Effect of acid pretreatment and extraction conditions on the yield and functional properties of gelatin from goat skin

The transition toward a circular bioeconomy requires the efficient valorization of tannery byproducts into high-value biomaterials. Although goat skin is recognized as a viable collagen source, there remains a critical research gap in understanding how breed-specific physiological differences, along with their interactions with extraction parameters, determine the functional quality of the resulting gelatins. This study systematically evaluated the effects of CH 3 COOH versus HCl pretreatment and extraction conditions (60–80 °C for 4–8 h) on the yield and functional performance of gelatin derived from indigenous and crossbred goat skin. A 2 × 3 × 3 × 2 full factorial design revealed that while the maximum yield (23.92%) was achieved at 70 °C for 8 h using HCl, these optimal recovery conditions were inversely correlated with functional integrity. Specifically, the highest gel strength (334.6 g) was extracted under milder conditions (60 °C for 4 h with CH 3 COOH), whereas superior water-holding capacity (4.05 ± 0.11 g/g) was observed under harsher conditions (80 °C for 8 h with HCl) in indigenous goat gelatin. Crossbred samples generally provided higher yields but exhibited lower protein purity than indigenous samples. These findings demonstrate that breed selection and precise parameter calibration are essential for balancing recovery rates with the specific functional requirements of halal-certified food and pharmaceutical applications.