Step 3: Making the Calcium Ascorbate
Now, if you’re a baker, you will be thinking that you should mix all the dry ingredients, then fold in the wet. That was my first instinct too, even though a little voice in the back of my head was saying “do what you oughta: add acid to water.” You can see from the first picture the result (bad is on the left, good is on the right). The calcium carbonate dissolved poorly and the whole thing is rather unpleasant. If your recipe calls for gritty, bitter meringue, then this may be the way to go. For our purposes though, it’s much nicer to mix the ascorbic acid in the water, then slowly add calcium carbonate while stirring.
Here’s how: in a small bowl, add 25 ml of near-boiling water and then add 10 grams of ascorbic acid. This will take a little while to dissolve. Stir carefully, grinding the powder with the back of your spoon to facilitate mixing. Now add the eggshell powder to the acid. Add a little at a time, stirring constantly. It will foam as the CO2 is liberated and the calcium combines with the ascorbic acid. It will not smell particularly nice. Once all of the eggshell has been added set the mixture aside for about an hour or two, until the foam subsides and the eggshells are almost entirely dissolved. You will want to filter this solution now, to remove any stubborn pieces of shell or other debris from your solution. When filtered, it will look cloudy, but there will be no grit or other solids.
As this reaction is not perfect, and not all of the CaCO3 reacts with the acid, the resulting solution will not be neutralized. You can expect it to be still a bit acidic. You can neutralize this a bit more by adding baking soda – not much! This creates sodium ascorbate, another buffered vitamin C, with its own benefits. Alternatively, if you have magnesium carbonate, you can add some of this increase pH.
Do NOT add potassium carbonate.
Although potassium is a vital nutrient, larger amounts of it can be quite dangerous. The final chemical in a lethal injection is frequently potassium chloride, which, in a high enough dose, stops the heart from beating. Don’t mess with potassium in your food unless you know what you’re doing.
Now, you have 25 milliliters of buffered vitamin C - AKA calcium ascorbate. Store this in the refrigerator until such time as you need it.