11/28/2015

How many grams is a cup of flour?

A key milestone for my bread making was beginning to measure flour with a scale. It happened very shortly after I started, and I believe it was key to the early success that kept me baking. I still advise anyone attempting bread baking to use a scale for the best results.

Recently, I received another request from my mother for my bread recipe converted to volume measurement. Such requests had been made just about every time I went home. Instead of treating this one as a heretical request like those past, I decided to embrace it as a challenge. I asked myself if it would be possible to reach some degree of accuracy using measuring cups and spoons.    

My enlightenment was partly inspired by Alice Medrich’s recent book Flavor Flours. As with most good baking books, she provides mass measurements for all of the formula. She also describes how to measure flour by volume and provides a helpful appendix of volume measurements for the non-traditional flours used in the book. The key was providing a standard way to measure the flour in her discussion on measuring by volume.

Using Alice's description as a starting point, over a weekend, I conducted an experiment and collected some data. I decided to test the primary flours I use for baking bread. This had the advantage of also extending the information provided by Alice's appendix. The flours tested were:

  • Unbleached All-Purpose Wheat Flour (Gold Medal)
  • Unbleached Bread Wheat Flour (Gold Medal)
  • Whole Wheat Flour (King Arthur)
  • Medium Rye Flour (Grocery Store Bulk )
  • White Rye Flour (Grocery Store Bulk)
  • Whole Spelt Flour (Arrowhead Mills)
  • Semolina Flour (Caputo)

I experimented with three different techniques to measure the flour. The different techniques demonstrated both the strong dependence on measuring technique, and the variability that occurs when measuring flour by volume. The three measuring techniques were as follows:

  • The first technique I call the “tamped” method. This is the “take the measuring cup and just scoop the flour out of the container” method. In most cases, flour started out rather compacted in the container and got tamped into the measuring cup by the side of the container on the way out. The only refinement in this method was a kitchen knife was used to strike the excess flour off the top of the measuring cup.
  • The second technique I call the “fluffed” method. In this case, a kitchen knife was used to aerate or fluff the flour in the container before the measuring cup was carefully used to scoop flour from the center of the container. Care was taken not to compact the flour on the way out. As with the tamped method, the kitchen knife was used to strike any excess flour off the top of the measuring cup to maintain uniformity.
  • The last technique tested was to spoon flour from the container into the measuring cup until there was a heaping mound. As with the others, a kitchen knife was used to strike the excess flour off to get a uniform measure. For this last technique, I selected the extremely original name of “spooned” method.   

For the three standard wheat flours and the two rye flours, I collected data for each of the three techniques. I don’t keep large amounts of spelt and semolina flour around so I only collected data for the fluffed and spooned techniques. In both cases, I didn’t feel I had a large enough volume to consistently collect data using the tamped technique.

To collect measurements for a full-cup of flour, I measured out four cups of flour and recorded the mass using a digital kitchen scale after each cup. After measuring four cups, I returned the flour to the storage container and repeated the procedure two more times for a total of three trials. After some subtraction, this resulted in twelve measurement samples for each experimental run.

When you combine the 7 flours with the 3 measuring techniques and 3 trials for each, you end up with a total of 57 experimental trials and 228 individual data points. A Google Docs spreadsheet was used to summarize the data and compute some statistics. With 12 measurements for each combination of flour and technique, the standard deviation for most of the combinations was in the 2-3 gram range. The tamped technique showed the most variability; this is an additional finding I will talk more about in the closing. The table below gives the mass in grams for 1 standard US cup (240 ml) of flour using each of the three measuring techniques.  

Mass in Grams per US Cup
Tamped
Fluffed
Spooned
AP Flour
148
140
135
Bread Flour
150
143
135
Whole Wheat
155
143
133
White Rye
130
120
112
Med Rye
125
119
112
Whole Spelt

149
138
Semolina

170
155

I also wanted to see how reliable the measurements would be when using a half-cup and a quarter-cup measure. I did experimental trials with bread flour as before, except I switched the size of the measuring cup from a full-cup to a half-cup and then a quarter-cup. The results were compared to what would be predicted by just taking the corresponding fraction from the mass for a full-cup. With surprising consistency, a lose of about 6% is observed as you move from one measuring cup size down to the next. For instance, a half-cup (fluffed technique) of flour measured out to be 67 grams when it would have been predicted to be 71 grams when you take the measurement for the full-cup (143 grams). For simplicity, 6% was selected as a uniform correction factor to generate the following tables for half-cup and quarter-cup measurements.   

