Three-stage extraction of gelatines from tendons of abattoir cattle: 2-properties of gelatines

Abstract

The subject of our previous paper (part 1) was three-stage extraction of gelatines from short cattle tendons. In this paper, we studied influence of extraction conditions on quality of produced gelatinesprotein content, ash content, rigidity of gelatine gels, viscosity, and distribution of molecular weights. Ash content of gelatines ranged in limits 3.5-10.5 %. Rigidity of the gels was influenced by extraction conditions and by elastin content in gelatines; highest-quality gels display rigidity of 213 Bloom. Viscosity of gelatines ranged from 2.47 to 12.11 mPa s. Molecular weights of gelatines display a proportion of fractions from 20 to 36 kDa, a quite high proportion of fractions from approximately 50 to 100 kDa, in some cases even fractions above 200 kDa appear. It was found that transition temperature and melting temperature of gelatines extracted from tendons are in accord with data on gelatines obtained by traditional extraction techniques from skins and bones. With respect to efficiency of the whole extraction process and to quality of extracted gelatine, we may recommend extraction conditions as follows: in the 1st processing stage, shaking degreased starting material with water in ratio 1:10 at 25 °C for 5 h; in the 2nd stage, treating the swelled material with 5 % (w/w) added proteolytic enzyme at 40 °C for 25 h; in 3rd stage, extracting gelatine while boiling for 16 min.