable, hypoallergenic, and antioxidant-rich functional food products.