01/22/2025
"Common Baking Substitution Questions
Can I swap light brown sugar for dark and vice versa?
Even though light and dark brown sugar are often used interchangeably and some recipes do work with both, they differ in their molasses content, which in turn affects their moisture level and pH.
The more acidic dark brown sugar was meant to help activate the baking soda and cause cookies to puff in the oven. Light brown sugar just didn’t have the same oomph and, thus, skinny cookies.
Swap with caution and, only if baking soda is not involved like in custards, puddings, sauces, cheesecake, etc."