Impact of antioxidant potential of rohu (Labeo rohita) swim bladder gelatin hydrolysate on oxidative stability, textural and sensory properties of fish sausage enriched with polyunsaturated fatty acids.

The impact of rohu swim bladder gelatin hydrolysate (SBGH) at different levels on textural, sensory, oxidative, and microbial properties of polyunsaturated fatty acids enriched rohu fish cooked sausages (PUFA-RFS) were investigated in the current study. SBGH addition enhanced the lightness values of PUFA-RFS compared to both control sausages (without SBGH and with butylated hydroxyanisole (BHA) (P > 0.05). PUFA-RFS added with 3% SBGH exhibited higher hardness, cohesiveness, and gumminess throughout the storage duration at both 4 °C and -20 °C temperatures when compared to other sausages counterparts. PUFA-RFS added with SBGH displayed lower PV, TBARS, and total microbial counts than the control sausages. Furthermore, PV, TBARS, and total microbial count values of sausage decreased with an increase in SBGH level, indicating retardation in lipid oxidation and microbial growth by SBGH in a dose-depended manner. Nevertheless, sausage added with 3% SBGH had higher overall acceptability than other sausage counterparts. Therefore, SBGH could retard lipid oxidation and improves textural properties of PUFA-enriched fish sausage.

Production of Antioxidant, Angiotensin-Converting Enzyme Inhibitory and Osteogenic Gelatin Hydrolysate from Labeo rohita Swim Bladder.

Optimization of antioxidants and angiotensin-converting enzyme (ACE) inhibitory potential gelatin hydrolysate production from Labeo rohita (rohu) swim bladder (SBGH) by alcalase using central composite design (CCD) of response surface methodology (RSM) was investigated. The maximum degree of hydrolysis (DH), 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis-3-ethylbenzthiazoline-6-sulphonic acid (ABTS), total antioxidants (TAO), and ACE inhibitory activity were achieved at 0.1:1.0 (w/w) enzyme to substrate ratio, 61 °C hydrolysis temperature, and 94-min hydrolysis time. The resulting SBGH obtained at 19.92% DH exhibited the DPPH (24.28 µM TE/mg protein), ABTS (34.47 µM TE/mg protein), TAO (12.01 µg AAE/mg protein), and ACE inhibitory (4.91 µg/mg protein) activity. Furthermore, SBGH at 100 µg/ml displayed osteogenic property without any toxic effects on MC3T3-E1 cells. Besides, the protein content of rohu swim bladder gelatin (SBG) and SBGH was 93.68% and 94.98%, respectively. Both SBG and SBGH were rich in glycine, proline, glutamic acid, alanine, arginine, and hydroxyproline amino acids. Therefore, SBGH could be an effective nutraceutical in functional food development.

Impact of different extraction conditions on yield, physicochemical and functional characteristics of gelatin from Labeo rohita swim bladder.

Influences of different extraction temperatures (50, 60, and 70 °C) and time (3, 6, and 9 h) on yield, physicochemical, and functional properties of gelatin from swim bladder (SBG) of rohu (Labeo rohita) were investigated. Gelatin extracted at 60 °C (G60-9 h), and 70 °C (G70-9 h) temperature for 9 h showed highest gelatin yield 54.91 g/100 g, protein (92.35 g/100 g), and hydroxyproline (77.50 mg/g) content (P < 0.05) compared to other counterparts. All extracted gelatin showed major protein components as α-, ß-, and γ-chain with slight changes in band intensity. FTIR spectra showed significant loss of molecular order of triple-helix as temperature and time increased. Furthermore, G60-9 h exhibited higher emulsion, foaming, and gel strength than G70-9 h, and G50-9 h, respectively (P < 0.05). Therefore, G60-9 h could be appropriate conditions for the extraction of SBG with better yield, physicochemical, and functional properties.

Influence of spray-drying, freeze-drying and vacuum-drying on physicochemical and functional properties of gelatin from Labeo rohita swim bladder.

Influence of different drying method on yield, physicochemical and functional properties of gelatin from rohu (Labeo rohita) swim bladder were investigated. Freeze-drying presented the highest gelatin yield (54.51 g/100 g, dry weight basis), followed by vacuum-drying (48.95 g/100 g) and spray-drying (41.76 g/100 g), respectively (P < 0.05). All gelatin samples showed glycine as the major amino acid followed by proline, glutamic acid, alanine, arginine and hydroxyproline, respectively. Freeze-dried gelatin (FDG) and spray-dried gelatin (SDG) showed α (α1 and α2), ß-chains and γ-chain as the predominant components, whereas an absence of ß- and γ-chains found in vacuum-dried gelatin (VDG). FTIR spectra revealed that the loss of the triple-helix was found in all gelatins which indicated the conversion of collagen to soluble gelatin. FDG and SDG had the highest surface hydrophobicity, protein solubility, emulsifying, foaming and gelation property than VDG (P < 0.05). Moreover, SDG showed slightly higher surface hydrophobicity, protein solubility, emulsifying and foaming properties as compared to FDG (P < 0.05). However, no significant difference was found in gelation properties of FDG and SDG (P > 0.05). Therefore, freeze-drying or spray-drying could be an appropriate drying method for preparation of gelatin from rohu swim bladder with better functionalities.

Effect of various acids on physicochemical and functional characteristics of gelatin from swim bladder of rohu (Labeo rohita).

Influence of various acids (acetic acid, phosphoric acid, and propionic acid) at different concentrations (0.05, 0.1, and 0.2 M) on the extraction yield, physicochemical and functional properties of gelatin from Labeo rohita swim bladder were investigated. Highest gelatin yield (44.22%, dry weight basis) was obtained in a sample prepared by without acid pretreatment (GWA) of swim bladder as compared to acid pretreatment counterparts. Amongst the acid pretreatments, propionic acid (GPrA) showed the highest gelatin yield, followed by acetic acid (GAA) and phosphoric acid (GPA) at all concentrations used, respectively. Moreover, with increased concentrations of all acids, the decrease in gelatin yield was observed for all the acids. GWA showed higher protein and hydroxyproline content than that of acid counterparts (P < 0.05). Amino acid analysis of gelatins showed glycine as the major amino acid in all gelatins followed by proline, glutamic acid and alanine, respectively. GWA showed α (α1 and α2) and ß-chains as the predominant components with low molecular weight peptides. However, GPrA, GAA, and GPA had α1 and α2 dominant constituents. FTIR spectra of gelatins revealed that the loss of the triple-helix was found in GPA, GAA, and GPrA, compared to GWA. Among gelatin samples, GWA showed the highest solubility at all pH tested followed by GPrA, GPA, and GAA respectively. Furthermore, GWA exhibited higher emulsifying, foaming and gelling properties as compared to GPrA, GPA, and GAA, respectively. Therefore, the acid pretreatment of swim bladder had a negative impact on the extraction yield, physicochemical and functional properties of gelatin from rohu swim bladder.