 | This article has not yet been rated on Wikipedia's content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||
| ||||||||||||||||||
Conversion Errors
editThere were errors in the volume-to-weight conversions in the original version of this article.
One cup of all-purpose flour weighs 120 to 125 grams depending on which converter is used, viz.:
http://www.kingarthurflour.com/learn/ingredient-weight-chart.html
We will take the median: 122.5 grams per cup of all-purpose flour. Three cups would thus weigh 3 x 122.5 or 367.5 grams.
In addition, one cup of water weighs 236.59 grams. 1 1/2 cups would thus weigh 355 grams.
The recipe has been corrected with the correct flour and water weights.
- I'm adding the table as calculated from the numbers you used (directly above) in this iteration of the conversion.
From Lahey's table on page 51 of My Bread
edit- I just placed the URL to Jim Lahey's My Bread recipe, which is the source of the formula per the article text. His numbers are different from your conversions. He doesn't include baker's percents, but they're easy enough to calculate.
Ingredients Grams Baker's % Bread flour 400 100% Salt 8 2% Instant yeast 1 0.25% Water 300 75% Formula 709 177.25%
It's possible this is not an optimum formula, but those are the gram weights Lahey used, and the "bread flour" he specified. Per the USDA Nutrient Data Laboratory, bread flour weighs 137 g per cup, which is heavier than all purpose flour. Gzuufy (talk) 13:52, 9 March 2016 (UTC)
The article says, "According to one version of the method developed by New York baker Jim Lahey,[1] as described in his book My Bread ", so shall we agree that the table should reflect the values given in the book? The first problem is that the conversions in the book are incorrect, with 1 C bread flour weighing 133.33 g vs. the USDA value of 137 g. His water conversion is way off, with 1 C water weighing 225 g (300 / 1.333) which is way off from the correct value of 236.59 g per cup.
In the NY Times article and the YouTube video they use volume measurements, so the conversions to grams should probably be corrected, keeping the volume measurements. In addition, previous Wikipedia versions of the formula gave 1 1/2 C water, yet the book gives 1 1/3 C water. This has been corrected. — Preceding unsigned comment added by 50.1.203.20 (talk) 12:13, 10 March 2016 (UTC)
- This table is from today's corrected values.
- I agree there are errors in the conversions! One of the issues is that we do not know how Jim Lahey's bakery actually measured, whether by weight or volume. Per Gisslen, professional and modern pastry chefs use weight measures due to their greater accuracy. It's possible that Lahey used weight in his bakery, but converted to volume measures for his book as the consumer cookbook market seems to demand volume measures. It's also possible that Lahey used volume measures in his bakery, and the conversion to weight was added since baking authors such as Reinhart have popularized the measurement by weight method. We don't know in which direction the conversion occurred when Lahey developed his method and wrote his book! A risk is that we can introduce greater ambiguity or more variance when we reconvert from the measure that represented Lahey's conversion. One issue with presenting it on the Wikipedia page has to do with sourcing, and keeping whatever is in the article understandable to anyone who may dig a little deeper and look at the references. Gzuufy (talk) 17:46, 10 March 2016 (UTC)
If he started with weight measurements and converted them to cups, he'd get some oddball fractional cup measurements, for example, 400 g flour = 2.9197 cups. It's important that the conversions be accurate, which they are not in the book and in previous versions of this article. Starting with even cup measurements and doing accurate conversions to grams is probably the most straightforward. — Preceding unsigned comment added by 50.1.203.20 (talk) 22:32, 10 March 2016 (UTC)
- Compared to cooking weight measures, volume measures always have errors due to fractions and the cup and spoon measures that are mass manufactured. In actual measurement, weight measures also have errors due to vagaries of the tools used to measure.
- 400/137=2.919708029. There are 48 teaspoons in a cup. Thus, 2.91970802919708 cups=140.14598540146 teaspoons. From that, and the use of a variety of spreadsheet tables consisting of fractions of cups and teaspoons, I can reduce 2.91970802919708 cups to
- 2 11/12 cups + 9/64 tsp, and I believe that is to about 15/1000 g accuracy (haven't double checked error).
- or stated differently
- 2 cups + 2/3 cup + 1/4 cup + 1/8 teaspoon + 1/64 teaspoon.
- There's an additional matter that with each volume measure, there will be an additional random measuring error of some sort, and since 4 to 5 tools are used, that error is magnified by some multiple.
- There is the practical matter that 1/64 teaspoon may not exist. If we drop it as an imaginary measure, the gram error increases. Whenever I have looked at these kinds of conversions, I have always asked myself what sane person would ever use such a convoluted measuring system? It seems to be designed to be confusing and tedious to quantify.Gzuufy (talk) 17:06, 11 March 2016 (UTC)
I don't know what your point is, but we're documenting the formula given in Lahey's book, which contained inaccuracies in the conversions. We've cleaned up the conversions and given weight measures which are more accurate than the volume measures. I think that's as far as we need go. — Preceding unsigned comment added by 65.197.211.2 (talk) 06:09, 12 March 2016 (UTC)
- My point is when have you ever seen a cookbook publish a measure such as "2 cups + 2/3 cup + 1/4 cup + 1/8 teaspoon + 1/64 teaspoon"? The author and the publisher would round that to 3 cups.
- From page 48 of Lahey's My Bread,
| “ | Plenty, probably most, home cooks in America do their baking without the use of a kitchen scale, but measuring by weight is the norm in many other parts of the world, and certainly in professional bakeries. Weight measurements are crucial for precisely standardized results. When you measure only by volume, there is a lot of room for variance: a cup of flour can differ in amount, depending on how densely it's packed, but the weight will be accurate no matter what. So I've included the metric weights in this book for those who want to use them at home.... | ” |
- If I'm understanding that correctly, he says he uses metric weights in his bakery. That implies the volume measures are the conversions.
- Can we agree that the table above starting with "Bread flour" and using 400 g for the 100% figure is closest to Lahey's intent? Gzuufy (talk) 13:23, 12 March 2016 (UTC)
That would require rewriting this part of the article and would make it erroneous. Here is what it would look like rewritten:
- "one loaf of the bread is made by mixing three cups (400 g) bread flour, 1¼ teaspoon (8 g) salt and ¼ teaspoon (1 g) instant yeast with 1 1/3 cup (300 ml) cool water"
The cup-to-gram conversions are now erroneous, which is why I made the table with 411 grams flour.
The other and probably preferable way to write it would be:
- "one loaf of the bread is made by mixing 400 g (approximately 3 cups) bread flour, 8 g (approximately 1¼ teaspoon) salt and 1 g (approximately ¼ teaspoon) instant yeast with 300 ml (approximately 1 1/3 cups) cool water" — Preceding unsigned comment added by 50.1.203.20 (talk) 22:20, 12 March 2016 (UTC)
- I think your second solution is excellent! You can also have a note section added to the article for explanatory text, if you feel more explanation is needed. The 11 gram difference is small and minor, but the flour-relative ratios (%) are a little different as well. Gzuufy (talk) 00:35, 13 March 2016 (UTC)
I think we've got it now. It's self explanatory, with no additional notation needed. — Preceding unsigned comment added by 65.197.211.2 (talk) 02:38, 13 March 2016 (UTC)