Abstract: In order to explore the effect of metal salt concentration, NaOH concentration, NaCl concentration and preserving temperature on spot formation on shell surface of preserved eggs, orthogonal tests were used to optimize the preserved formula. The results indicated that the order of factors for spot formation on shell surface was NaCl concentration, NaOH concentration and metal salt concentration. The optimal formula was composed of 6% NaOH, 2% NaCl and 0.3% CuCl2, which was better than traditional process. In this case, the spots on shell surface were fewer and the color of spots was light. Therefore, the quality of preserved eggs using optimal preserved formula was greatly improved.

Key words: vision system, preserved egg, spots on surface, formula