The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

From volume to mass

Darth Lefty's picture
Darth Lefty

From volume to mass

Greetings everyone.

I have for a year or so now been using a San Francisco sourdough culture I bought at the supermarket.  It takes the form of a batter and works fine.  I'd like to get more scientific but everything in the included recipe is in volume units, so for instance:

Mother sponge is fed with 1c flour to 1c water

Baby sponge is 1c mother, 1.5c flour, 1c water

Bread is 2c baby, 2/3c water, 4c flour, 2tsp salt

In the process this recipe seems to self-destroy information about mass.  Is there any reliable way to figure how much water and flour is in that final dough?  Each cup of sponge, mother and baby alike, is denser than water but also full of bubbles.  Their textures are noticeably different but their densities aren't.  Do I need to go back and start feeding the mother by mass instead of volume, both weigh and measure out every single step, and hope I get enough info that it works out eventually?

The recipe also suggests mixing the leftover baby back into the mother, which would really throw things off, and really doesn't sit right with all those chemistry classes I took where you never put leftovers back for fear of contamination.  So I haven't.

Finally, most sourdough recipes I find don't have a mother and baby sponge.  A portion of the mother just goes straight into the dough.  Is this some regional variant?  Is it appropriate for the ostensible San Francisco style?  I do like the loose mother sponge, it's really easy to maintain.  To feed, just dump in the flour and water, and shake.  To measure out, just pour.

Yumarama's picture

Hydration levels are measured via weight so "4 cups" of flour is too inaccurate to use for a good gauge. Since a cup of flour can range easily from 110 to 160g, that's a fairly large discrepancy. And since there's no "official" weight that a cup of flour is supposed to be, you can't truly convert with certainty. 

Just to show the variances here's what several published bakers say a "cup" is for them:

Peter Reinhart says 4.5 oz  (127g)
Jeffrey Hamelman says 4.3 oz (123g)
King Arthur says 4.25 oz (120g)
Maggie Glazer says 4.8 oz (136g) - though to her credit she ALWAYS qualifies it as "About X cups..."
Rose Levy Beranbaum says 5.5 oz (157g)
Toba Garrett says 3.8 oz (107g)

Then there's the matter of one person measuring slightly different each time. If you scoop with a little more or less force, you'll be packing the flour into your cup differently and even your own measures will differ.

One person may scoop out of the bag the next whisks the flour and spoons it into the cup, another sifts it directly in a cup.

Further, the flour may have settled and packed or the next bag is "fluffy". More changes. Different brands may have different densities. The same brand may fluctuate. The weather or humidity may affect it.

Simply put, too much potential variance in 'cups" to make a clear call.

But 150g of flour is pretty much 150 grams of flour no matter how you scoop.

I'll also point out that your "1 cup of flour plus 1 cup of water" starter is NOT 100% hydration starter. The water weighs a whole lot more than the flour, about 236g water to ~145g flour which would make it more like 162% hydration. But that's just a guess since we don't know how much that last cup of flour really weighed.

If you want to use that recipe, then just make a decision and pick a number for what each "cup" of flour shall weigh and then calculate what that is and stick to it. Or at least make the bread and if you like it, then whatever the weight was you used, that's the weight it should be. But you can't judge what the hydration is based on the numbers in that recipe. And even if you make a great loaf one day, you'll likely be making a different loaf next time because your "cups will be a little different.

But if it's "361g of flour, 284g water", etc. then you can replicate that exactly from here on. (I just made those amounts up for illustrative purposes, they're not based on anything.)

Personally, I'd say ditch the volume recipe and find a similar one in weights. And grams is better than ounces since they're very easy to add, divide and multiply where with ounces you may run into 16ths and such. Possible, but a little more tricky to calculate.

As to the "mother and baby" issues, that sounds like the author's personal touch. Some people use their mother to make the dough or preferment then hold some back to use as mother again. Others (and this is what I follow) build up the required sourdough for the recipe from the discard of the mother's lat feed. That way, you never actually use the mother and accidentally forget to hold some back then remember as you're pulling out the baked loaf that you just killed the last of your starter. Someone on here did that a few days ago and, although I haven't I don't discount the very real possibility I would. 

There's so so so much more stuff to read and absorb about starter cultivation and use, I would say don't go by just one source - even if that is me. Read a lot and make up your own mind to follow someone who you feel has a good grip on the issues. But you'll want to read various viewpoints before you can gauge if someone has a "good grip".

And remember, everything you read should be considered "guides" not "rules". 

So crack open a few more books and/or read the many fine threads here and on other sites. Then decide what is, to you, sensible. 

Good luck and happy info hunting!

flournwater's picture

I share your frustration in making a decision regarding how much a cup of flour is supposed to weigh.  What I've come up with is the fract that if I take all of the professional information about how much a cup of flour should weigh and average the numbers, it comes out to 128 grams.  So that's what I use.  Then I do my best to read the dough as it develops and adjust flour/water to achieve the consistency I'm looking for in the final dough.

Yumarama's picture

There's that (often unwritten) "Adjust as necessary" part to any bread recipe to account for dryer or softer doughs. So even the most precise recipe will still need to be fiddled a bit to get the dough to the "right" consistency.

This is the "art" part of the process.

marieJ's picture

I bake a loaf once or twice a week, every week and long ago dispose of the restraints of measuring ingredients. 

My approach these days is successful . ........and pure art........! 

I love the loaves I'm creating.  They are created over 3 days from starter, stoneground wholemeal flour, stoneground wholemeal spelt and spring water (and sometimes a some stoneground white flour).  I no longer use warm water either and find the end result is a beautiful loaf with aromatic flavours and aromas of the starter and more importantly the original grain.  It is a process of 2 days feeding and watering, then tipping flours onto the bench, incorporating salt, then pouring over the starter that has a little water mixed into it, then massaging everything together to develope the gluten and incorporate all incgredients. Endless practice, knowing my starter and experience in knowing how the dough should look and feel (with a huge dose of love and care!) has resulted in achieving beautiful desired  results.

bonniebateman's picture

I live in a place that is extremely dry and hot in summer, very wet and cool in winter.  All my ingredients react to the weather.  

I've completely given up volume measurements (cups) in favor of weighing things in ounces or grams, with a kitchen scale.  Much better results.  I do find, however that in dry weather I often have to add more liquid "by eye", even after weighing.