Posts Tagged ‘easter’

Towards the perfect soft boiled egg

Thursday, April 9th, 2009

egg-tray

Many cookbooks suggest the following for boiling eggs: 3-6 min for a soft yolk, 6-8 min for a medium soft yolk and 8-10 min for a hard yolk. If you are satisfied with this, there is no need for you to continue reading. But if you’ve ever wondered whether the size of an egg has any impact on the cooking time you should read on. And if you search the ultimate soft boiled egg we share a common goal! From a scientific view point, a cooking time of approximately 3-8 minutes to obtain a soft yolk is not very precise. A number of important parameters remain unanswered: What size are the eggs? Are they taken from the fridge or are they room tempered? Are they put into cold or boiling water? And if using cold water – when should the timer be started? When the heat is turned on or when the water boils? And would the size of the pan, the amount of water and the power of the stove top matter?

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Dyeing eggs for the easter holiday

Thursday, April 5th, 2007

About.com has a nice guide on how to color eggs, and the list of colors is quite impressive (click for instructions):

Lavender
Small Quantity of Purple Grape Juice
Violet Blossoms plus 2 tsp Lemon Juice

Violet Blue
Violet Blossoms
Small Quantity of Red Onions Skins (boiled)

Blue
Canned Blueberries
Red Cabbage Leaves (boiled)
Purple Grape Juice

Green
Spinach Leaves (boiled)
Liquid Chlorophyll

Greenish Yellow
Yellow Delicious Apple Peels (boiled)

Yellow
Orange or Lemon Peels (boiled)
Carrot Tops (boiled)
Celery Seed (boiled)
Ground Cumin (boiled)
Ground Turmeric (boiled)

Brown
Strong Coffee
Instant Coffee
Black Walnut Shells (boiled)

Orange
Yellow Onion Skins (boiled)

Pink
Beets
Cranberries or Juice
Raspberries
Red Grape Juice
Juice from Pickled Beets

Red
Lots of Red Onions Skins (boiled)

More information about the chemistry behind can be found in the article “Chemistry in the dyeing of eggs” (Journal of Chemical Education, 1987, 291). The article discusses anionic dyes with sulfonate groups. These bond to the cuticle (protein) covering the egg shell forming salt linkages as shown (illustrated using FD&C yellow no. 6):

egg-colouring.jpg

By lowering the pH (for example by adding vinegar), more amino groups in the proteins covering the egg shell are protonated and thus available for formation of the salt linkages with the anionic dyes.