Protein–β-Glucan Nanoparticle-Enriched Peach Juice: In Vitro Bioaccessibility, Metabolic Enzyme Inhibition, and Sensory Evaluation

This study introduces a novel food-grade protein–β-glucan nanoparticle system based on Fusarium venenatum protein isolate and Fuscoporia torulosa β-glucans, designed as a multifunctional ingredient for improving the physicochemical stability, bioaccessibility, and functional performance of peach juice beverages. Therefore, this study aimed to develop and evaluate a functional peach juice enriched with protein–β-glucan nanoparticles and to investigate their effects on physicochemical stability, gastrointestinal behavior, metabolic enzyme inhibition, antioxidant retention, and sensory acceptance. Protein–β-glucan nanoparticles produced from Fusarium venenatum protein isolate and Fuscoporia torulosa β-glucans were incorporated into peach juice formulations (V1–V4) and characterized using dynamic light scattering, zeta potential analysis, transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). In vitro gastrointestinal digestion was performed to assess β-glucan bioaccessibility, protein digestibility, antioxidant activity, and release kinetics, while α-amylase and α-glucosidase inhibition assays, sensory evaluation, digital sensory analysis, principal component analysis (PCA), and exploratory multivariate analysis were used to evaluate relationships among formulation characteristics and functional performance. The nanoparticles formed stable colloidal systems with mean particle sizes ranging from 176 to 229 nm and maintained structural integrity during 28 days of refrigerated storage. Nanoparticle-enriched formulations exhibited higher β-glucan bioaccessibility, improved antioxidant retention, and stronger α-amylase and α-glucosidase inhibitory activities, with the greatest effects observed in V4. Protein digestibility remained high across all formulations, while sensory evaluation revealed improved overall liking and purchase intention. PCA indicated that nanoparticle concentration was the main factor differentiating the formulations based on their physicochemical and functional characteristics. Overall, protein–β-glucan nanoparticles enhanced the physicochemical, functional, and sensory properties of peach juice, supporting their application as multifunctional ingredients for functional beverage development.