Starter - as it rises, does it gain in mass?
I'm new to sourdough baking (thanks Covid-19!), but have had luck using some online resources and have baked several reasonable loaves. A question I have always had though is when the starter is fed and rises in its container, is it gaining mass or just volume? The question becomes critical as I determine how much starter to begin with. If my recipe calls for 200 grams of starter, do I need to start with 100 grams, feed it 100 grams of flour and another 100 grams of water so that I have 100 grams of starter left?
Let me try that another way. If I start with 300 grams of total "starter" in my container right after feeding the original 100 grams, I should not expect to get more than 300 grams after the feeding is complete - right? I WILL see the volume increase as the starter should more than double in VOLUME in 3-4 hours. But no increase in weight - right?
I have weighed my own starters and don't see any change in weight throughout the feeding process, but wanted to check with the experts here.
Thanks in advance for any clarification you can provide.
David
David, my experience has been if I need 300 grams of starter, and I am using a 1:1:1, I would use 102 starter, 102 flour and 102 water, because i normally can not get 100% of the starter out of the container.
The starter does gain volume.
I am not a scientist, but I think that the mass would not increase at all, and in fact, it is likely that while slight, the mass will decrease as the yeast consume the food in the dough and produce gas.
Thanks for your insight and thoughtful response.
No, your starter can't really get what ain't there.
Actually, in my experience starters lose a little weight between feedings, which makes sense due to evaporation and digestion. It's not a lot, but enough to adjust my feeding a little if I wanna use my starter.
Say I need 200 g of starter, then I will take 50 g ripe starter and mix it with 80 g each water and flour. Should equal to 210 g when it's mature (so enough for loaf and next feeding), right? Nope, it's more like 190-200 g, which is not enough for my loaf and continuing the feeding. So I adjust to 90 g each water and flour, then it's enough.
To be fair, there would be some extra grams left if I scraped every little piece out, but that doesn't make a huge difference.
Thanks for your insights and thoughtful response.
The answers you've gotten already are correct. You'll want to make a little extra. Some will be left behind in the container, and some will be lost to evaporation.
Also, some is lost to CO2. What causes the starter to rise is a chemical reaction (which the yeasts perform inside their cells) that gives off CO2. If the CO2 is trapped inside your starter (in a very liquidy one it'll rise to the top, the bubbles will pop, and it won't get trapped), you'll see it as bubbles inside the dough, and it is these bubbles that cause the starter to increase in volume.
Thanks for your insights and thoughtful response.