皮蛋又稱千年蛋，是亞洲歷史悠久的蛋類加工品，在台灣頗為盛行。在皮蛋製造過程中，會在醃漬液中添加金屬離子，如鉛或銅，做為加工助劑，以穩定品質及安定色澤，而鉛和銅離子皆會導致蛋殼中上有黑點形成，使消費者不易辨識所購買的皮蛋是否含鉛。本研究旨在利用兩種不同金屬離子的鐵鋅混合法，取代鉛銅離子，於25℃恆溫室中，以醃漬法醃漬鴨蛋20天，並加入無添加金屬離子的空白組及市售組一起比較。鴨蛋於每5天撈取觀察其理化性質，在20天時全數撈取，探討其品質之差異並且計算製成率。根據實驗結果顯示，C組即硫酸亞鐵與硫酸鋅混合組，為本研究實驗組最高達製成率72%，且蛋殼無黑色斑點，其蛋白及蛋黃最終pH為11.06及10.56；蛋白膠著性達0.337±0.057 N較市售組高；而蛋白及蛋黃其L, a, b值為26.33±0.02、1.76±0.08、1±0.07及30.22±0.01、-0.58±0.07、2.66±0.06，與市售組具有顯著性差異(p<0.05)；而在可溶性蛋白質含量方面，在第20醃漬天時為187.50 ppm，為所有組別中最小值；其鉛、銅、鋅含量為未檢出、1.1 ppm和14.1 ppm，雖然鋅含量較高於市售組，但仍在可接受範圍內；而在最後感官品評部分，雖然色澤與市售組差異較大，但可以看到其在彈性部分獲得最高分數；在整體接受性結果中，也僅次於市售組。綜合以上結果，利用硫酸亞鐵與硫酸鋅是較適合用來代替皮蛋醃漬液中的鉛銅離子。

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.

Agency for Toxic Substances and Disease Registry (ATSDR). 2004. Toxicological Profile for Copper. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.
Agency for Toxic Substances and Disease Registry (ATSDR). 2005. Toxicological Profile for Zinc (Update). Atlanta, GA: U.S. Department of Public Health and Human Services, Public Health Service.
Agency for Toxic Substances and Disease Registry (ATSDR). 2007. Toxicological Profile for Lead. Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service.
American Egg Board. 1974. A scientist speaks about eggs. American Egg Board, Chicago.
C.M. Ho. 1952. A study on the process of manufacturing preserved eggs. Journal of Agricultural Research of China 3(4): 55-66.
Certified Agricultural Standards Association. 2017. Product verification standard of CAS. Certified Agricultural Standards Association, Taipei City.
Chantrapornchai, W. and Mcclements, D.J. 2002. Influence of NaCl on optical properties, large-strain rheology and water holding capacity of heat-induced whey protein isolate gels. Food Hydrocolloids 16: 467–476.
Chen J.W. 2000. A new process for preparing Pidan without spots in the egg shell and its quality. Master Thesis. Graduate Institute of Animal Science, National Taiwan University.
Chen J.W., Su H. P. 2004. A New Process for Preparing Spots-free Pidan. Chinese Society of Animal Science. 33(1):79-88.
Chen L., Lu L., Shen J., Zhao A. Z., Xu S., Zhao Y. G., Ciao L. S., Zhang S. F., Wang J. 2000. A stability test on nucleus material of Pidan pickle agent. China Poultry. 22(7):13-14.
Chen M. Z. 1990. Egg science and technology. Yihsient Publisher, Taipei City.
Chen P. 1997. Study on the Existing Forms of Organic Sulfur in Various Microcomponents of Yanzhou Coal by XPS. Journal of Fuel Chemistry and Technology. 25(3):238-241.
Chen S. J. 2014. The influence of alkali on egg shell and gel mechanism of duck egg white. Master Thesis. College of Food Science & Technology of Huazhong Agriculture University. China.
Chen Y. C.2001. Egg processing technology. Vol. 114. Council of Agriculture, Executive Yuan, Taipei City.
