Effects Of Frozen Time And Freezing Thawing Times On Electric Impedance And Quality Properties Of Chicken Breasts

As a basic method to prolong the shelf-life of meat, freezing has been provided to have a negative impact on tissue structure. Electric impedance properties of biological tissue closely relate with their tissue structure. A few published investigations have shown that electric impedance has a rapid detection capability to meat quality. To explore the impedance detection ability for frozen-thawed meat, electric impedance magnitude and phase properties of unfrozen and frozen-thawed chicken breasts subjected to different thawing times were studied. The maximum freezing-thawing circle was three times. Impedance characters and quality parameters of samples were investigated. The impedance detection ability for frozen meat and the relations between impedance and quality parameters were analysised. These results showed impedance measurement is a simple innocuous tool for frozen meat characterization.1. Effects of frozen time on electric impedance and quality properties of chicken breastsElectric impedance properties (magnitude and phase) at 50 Hz-200 kHz frequency range and quality of frozen chicken breasts subjected to different storage time were studied to estimate its relationship. Results showed that the impedance magnitude would decrease as the frequencies increasing. While opposite trend was found in impedance phase angle. Significant difference was found in high-frequency phase angle and low-frequency impedance magnitude between chilled and frozen meat (P<0.01). Quality parameters and low frequency impedance magnitude decreased with prolonged frozen storage (-20℃) time (P<0.05) but no significant difference was found in phase angle(P>0.05). A significant relationship were found between impedance and frozen time, quality parameters. Those results indicated that impedance has an ability to differentiate fresh meat from thawed samples and distinct the meat with different frozen history.2. Effects of freezing-thawing times on electric impedance and quality properties of chicken breastsIn order to explore the impedance detection ability for frozen-thawed meat, electric impedance magnitude and phase properties of unfrozen and frozen-thawed chicken breasts subjected to different thawing times were studied. The maximum freezing-thawing circle was 3 times.16 different frequencies from 50 Hz to 200 kHz and quality parameters like thawing loss, cooking loss, pH and TBARS of 20 samples of each group were investigated.The impedance magnitude of both fresh and frozen-thawed meat would decrease as the frequencies increasing and impedance magnitude of fresh meat was significantly higher (P< 0.01) than frozen-thawed meat in low-frequency range, while the opposite trend was found in high-frequency range. Impedance phase angle of both fresh and frozen-thawed meat would increase as the frequencies increasing. Compared with frozen-thawed meat, fresh meat had a higher (P<0.01) impedance phase angle in low-frequency range but a lower (P<0.01) value in high-frequency range. After freezing-thawing cycles, low-frequency impedance magnitude would decrease significantly (P<0.05), but the difference between two and three times freezing-thawing cycle was not significant (P>0.05). High-frequency phase angle would increase (P<0.05) which was different with normal frozen processing groups, especially higher than 100 kHz. On quality aspect, more thawing loss, cooking loss and higher TBARS value were found after freezing-thawing cycles. It could not precisely calculate the quality by impedance measurement for no accordant significant correlation (P>0.05) was found between impedance properties and quality parameters in different groups.3. Classification of chicken breasts with different freezing-thawing cycles by impedance properties and artificial neural networksRadial Basis Function (RBF) Neural Networks that built up basing on impedance magnitude and phase angle of specific frequencies from 50 Hz to 200 kHz (Total 12 frequencies) could give a solution to estimate the freezing-thawing cycles of meat without complex mathematics modeling and the prediction accuracy satisfies the requirement. Accuracy of the training and testing samples of fresh chicken meat was up to 100%, one time freezing-thawing cycle samples also had a high degree of distinction from two and three times. These results reflected electrical impedance measurement is a simple innocuous tool for frozen meat characterization.