Effect Of Chlorine Dioxide To Disinfection And Fresh-keeping Of Eggs

Egg is a product with high quality and low price, which is often contaminated by bacteria in course of output and sales process, and even contaminated by pathogenic bacteria such as salmonella,all of these influence the safety of egg directly. In this paper, chlorine dioxide sterilization was used to extend the shelf life and raise the quality and safety of eggs.Microorganisms on the surface of the eggs are studied in this research. Eggs were sampled from Changqing Vegetable Market (treated and untreated), Shangchu Supermarket, Zhongbai Supermarket and Wal-Mart supermarket at random. This sdudy included the total number of bacteria, the number of coliforms and salmonella. The results indicated that the average number of the bacteria on the surface of the eggs from Changqing Vegetable Market (without treated) was the most of all, about 8.4×10⁵ cfu evry one. The eggs from Changqing Food Market (treated) were ranked the second with the number of 5.6×10⁶ cfu evry one. Next were Shangchu Supermarket and the Zhongbai Supermarket. The eggs from the Wal-Mart Supermarket with number of 1.8×10⁵ cfu evry one were the least. The average number of coliform bacteria on the surface of the eggs from Changqing Vegetable Market (without treated), Wal-Mart supermarket, Zhongbai Supermarket, Shangchu Supermarket and Changqing Vegetable Market (treated) were respectively 2.9×10⁴, 2.2×10³, 3.8×10³, 1.5×10⁴, 1.8×10⁴ evry milliliter; the number of the detection of Salmonella from all eggs were respectively three, one, one, one, two.Study on the effects of preservation of eggs by chlorine dioxide disinfection. After selecting and grading, eggs were dipped into the concentration of 30mg/L, 40mg/L, 50mg/L of chlorine dioxide solution for 5min, 10min, 15min respectively. Put some eggs in the concentration of 50mg/L of chlorine dioxide solution for 10min which were regarded as closed packaging group. The CK group was treated with nothing. All groups were stored at room temperature. Weight loss, Yolk index, Haugh unit and VBN were tested in the 10th, 20th, 30th, 40th day, respectively. The results indicated that the disinfection effects on egg shells of chlorine dioxide were significantly, but the effect of preservation of the eggs were not significantly. The eggs after disinfection were placed in sealed bags, which had well preservation.Studied the disinfection effect of chlorine dioxide solution to the surface of eggs of E.coli, Staphylococcus aureus, Bacillus subtilis, the effect of various factors on the chlorine dioxide sterilization were researched. The result showed that the optimal sterilization conditions to Escherichia Coli,Staphylococcus Aureus,Bacillus Subtilis with chlorine dioxide were containing ClO₂ 50mg/L for 15min at 30℃.Study the disinfection effect of chlorine dioxide combining with ultrasonic synergy to E. coli, Staphylococcus aureus, Bacillus subtilis bactericidal on the egg surface. All these eggs were treated at the concentration of chlorine dioxide 0, 30, 40, 50, 60mg/L, with and without 59KHz ultrasonic treatment for 1, 5, 10min, respectively. The result showed that the bactericidal capacity of chlorine dioxide plused 59KHz ultrasonication on the three strains for 10 min was more than 4.00 log cfu/mL, the chlorine dioxide concentration was reduced from 60mg/L to 50mg/L. The bacterial reduction of Escherichia Coli, Staphylococcus Aureus removed more than 4.00 log cfu/mL by chlorine dioxide at 50mg/L, the treatment time was shortened from 10min to 5min.