Williams Pear Canning-Industrial Residues Suitable for Powdered Products: Effect of Particle Size and Acid Immersion on Physicochemical and Bioactive Properties

Powdered fiber- and polyphenol-rich ingredients derived from pear canning residues were obtained by direct processing. Residues were subjected to acid immersion and subsequent convective drying, milling, and sieving. Drying kinetics were studied to select the best operative drying conditions (70 °C, 3 h) for both acidified (CIT) and non-acidified (C) samples. Two granulometries were also assessed (<210 and <590 μm). The resulting powders (C210, CIT210, C590, CIT590) were characterized as bioactive compounds, techno-functional fiber properties, physical and stability attributes, as well as <i>in vitro</i> bioaccessibility. All powders were rich in dietary fiber (52-54%) and exhibited a polyphenol content ranging from ~390 to 567 mg GAE/100 g on a dry basis for CIT and C powders, respectively. Also presented good hydration properties and low oil absorption. Sample C210 was particularly noteworthy due to its higher polyphenol level and better physical and stability properties. Acid immersion slightly reduced browning during drying and, although it caused a polyphenol loss (29%), CIT samples showed a better functional potential in terms of bioaccessibility of polyphenols (83 ± 6%) and of antioxidant capacity (58 ± 1%). By analyzing multiple properties, this study offers a comprehensive evaluation of simple and cost-effective biomass utilization strategies for the production of functional ingredients.