What’s the difference between baking powder and cream of tartar? Well, if you’re of the gluten-free variety and ditching the spelt, wheat and other rising stars then chances are you might be sprinkling a few pinches of rising agents such as baking powder or cream of tartar into your magical mix. So let me level the playing field when it comes to chemical leavening. You’ll need to have your science hat on for this.
According to author Harold McGee and his wonderful world of On Food and Cooking: The Science and Lore of the Kitchen (a must for every cook), yeast produces carbon dioxide slowly and will leave you with a deflated cake – and ego – as the gas can escape quickly once the resting or fermentation period takes place.
So this is where chemical leavening kicks in. Harold reckons that it exploits the reaction between the pH compounds – acid and alkaline – and creates the same yeast-producing gas, carbon dioxide.
You can read more about yeast here
Now, the alkaline part is sodium bicarbonate NaHCO3 a.k.a. ‘carb soda’, Bicarbonate/Baking Soda or Baking Powder. It’s non-toxic and tasteless according to Harold. So if we have a batter or dough made with a sour starter like yoghurt or sour milk containing lactic acid and we add the alkaline sodium bicarbonate we will get the chemical leavening reaction that causes bubbles in the wet mixture to expand and the bread will rise.
Ok, just because “‘carb soda” – that’s how my Nan, Evie used to say it, bless her – don’t think you can go scoffing it by the bucketful to make you more alkaline. You have to eat veggies for that, or you may be in danger of creating a high alkalosis condition requiring immediate placement of a breathing tube and mechanical breathing support. Not fun.
From a health perspective, you also do not want any pesky sodium aluminum sulphate added to your bicarb. No, no, no. Why? Well, aluminum is dodgy. We know that. Paul Pitchford, my food as medicine mentor and author of Healing with Whole Foods reckons it’s the kryptonite of the food world. Well actually I said that, but he reckons it’s super strong and leeches out of EVERYTHING, which is why we should steer clear of all aluminium-lined tetra packs, cans and tin foil.
Cream of Tartar
Potassium bitartrate KHC4H4O6 is tartaric acid a common fast-acting acid salt and will often have sodium aluminum sulphate added Na2SO4 Al2(SO4)3. It’s a by-product of winemaking caused by the crystallisation in wine casks during the fermentation of grape juice. It’s sold commercially as a white, acid, crystalline solid or powder and is also used in the tinning of metals and as a component of laxatives.
When combined with baking soda forms CO2, similar to the action of the aforementioned yeast and helps to leaven loaves. It helps fluffy, whisked egg whites by maintain their form by strengthening the tiny air bubbles and decreases the rate at which they deflate. It will also prevent crystallisation in sugar syrups by preventing the re-bonding of the molecules once heated.
So that’s your culinary science lesson for now and don’t worry, there won’t be a test after class 😉
If you want to know more highly useful information like this then buy yourself a copy of my book The Healing Feeling.
This blog was first published 26/01/2013
Furthermore, food writer Richard Cornish explained in Good Food in 2014
I was once taking a cooking class and had portioned out bags of baking powder into those resealable coin bags used by banks. Well, did the head of the department at the TAFE curdle her custard when she saw them. She had obviously had a previous life in the music industry or something before cooking education as apparently little baggies of white powder look just like Class A drugs. Anyway, cream of tartar is tartaric acid, traditionally a byproduct of the wine industry. Ever had little crystals form in a particularly icy bottle of white? That’s tartaric acid. Baking soda is sodium bicarbonate and can form naturally around mineral springs but is usually made by a chemical reaction. It is alkaline. When you combine tartaric acid with alkaline baking soda a chemical reaction takes place and gas forms. When this happens in a batter, the gas is captured by the hardening dough, thus giving it lightness. Because this is an instantaneous reaction, batters and dough made with cream of tartar and baking soda should be cooked quickly after mixing. Baking powder, however, is a mixture of baking soda, starch and a mild acid, which gives off gas when the batter or dough is heated.
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