Biochemical and Microstructural Properties of Lizardfish ( Saurida tumbil ) Scale Collagen Extracted with Various Organic Acids.

The purpose of this research was to extract collagen from the scales of lizardfish ( Saurida tumbil ) using various acids. Acetic acid-extracted collagen (AScC) produced a higher yield (1.8 mg/g) than lactic acid-extracted collagen (LScC) and citric acid-extracted collagen (CScC) although not significantly different ( p > 0.05). All extracted collagens were categorized as type I collagens with the presence of alpha chains (α 1 and α 2 ) based on the SDS-PAGE profiles. The triple-helical structure of the collagen was maintained in the AScC, LScC, and CScC as confirmed by the FTIR spectra. The UV-vis and X-ray diffraction spectra observed in all collagens were in agreement with previous work on fish scale and calfskin (commercial) collagens. The thermal stability of AScC ( T max = 31.61 °C) was greater than LScC ( T max = 30.86 °C) and CScC ( T max = 30.88 °C). The microstructure of acid-extracted collagens was characterized as complex, fibrous, and multilayered, with irregular sheet-like structures. All samples were highly soluble in acidic pH (1.0-4.0) and in low concentrations of NaCl (0-20 g/L). In conclusion, the lizardfish scale collagen, particularly AScC, may be used as an alternative to terrestrial animal collagen.