Firmness of Heat Induced Albumen Coagulum

Abstract

Firmness of heat induced albumen coagulum was measured with a multiple blade shear-compression cell equipped shear press. Maximum shearing force increased with both cooking time and temperature from 2.6 ± .2 kg (77 C, 7 min) to 15.8 ± .25 kg (77 C, 60 min); from 4.7 ± .4 kg (80 C, 7 min) to 15.0 ± .4 kg (80 C, 60 min); from 14.8 ± .2 kg (85 C, 7 min) to 22.9 ± .3 kg (85 C, 60 min); from 19.8 ± kg (90 C, 7 min) to 25.0 ± 1.6 kg (90 C, 60 min). Ranges shown are standard deviations. Water dilution (up to 50 ml H2O/100 ml albumen) resulted in an exponential decrease in shear force values to about 71% of the value at no dilution. Coagulum firmness at pH 7 decreased to about 50% of the shear value obtained at pH 9 then rose to a value greater by 75% at pH 5.5 Compared to 0-level control samples, NaCl (.9M) reduced coagulum firmness 16%, CuSO4·5H2O (1.0 × 10−3 M) 22%, ALCL3·6H2O (1.0 × 10−3 M) 18%, and KIO3 (1%) 61% whereas FeCl3·6H2O (5.0 × 10−4M) increased firmness about 90%. Digestion of albumen with the proteolytic enzymes papain, ficin, and pronase (.1%) for 2 hr at room temperature prior to thermal treatment produced mushy coagula.