Effects of Organic Acids on the Extraction and Properties ofAcid-soluble Collagen from Tilapia Skin

The effects of three organic acids, namely, acetic acid (AA), tartaric acid (TA), and citric acid (CA), on the structure and properties of acid-soluble collagen (ASC) from tilapia skin were compared in this study. The secondary structure of the collagen samples was analyzed by circular dichroism (CD) spectrometry and Fourier transform infrared spectroscopy (FTIR). The thermal stability of the collagen samples was determined by differential scanning calorimetry (DSC), and the fibroblast ability of ASC was analyzed. Results showed that, the extraction yields of AA-ASC, TA-ASC and CA-ASC were 15.87%, 17.69%, and 28.63%, respectively. The content of triple helical conformation of AA-ASC was similar to that of CA-ASC, which was higher than that of TA-ASC. The FTIR data showed that AA-ASC had the highest hydrogen bond content, followed by CA-ASC and TA-ASC. No significant difference was found in the thermal transition temperature (T_m) of the extracted three collagens, but the enthalpy values of AA-ASC, TA-ASC, and CA-ASC were 1.18, 0.73, and 0.35 J/g, respectively. The fibrogenesis experiment revealed that AA-ASC had the highest fibril-forming rate and absorbance, followed by CA-ASC and TA-ASC. The results of this study suggest that the number and dissociation constant of carboxylic acids may play an important role in the effect of organic acids on the extraction and properties of collagen from tilapia skin.