Change of alkalinity, pH and texture properties during pidan pickling

Pidan (Chinese preserved egg) had prepared by the traditional copper method. The change of alkalinity of curing liquid, pH and free alkalinity of albumen and yolk, textural properties of albumen were studied during pickling, which could provide basic data for the quality control of pidan during pickling, exploiting the substitute of metal additives, and researching new processing technic. The result showed that alkalinity of curing liquid presented a declining curve. The pH and free alkalinity of albumen increased rapidly at first and decreased gradually, then slowly increased again. The pH and free alkalinity of yolk showed an increasing trend. Hardness of albumen presented an upward trend overall. Flexibility, chewing and cohesion of albumen all increased firstly, then decreased slightly, and finally remain stable.