Effect of alkaline and acid pre-treatment on yield and properties of gelatin extracted from tuna (<i>Thunnus albacares</i>) skin

Abstract The yield and characteristics of gelatin are influenced by its source and the methods and conditions employed during pre-treatment and extraction. The study investigated the impact of NaOH and H 2 SO 4 pre-treatment on the yield and some chemical properties of gelatin extracted from the skin of yellowfin tuna ( Thunnus albacares ). Gelatin was extracted following pre-treatment with alkaline (NaOH) and acid (H 2 SO 4 ) solutions at varying concentrations, i.e. 0.1, 0.15, 0.3%. The yield, emulsification activity index (EAI), foaming capacity and stability, and pH of the resulting gelatin were analyzed to assess the efficiency of the pre-treatment method. Results indicated that both alkaline and acid pre-treatment significantly affected gelatin yield and properties. Increasing NaOH and H 2 SO 4 concentrations up to 0.15% produced gelatin with higher overall yield with the highest (p&lt;0.05) being 19.45%. The EAI (averaged 28.47 m 2 /g) improved with increasing NaOH concentration, while H 2 SO 4 pre-treatment had a negative impact on emulsification. A foaming capacity increased to 73.3% with increasing NaOH concentration up to 0.15%, though foam stability remained essentially constant. This study emphasizes the significance of optimizing pre-treatment conditions to customize gelatin characteristics for specific applications, particularly in the food, cosmetics, and pharmaceutical sectors