Fish protein hydrolysates were prepared from Catla catla using different proteases viz. alcalase, bromelain, flavorzyme and protamex and designated as HA (alcalase), HB (bromelain), HF (flavorzyme) and HP (protamex), respectively. HB was found to have higher 2, 2 diphynyl‐1‐picrylhydrazyl (DPPH) free radical‐scavenging activity followed by HF, HP and HA. HB had higher ferric‐reducing power followed by HP, HF and HA. Linoleic acid peroxidation inhibition of HA, HB, HF and HP were 54 ± 4.75, 50 ± 2.60, 49 ± 3.00 and 36 ± 6.15%, respectively. Higher emulsion stability index and foaming capacity were recorded for HB. The emulsion activity index was higher in HP (52.76 ± 1.27 m2/g). The foaming stability was found to be good in HF.
Practical Application
The properties of fish protein hydrolysates from Catla catla using different enzymes have been studied. The protein hydrolysates prepared from C. catla can be used as antioxidant and functional ingredient in the processed food products. Among four different enzymes used, bromelain was effective in obtaining the protein hydrolysate with desired antioxidant and functional properties. The potential to use bromelain for hydrolysate preparation is high considering the abundance of pineapples in southern India.
Enzymatic conversion of fish frame waste of threadfin breams (Nemipterus japonicus) to protein hydrolysate could be a solution for minimizing the pollution issues related to seafood processing operations and a way for the value addition to processing by-products. Protein hydrolysates from fish frame waste (FW) of thread fin breams (N. japonicus) were prepared and evaluated for bioactive properties such as angiotensin-I-converting enzyme (ACE) inhibitory activity and antioxidant and functional properties as a function of degree of hydrolysis (DH). Two different plant proteases, papain and bromelain, were used to prepare fish protein hydrolysates (FPH) and designated as HP (hydrolysates prepared using papain) and HB (hydrolysates prepared using bromelain). The ACE inhibitory activity of HP samples was higher at 5 and 10 % DH than that of the HB samples at DH 15 %, and there was no significant difference (p < 0.05). Antioxidant properties (2, 2 diphenyl-1-picrylhydrazyl [DPPH] radical scavenging activity, ferric reducing power and lipid peroxidation inhibition) of hydrolysates increased with increase in DH. The HB samples at DH 15 % had significantly higher antioxidant properties than HP samples (p < 0.05). The solubility of HP and HB samples was high in a wide range of pH and increased with DH. The functional properties of HP and HB samples decreased significantly with increase in DH (p < 0.05). The fractionation of the HB-DH 15 % sample yielded three peptide fractions with the approximate molecular weight of peptides in the range of 7562-812 Da. Relatively, bromelain enzyme is more effective in producing the FPH with desirable bioactive and functional properties.
In the present study, the gelatin from fresh croaker fish (Johnius sp) skin was obtained by rapid extraction and its properties were assessed. The gelling and melting temperature of croaker skin gelatin was 17.4 and 23.8°C as revealed by dynamic visco-elastic analysis using Controlled Stress Rheometer. Croaker skin gelatin (CSG) had the bloom value of 193.4 g. Scanning electron microscopic analysis of freeze dried gelatin showed the presence of voids surrounded by a loose network imitating a sponge or coral like structure. Texture profile parameters such as hardness, springiness, cohesiveness, gumminess, and chewiness of croaker fish skin gelatin gel were relatively lower than the porcine gelatin gel. The amino acid composition of gelatin revealed a higher proportion of glycine, alanine, and hydroxyl proline (30.25, 23.4, and 11.82 g/100 g protein, respectively) content. The electrophoretic analysis showed the presence of two peptide chains with the approximate molecular weight of 200 and 116 kDa corresponds to β and α peptide chain of collagen. The Fourier Transform Infrared (FT-IR) spectra of gelatin showed peaks correspond to the structures like α helix, β sheet, and random coil in the gelatin preparations.ARTICLE HISTORY
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