I have been told quite emphatically that traditional Irish Soda Bread has four ingredients: flour, salt, baking soda, and buttermilk. Alas, for those of us who love to bake with sourdough, this wonderful tradition seems closed to our participation. If we want make Irish Soda Bread, we have no choice but to put aside our starter and run to the store for buttermilk.
As I thought about this, though, I was struck by the realization that Irish Soda Bread is nothing more than a quick bread. The function of the buttermilk in a Irish Soda Bread recipe is to provide the acidity to interact with the baking soda so the bread will rise. This is the same function that our starter performs when we make sourdough biscuits or sourdough pancakes or anything else with our discarded starter. For these quick breads, we are not relying on the wild yeast in our starter to create the rise to our dough; rather, we are relying on the lactobacillus in the starter to interact with the baking powder and the baking soda to create a chemical rise. Thus, the for quick breads we need the lactobacillus, which produces lactic acid.
This led me to wonder what was in buttermilk to create the acidity necessary to make Irish Soda Bread rise. I found out that the term “buttermilk” can mean different things depending on where you live and where you buy it. Traditionally, buttermilk was the liquid left over from churning butter that was allowed to ferment overnight. However, now in many places in the world, such as here in the United States, the “ buttermilk” you get in the grocery store is not buttermilk at all, but a cultured buttermilk that is made from adding a bacteria culture to milk. The bacteria, of course, is lactobacillus, which makes manufactured buttermilk more like yogurt than traditional buttermilk. And, it also means that those of us who bake sourdough bread already have a source of lactobacillus in out very own kitchens. As I mentioned above, it’s in our starters!
So why not use the lactobacillus in our starters to make traditional Irish Soda Bread? Would it be less traditional to use a culture I have developed and nourished in my own kitchen than to use the manufactured buttermilk purchased from a commercial dairy? I’ll let the purists answer this question. For myself, I decided to (possibly) buck tradition and go ahead and and make it with my starter.
This is what I did:
First, I found a traditional Irish Soda Bread recipe. I took this one from the New York Times (which I adapted slightly by changing volume measures to weight):
• 450 grams all-purpose flour (about 3 ½ cups)
• 3 grams fine sea salt (about ½ teaspoon)
• 4 grams baking soda (about ¾ teaspoon)
• 360 grams buttermilk (about 1 ½ cups)
Second, I replaced the “buttermilk” with starter. To do this, I followed guidance from Cultures for Health on how to convert quick breads to sourdough. It’s really pretty simple. You just replace the buttermilk in your recipe with starter and milk. You have to reduce the amount of flour in your recipe by the amount of flour in your starter and reduce the amount of liquid (i.e., buttermilk) by the amount of water in your starter.
I generally keep my starter at 80% hydration. Therefore, to replace the 360 of buttermilk in the NYTimes recipe, I used 360 grams of starter, but reduced the flour by 200 grams and added 160 grams of regular milk. The math is a little difficult, but not insurmountable. If I make 80% hydrated starter with 100 grams of flour, then I would add 80 grams of water. The total weight would be 180 grams. Thus, the proportion of flour in the starter is 100/180 or 56%. The amount of flour to subtract from the recipe is therefore 56% of 360 (i.e., 360 X .56), which equals 200 grams. The amount of milk to add, consequently is 360 – 200, or 160 grams.
If this confusing, just know that 100% hydrated starter would mean you split it 50/50. That is, you would divide 360 by 2 and subtract 180 grams of flour and use 180 grams of milk. Moreover, I suspect that a few grams one way or another would not make that much different. Ultimately, you’ll add milk until the dough feels right. So you would probably be pretty safe by splitting it 50/50 regardless of your starter’s hydration.
At any rate, the recipe I came up with is this:
• 200 grams all-purpose flour
• 3 grams fine sea salt
• 4 grams baking soda
• 160 grams milk
• 360 grams of 80% starter
The directions are simple:
1. Heat oven to 450 degrees Fahrenheit
2. Sift the dry ingredients.
3. Add the milk and starter
4. Turn out onto the counter and knead briefly
5. Shape into a round about an inch and a half thick
6. Place on oiled cooking sheet
7. Bake at 450 degrees Fahrenheit for 15 minutes
8. Reduce heat to 400 degrees Fahrenheit and bake another 30 minutes
My first attempt came out pretty good. It’s not really sourdough Irish Soda Bread as the starter I used had not been fed (so there wasn’t much active yeast) and I didn’t let it ferment.
I don’t know if it’s Traditional Irish Soda Bread, though. You tell me.