Chen Z., Li J., Tu Y., Zhao Y., Luo X. 2015. Changes in the gel characteristics of egg white under strong alkali treatment. Food Hydrocolloids 45: 1-8.
Cheng S.Y. 2005. Effect of Acids and Salts on Physicochemical and Rheological Properties of Pickled Duck Eggs (Meidan). Graduate Institute of Food Science, National Chung Hsing University. Master Thesis.
Chu C.W. 2015. Effect of different rice flour proportion, barrel temperature and screw speed on the physicochemical properties of rice-based fries. Department of Food Science, National Pingtung University of Science and Technology. Master Thesis.
Ciou Y. C., Gao Y. M., Zhou X. G., Jheng S. S., Syu J. F., Shih Y. J. 2008. Investigation on the Content of Heavy Metals (Cadmium, Mercury and Lead) in Rice. Ann Rept. BFDA Taiwan R.O.C. 26:198-206.
Cotterill, O. J., Marion, W. W., Naber, E. C. 1977. A nutrient re-evaluation of shell eggs. Poultry Sci. 56:1927.
Council of Agriculture, Executive Yuan (COA). 2007. Duck Hall，Taipei City.
Cowell, B. A., Wilcox, M. D., Schneider, R. P. 1997. Aus. J. Ophthalmol. Suppl 1:23.
D.W. Wong. 1989. Mechanism and theory in food chemistry. Van Nostrand Reinhold.
Dong J.S. 1984. Analysis of Zinc-containing (non-leaded) preserved egg. Food and Fermentation Industries. (4):56-58.
Food and Drug Administration, TFDA. 2014. General Method of Test for Heavy Metals. Ministry of Health and Welfare, Taipei City.
Food and Drug Administration, TFDA. 2018. Food and Drug weekly report. 647.
Food and Drug Administration, TFDA. 2018. Ministry of Health and Welfare, Taipei City.
Ganasen P., Benjakul S. 2010. Chemical composition, physical properties andmicrostructure of Pidan white as affected by different divalent and monovalent cations. Journal of Food Biochemistry 35:1528-1537.
Gao F. and Ma M. H. 2014. Research Progress of S-ovalbumin in Eggs. China Poultry 36(2):43-45.
Gregory P. J., Wahbi A., Adu-Gyamfi J., Heiling M., Gruber R., Joy E.J.M., Broadleye M. R. 2017. Approaches to reduce zinc and iron deficits in food systems. Global Food Security. 15:1-10.
Guo W. Y., Liu F. Y., Ciou Z. F. 2011. Food processing Ⅱ. Fu Wen Books Co., Ltd. Tainan City. P.156-157, 162-163, 166.
Health Promotion Administration. 2011. Dietary Reference Intakes, DRIs. Health Promotion Administration, Ministry of Health and Welfare, Taipei City.
Ho C. M. 1952. A Study on the Process of Manufacturing Preserved Eggs. Journal of Agricultural Research of China, 3(4): 55-66.
Ho C. M. 1971. Animal Industry Division. 4:105.
Ho C. M. 1976. Animal Industry Division. 9(1):85.
Hongsprabhas P., Barbut S. 1997. Effects of N-ethylmaleimide and CaCl2 on cold gelation of whey protein isolate. Food Research International, 30(6): 451-455.
Hou D. J., Li H. J. 2008. Influence of alkali process on the physical quality of flavor preserved egg. Science and Technology of Food Industry. 29(5):119-121.
Hu C. X. 2006. XRD Experiment Research of Eggshell. The Journal of Light Scattering. 18(3):282-287.
Hu, X., Wu, Y. F., Xu, J., 2013. Research and Manufacture of duck egg cake. Food Research and Development 34(18):24-27.
Hwang I. H. 2002. Studies on Changes of Physico-Chemical Properties of Salted Duck Egg during Pickling. Ph.D Thesis. Department of Animal Science and Technology, National Taiwan University.
