The texture profile analysis and functional properties of gelatin from fresh water fish (carps) and porcine skin were measured. Texture profile analysis revealed that the porcine gelatin showed significantly higher values for hardness, springiness, cohesiveness, gumminess, and chewiness than carp skin gelatin (p < 0.05). The bloom strength of gelatin from a porcine source was higher (466.40 g) than carp skin. The solubility profile of gelatin from carps and porcine as function of sodium chloride concentration indicated a maximum solubility at 0.3 M. The relationship between emulsion capacity values and concentration of proteins were found to be inversed in all of the gelatin samples.

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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

The average yield of gelatin from the bone of freshwater fish (Cirrhinus mrigala) was 6.13%. The fluorescence spectra revealed maximum emission at 303 nm indicating the exposure of chromophores to bulk solvent. The amino acid profile of gelatin revealed a higher proportion of glycine and imino acids. The bloom strength of gelled gelatin was 159.8 g. The average molecular weight of fish bone gelatin was 281 kDa as determined by gel filtration technique. The dynamic oscillatory test of gelatin solution as a function of time and temperature revealed gelling and melting temperatures of 8.0 °C and 17.0 °C, respectively. The flow behavior of gelatin solution as a function of concentrations and temperatures revealed non-Newtonian behavior with pseudo-plastic phenomenon. The Herschel-Bulkley and Casson models were found suitable to study the flow behavior. The emulsion capacity (EC) of gelatin was inversely proportional to its concentration.

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BACKGROUND Proteins recovery using hydrochloric acid (HCl) in acid‐aided solubilization could cause greater loss in its functionality over alkali‐aided solubilization. Moreover, using HCl in edible foods is also a health concern. Replacing HCl with organic acids for acid‐aided solubilization could address these problems. The aim was to study the effect of organic acid (glacial acetic acid) as a replacement for HCl during pH shift processing on the characteristics and functionality of rohu (Labeo rohita) protein isolates. Rohu proteins were obtained by solubilizing at pH 3.0 and pH 11.0 using glacial acetic acid and sodium hydroxide (10 mol L−1). RESULTS Results showed that solubilization at pH 11.0 gave higher protein yields (766.8 ± 2.4 g kg−1) compared to solubilization at pH 3.0 (735.7 ± 7.1 g kg−1) (P < 0.05). Isolates from acid‐aided solubilization had higher whiteness and total pigment content over isolates obtained by alkali‐aided solubilization. Rohu isolates recovered by alkaline solubilization showed higher water and oil holding capacity, gel strength, folding scores, foaming and emulsion capacity than acid processed isolates (P < 0.05). Solubilization of rohu proteins using glacial acetic acid produced isolates with low breaking force (149.0 g), low storage modulus (G′) values and low folding test score (1.0) over the alkaline isolates (P < 0.05). CONCLUSION Results indicated that, recovering rohu proteins using organic acid (glacial acetic acid) could produce isolates with poor functional properties, while using the organic acid to precipitate the proteins solubilized by alkali‐aided processing could produce proteins with better yields and functionality. © 2019 Society of Chemical Industry

Influence of heat penetration on the quality changes of ribbon fish canned in different media, oil and curry using tin-free steel cans, was assessed. The total process time for ribbon fish in oil pack was 47 min, and curry pack was 68 min, with a lethality value of 12.84 and 10.8 min for oil and curry pack, respectively. The biochemical and sensory analysis of the products was done during a storage period of 5 months. Total volatile base nitrogen and tri-methylamine nitrogen contents were found to be slightly higher but within the acceptable limit at the end of 5-month storage, while thiobarbituric acid and free fatty acid content increased slightly in curry and oil pack at the end of the storage period. The sensory quality of the processed products was rated as good by the taste panel, and the products were in acceptable condition even after storage of 5 months at room temperature (28 Ϯ 2C).