What's The Problem - #3

[Michael in FtW]

The answer is:
Bread Flour = 4 Cups
Whole Wheat Flour = 3 Cups

Congrats go to masteraznchefjr, subfuscpersona, and Andy M! It was really interesting to see the different approaches used.
And a bottle of hair restorer tonic to everyone who pulled their hair out trying to figure this one out!

And I forgive everyone who called me a ...


Once again Shirley Corriher and Cookwise get most of the credit - after Consul's comments on the last problem. If you can estimate the weight of a cup of a certain type flour by how you measure it - why not be able to estimate the weight if you use a standardized method of measuring that you knew would put your volume measurment close to scale weight if you know the info on the side of the bag?

I know, I should be ashamed - the "trick" was to read the serving size information and the number of servings on the bag. Using 1/4 cup for one and 3 Tbsp for the other was a little mean of me. But, they are directly off 2 bags of flour I have. For the Bread flour I used the info off a bag of Gold Medal unbleached all-purpose, and for the Whole Wheat I used the info off a bag of Bob's Red Mill #1 Semolina for Pasta.

The methods I used when I thought this one up:

Tablespoons (Tbsp)

This is probably the easiest one to figure out ....

1) Tablespoons per serving X servings per bag = total Tbsp per bag
2) Oz per bag / total Tbsp = weight per Tbsp (in oz)
3) Oz per Tbsp X 16 = Oz weight per Cup
4) Weight of flour needed (in oz) divided by the weight of a cup of flour (in oz) = number of cups needed

This is where the 1 Cup = 16 Tbsp was most important

Bread Flour:
4 Tbsp (1/4 Cup) X 75 Servings = 300 Tbsp
80 Oz / 300 = 0.2666 per Tbsp
0.266 X 16 = 4.267 oz ... rounds to 4.25 oz per cup
1-lb 1-oz = 17-oz
17 / 4.25 = 4

Wheat Flour:
3 Tbsp X 72 = 216 Tbsp
80 oz / 216 = 0.37 oz per Tbsp
0.37 X 16 = 5.93 oz ... rounds to 6 oz per cup
1-lb 2-oz = 18-oz
18 / 6 = 3

Cups

This one is converting everything to cups is a different way ...

Bread Flour:
1) Since a 1/4 is 0.25 of a Cup and there are 75 1/4 cups
the number of cups per bag is 0.25 X 75 = 18.75 Cups
2) The weight of a Cup of flour is therefore the total weight divided by the number of cups ... 80 oz / 18.75 cups = 4.266 oz per cup .... rounds to 4.25 oz per cup
3) 1-lb 1-oz = 17-oz
4) 17 / 4.25 = 4 cups

Wheat Flour: this one is a little trickier and takes an extra step ...

1) 3-Tbsp is 0.75 of a 1/4 cup - so to convert 72 3-Tbsp servings into 1/4 cups servings ... multiply the number of servings X 0.75 .... 72 X 0.75 = 54 1/4 cup servings.
2) Convert 1/4 Cups to Cups ... 54 X 0.25 = 13.5 Cups
3) The weight of a Cup of flour is therefore the total weight divided by the number of cups ... 80 oz / 13.5 cups = 5.925 oz per cup .... rounds to 6.0 oz per cup
4) 1-lb 2-oz = 18-oz
5) 18 / 6 = 3 cups

Charlotte - I would be very interest in seeing how your daughter would solve this problem! Wonder how her math teacher would approach it ...???

Conclusion: I like scales for baking - and I really need to break down and get a digital model, my old analog cheap thing is really only good for jelly and jam sessions. But, if you don't have a set of scales and you want to try a recipe - it's nice to know you can get within the ballpark.

 

[Charlotte]

Ahhhh Michael... it was fun to try!

Congrats to those who managed it! We gave up over here...

 

[subfuscpersona]

free office suite I used to solve the problem

Thank heaven for spreadsheets. If you don't have one, a most excellent free office suite called OpenOffice may be downloaded from http://www.openoffice.org/ It is just as good as Microsoft's office suite and has a word processor, spread sheet, presentation manager and lots of other goodies.

OpenOffice is available for Windows [Windows 98, Windows ME, Windows 2000 (Service Pack 2 or higher), Windows XP, Windows 2003] and linux (guess MAC users are out of luck for this one).

