· Posted by Kirsten,Kitchen Science

Jen from Calgary organized another fabulous kitchen science experiment. This one was looking at the effect of different ingredients used in baking scones. Many scone (and muffin) recipes call for buttermilk and one of our questions was: Can we just use milk or does buttermilk make a difference?

We started by looking at the different reactions you get when you combine baking soda, cream of tartar and baking powder with water, vinegar and lime juice. We created a grid in a muffin tin to help us keep track of the various combinations. We put 1/4tsp of each powder in and about a tbsp of each liquid.

We observed the following:

  • baking soda on its own did not react to water but did react a bit to vinegar and lime juice
  • the addition of cream of tarter to baking soda created the biggest reactions, especially with the lime juice
  • baking powder reacted well with all three, but again, the biggest reaction was with the lime juice

This little video clip explained nicely what was going on in these various reactions. To sum up:

Baking soda is a base and it needs acid to create a reaction. There is no acid in water (so no reaction) but there is in vinegar and lime juice.

Cream of tartar is an acid so when you combine it with baking soda, you have the ingredients for a reaction once a liquid is added.

Baking Powder is a combination of ingredients including baking soda and an acid so it is sort of like the combo of baking soda and cream of tartar.

Next, we looked at how the three powders react to milk vs buttermilk. We set up a similar muffin tin grid.

We observed that the reactions were bigger and faster with the buttermilk. The reason is that buttermilk contains more acid than regular milk.

Next we mixed up a batch of lemon poppyseed scones (recipe below) using regular milk for one half of the dough and buttermilk for the other half. We predicted (based on our experiment) that the buttermilk ones would rise more. And we were correct! The buttermilk ones are the ones on the left and you can see how much bigger they are compared to the ones made with just milk!

So now we know why buttermilk is recommended in these recipes! And it is why if you don't have any on hand, you'll want to create a substitute by adding a bit of lemon/lime juice to milk. You need the acid to create the reaction to make your scones nice and fluffy.



  • 2.5 cups all purpose flour
  • 2 tbsp granulated sugar
  • 2.5 tsp baking powder
  • 1/2 tsp each baking soda & salt
  • 1 tbsp grated lemon rind
  • 4 tsp poppyseeds
  • 1/2 cup cold butter (cubed or grated)
  • 1 cup buttermilk
  • 1 egg


  1. Preheat oven to 400F. Line a baking sheet with parchment paper or dust with flour.
  2. In a large bowl whisk dry ingredients together (flour, sugar, baking powder, baking soda & salt).
  3. Add lemon rind and poppyseeds.
  4. Using a pastry blender (or two knives), cut in butter until crumbly. It will seem very dry at first so be patient.
  5. In a separate bowl, whisk egg and add buttermilk. Pour into the bowl with dry ingredients and mix with a fork to make a soft ragged dough (it will be quite stiff).
  6. With floured hands, press the dough into a ball and place on a floured surface. Pat out into a rectangle about an inch thick.
  7. Cut into squares and then triangles. Place scones on the prepared pan and bake 18-20 minutes until golden.
  8. Cool on a rack and enjoy!
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