Effect of alkaline and acid pre-treatment on yield and properties of gelatin extracted from tuna (Thunnus albacares) 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 H2SO4 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 (H2SO4) 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 H2SO4 concentrations up to 0.15% produced gelatin with higher overall yield with the highest (p<0.05) being 19.45%. The EAI (averaged 28.47 m2/g) improved with increasing NaOH concentration, while H2SO4 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.