Jiang W., He X., Yang H., Xiang X., Hu S., Li S., Liu Y. 2017. Histamine reduction by Maillard reaction with glucose. Food Control 82:136-144.
Johnson, R.E. and Phillip, D.C., 1965. Nature 206:761.
Kaewmanee, T., Benjakula, S., and Visessanguanb, W., 2009. Changes in chemical composition, physical properties and microstructure of duck egg as influenced by salting. Food Chemistry 112:560-569.
Kato, A., Oda, S., Yamanaka Y., Matsudomi, N., Kobayashi, K. 1985. Functional and structural properties of ovomucin. Agricultural and Biological Chemistry 49:3501-3504.
Khan, M. V., Ishikhar, M., Rabbani, G., Zaman, M., Abdelhameed, A. S., Khan, R. H. 2017. Polyols (Glycerol and Ethylene glycol) mediated amorphous aggregate inhibition and secondary structure restoration of metalloproteinase-conalbumin (ovotransferrin). International Journal of Biological Macromolecules. 94:290-300.
Kovae-Nolan J., Phillips M., Mine Y. 2005. Advances in the Value of Eggs and Egg Components for Human Health. Agric Food Chem. 53(22):842l-8431.
Kuehner, D. E., Engmann, J., Fergg, F., Wernick, M., Blanch, H. W., Prausnitz, J. M. 1999. Lysozyme net charge and ion binding in concentrated aqueous electrolyte solutions. Phys. Chem. B, 103:1368-1374.
Leitch, E. C., Wilcox, M. D. 1998. J. Med. Microbiol. 47:837.
Li J., Zhang Y., Fan Q., Teng C., Xie W., Shi Y., Shi Y., Su Y., Yang Y. 2018. Combination effects of NaOH and NaCl on the rheology and gel characteristics of hen egg white proteins. Food Chemistry. 250:1-6.
Li Y. 2009. Effect of Different Processing Process and Drying Temperatures on the Quality of Pregelatinized Rice. Department of Food Science, National Pingtung University of Science and Technology. Master Thesis.
Li-Chan, E. C. Y., Kim, H. O. 2008. Structure & Chemical composition of egg. Y. Mine (Ed.), Egg Bioscience and Biotechnology, John Wiley and Sons, NJ. 1-98.
Lin Q. W. 1983. Chemical Utilization of Eggs. Huaxiang Garden Publisher. Taipei City. P.340-350.
Lin Q. W. 2000. Chemical Utilization of Eggs. Huaxiang Garden Publisher. Taipei City. P.59, 67, 446.
Lin Y. L. 2015. Effect of brewer’s spent grain addition on physicochemical properties of corn snack food. Master Thesis. Department of Food Science, National Pingtung University of Science and Technology.
Liu L. Z., Peng G. H., Kuang Y. X., Zhang S. H. 2003. Study on salt-based processing of preserved eggs with zinc salt. Food and Fermentation industries. 07:93-94.
Liu S. Q., Lin X. Y., Zhu F., Li S. S., Zhu Y. Y., Chen H. L. 2015. Using the NMR to study the effect of quality of duck egg yolk with salt. The 12th National Agricultural Product Storage and Processing Technology Exchange Conference.
Liu, Y. C., Zhang S. A. 1989. Egg processing and Technology. Agriculture Press, P.3. Beijing.
Livestock Research Institute of COA. 2017. Animal Genetic Resources Information Network in Taiwan. Council of Agriculture, Executive Yuan (COA), Taipei City.
Lu L. J. 2009. Promoting CAS Certification Certificate for Good Agricultural Products - Performance of Egg Products. Vol. 206. Council of Agriculture, Executive Yuan, Taipei City.
Lui Y., Luo C., Ou Y. Y., Du J. P. 2013. Effects of Tea Types and Adding Quantity on the Quality of Preserved Egg. Journal of Tea Science. 33(2):116-124.
Maullu, C., Lampis, G., Basile, T., Ingianni, A., Rossolini, G. M., Pompeo, R. 1999. Lett. Appl. Microbiol. 21:50.
