Effect of different metal ions immersion solution on the quality of pickled duck egg

• Main Authors: Ou, Li-Hsin, 歐俐昕
• Other Authors: Lin, Jenshinn
• Format: Others
• Language: en_US
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/r35xwb

碩士 === 國立屏東科技大學 === 食品科學國際碩士學位學程 === 106 === Preserved eggs (Pidan) known as thousand years egg, is a long-established egg processing product in Asia and is quite popular in Taiwan. In the production process of preserved eggs, metal ions such as lead or copper are added to the immersion solution as a processing aid to stabilize the quality and color. Both of lead and copper ions would cause black spots on the eggshell making it difficult for consumers to identify whether the preserved eggs are lead-free or not. The purpose of this study was to use two different metal ions, iron-zinc, mixing methods to replace lead and copper ions, and to pickle duck eggs in a 25°C constant temperature room for 20 days, and include blanks, without metal ions added, and commercial groups as comparison. The duck eggs were taken out every 5 days for observing the physicochemical properties. At the end of 20 days immersion, the eggs were all collected and the differences in quality were explored, the production rate was calculated as well. According to the experimental results, Group C, a group consisting of ferrous sulphate and zinc sulphate, was the highest in the experimental groups with a production rate of 72% and no black spots were found on the eggshell. The final pHs of the protein and egg yolk were 11.06 and 10.56, respectively. The egg white gumminess of 0.337±0.057 N was higher than that of the commercial group. The egg white and egg yolk had L, a, and b values of 26.33±0.02, 1.76±0.08, 1±0.07, and 30.22±0.01, -0.58±0.07, and 2.66±0.06, respectively, which were significantly different from those of the commercial group (p<0.05). In terms of soluble protein content, it was 187.50 ppm at the 20th day of pickling, which was the smallest value among all groups. The lead, copper, and zinc contents were undetected, 1.1 ppm, and 14.1 ppm, respectively. Although the zinc content was higher than the commercial group, it was still within the acceptable range. In the last part, the sensory evaluation, although the color was quite different from the commercial group, it still had the highest score in thespringness. As to the overall acceptance, it was only second to the commercial group. Based on the above results, the use of ferrous sulfate and zinc sulfate was found to be more suitable for replacing the lead and copper ions in immersion solution of preserved eggs.