Effects of Alcalase and Pepsin Hydrolysis on Gel Forming Behavior and Technological Properties of Porcine Skin Gelatin

The gelation ability of gelatin is useful for improving texture and stabilizing food structure, but excessive gelation may limit its application in liquid and high-moisture food systems. Therefore, this study compared the effects of Alcalase and pepsin hydrolysis on the gel-forming ability, viscosity, and functional properties of porcine skin gelatin. o-Phthaldialdehyde (OPA) analysis showed that the Alcalase hydrolysate had a higher free amino group content (0.77 meqv/g protein) than the pepsin hydrolysate (0.23 meqv/g protein), indicating more extensive peptide bond cleavage (p < 0.05). The control formed a stable gel structure after 60 min at 25 °C, whereas both hydrolysates showed reduced gel-forming ability. In particular, the Alcalase hydrolysate was found to maintain high fluidity, completely inhibiting gel formation. Furthermore, 17.5% (w/v) Alcalase hydrolysate solution showed no measurable viscosity. In contrast, 17.5% (w/v) pepsin hydrolysate solution exhibited a viscosity of 653.88 cP. In contrast to the Alcalase hydrolysate, the pepsin hydrolysate also showed the highest oil absorption capacity (8.81 g/g), emulsion stability index (854.09 min), and a slightly higher in vitro digestibility (29.36%) (p < 0.05). These results demonstrate that enzyme-specific hydrolysis can differentially modify the balance between gel suppression and techno-functional properties of porcine skin gelatin.