Buttermilk Crumb Muffins and some thoughts on chemical leaveners

Several years ago I ran across a recipe in Dorie Greenspan's Baking with Julia for Buttermilk Crumb Muffins.  I found this simple, lightly spiced muffin with its homey buttermilk and brown sugar flavors, to be very appealing.  But what really induced my to try it out was how fast and easy it is to make. The butter is rubbed into the sugar and flour—just as for traditional scones or biscuits. Some of this mixture is then removed and reserved for the streusel topping. The remaining dry ingredients are added to the bowl, followed by a mixture of eggs and buttermilk. The dry ingredients can be mixed up ahead, as can the liquids.  With this small amount of advance preparation, you can easily have warm muffins on the table within 30 minutes of when you get out of bed in the morning. What could be better?

Well, I seem to be afflicted with a desire to always try and make things better. And to be honest, for all its positive qualities, there were a couple of things about the original recipe that bothered me. For one thing, the original recipe used all vegetable shortening. While vegetable shortening has some practical and beneficial uses in baking (it is a very stable fat over a wide range of temperatures), I really do try to avoid using it in large quantities. The other thing was that the recipe seemed to have an excessive amount of sugar—particularly for a breakfast muffin. To correct these two things I substituted unsalted butter for the vegetable shortening and reduced the sugar from 2 cups to 1 1/4 cup...a much more typical amount for a recipe that produces 12 to 16 muffins.

Frankly the fact that these changes—particularly the change in the quantity of sugar—worked at all was pure dumb luck. At the time I knew very little about the chemistry of baking. In any case, I happily made this muffin, using my slightly amended version, for years. They have a soft, springy texture with a pleasantly chewy, lightly streusel-y top. They are plain enough so that everyone likes them, and are also amenable to additions of berries, dried fruits or chocolate chips—a good all-purpose, all-occasion breakfast muffin. A few years ago, when I no longer had regular access to a convection oven, I began to notice that whenever I baked them in a conventional oven that they had a tendency to sink. Even when they didn't sink, they turned out disconcertingly flat.

As I have learned more about the chemistry of baking I began to suspect that the muffins were over-leavened. It is a bit counterintuitive, but as it turns out, too much baking powder or baking soda can cause a baked good to sink. If you have ever made a cake and observed that initially it rose very quickly, only to then suddenly collapse into a dense, gooey mess, it is probable that the recipe that you were using called for too much leavener.  An excessive amount of leavener is a fairly common problem—even in otherwise reliable cookbooks.

The topic of leaveners in baked goods is a big one and I don't feel that I am particularly qualified to tackle it in its entirety. For my purposes today, I think it is sufficient to state that even though the amount and type of leavener required by a particular cake, cookie, quick bread, etc. is a function of many different things, most bakers use the quantity of flour in a recipe to estimate the necessary amount of leavener. In general, if you use 1 to 1 1/4 teaspoon of baking powder OR 1/4 teaspoon of baking soda for every cup of flour in a recipe, you will be in the right ball park.

Please notice that baking soda has four times the leavening power of baking powder. When a recipe is over-leavened, more often than not, the culprit is too much baking soda—many people just don't realize it is so powerful. The choice between baking powder and baking soda in a recipe has to do with whether or not the recipe includes acidic ingredients like buttermilk, sour cream, molasses, brown sugar, etc. A teaspoon of baking powder contains a quarter teaspoon of baking soda along with the exact amount of acid needed to neutralize the baking soda. When baking soda is used in a recipe, the necessary acidity must come from the other ingredients. (For those interested, the rule of thumb here is that for every cup of buttermilk in a recipe, you may substitute 1/2 teaspoon of baking soda for 2 teaspoons of the baking powder.)

Today's post has been a purposefully shallow discussion of chemical leaveners.  I didn't want to get bogged down in too much detail because I think most people are more interested in just making a recipe work—or in spotting one that won't work ahead of time—than they are in understanding why a particular recipe didn't (or won't) work.  For those interested in a more in-depth treatment of chemical leaveners, I particularly recommend both of Shirley Corriher's books (Cookwise and Bakewise). Rose Levy Beranbaum's The Cake Bible and Madeleine Kamman's The New Making of a Cook also have very readable discussions of this topic.

Going back to my Buttermilk Crumb Muffin recipe, you will notice that the recipe calls for 2 1/2 cups of flour. This means that the amount of leavener should probably be somewhere between 2 1/2 and 3 teaspoons of baking powder. But the original recipe used 2 teaspoons of baking powder and a 1/2 teaspoon of baking soda—the equivalent of 4 teaspoons of baking powder. No wonder my muffins were collapsing in a conventional oven. I hadn't noticed the effects of the excess leavener when I was using a fast convection oven because the muffins were setting up before they had a chance to collapse. In a slower conventional oven the effects of too much leavener showed up immediately. From my discussion above, it should be obvious that since 1/2 teaspoon of baking soda is equivalent to 2 teaspoons baking powder that there should only be 1/2 to 1 teaspoon of baking powder in the recipe...not 2 teaspoons.

For as long as I have been making them, these muffins have been one of my favorite quick breakfast breads—even in their old, over-leavened incarnation. I particularly like them with chocolate chips and I have a good friend whose sons make them regularly with blueberries (blueberries go especially well with the nutmeg and the cinnamon). This recipe even makes a nice, everyday coffee cake—simply spread the batter in a buttered and floured 9-inch square pan and spread the streusel over the top. Whether you make them plain, with additions, or as a cake, I think this recipe could become one of your favorites, too.



Buttermilk Crumb Muffins

2 ½ c. all-purpose flour (10 oz)
1 ¼ c. golden brown sugar (8.75 oz.)
2/3 c. (10 T. plus 2 t.) unsalted butter
½ t. baking powder
½ t. baking soda
½ t. cinnamon
¼ t. ground nutmeg
½ t. salt
3/4 c. buttermilk
2 large eggs, well beaten

Preheat the oven to 375°. Butter and flour, or line with muffin-liners, a 12-cup muffin tin. Set aside.

In a large bowl, combine the flour and brown sugar. Cut the butter into small pieces and add to the bowl. Rub the butter into the dry ingredients. When the mixture looks like coarse breadcrumbs, measure out ½ cup and set it aside to use as the crumb topping.

Add the baking powder, baking soda, cinnamon, nutmeg, and salt to the remaining flour mixture and stir to combine. Combine the buttermilk with the beaten eggs and add. Using a rubber spatula, mix until the ingredients are well blended.

Divide the batter among the 12 muffin cups (an ice cream scoop works well for this). Sprinkle the top of each muffin with a rounded teaspoon of the reserved crumb mixture and pat it gently onto the batter.

Bake for 20 to 25 minutes, or until a toothpick inserted into the center of a muffin comes out clean. Serve warm. Makes 12 muffins.

Variations:
• Add ½ cup chocolate chips along with the spices.
• Add ½ cup chopped nuts to the reserved topping mixture.
• The batter and crumb topping may be spread in a greased and floured 9x9-inch baking pan to make a coffee cake.