Mass in Grams per US Half-Cup
Tamped
Fluffed
Spooned
AP Flour
69
66
64
Bread Flour
70
67
63
Whole Wheat
73
67
63
White Rye
61
56
53
Med Rye
59
56
52
Whole Spelt

70
65
Semolina

80
73


Mass in Grams per US Quarter-Cup
Tamped
Fluffed
Spooned
AP Flour
33
31
30
Bread Flour
33
31
30
Whole Wheat
34
32
29
White Rye
29
26
25
Med Rye
27
26
25
Whole Spelt

33
30
Semolina

37
34

For completeness I provide the following table for tablespoons, however it is just a guide. By the time you get down to a tablespoon fraction, the error of the experimental measurements starts to be on the same scale as the amount of flour you are measuring. You would need to actually collect experimental data using tablespoon measures to resolve this. For the same reason, I only present the fluffed technique.

Mass in Grams per US Tablespoon
Tamped
Fluffed
Spooned
AP Flour

8

Bread Flour

8

Whole Wheat

8

White Rye

7

Med Rye

7

Whole Spelt

8

Semolina

9


One additional outcome is a recommendation on measuring technique. As hinted before, the tamped technique of measurement had the most variability in the experimental data. This stands to reason given the nature of the food stuff that is being measured. I would recommend sticking to either the fluffed or spooned methods. This is consistent with the advice given by Alice, and I have found the same guidance in other cookbooks as well.    

The goal of this exercise was to come up with a reasonably accurate way to measure flour using traditional volume measuring cups. The tables presented accomplish that goal, and give a series of conversions that allow someone to go from grams to US cups, half-cups and quarter-cups. Happy baking.  

7/19/2014

"What flour do you use?"

CC BY-NC-SA mark@markrank.net
A “baguette de tradition fran├žaise” can only have 4 ingredients; wheat flour, water, salt and yeast*. That does not leave much room for generating flavor and thus puts much of the focus on the quality of the flour. As I developed my hobby, I have tried many different types and brands of flours. Just as a bourbon drinker is loyal to a favorite brand, I bake using the Gold Medal brand. For most of my baking, I use the “Better for Bread” label. For artisan breads such as baguettes, freestanding or hearth loaves, I use a 50/50 mix of Gold Medal “Better for Bread” and Gold Medal Unbleached All-Purpose. I find these give me the results I am looking for. They are also a good balance of economy and quality, thanks in no small measure to the national distribution might of General Mills.

When I am evaluating a flour, I look at a couple of factors:

  • Type and extraction
  • Percentage gluten forming proteins
  • Quality and consistency
  • Unbleached
  • Cost and availability

At its most basic, flour can be defined as any finely ground foodstuff. It is possible and desirable for many reasons to use flours made from other grains, pseudo-grains, legumes and nuts. However, each flour will have different characteristics. To keep our discussion focused I am going to stick to wheat flour. In U.S. grocery stores, wheat flour is either all-purpose, bread flour, or whole wheat. What differentiates the first two from whole wheat is a concept called extraction. To understand extraction, we need to look at where flour comes from. Each wheat kernel is composed of three major parts; the fibrous outer bran layer, the starchy endosperm and the fat rich germ.

CC-BY-SA: http://commons.wikimedia.org/wiki/User:Jkwchui   http://en.wikipedia.org/wiki/File:Wheat-kernel_nutrition.svg
If you took a hammer and crushed some wheat berries, you would effectively have whole wheat flour. Now before you reach for the hammer and a hand full of wheat berries, stick with me a bit. The art, science, and technology of flour milling is the evolution of that basic crushing process to something more elegant. The miller will use a combination of crushing and sifting operations to separate the bran and germ from the endosperm. This is what we mean by “extraction” and is percentage of whole wheat kernel contained in the resulting flour. Full extraction would be whole wheat flour, but that is the opposite of what we are looking for. In the US, we are looking for extraction to go from 100% of the whole kernel to somewhere around 50% or 60% for your typical white, all-purpose flour.**

This sorting process has some side effects. Think of a wheat berry like an egg. You can separate the egg whites from the yoke and the shell easy enough. You can take the egg whites and whip up a nice fluffy meringue, but without augmentation it really will not have much flavor or nutritional value. Much of that was contained in the egg yoke. The same goes for the endosperm of the wheat berry. The endosperm has the gluten forming proteins needed to make light and fluffy bread but does not have the fats and vitamins of the wheat germ or the healthy fiber of the wheat bran. While present in small quantities in an all-purpose flour, the healthy benefits of whole wheat flour comes from having 100% of the wheat berry present.

