Collagen extracted from rabbit: Meat and by-products: Isolation and physicochemical assessment.

Obtaining collagen from rabbit meat, skin and ears is a great way to add value to these by-products. The collagen extracts from meat, skin, and ear showed high levels of protein 80.7, 95.5, and 94.5% and yields of 9.0, 24.4, and 23.8% on a dry basis, respectively. SDS-PAGE analysis showed that the collagens mainly consist of type I collagen, and the FTIR spectra displayed the characteristic peaks of amide A, B, I, II, and III; in addition, the collagens showed greater solubility in acidic pH. The foam production capacity of the collagens was low compared with other collagen sources. However, foam rabbit-collagen stability was high. The emulsifying activity index for the meat, skin, and ears was 44.7, 46.6, and 48.2 m2/g, respectively. Based on the results, the meat, skin, and ears of the rabbit proved to be a viable source for collagen extraction and a possible alternative to add value to the by-products (skin and ears) of these raw materials.

Gelatin extracted from jundiá skin (Rhamdia quelen): An alternative to the discarded by-product.

The production of gelatin from by-products of the fishing industry values ​​the discarded raw material and serves a part of the population that does not consume products originating from mammals. Therefore, the objective of the research was to use the jundiá skin (Rhamdia quelen) (JS) to obtain gelatin (GJS) and characterize this product, not yet studied until the present moment. Thus, the extraction process showed a yield of 7.3 % for JS and 18.2 % for GJS (in wet weight). Both JS and GJS presented, in their composition, high concentration of protein (26.3 and 88.1 %), low levels of fixed mineral residue (1.0 and 1.9 %), lipids (1.7 and 1.5 %) and hydroxyproline content (1.5 and 7.2 %), respectively. The GJS dispersion had a pH value of 4.7 and the color analysis indicated a snow effect with a white appearance. Fourier transform infrared spectroscopy (FTIR) showed amide bands commonly found in gelatin, gel electrophoresis (SDS-PAGE) showed high molecular weight bands, differential scanning calorimetry (DSC) revealed a denaturation temperature of 69.4 °C and scanning electron microscopy (SEM) showed a compact and non-porous structure. The emulsifying property was high when subjected to a temperature of 80 °C for 30 min, while the foaming capacity was significant at a concentration of 1 %. The highest dispersivity was observed at pH 2.0 and, in this condition, the viscosity was higher than that of other gelatin sources (25.5 cP). In view of the above, attention is drawn to the use of JS as a raw material for obtaining gelatin and for the various possibilities of application.