The objective of this research was to recover protein and water from tuna defrosting wastewater. Tuna defrosting wastewater (TDW) was evaporated and centrifuged to separate protein residue (PR) from aqueous solution (cTDW). Protein in the cTDW was precipitate (PP). Salt was removed from PR and PP by using hot water. Dried PR and PP were analysis for total protein, amino acid profile and salt content. Salt solution was collected and evaporated, then the resulting protein concentrated solution (PCS) was analyzed for pH, total protein, salt content, amino acid profile and antioxidant properties. Water from the protein recovery procedure was collected and analyzed for biological qualities (heterotrophic plate count, coliform bacteria, E. coli, Staphylococcus aureus, Salmonella spp. and Clostridium perfringens), physical qualities (apparent color, turbidity, pH) and chemical qualities (total dissolved solids, total hardness and sulfate).The results showed that cTDW contained 11.57%protein and 3.36%NaCl. Dried PR and PP contain 33.10% and 6.92% protein, respectively, with 9 essential amino acids and 0.23% and 0.05% NaCl. PCS contained 8.05% protein. Antioxidant properties were shown by values for DPPH, ABTS and FRAP. Physical, chemical and bacterial parameters of recovered water met guidelines for drinking water quality.
Tuna viscera as a common waste product from the tuna processing industry contributes to environmental pollution. The effects were determined of peptide fractions and amino acids on the antioxidant properties of protein hydrolysate from tuna viscera. We converted this waste into protein hydrolysate, a high added-value product, using autolysis. Tuna protein hydrolysate was fractionated by ultrafiltration into four fractions (>10 kDa, 5–10 kDa, 1–5 kDa and <1 kDa) and each was examined for its antioxidant properties (DPPH, ABTS, FRAP and metal chelating) and amino acids composition. The MW and amino acids of the tuna protein hydrolysate peptide fractions were not directly correlated with DPPH radical scavenging activity and metal chelating. The ABTS radical scavenging activity and ferric reducing antioxidant power (FRAP) of the 1–5 kDa fraction were higher than for the other fractions. The tuna protein hydrolysate peptide fractions contributed to antioxidant activity and should be used to their full advantage by the nutritional and food industries
Thailand is a leading exporter of canned tuna globally. Many by-products are created during processing, including head, bone, blood and stomach. The stomach can serve as a promising source of pepsin, while collagen hydrolysate can be obtained as a new value-added product with high market value. The objectives of this study were to characterize pepsin from tuna stomachs and evaluate its application for extraction of collagen hydrolysate from tilapia skin. Pepsin from the stomachs of albacore tuna, skipjack tuna, and yellowfin tuna was characterized. Pepsin from all tuna species was extracted with phosphate buffer (pH 7) at 4°C for 3 h then mixed with 2 M acetic acid at 1:1 (w/v) for 30 minutes. The characterization of crude enzyme was determined. The optimum pH of all tuna pepsin was 2, and stable at pH2-3. Optimum temperature of all tuna pepsin was 50 °C, and it was stable at 10-50 °C. This enzyme responded to EDTA, urea, copper sulfate and magnesium sulfate. Albacore tuna (3.52±1.09 unit/ml), skipjack tuna (3.42±1.008 unit/ml), yellowfin tuna (3.51±0.29 unit/ml) and porcine pepsin (3.96±0.00 unit/ml) were applied for collagen hydrolysate extraction at 50 °C for 0-3 h. Degree of hydrolysis (%DH) of yellowfin tuna pepsin was highest (75.99±0.02%) at 50 °C for 1 h. Collagen hydrolysate showed antioxidant properties (DPPH, ABTS and FRAP). Yellowfin tuna pepsin can be applied in food supplement production as well to commercial porcine pepsin.
Tuna viscera consist of high levels of protein and enzymes which have the potential to be used for protein hydrolysate production. The objective of this study was to produce protein hydrolysates from yellowfin and skipjack tuna viscera. Tuna viscera were autolyzed at various temperatures (33, 35, 55°C) for 10 days. Protein hydrolysate produced from tuna viscera contained 15.09-22.65% protein, 0.48-0.59% fat, and 1.88-1.95% salt. The levels of TVB-N (9.52-45.39mg·100 g -1 and histamine (276.87-289.95 mg·kg -1 were below the maximum levels for human consumption. Protein hydrolysate from skipjack tuna viscera contained a greater amount of protein and a lower level of fat than yellowfin tuna viscera. Protein hydrolysate from yellowfin and skipjack tuna viscera showed antioxidant activity as determined by DPPH (2,2-diphenyl-l-picrylhydrazyl) and ABTS (2, 2'-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid)) radical scavenging activities with acceptable qualities. The protein hydrolysate from skipjack tuna viscera could be a new source of protein for humans.
The objective of this research was to recover protein and water from tuna defrosting wastewater. Tuna defrosting wastewater (TDW) was concentrated, and salt protein residue (PR) was separated from concentrate TDW (cTDW). Protein in the cTDW was precipitated (PP). Salt was removed from PR and PP by using hot water (60 °C). PR and PP were dried at 50 °C before analysis for total protein, amino acid profile and salt content. Salty protein solution (PS) following salt removal from the precipitate was collected and concentrated. Then salt cPS was desalted by Sephadex G-25, and the elution was collected and concentrated. The resulting cPS was analyzed for pH, total protein, salt content, amino acid profile and antioxidant properties. Water from the protein recovery procedure was collected and analyzed for biological qualities (heterotrophic plate count, coliform bacteria, E. coli, Staphylococcus aureus, Salmonella spp. and Clostridium perfringens), physical qualities (apparent color, turbidity, pH) and chemical qualities (total dissolved solids, total hardness and sulfate).The results showed that cTDW contained 11.57 ± 0.03 % protein and 3.36 ± 0.03% NaCl. After salt was removed, the dried PR and PP contained 33.10 ± 0.16% and 6.92 ± 0.13% protein, respectively, and 0.23 ± 0.00% and 0.05 ± 0.00% NaCl, respectively. Dried PR contained 9 essential amino acids at higher concentrations than in PP. Concentrated PS contained 3.15 ± 0.12% protein and no NaCl. Histidine (254.15 mg/100 g) was the dominant amino acid in cPS. Antioxidant properties are shown by values for DPPH, ABTS and FRAP. The physical, chemical and bacterial parameters of recovered water met the guidelines for drinking water quality. These results indicate that recovery of protein and water is possible in fish processing, which could reduce costs for processors and benefit the environment.
The tryptic and chymotryptic activities of extraction of spleen, liver, stomach, intestine and mixed viscera of Nile tilapia ( Oreochromis niloticus Linneaus) were compared. Intestine was the best sources for trypsin and chymotrypsin. Trypsin and chymotrypsin fractions were extracted from intestine of Nile tilapia by 30-70% saturated ammonium sulfate precipitation, dialyzed, acetone precipitation and separated by SBTI affinity chromatography column. Specific activities of trypsin and chymotrypsin were 0.529 and 0.380 unit/mg protein, respectively. The purities of trypsin and chymotrypsin fraction were increased by 5.56 and 3.62 folds, respectively. The optimum temperature and pH of trypsin fraction were 80°C and pH 9.0. The optimum temperature and pH of chymotrypsin fraction were 60°C and pH 9.0. Trypsin fraction was stable at 0-60°C and chymotrypsin was stable at 0-50°C for 30 min at pH 8.0.