Antioxidant properties of papain mediated protein hydrolysates from fresh water carps (Catla catla, Labeo rohita and Cirrhinus mrigala) and its application on inhibition of lipid oxidation in oil sardine mince during ice storage

Fish protein hydrolysates (FPH) from fresh water carps Catla catla, Labeo rohita and Cirrhinus mrigala were prepared with 5, 10, 15 and 20% degree of hydrolysis (DH) using papain enzyme. FPH were evaluated for antioxidant properties using in vitro assays such as DPPH free radical scavenging activity (at 10 mg/ml), ferric reducing antioxidant power assay (at 20 mg/ml) and linoleic acid peroxidation inhibition activity (at 10 mg/ml). Antioxidant properties of FPH varied with species and DH. The DPPH radical scavenging activity, linoleic acid peroxidation inhibition activity and ferric reducing antioxidant power (as absorbance at 700 nm) of FPH from carps was in the range of 59-92%, 52-85% and 0.388-0.663 respectively. Based on the overall antioxidant activity, FPH from C. catla with 20% DH was added to oil sardine mince at different concentration (0.1, 0.2 and 0.4%) and found to inhibit effectively the formation of peroxides and malonaldehyde in dose dependent manner. FPH from C. catla with 20% DH was fractionated using size exclusion chromatography and had three different peptide fractions with the approximate molecular weight of 6561-2106 Da (fraction 1), 1942-994 Da (fraction 2) and 935-383 Da (fraction 3). The present study showed promising results that the fish protein hydrolysates from fresh water carps muscle proteins can be used as natural antioxidants in food system. Production of fish protein hydrolysates with nutraceutical properties could be the way forward for better utilization and value addition.

Bioactive peptides from fisheries residues: A review of use of papain in proteolysis reactions

Papain is a cysteine endopeptidase of vegetal origin (papaya (Carica papaya L.) with diverse applications in food technology. In this review we have focused our attention on its application in the production of bio-peptides by hydrolysis of proteins from fish residues. This way, a residual material, that can become a contaminant if dumped without control, is converted into highly interesting products. The main bioactivity of the produced peptides is their antioxidant activity, followed by their nutritional and functional activities, but peptides with many other bioactivities have been produced. Thera are also examples of production of hydrolysates with several bioactivities. The enzyme may be used alone, or in combination with other enzymes to increase the degree of hydrolysis.

Antioxidant activities of squid protein hydrolysates prepared with papain using response surface methodology

Squid protein hydrolysates (SPH) were prepared from the Indian squid Loligo duvauceli using papain. Response surface methodology (RSM) was used for optimization of hydrolysis conditions, including temperature, time, and the enzyme-substrate ratio using DPPH radical scavenging activity as a response. The amino acid composition of SPH was compared with raw squid muscle. In vitro antioxidant activities were evaluated based on reducing power, metal chelation, ABTS, hydroxyl radical, and superoxide anion radical scavenging assays. SPH exhibited good ABTS radical scavenging activities of 96.50±0.90%, superoxide anion radical scavenging activities of 96.4±0.89%, reducing powers of 0.71±0.02, moderate hydroxyl radical scavenging activities of 64.03±2.11%, and metal chelating activities of 52.04±1.02%. In vivo antioxidant activities determined using a sardine minced model system showed 42% reduction in formation of secondary oxidative products as thiobarbituric acid reactive substances (TBARS), almost equivalent to reduction by ascorbic acid of 41.42% at 400 ppm.

The ability of in vitro antioxidant assays to predict the efficiency of a cod protein hydrolysate and brown seaweed extract to prevent oxidation in marine food model systems

BACKGROUND

The ability of different in vitro antioxidant assays to predict the efficiency of cod protein hydrolysate (CPH) and Fucus vesiculosus ethyl acetate extract (EA) towards lipid oxidation in haemoglobin-fortified washed cod mince and iron-containing cod liver oil emulsion was evaluated. The progression of oxidation was followed by sensory analysis, lipid hydroperoxides and thiobarbituric acid-reactive substances (TBARS) in both systems, as well as loss of redness and protein carbonyls in the cod system.

RESULTS

The in vitro tests revealed high reducing capacity, high DPPH radical scavenging properties and a high oxygen radical absorbance capacity (ORAC) value of the EA which also inhibited lipid and protein oxidation in the cod model system. The CPH had a high metal chelating capacity and was efficient against oxidation in the cod liver oil emulsion.

CONCLUSION

The results indicate that the F. vesiculosus extract has a potential as an excellent natural antioxidant against lipid oxidation in fish muscle foods while protein hydrolysates are more promising for fish oil emulsions. The usefulness of in vitro assays to predict the antioxidative properties of new natural ingredients in foods thus depends on the knowledge about the food systems, particularly the main pro-oxidants present.