The gluten forming proteins contained in the endosperm leads us to the second factor we care about for flour, the percentage of these proteins. It is these proteins we depend on to form the gluten matrix when we bake and have the most effect on the structure of our bread. The target for an artisan loaf of bread is around 11.5%. For reference, a pastry flour where you don’t want gluten development would target something in the 9% range. On the other side, some high-gluten flours used for pan, sweet or rye breads go into the 13% to 14% range. In the United States, the difference between the all-purpose and bread labels is mostly the percentage of gluten forming proteins. I compiled Table 1 in 2011 and it gives the gluten forming protein for several retail flours.

Flour% ProteinReference
King Arthur All Purpose11.7Website
King Arthur Bread12.7Website
Gold Medal Unbleached All Purpose9.8 - 12Vendor Email
Gold Medal "Better for Bread"11.7 - 12.3Vendor Email
Pillsbury Best Unbleached All Purpose10.5Vendor Email
Pillsbury Best Bread12Vendor Email
Central Milling Unbleached All Purpose10.5Vendor Email
Hodgson Mills All Purpose10 - 12Vendor Email
Hodgson Mills Bread13Vendor Email
Bob's Red Mill Unbleached White Flour12 - 13Vendor Email
GM Harvest King Commercial12Product Spec Sheet - gmflour.com
Table 1 - Flour Brands

One item to notice is that some vendors quote a range. The Gold Medal flours for instance will vary depending on time of the year and region. Having used Gold Medal so often, I really do not notice the differences but every once in a while a batch of dough will not feel right. This was especially true when I moved from the midwest to the west coast. All of the hydrations seemed to be off just a bit. On the other hand, the King Arthur maintains very tight and uniform controls on its offerings. I often recommend the King Arthur All-Purpose to people who want to try baking bread. King Arthur All-Purpose falls almost exactly where a baker would want a flour for artisan bread baking and the consistency makes it a very good product to bake with and well worth the slightly higher cost for the occasional or first time baker.

One other observation from the table of flours should be most of the flours have unbleached in the label. Those that don't are still unbleached flours, just unneeded for branding reasons. The natural color of a good quality four is a creamy off white and an unbleached flour is the type you want to use for bread. The hint of yellow is coming from carotenoid pigments. These are the same class of natural molecules that make carrots orange and is an indication of a flour with valuable vitamins still intact. My objection to using a bleached flour for artisan bread is rooted in protecting these components of the flour. By breaking down these molecules, the quality of the end product is compromised. In the end, I bake bread because I believe I can make a good product in my kitchen.

Bleaching agents were originally introduced into flour to make pure white flour with good handling properties for large commercial scale bakeries so baby boomers could grow up on PBJ and grilled cheese. The agents are also added to age freshly milled flour to also improve the handling properties. This is where the life of bleached bread flour and yoga mats intersect. It is not new that bleaching agents are used in commercial bakery products. What is new is using social media as a megaphone to call attention to what we eat. Not that I am defending ADA use. As the article points out, it may be time to revisit the science on this. That really is my underlying point. For home baking, there is no need for these additives and unbleached flour will lead to a very successful product.

There are several other parameters and characteristics related for flour, but that is what books and reading are for. For those interested in the history, 6000 Years of Bread by H.E. Jacob is a good read. For a more technical deep dive, check out Wheat and Flour Testing Methods book. It was produced under contract by the International Grains Program of Kansas State University and a gives a good insight into just how complex of a commodity wheat flour has become.

That brings me full circle. The last parameters to talk about are cost and availability. I use Gold Medal because I am familiar with it and no matter where I am, I can find it. I recommend King Arthur because I believe the incremental extra cost is worth the tighter tolerances when someone is first learning to bake. There are store brand flours and there are ultra premium organic flours. Each can be used to make good bread. Part of the art and fun of baking is the choices made.    

* Well, and just a touch of bean flour or malted wheat flour, but let us not quibble.
** Don’t be confused with white whole wheat flour. Wheat comes in two colors, white and red. The color is reflected in the bran. Most whole wheat flour is made from red varieties and thus a darker color. White whole wheat flour has become popular as a way to incorporate healthy whole grains into foods without making them look that way. White whole wheat flour has different handling properties that align closer to whole wheat flour and thus are not a direct substitute for all-purpose or bread flour.