Indirect Measurement of Changes in Hardness of Enzyme-treated Beef in Retort Pouch Using an Electrical Impedance Method

摘要

We examined a method to estimate the changes in hardness of enzyme-treated beef in a retort pouch using electrical impedance measurement. Beef shoulder meat immersed in papain enzyme solutions for 1 minute and enclosed in pouches were used as the samples. The impedance of samples before and after papain enzyme treatment was measured by a LCR meter. After immersing the beef samples in each papain enzyme solution (0, 0.5, 1.0, and 1.5 %) and deactivated enzyme solution for 1 minute, samples were enclosed in pouches and impedance at 24 370 Hz was measured over time. Additionally, portions of beef samples prepared under the same conditions as for impedance measurement were removed and subjected to measurement of changes in hardness (fracture energy) over time using a rheometer. In the samples immersed in the 0 % enzyme solution (distilled water) and deactivated enzyme solution, both impedance and fracture energy did not significantly change in a time-dependent manner. In contrast, in the samples immersed in the 0.5, 1.0, or 1.5 % enzyme solution, impedance values decreased and rupture energy showed a tendency to decrease in a time-dependent manner. According to the regression lines of impedance and fracture energy, the correlation coefficients were determined to be R-2 = 0.933, 0.984, and 0.986 for each enzyme concentration. Thus, the results of our study demonstrate that impedance measurement is a feasible method to nondestructively estimate the changes in hardness of enzyme-treated beef samples in retort pouches.