Ou S. M. 2003. Food Sensory Evaluation and Exercise. Wagner Publishing Co., Ltd. Taichung City.
Qiao J. H., Li Q. L. 2005. Study on non-lead Mixture of Five Spices Preserved Eggs Fast. Food science and technology. 9:52-53.
Shao Y. Y., Zhao Y., Xu M. S., Xu L. L., Tu Y. G. 2017. A Review of Effects of Metal Ions on Gelation Behavior of Protein. Food Science, 38(5):299-304.
Shiau M. J. 2007. Knowing the ducks. Council of Agriculture, Executive Yuan, Taipei City.
Sun J., Pi J. S., Pan A. L., Shen J., Liang Z. H., Wu Y., Pu Y. J., Zhang H., Du J. P. 2014. Components of Spots on Pidan’s Shell. Hubei Agriculture Science. 53(22):5478-5482.
Tang C. L. 2006. A study of zinc rich preserved egg processing and technology. Master Thesis. Sichuan Agriculture University. China.
Tang C. L. 2009. Study on the processing technology of spotless preserved egg. Processing of agricultural products, 10:69-71.
Tanizaki, H., Tanaka, H., Iwata, H., Kato, A. 1997. Activation of macrophages by sulfated glycopeptides in ovomucin, yolk membrane and chalazae in chicken eggs. Bioscience, Biotechnology and Biochemistry 61:1883-1889.
Wang J., and Fung D. Y. C. 1996. Alkaline-fermented foods: a review with emphasis on Pidan fermentation. Crit. Rev. Microbiol. 22(2):101-138.
Wang, L.F., Kim, D.M. and Lee, C.Y. 2000. Effects of heat processing and storage on flavanols and sensory qualities of green tea beverage. J. Agric. Food Chem. 48, 4227–4232.
Wei N. J. 2010. Study on the Preparation and Safety of Flavored Eggs. Master Thesis. Southwest University. China.
Yan H. 2008. Effects of different metal scrap on preserved eggs quality during process. Jiangsu Agricultural Sciences. (3)：208-209.
Yan H., Zhu D.W. 2006. Study on Different Effect of Copper, Zinc and Iron in Preserved Eggs Processing. Journal of Food Science. 27(12):164-167.
Yang C. C., Chen, C. C., and Chang, H. M. 1998. Separation off egg white lysozyme by anionic polysaccharides. J. Food Sci. 63(6):962-965.
Yu D. X. 2011. Egg soaking production process. Modern Agricultural Sciences and Technology. 12:333-336.
Zamora R., Alaiz M., Hidalgo F. J. 2000. Contribution of pyrrole formation and polymerization to the nonenzymatic browning produced by amino-carbonyl reaction. Journal of Agricultural and Food Chemistry. 48:3152-3158.
Zhang B. Y. 1986. Gelation of protein. Food Industry. 18(5):16-19.
Zhang F. X. 2004. Changes of Alkalinity during Preserved Chicken Egg Processing. Food and Fermentation Industries. 30(10):81-83.
Zhang S. S. 1999. Egg processing. Huaxiang Garden Publisher. Taipei City. P. 81, 84, 87, 251, 547.
Zhang X. W., Guo S. G., Jiang A. M., Zhang J. L. 2011. Studies on processing technology of lead-free preserved egg with zinc and copper salt. FOOD &MACHINERY. 02:149-152.
Zhang X., Jiang A., Chen M., Ockerman H. W., Chen J. 2015. Effect of different alkali treatments on the chemical composition, physical properties, and microstructure of pidan white. J Food Sci Technol 52(4):2264-2271.
Zhang Z. J. 1997. Trace Minerals – A study of important of Iron and Zinc to Athletes. Tpec Press, (6) :99-104.
Zhou Y. C. 1993. Egg and Egg Products Technology. China Agricultural Press, Beijing, China. P. 1-29.
Zhu Y. 1994. Production quail preserved egg by zinc method. Journal of Food Science. 15(12):63-66.