Development of Instantly Dispersible Soy Protein Isolate Granules via Wet Granulation with HPMC and Crospovidone

Soy protein isolate (SPI) is a highly nutritious plant-based protein essential for preventing age-related conditions like sarcopenia; however, its application is severely hindered by inherent hydrophobicity and poor water dispersibility, which causes severe lumping. This study aimed to develop dispersible SPI granules by applying pharmaceutical excipients via wet granulation. SPI was granulated using hydroxypropyl methylcellulose (HPMC; 0.5-1.5%) as a binder and crospovidone (1.0-2.0%) as a superdisintegrant. The physicochemical and reconstitution properties were evaluated. The granulation process successfully transformed fine SPI powder into large, highly porous agglomerates. The optimized formulation (1.5% HPMC and 2.0% crospovidone) significantly reduced the dispersing time to 5.33 s and lowered the equilibrium contact angle (32.08°), promoting fast capillary water uptake. FTIR and XRD analyses confirmed the protein's chemical and structural integrity remained unaltered, indicating purely physical interactions. DSC revealed a binder-concentration-dependent decrease in denaturation temperature due to plasticization. Furthermore, the reconstituted formulations exhibited shear-thinning rheological behavior. This study shows that the application of HPMC and crospovidone as modifying excipients in wet granulation presented a chemically inert granulation approach that overcomes hydrophobic lumping and improves plant protein dispersibility. This strategy highlights a strong potential for creating convenient nutritional supplements for the elderly.