Yuyao Century Egg

Yuyao Century Egg

The Yuyao Century Egg is a protected geographical indication product.

　　Yuyao Century Egg

　　Administrative region under the current jurisdiction of 14 towns in Yuyao City, Zhejiang Province, including Simen Town, Mou Mountain Town, Liangnong Town, Hemudu Town, Luting Township, Huangjiabu Town, Xiaocaobo Town, Sanqishi Town, Lubu Town, Dalan Town, Linshan Town, Zhangting Town, Dayin Town, and Mazhu Town

　　 “Approval from Yuyao Municipal People’s Government Regarding the Application for Declaring the Geographical Indication of Origin for ‘Yuyao Salted Egg’ and ‘Yuyao Century Egg’”, Yuyao Government Document No. 104 [2011]

　　“Quality Control Technical Specifications for Yuyao Century Eggs” by Ningbo Jinluan Poultry & Egg Food Co., Ltd., Ningjin Office Document No. 06 [2012]

　　Quality and Technical Requirements for Yuyao Century Eggs

　　 I. Requirements for Raw Materials and Auxiliary Materials

　　　　1. Duck Eggs:

　　 （1）Breed: Local Muscovy ducks with ringed white-wing feathers.

　　 （2）Breeding Requirements:

　　① Breeding Environment: The breeding farm is located in the lake area within Yuyao. For every 100 ducks, the area allocated for duck beaches and water enclosures shall be no less than 50㎡ each. The depth of water in the enclosure shall be greater than 1 meter.

　　② Breeding Management: The feed consists of locally produced self-mixed feed ingredients such as distiller’s grains, shell powder, cornmeal, wheat flour, and fish meal. No artificial colorants shall be added to the daily feed.

　　③ The environment for raising ducks, the breeding process, the feed and feed additives used, and the use of veterinary drugs shall comply with relevant national regulations.

　　（3）Raw Egg Requirements: Fresh local duck eggs no more than 7 days old. Eggshells must be clean. After cracking, the yolk should be raised, resilient, while the egg white should be clear and transparent, free from impurities, odor, blood clots, or other foreign tissues.

　　　　2. Auxiliary Materials:

　　（1）Processing Water: Should be sourced from the water supply in the Siming Mountain area of Yuyao, and the water quality shall meet the national standards for drinking water.

　　（2）Edible Alkali: Shall comply with national standards for edible alkali.

　　（3）Edible Salt: Shall comply with national standards for table salt.

　　（4）Tea Powder: Locally produced tea powder that is pure, dry, and free from mold.

　　（5）Yellow Clay: Should be selected from the mountain yellow clay of the Siming Mountain area in eastern Zhejiang. The clay must be free from odor, pollution, or impurities, possess good viscosity, and be dry.

　　（6）Rice Husks: Golden yellow, clean, dry, and free from mold, harvested in the same year.

　　 II. Processing Technology

　　　　1. Processing Flow:

　　Egg Selection → Ingredient Mixing → Pickling → Drying → Grading → Packaging and Storage　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　

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　　　　　　　　　　　　　　　　Mud Coating → Packaging and Storage.

　　　　2. Key Processes:

　　 (1) Egg Selection: Rotate and lightly inspect the eggs under light 1 to eliminate substandard eggs such as those without pores, poor translucency, or sandy shells.

　　 (2) Ingredient Preparation:

　　① Brine Preparation: Mix edible salt, edible alkali, tea powder, and water in certain proportions, stir well, keep it clean, and set aside as brine for curing.

　　② Clay Mixture Preparation: Combine the prepared brine with mountain yellow clay in specific proportions, mix evenly, and form the clay mixture.

　　(3) Curing: Layer the selected fresh duck eggs into the brine for curing. Do not move the soaking container within the first two weeks of immersion. The curing temperature should be between 20°C and 25°C, and the usual soaking duration is 30 days. Monitor frequently during the soaking period to prevent alkali damage to the eggs.

　　(4) Drying: Immediately remove the eggs from the vat and allow them to dry after soaking.

　　(5) Grading: Grade intact preserved eggs by weight into different specifications.

　　(6) Mud Coating: For products requiring mud coating, evenly cover them with the clay mixture and roll them in a layer of rice husks after curing.

　　III. Quality Characteristics

　　1. Sensory Characteristics:

　　 (1) Appearance: The eggshell is intact, glossy, elastic, not adhered to the shell, with “pine flower” patterns or other markings. The yolk is soft-centered, which may vary from large soft center, small soft center, to hard center.

　　 (2) Color: The egg white appears translucent bluish-brown, brown, or opaque dark brown; the yolk may be transparent yellow.

　　 (3) Aroma and Flavor: Possesses the characteristic taste and aroma of preserved eggs, free from off-odors.

　　 　 2. Physicochemical Indicators: Moisture content 66% to 70%; fat content greater than 12%.

　　3. Safety and Other Quality Technical Requirements: Product safety and other quality technical requirements must comply with relevant national regulations.