November 5, 2010 - 10:21am
How to calculate the percentage of protein in #50 of grain ?
I have seen organic companies that say 14% protein content, others 12%, but how do you figure that? I currently found an organic wheat with no pesticide use or genetically altered, but it says 6 grams of protein for 1/4 cup.
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Different types of wheat have different protein levels, usually. Hard red spring wheat is usually said to have the highest protein. There are several types of wheat, red, white, hard, soft, spring, winter; all with varying protein levels.
So you have to know the wheat. Take flourgirl, for instance. She grows her own wheat, so she knows her hard red spring wheat(for example) should have a certain protein level. Even so, the accurate, precise levels have to be determined by taking samples of each crop, and having it scientifically tested.
Hope this is what you are asking. If you are speaking of reading a product nutrition label to determine a precise protein %, you usually can't.
You know one of the two things to calculate Protein % - there are 6 grams of protein in 1/4 cup of this organic flour. If you knew the exact weight of a 1/4 cup of this flour in grams then you could calculate the Protein % for this particular flour. It would be
Protein % = (6g * 100) / (number of grams in 1/4 cup flour)
for example, if a cup of this flour weighed 120 grams then 1/4 cup = 30 g and the formula would yield
Protein % = (6g * 100) / 30g
= 600g / 30g
= 20 %
This is the math for this one EXAMPLE.
We know the flour most likely does not have a Protein % = 20 %, so what do you really need to know:
- again what does 1/4 cup of this flour weigh in grams, and
- what is the EXACT - or at least a much more precise - number of grams of protein in 1/4 cup of this flour (e.g. protein in grams to 4 decimal places).
hope this helps.
Ben
What you really care about is the gluten content. It's quite often true that nearly all the protein in wheat is the two components of gluten ...but not exactly and not always. My personal suggestion is to always ask about "gluten", but be willing to accept "protein" numbers instead if that's all you can get.
The federally mandated "nutrition label" usually will not work, because it's "serving size" is too small so the gluten differences you care about get lost in the roundoff errors. The law apparently wasn't really intended for flour, and isn't very useful to home bakers; it's nice that you can always find that "nutrition label", but in fact it isn't worth very much to you.
Hopefully the miller knows the gluten content (to the nearest tenth of a percent) and will tell you when asked. Otherwise your options are to i) ask other customers (less likely with a local miller) or ii) have a lab analyse it (expensive) or iii) ask the miller for the results of their lab analysis (but they'll probably just tell you to shove it if you're not a large quantity customer like a bakery) or iv) figure out some way to measure the gluten yourself at home (messy, troublesome, and not very accurate).
An alternative is to just buy it anyway, and take it home and see how long it takes for a dough to feel like a rubber ball - you'll figure it out pretty quickly.
Beware that you want a particular value, not just "more is better". It's fairly easy to get too much gluten, which makes great bagels and pizza dough but will probably result in bread that's too "chewy".
This sounds to me like the equivalent of a "nutrition label", so inexact as to be pretty much useless. A "cup" can be anywhere from 105 to 150 grams. And the amount of "protein" can be anywhere from 5.5 to 6.5, all of which will be legitimately rounded off to 6.
Depending on which values I choose, protein content could be anywhere from 14% to 21%. That's a huge difference when only about 1% separates the typically available King Arthur "All Purpose" and "Bread" flour lines.
In any case (unless a very significant portion of this "protein" is not gluten), this flour seems to me to have much too high a gluten content to make decent bread by itself. It would need to be mixed with some other flour with a much lower gluten content. What does the miller advise? What do other customers do?
Azurestandard.com has organic wheat kernal,- hard red wheat with 1/4 cup (46 grams) with 6 grams peotein, Hubby says you take the 6 grams and divide by 46 which gives you 13%. Does this make sense?
INGREDIENTS: Organic Hard Red Wheat Berries.
Nutrition Facts
Serving Size: 1/4 cup (46 g)
Servings per Container: About 493 (50 lb. size)
Servings per Container: About 246 (25 lb. size)
Servings per Container: About 49 (5 lb. size)
Nutrient Amount %DV
Calories 150
Calories from Fat 5
Total Fat 0.5 g 1%
Trans Fat -- g
Sodium 0 mg 0%
Total Carbohydrate 33 g 11%
Dietary Fiber 6 g 24%
Protein 6 g
Iron 10%
Sorta. It's misstated. And I still disagree.
It should be 46 divided by 6 (not 6 divided by 6).
And I still think the serving size is small enough to allow the "rounding error" to make this number not all that useful. Since the reported "6 grams" could really have been anything from "5.5 grams" to "6.5 grams" before rounding, even with your more exact definition of what "1/4 cup" is (i.e. 46 grams), my calculations give a protein content range of 11.9% - 14.1% ...and that's a fairly big difference.
I may be courting a "stoopid award" here, but: I personally suspect it may not make much difference. If the kernels have that much protein, and you have to grind them into flour to make bread, then the flour is likely to have about that much protein too.
(Of course if you have some way to closely control the grind and produce either "white flour" or "whole wheat flour", the resulting gluten content may be significantly different from the kernels you started with.)
Weigh 1/4 cup of the wheat.
Divide 6g by the weight in grams of 1/4 cup of wheat and multiply by 100.
The result will be the percentage of protein in the wheat.
...
Here the math is correct, but failing to allow for "rounding error" puts it in the context of misleading at best.
(In my experience, Yahoo Answers is quite often off the reservation:-)
I guess I will play ignorant like I did in the 80's when I bought wheat from the mormons. I asked no questions and just bought and baked. So the real criteria is if when I grind it and make bread what the bread come out like! :) I always hated math and failed algebra. That was a typo, I corrected a few minutes later on the 46 grams.
When farmers sell their grain to the mill they have the option for it to be tested for protein levels. The higher the protein level, the more that they get for their grain if they choose to get it tested. After the wheat is sold to the mills, many times the low protein and high protein wheats are blended together to make a medium level flour as it is not easy to get a high protein crop and low protein wheat is more prevalent.
We grow our own certified organic wheat and have the protein tested in each load of wheat that we grow. There are many variables in obtaining high protein wheat such as the variety of wheat grown, growing conditions and the amount of nitrogen in the soil as that is key to getting a good crop of high protein wheat.
We are also a certified seed dealer and our wheat is tested by State labs for various things including protein levels and we have been fortunate to have good protein levels so far.
There are other variables as to how your bread will turn out. Every baker treats the handling of the dough differently. People that don't measure the temp. of their liquids when using yeast can easily kill the yeast if the liquids are too warm. If the salt comes in direct contact with the yeast that can also make it not perform like it is supposed to.
Anyway, try to enjoy the process of bread baking. If you have mistakes, eat them and try again!