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

Abstract

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.

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“…This is because ultrasonication favors the penetration of extraction solvents into the internal structure and therefore can enhance mass transfer, resulting in the increase of extraction yield 26 . Petcharat et al 9 found that increased yield of protein extracted from frog skin could be obtained with UAP at higher amplitude and longer ultrasonication time. In addition, Choi, et al 27 reported that UAP had an impact on alleviating protein extraction yield from Silkworm pupae where the highest yield was obtained with a 5 min ultrasonication time.…”

“…On the contrary, with a 10-min ultrasonication time, there was a decrease in protein recovery with amplitude increased. It had been previously shown that the higher energy from ultrasound, particularly with higher amplitude and ultrasonication time, generally resulted in higher protein extraction yield from rice bran 10 , fish skin 9 and edible insects 27 . However, Petcharat et al 9 showed that energy from UAP could destroy the insect powder matrix, in which some other co-extraction soluble solids could also be leached.…”

“…It had been previously shown that the higher energy from ultrasound, particularly with higher amplitude and ultrasonication time, generally resulted in higher protein extraction yield from rice bran 10 , fish skin 9 and edible insects 27 . However, Petcharat et al 9 showed that energy from UAP could destroy the insect powder matrix, in which some other co-extraction soluble solids could also be leached. This caused the dilution effect of extracted protein with the lower protein recovery.…”

“…The main factor of ultrasonication that governs protein extraction efficiency is the cavitation effects of ultrasound, which could cause pressure fluctuation leading to explosion of microscopic bubbles. This phenomenon leads to disruption of tissue and decreases the particle size, thus providing intensification of mass transfer 7 – 9 .…”

“…It has been reported that ultrasound-assisted processing (UAP) increased protein extraction from various sources including the skins of clown featherback fish ( Chitala ornate ) 9 , rice bran 10 , and edible insects 11 . Also, UAP has been shown to change the molecular characteristics of proteins in a way that can improve their functional and antioxidative properties including their solubility, foaming and emulsion properties 8 , 12 , thermal properties 9 and antioxidative activity 13 . However, the application of ultrasound under inappropriate conditions could also have detrimental effects on protein characteristics that consequently could affect their quality 7 , 13 .…”