OpenOffice is one example of open source software. Much open source software is free and many are cross-platform, which means that there's a version for different operating systems (most readers here probably use some version of Windows but yes, there are other operating systems for the home user out there).

To explore open-source software, check out http://sourceforge.net/

 

[oldcoot]

If 5 lbs flour = 75 servings @ 1/4 cup ea, then (5 x 16) 80 oz / 75 = 1.07 oz per 1/4 cup.

So 1 lb. + 1 oz = 17 oz / 1.07 = 15.9 quarter cups or 4 cups Bread Flour.

Whee did I go wrong?

BTW: isn't "bread flour" made of wheat, too? Stuff I buy is!

Just fooling around, I weighed four measured by the "standard" system of spooning it into the measuring cup, and then by sifting the flour onto a paper towel and gently pouring it into the cup. Came up with a whopping 10% difference in weight! A sufted 1/4 cup weighed a bare 1 oz, while the spooned 1/4 cup came in at 1.1+ oz.

Bt is all that really important? For example, changes in humidity can effect the weight greatly - depending upon how the flour is stored: an open bag?...a cannister with a loose lid?...Recently we use an SS cannister with an hermetically sealing lid (a present from a delightful young neighbor). The difference can be appreciable.

Still, since I simply estimate the quantities of everything in the white bread I bake, with essentially identical results each time, and toss all into the mixing bowl in random fashion before turning on the KA, I am unsure all this attention to detail is needed. I just adjust the consistency of the dough - if necessary - after a few minutes of mixing. Works for me.

 

[Andy M.]

If 5 lbs flour = 75 servings @ 1/4 cup ea, then (5 x 16) 80 oz / 75 = 1.07 oz per 1/4 cup.

So 1 lb. + 1 oz = 17 oz / 1.07 = 15.9 quarter cups or 4 cups Bread Flour.

Whee did I go wrong?

You didn't go wrong. 4 cups is the correct answer for bread flour.

 

[oldcoot]

Oops - sorry - I thought it was 3 for Bread and 4 for wheat - had it backwards. Not unusual for me!

Anyway, that didn't require any involved math - which I never could fathom. Just simple arithmetic.(Yeah, I used my on-screen calculator! )

 

[Consul]

I just keep adding flour until I get the right feel to the dough. That works for making focaccia.

Sorry I wasn't here in time for this one. My Internet access went away on a misunderstanding, and I only just now got it back.

The rule of thumb I follow is based on a conversion chart I found, that 4 ounces of flour equals one cup, as measured out using Michael's method above. So, dividing ounces by 4 should yield cups, in theory. This only applies to white flours (bread and all-purpose, and maybe cake), so the heavier flours will need different calculations.

 

[Michael in FtW]

Consul - the problem with "the chart" is that it really doesn't really work for baking. While 4-oz/cup is about right for cake flour, all purpose is about 4.25-oz, and bread flour is a little over 5-oz. Someone somewhere mentioned a chart in "Baker's Illustrated" - published by the folks at "Cook's Illustrated" that I admire 2nd only to Alton Brown for TV shows ... but they are in the NorthEast - and didn't include Southern milled flours.

The "problem" didn't allow for using "charts" - it required you to figure it out from the information on the bag. That's why I used semolina flour data for the whole wheat flour.

 

[oldcoot]

Mike, I'm not sure any weight per cup is of any real use, as too many factors affect the amount of flour in a measured cupful.

Obviously, the most precise recipe would give the weight, not the volume, of flour. With electronic kitchen scales so inexpensive now (mine was under $25), such might not be too exclusive. (Or both volume & weight could be noted?)

But then, with all the other variables present in bread making, even that would be no guarantee.

 

[Consul]

I know the problem didn't allow for charts. I just told the way I go about it since the problem had been solved and explained already.

One of the things I learned in chemistry class was all about inaccuracy in measuring (which relates to significant digits). I think you'll find if you measure a dozen one-pound bags of the same flour using a nice, super-accurate scale that you'll get a wide variance of weights from bag to bag, maybe by as much as a three to four ounce range.

One of the things on my shopping list is a nice and accurate digital scale for the kitchen. I wouldn't mind getting some pipettes and a buret or two, either. I'd also like one of those infrared thermometers (the kind that can tell you the temperature of a surface at a distance), but that's another post.