Selective Extraction of Collagen Peptides with High Purity from Cod Skins by Deep Eutectic Solvents

Abstract

This paper reports an efficient and eco-friendly extraction and separation method of collagen peptides from cod skins based on a nascent class of green and sustainable deep eutectic solvents (DESs). Six kinds of DESs were designed and synthesized. On the basis of the principle of high extraction efficiency and high purity, choline chloride–oxalic acid was selected as the optimal extraction solvent. In the process of collagen peptides purification, ethanol was the optimal precipitation reagent due to the low toxicity. Afterward, single factor experiments proved that the extraction efficiency and purity of collagen peptides were influenced by the molar ratios of choline chloride–oxalic acid, extraction temperature, reaction time and solvent-to-solid ratio. Under the optimal conditions, higher and lower molecular weight collagen peptides were obtained. The values of their respective extraction efficiencies were up to 91.57% and 96.01% and the corresponding purity was up to 93.14% and 100%, respectively. Finally, UV–vis and Fourier transform infrared spectrometry were utilized to study the extraction mechanism. The results from this study demonstrate that choline chloride–oxalic acid is a green, efficient and promising solvent for extracting collagen peptides from cod skins.

Fish Collagen: Extraction, Characterization, and Applications for Biomaterials Engineering

“…Therefore, for the extraction, the use of specific extraction techniques is required to increase the solubilization of collagen proteins and accomplish their isolation. Extraction of acid-solubilized collagen (ASC), extraction of pepsin-solubilized collagen (PSC), deep eutectic solvent (DES), and supercritical fluid (SF) extractions are the major methods reported in the literature [ 69 , 77 ] for collagen isolation from fish by-products.…”

“…ASC is known when collagen is extracted by only acid. Acids (such as HCl and AcOH) hydrolyze the triple helix of collagen and solubilize its single chains in solution, where the depolymerization of heavyweight proteins into shorter peptides (0.3–8 kDa) takes place [ 77 ]. The interaction between the acid and the collagen molecules breaks the crosslinks present in the collagen helix and increases the extraction efficiency.…”

“…Out of the six different DES investigated by Bai et al (2017) [ 77 ], the mixture of choline chloride (CC) and oxalic acid (OA) has proved to be the most effective one, showing extraction efficiencies close to 90% for cod skins. This value is almost four times higher than the extraction yields obtained with AcOH extractions from the skin of tilapia (27.2%) [ 84 ].…”

Nano‐liquid chromatography combined with a sustainable microextraction based on natural deep eutectic solvents for analysis of phthalate esters

“…In order to develop a more eco-sustainable analytical method, sample preparation was developed combining a microextraction with the use of DESs as a non-toxic extraction solvent. Recently, special attention has been paid to NADES, which are DES composed by natural products such as organic acids, amino acids, sugars, etc., due to their great availability, low cost, chemical diversity, biodegradability and low toxicity [31] NADESs based on formic acid/acetic acid and ChCl have been previously applied for the extraction of saponins [32], pretreatment of rice straw [33], extraction of collagen peptides from cod skins [34], etc. Nevertheless, to the best of our knowledge, ChCl-organic acid NADESs have been not applied to extract PAEs in grape-based beverage samples.…”

Development of different deep eutectic solvent aqueous biphasic systems for the separation of proteins

“…Based on this, DESs have been regarded as excellent substitutes for toxic organic solvents in many elds such as catalysis, 7 organic synthesis, 8 and separation. [9][10][11] Proteins are bioactive macromolecules, which play an important role in life activities and have extensive applications in food and medical elds. Therefore, it is crucial to achieve the purication of proteins.…”