Extraction of functionally active collagen from fish by-products

Author: Neha Ketanbhai Rathod

Rathod, Neha Ketanbhai, 2021 Extraction of functionally active collagen from fish by-products, Flinders University, College of Medicine and Public Health

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The skin of salmon (Salmo salar), a waste product of the filleting process line, could serve as a good source of aquatic collagen. Until to date, however, the standard extraction and purification of collagen is time-consuming, delivering relatively low yields. Ultrasound can improve the extraction efficiency of many materials. To find a green and advanced method for collagen extraction, this study investigated the suitability of ultrasound for the extraction of acid-soluble collagen from salmon skin and compared yields and purities with the conventional extraction method. Salmon skin was pre-treated for both methods with 0.5 M acetic acid. The collagen subunits extracted by these processes were then analysed by sodium dodecyl sulphate polyacrylamide gel (SDS-PAGE) to determine the peptide chains of 1, 2 and . For extraction of acid-soluble collagen using ultrasound, the following parameters settings were investigated to optimise performance: amplitude (80 and 100%), sample:solvent ratio (1:10-1:30), concentration of acetic acid (0.5 and 1 M) and extraction time (30-120 min). The collagen yield for the conventional method was 34.5%, while ultrasound-assisted extraction increased yields to 46%. SDS-PAGE analysis confirmed that ultrasound-assisted processing did not change the main component of the collagens, 1, 2 and  chains. A soluble collagen assay confirmed that collagen was extracted. The techno economic analysis showed that ultrasound extraction of collagen from salmon skin returned a three-times higher net income ($1,382 million per year) compared to the conventional method ($499,000 per year) at a sales price of 510 USD/kg but was not economically feasible regardless of extraction method used at sales prices of 219 USD per kg or less. Since ultrasound-intensified extraction of collagen has advantages over the conventional method due to reduced extraction time and improved yield, losses generated at a sales price of 219 USD per kg were three-times lower than for the conventional method. Given the large capital investment required to build the plant, it would take nine years to break even based on the most profitable scenario. It is therefore concluded that the adoption of ultrasound-assisted production of collagen from salmon skin is economically feasible and preferable over the conventional extraction method, if a processing facility that could be retro-fitted with the required equipment, already existed close to the filleting industry. If the processing plant has to be built completely a new, the waiting period for returns on investment would dissuade investment.

Keywords: Collagen, Marine By-products, Ultrasound, Extraction, Salmon fish, Techno-economic feasibility

Subject: Medical Biotechnology thesis

Thesis type: Masters
Completed: 2021
School: College of Medicine and Public Health
Supervisor: Kirsten Heimann