Chicken Breast Quality Assessment by Lyophilisation, Differential Scanning Calorimetry and Electric Impedance Spectroscopy

摘要

The study makes an effort to establish the ability of three different physical methods to assess the quality of chilled chicken breasts. 8 different common for the local market in Bulgaria brands were included in our investigation. The water content was directly obtained by weight method from lyophilisation (-50°C, 10 Pa, 24 hours). The results showed main variation from 73÷76 wt %, with two exceptions - one of 91 wt%, and one of 69 wt%. By means of differential scanning calorimetry, the general tendency of protein endothermic peaks shifts to higher temperatures was detected, which might be attributed to some stabilizing proteins state additives. Based on the enthalpies of ice freezing-melting and the cumulative peak of protein denaturation and water evaporation, a master curve of water content is proposed. Electric impedance spectroscopy in the range 20 Hz-1 MHz was used to additionally prove the water content. It can be done by measuring impedance modulus value at low frequency. In this frequency range, a clear dependence of impedance modulus on temperature, pH, and water contents was observed. Meanwhile, the phase angle did not show and specific tendency.