Abstract
The extraction and enzymatic hydrolysis of collagen from sheepskins at different times of hydrolysis (0, 10, 15, 20, 30 min, 1, 2, 3 and 4 h) were investigated in terms of amino acid content (hydroxyproline), isoelectric point, molecular weight (Mw) by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) method, viscosity, Fourier-transform infrared (FTIR) spectroscopy, antioxidant capacity by 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) assays, thermal properties (Differential Scanning Calorimetry) and morphology by scanning electron microscopy (SEM) technique. The kinetics of hydrolysis showed an increase in the protein and hydroxyproline concentration as the hydrolysis time increased to 4 h. FTIR spectra allowed us to identify the functional groups of hydrolysed collagen (HC) in the amide I region for collagen. The isoelectric point shifted to lower values compared to the native collagen precursor. The change in molecular weight and viscosity from time 0 min to 4 h promoted important antioxidant activity in the resulting HC. The lower the Mw, the greater the ability to donate an electron or hydrogen to stabilize radicals. From the SEM images it was evident that HC after 2 h had a porous and spongy structure. These results suggest that HC could be a good alternative to replace HC from typical sources like pigs, cows and fish.
Highlights
Collagen is the most abundant protein in bones and connective tissue in vertebrates, and there are at least 29 types
The structure of collagen is a triple helix formed for 3 α chains Gly-X-Y, where X is proline, Y is mainly hydroxyproline, and the triple helix is stabilized for hydrogen bonds with continuous repetition of the Gly-X-Y depending on the collagen type [3]
Hydrolysed collagen (HC) refers to a group of peptides that results from the proteolysis of native collagen type 1; its molecular weight (Mw) varies from 0.3 to 8 KDa [10]
Summary
Collagen is the most abundant protein in bones and connective tissue in vertebrates, and there are at least 29 types They are different in terms of their amino acid sequence and composition, the function in the organism, and the structure [1,2]. Hydrolysed collagen (HC) refers to a group of peptides that results from the proteolysis of native collagen type 1; its molecular weight (Mw) varies from 0.3 to 8 KDa [10]. Hydrolysed collagen has a neutral smell, is colourless, and can be used in emulsions as a stabilizer It is widely used in the pharmaceutical industry for the treatment of diseases like osteoarthritis and osteoporosis. In the cosmetics and food industries it is applied for the preparation of fruity beverages and nutritional supplements [14,15,16,17]
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