I told you I’d get back to you on the role of salt in baking! 🙂
(Is a minorly aggressive I-told-you-so an appropriate way to begin a blog post?)
According to King Arthur Flour (the source of all magnificence), salt has five main purposes in bread-making: it contributes to flavor, tightens the gluten structure, retards the yeast, helps to color the crust, and helps preserve the color and flavor of flour.
The two pieces that interest me are its contribution to flavor and its preservation of the flour’s flavor, because they sound extraordinarily similar but are actually distinctive. As a result, that’s what I’ll be discussing in this post.
(If you’d like to read the full article, find it here.)
First, salt adds to flavor. Further research (using http://www.sciencefocus.com and my amazing Chemistry teacher) informed me that there are five distinct tastes on the human tongue – salty, sweet, sour, bitter, and umami. However, low concentrations of one flavor can enhance other flavors because cells have multiple receptors for each taste, with different sensitivities for different tastes. This is why if you add salt, you enhance sweet, sour, and umami flavors; hence, if you add salt to an amazing batch of lemon squares, it tastes even MORE lemony and sweet (which can only be a good thing).
Second, salt preserves the flavor of flour. According to King Arthur Flour, flours have carotenoids, and salt (as a preservative) conserves the carotenoids, which can be destroyed during the mixing and kneading process while making bread. (So, add the salt at the beginning of the bread-making process, folks!)
While I was learning about salt, I also researched another aspect of baking chemistry that interests me: baking powder!
In short, baking powder is made of NaHCO3, or baking soda, with cream of tartar and other leaveners. When it reacts with an acid, baking powder produces carbon dioxide, which then inflates your baked good. The gluten in flour traps the carbon dioxide, stretches, and, once baked, stays in place to preserve the structure of the bread. (This is why baking gluten-free is hard, since the lack of gluten makes achieving a decent rise difficult.)
Wait! There’s more! What about baked goods with baking powder that DO NOT contain acids? (Insert gasp here!)
It turns out that most recipes with baking powder will call for eggs, and eggs are mildly acidic, so there is an acid present after all. But the acid only speeds up the reaction turning the baking powder into carbon dioxide; basically, using an acid makes your cookie/bread/brownie puffier. If you don’t use an acid, your cookies will simply rise less and be flatter.
Of course, most breads use yeast. The yeast, like the baking powder, also produces carbon dioxide via cellular respiration; it just does so before going into the oven. This is why rising times are so important (besides being ideal intervals in which one should complete her mountain of homework).
So, there you have it! If you ever have any questions about baking chemistry, let me know and I’ll do another post!