Effect of Acetic Acid Concentration on Acid-Soluble Collagen Extracted from Red Tilapia Skin: A Preliminary Study

Abstract

The present work investigated the effect of acetic acid concentration on the yield and physicochemical properties of acid-soluble collagen extracted from red tilapia skin. Treated fish skin was extracted using three acetic acid concentrations, namely 0.1 M, 0.5 M and 0.9 M, followed by evaluation of collagen yield, hydroxyproline content, moisture, protein, ash, pH, colour and relative viscosity. The results showed that acetic acid concentration significantly influenced collagen recovery and quality. Collagen extracted using 0.5 M acetic acid produced the highest yield, with values of 5.88 ± 0.87%, 12.42 ± 1.84% and 12.81 ± 1.91% on wet, dry and protein bases, respectively. The same treatment also showed the highest hydroxyproline content (55.59 ± 0.11 mg/g) and protein content (88.73 ± 2.14%), indicating better collagen purity. Moisture content remained low across all treatments, while ash content increased slightly with acid concentration. The pH decreased from 4.37 to 3.68 as acetic acid concentration increased, reflecting greater residual acidity. Colour analysis showed that 0.1 M produced the lightest collagen powder, whereas 0.5 M provided better compositional quality. Relative viscosity declined with increasing temperature in all samples, but 0.5 M collagen consistently showed the highest viscosity, suggesting better molecular integrity and thermal-related functional stability. Overall, 0.5 M acetic acid was the most suitable concentration for extracting acid-soluble collagen from red tilapia skin.