Ultrasound-assisted extraction of collagen from clown featherback (Chitala ornata) skin: yield and molecular characteristics

BACKGROUND Clown featherback (Chitala ornata) skin, a by-product from the filleting process line, could serve as a good aquatic collagenous source. Nevertheless, the typical collagen extraction method is a time-consuming process providing a relatively low yield. Ultrasound had been reported to be an alternative technique for enhancing the extraction efficiency of several compounds, although the harsh conditions of ultrasound could affect their physicochemical and molecular characteristics. Thus, the application of ultrasonication under appropriate conditions could comprise a promising means for improving the extraction efficiency of collagen from clown featherback skin. RESULTS Ultrasonication using different amplitudes (20-80%) and times (10-30 min) was implemented during extraction. An ultrasound-assisted process (UAP) was able to increase the yield of collagen (P< 0.05) and could also result in a collagen purity decrease as evaluated by hydroxyproline content. There was no dramatic change in the solubility of resulting collagens. UAP induced protein degradation, particularly with an increasing amplitude and time, where slight changes in the isoelectric point value of collagen were observed. UAP had no adverse effect on molecular structure, where a triple-helical structure was still retained when an 80% amplitude was employed for 10 min (UAP-80/10-C). The amino acid composition of UAP-80/10-C reconfirmed the unique characteristic of collagen containing imino acid. CONCLUSION An UAP under appropriate conditions could be used to improve the extraction yield with minimal effects on the molecular integrity of the resulting collagen. In addition, fish skin waste from the cutting process line, particularly clown featherback skin, could be exploited as a value-added product, comprising fish skin collagen. (c) 2020 Society of Chemical Industry

Automated summary

Clown featherback skin can serve as a good source of aquatic collagen and ultrasound-assisted extraction can significantly improve the extraction efficiency of collagen. However, it may lead to a decrease in purity. Ultrasound-induced protein degradation does not have adverse effects on the molecular structure of collagen.