Hajime Hatta1,*, Ayami Nakamoto1, Yasumi Horimoto2
1Department of Food and Nutrition, Faculty of Home Economics, Kyoto Women's University, Kyoto 605-8501, Japan.
2Department of Food Science University of Guelph, Guelph, ON, N1G 2W1, Canada.
*Corresponding author: Hajime Hatta
Abstract
A method for preparing a reversed boiled egg introduced in an old Japanese recipe book has been a mystery for a long time until we recently succeeded in reproducing it 220 years later. The recipe book was published in 1785, in which 103 recipes for cooking eggs were introduced. Although 102 recipes have been recreated, only the reversed boiled egg failed to be reproduced, despite numerous challenges had been carried out. The recipe book reads, “Prepare a fresh egg and pierce the eggshell by about 3 cm depth with a needle. Leave it in fermented, salted rice-bran paste for three days, and then boil the egg to ensure the yolk in-side out”. The key to solving the mystery lay in the idea that the eggs used for cooking in such an old period could be mostly fertilized eggs. We finally reproduced the reversed boiled egg by using fertilized eggs incubated for three days at 38ºC. The objective of this study is to reveal the cooking principle of a reversed boiled egg. Fertilized and unfertilized eggs were incubated for seven days at 38°C with a relative humidity of 70% (hatching condition). The changes in fertilized and unfertilized eggs (such as a ratio of egg yolk and egg white, water content, pH, yolk viscosity, and gelation temperature by heat treatment) were compared. For 3-4 days incubation of fertilized eggs, water in the egg white is transferred to the egg yolk. As a result, the weight of the egg yolk doubled, and the viscosity of the egg yolk significantly decreased by one hundredth, becoming watery. On the other hand, the egg white weight halved, and it got thick. During this process, the vitelline membrane became very weak and easy to be broken. Upon being ruptured the membrane, the runny yolk diffused inside the eggshell, and the watery yolk gelled outside the thick egg white during heated. Thus, the reversed boiled egg (the Yolk Inside Out) was reproduced.
References
[1] Hatta, H., Nomura, M., Takahashi, N., and Hirose, M. (2001). Thermostabilization of Ovalbumin in a Developing Egg by an Alkalinity-regulated, Two-step Process: Bioscience, Biotechnology, and Biochemistry, 65, 2021-2027.
[2] Laemmli, U. K. (1970). Cleavage of structural proteins during the assembly of the head of bacteriophage T4: Nature, 227: 680-685.
[3] Matsumura, Y. and Mori, T. (1996). 4 Gelation in Methods of Testing Protein Functionality, G. M. Hall (Eds.), Blackie Academic & Professional, pp. 76-109.
[4] Caner, C. and Yuceer, M. (2015). Efficacy of various protein-based coating on enhancing the shelf life of fresh eggs during storage: Poultry Science, 94: 1665-1677.
[5] Zang, Y. T., Bing, S. H., Li, Y. J., Shu, D. Q., Huang, A. M., Wu, H. X. Lan, L. T., and Wu, H. D. (2019). Efficacy of slightly acidic electrolyzed water on the microbial safety and shelf life of shelled eggs: Poultry Science, 98: 5932-5939
[6] Gul, H., Chen, X., and Geng, Z. (2021). Comparative Yolk Proteomic Analysis of Fertilized Low and High Cholesterol Eggs during Embryonic Development: Animals, 11, 744.
[7] Tahara, Y. and Obara, K. (2021). Ex Ovo Culture System for Avian Embryos and its Application: J. Poult. Sci., 58: 1-4.
[8] Akazawa, T., Ogawa, M., and Hayakawa, S. (2019). Migration of chicken egg-white protein ovalbumin-related protein X and its alteration in heparin-binding affinity during embryogenesis of fertilized egg: Poultry Science, 98: 5100-5108.
[9] Gao, D., Qiu, N., Liu, Y., and Ma, M. (2017). Comparative proteome analysis of egg yolk plasma proteins during storage: J. Sci. Food Agric., 97: 2392-2400.
[10] Hatta, H., Hagi, T., and Hirano, K. (1997). Chemical and physicochemical properties of hen eggs and their application in foods, in Hen eggs; Their basic and applied science, Yamamoto, T., Juneja, L. R., Hatta, H. and Kim, M. (Eds.), CRC Press, pp. 117-133.
[11] Donovan, J. W. and Mapes, C. J. (1975). A differential scanning calorimetric study of conversion of ovalbumin to S-ovalbumin in eggs. J. Sci. Food Agric., 27, 197-204.