Preheat oven to 180ºC.
Place muffin liners in a 12 hole muffin tin.
Add lemon juice to milk, it will curdle, this is fine.
Sift dry ingredients together, sift at least three times.
With an electric beater, beat the sugar and butter until light and airy.
Add eggs, one at a time, beating well between additions.
Add a third of the dry ingredients and a third of the milk and mix well, repeat with twice more with the remaining two thirds.
Fold in the blueberries and the lemon zest.
Divide the batter between the 12 muffin holes. Level the top of each muffin with a spoon.
Bake for 25 to 30 Minutes, until golden. (reduce the baking time to 15 minutes when you use fresh berries)
Cool on a wire rack. Best eaten the day of baking, but these are still delicious the day after.