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Inside the shell of an egg is egg white that encircles egg yolk - VCE - SSCE Chemistry - Question 7 - 2020 - Paper 1
Question 7
Inside the shell of an egg is egg white that encircles egg yolk. The nutrition information for egg yolk and egg white is given in Table 1. **Table 1** | Nutrient ... show full transcript
Worked Solution & Example Answer:Inside the shell of an egg is egg white that encircles egg yolk - VCE - SSCE Chemistry - Question 7 - 2020 - Paper 1
Step 1
Using your knowledge of chemistry, explain why vinegar is sometimes added to the water to produce a poached egg with a runny yolk.
Answer
When poaching an egg, vinegar is often added to the water to help ensure that the proteins in the egg white denature properly. The denaturation changes the structure of the proteins, causing them to coagulate or solidify, which is essential to encapsulate the liquid yolk effectively.
Vinegar, which contains acetic acid, lowers the pH of the water. This acidic environment allows the proteins (primarily albumin in egg white) to denature at a lower temperature, enhancing their ability to coagulate swiftly and tightly. Thus, adding vinegar can help form a more compact structure around the yolk, allowing it to remain runny inside while the egg white solidifies around it.
Additionally, since the egg yolk is protected by a thin layer of egg white, the presence of vinegar minimizes excessive spreading of the egg white, leading to a well-formed poached egg. Without vinegar, the egg white may not coagulate as efficiently and could result in a less appealing presentation.