Leaveners work best when fresh.
Eggs: Date marking codes: see "Use by date" and the 3 number code is day of year packed, 001-365. Allow eggs to come to room temperature, set out for 30 minutes. Whites separate best while cold, and increase to maximum volume when brought to room temperature.
Baking soda: Write the date of first use on the box.
Baking powder: Check for "Use by date"; shake vigorously before measuring
Fermentation: Check yeast use by date on package.
About eggs. For consistent baking results use fresh, Grade AA or A large eggs. A fresh egg has a thick, non-spreading white and a rounded yolk, perfect for beating to triple the volume with the structure to hold its volume after adding other ingredients and during baking. As an egg becomes older, the structure breaks down, the white becomes thinner and the yolk flattens. These eggs are poor at holding lots of air when beaten. Lately, I have found success using jumbo eggs to add that extra moisture and fat when converting a recipe using conventional gluten containing flours. I still favor breaking the eggs one at a time in a small custard cup or separate container. This allows for close inspection of structure and easy retrieval of any broken shell. Most recipes are based upon use of room temperature, size “large” eggs. An average large egg equals ¼ cup liquid, but can whip up to over three times the original volume.
To retain freshness store eggs covered in the refrigerator, narrow end of the egg down. The egg carton is perfect to prevent eggs from losing moisture and absorbing refrigerator odors. Allow 30 minutes for eggs to come to room temperature. (For best baking results take time to bring all ingredients to room temperature before mixing.) Date marking codes: Use by date listed plus a 3 number code on day of year packed, 001- 365.
Any recipe that results in serving raw or runny eggs is not recommended according to the Center for Disease Control, because of the danger of the salmonella bacteria. That means no tasting of raw batter and dough. Discard cracked eggs. A type of bacterium, Salmonella, can be on both the outside and inside of eggs that appear to be normal, and if the eggs are eaten raw or lightly cooked, the bacterium can cause illness.
In the United States of America, it has been estimated that 1.4 million cases, 16 430 hospitalizations and 582 deaths are caused by salmonellosis annually. 2002 Safety Report The poultry industry has addressed this concern and numbers are decreasing. The American Egg Board states (2016) the risk of any one egg being contaminated with Salmonella bacteria is very low, about 1 in 20,000 eggs.
Also see: GF Baking Trouble Spots