The extraction of catfish (Clarias gariepinus) bone gelatin was optimized by using Response Surface Methodology (RSM) involving 4-factors, 5-levels Central Composite Design (CCD). The optimum conditions for extraction were produced by a pre-treatment of 3.35% HCl for 14.5 h along with hot water extraction at 67.23°C for 5.2 h. Results showed that the predicted yield by RSM (61.81%) was closely matched the experimental yield of 60.54%. The results also indicated that the extracted bone gelatin possessed high protein content (81.75%) and imino acid (proline and hydroxyproline) (144 residues per 1000 residues), with gel strength (230.25 g), viscosity (4.64 mPa.s) and isoionic point (5.35) comparable to that of bovine gelatin. The results suggested that RSM is a great optimizing tool for extraction of gelatin from clarias catfish bone and values of the physicochemical properties of gelatin are higher or comparable than those from other fish species and bovine gelatin.
Skin and bone gelatins of pangasius catfish (Pangasius sutchi) were hydrolyzed with alcalase to isolate Angiotensin Converting Enzyme (ACE) inhibitory peptides. Samples with the highest degree of hydrolysis (DH) were separated into different fractions with molecular weight cut-off (MWCO) sizes of 10, 3 and 1 kDa, respectively and assayed for ACE inhibitory activity. Skin and bone gelatins had highest DH of 64.87 and 68.48 % after 2 and 1 h incubation, respectively. Results from this study indicated that by decreasing the molecular weight of fractions, ACE inhibitory activity was increased. Therefore, F3 permeates (MWCO
In the present study, to establish the optimum gelatin extraction conditions from pangasius catfish (Pangasius sutchi) bone, Response Surface Methodology (RSM) with a 4-factor, 5-level Central Composite Design (CCD) was conducted. The model equation was proposed with regard to the effects of HCl concentration (%, X1), treatment time (h, X2), extraction temperature (°C, X3) and extraction time (h, X4) as independent variables on the hydroxyproline recovery (%, Y) as dependent variable. X 1 = 2.74 %, X 2 = 21.15 h, X 3 = 74.73 °C and X 4 = 5.26 h were found to be the optimum conditions to obtain the highest hydroxyproline recovery (68.75 %). The properties of optimized catfish bone gelatin were characterized by amino acid analysis, SDS-PAGE, gel strength, TPA and viscosity in comparison to bovine skin gelatin. The result of SDS-PAGE revealed that pangasius catfish bone gelatin consisted of at least 2 different polypeptides (α1 and α2 chains) and their cross-linked chains. Moreover, the pangasius catfish bone gelatin was found to contain 17.37 (g/100 g) imino acids (proline and hydroxyproline). Pangasius catfish bone gelatin also indicated physical properties comparable with that of bovine and higher than those from cold water fish gelatin. Based on the results of the present study, there is a potential for exploitation of pangasius catfish bone for gelatin production. Furthermore, RSM provided the best method for optimizing the gelatin extraction parameters.