Films of 0.11 to 0.13 mm thickness were prepared using gelatins from the skins of cultured freshwater carp species and mammalian gelatins viz., porcine and bovine skin gelatin. A comparative study was made on the physical, mechanical, and barrier properties of these films. The amino acid composition, gel strength, clarity, and gel setting point of the gelatins were also determined. Carp skin gelatins had a lower imino acid content (19.16% to 20.86%) than mammalian skin gelatins (22.91% to 23.7%). Grass carp gelatin had gel strength of 230.2 B that is comparable to the reported value for bovine skin gelatin (227.2 B). The bloom values of rohu and common carp skin gelatins were 188.6 B and 181.3 B, respectively, which were significantly lower than mammalian gelatins. Mammalian gels have significantly higher (P < 0.05) setting temperatures (23.7 to 24.2 °C) than carp skin gelatins. Tensile strength (TS) was lowest for films from common carp and rohu skin gelatin (490 and 497 kg/cm(2), respectively) and highest for porcine skin gelatin film. The degree of transparency (L*) was significantly higher for films from grass carp, bovine hide, and pork skin gelatin films. Carp skin gelatin films had significantly lower water vapor permeability (WVP) and oxygen permeability (OP) than mammalian skin gelatin films, which indicated that carp skin gelatin based films have superior barrier properties than mammalian skin gelatin films.

Gelatin was extracted from the skins of rohu and Common carp, and its physicochemical properties were studied. The yield of gelatin obtained from the skin of rohu and Common carp were 12.93 and 12%, respectively. The corresponding viscosity values were 6.06cP and 5.96cP. Rohu and Common carp skin gelatin had high content of imino acids i.e., 20.49 and 19.16%, respectively. Rohu gelatin had a significantly higher (P < 0.05) melting point than that of Common carp skin gelatin. The setting temperature observed for the gels from rohu and Common carp was 18.52 and 17.96C, respectively. Rohu and Common carp skin gelatins were found to have a mild but easily perceivable odor. The gelatins from the skin of rohu and common carp had a snowy white appearance and were light‐textured. Rohu skin gelatin had significantly higher gel strength compared with Common carp skin gelatin. Foam formation ability and form stability of Common carp gelatin was significantly lower (P < 0.05) than that of Rohu gelatin. Rohu skin gelatin had the high fat‐binding capacity. In this study, the functional properties observed for gelatins from the skin of rohu and Common carp are similar, if not better than many of the gelatins from other fish sources, and can be used as potential substitutes for the same in many applications. PRACTICAL APPLICATIONS Among the cultured carps, rohu (Labeo rohita) and Common carp (Cyprinus carpio) contribute significantly to the Aquaculture production in India. These species are presently being increasingly used for the preparation of mince and fillet‐based value added products, with skin forming a major portion of the fishery waste thus generated. Hence, based on the availability and commercial importance and with the objective of efficient utilization of fish skin waste, these species were chosen for studies on gelatin extraction. It was observed that the physicochemical and functional properties for rohu and Common carp skin gelatins are similar, if not better than many of the gelatins from other fish sources and can be used as potential substitutes for the same in many applications. There is a future scope for developing binary blends of these gelatins with animal gelatins that are completely compatible and commercially useful in many applications.

Present study addresses the fortification of mayonnaise with fish protein hydrolysate by partial replacement of egg yolk in the product. Red meat of yellowfin tuna (Thunnus albacares), a by-product from tuna canning industry was used as the source of protein hydrolysate (TPH). Substitution of egg yolk with hydrolysate imparted noticeable fish flavor to the product only at higher levels of replacement (50% and above). Emulsion stability of mayonnaise samples was not significantly affected at the given range of substitution. The preliminary product acceptability parameters indicated higher desirability with a sensory score of 7.6 ± 0.7 for a replacement ratio of 1:2::TPH:egg yolk. Hence, the same combination was further subjected to morphological, rheological characterization, and opted for storage stability studies. Fortified mayonnaise exhibited lower particle size, indicative of higher emulsion quality which was also evident in the rheological properties of the sample. Results indicated better oxidative and physicochemical stability for fortified samples compared to control under chilled conditions, suggesting the applicability of fish protein hydrolysate as fortifying and stabilizing agent in mayonnaise preparations.

No abstract

No abstract