Applying non-destructive techniques to inspect preserved egg products by decay rates

Preserved eggs are a special Asian food. Traditionally, the gelling of preserved eggs is tested intuitively by feeling the slight vibrations that occur when the preserved egg is tapped with a finger. However, the effects of extended tapping and individual subjectivity lead to inaccurate results. This study thus attempts to devise a scientific method for inspecting the gelling of preserved eggs. Regression analysis of the peaks of the time response starting at 50 ms following the trigger yielded an exponential tendency line that indicates the decay rate of vibration theory. Distinct vibration analysis revealed that a decay below 80 represents complete gelling. Receiver operating characteristic curve analysis reveals an area under curve of 0.963, a cut-off point at 0.000 (x axis) and 0.882 (y axis), and a decay rate of 84.7995. The accuracy was 96.7%. This method provides a foundation for future development of an automatic preserved egg inspecting system.