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  • sour cream

    The converter lists sour cream as having a density of .51 and mayonnaise as having a density of .93. My sour cream is not half as thick as my mayo, they are about the same texture. Both weigh around 220 or 230 grams per cup.

    Love the calculator though, when the densities are correct. I don't agree with the all purpose flour density either, I think a cup of flour weighs about 140g, not 100. But you'll get a different answer for flour density everywhere.

    But I still love the calculator. Really.

  • #2
    Re: sour cream

    The data I used came directly from the rec.food.cooking newsgroup FAQ, and seems to be off on quite a few things.

    Much more accurate data can be found in the USDA database, found in the post here:
    http://forum.onlineconversion.com/showthread.php?t=7086

    The data I used is freely available to use for any purpose, not sure if the USDA data is the same way. I contacted the USDA about getting permission to use their data, but they have not gotten back to me, I will try again.

    While its perfectly legal to use small amounts of the data without permission, I cant simply take large chunks and use it on this website without permission. Similar to how words in the dictionary are not copyrighted, but the dictionary as a whole is. But I will try harder to contact them this time and see if I can get permission.

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    • #3
      Re: sour cream

      Robert,

      I believe the FAQs will answer your question. The entire dataset is available for download. It appears to be a relational database, and the structure of the individual files is "unhelpful." You would have to look at the whole thing and figure how how to extract food identitites and densities in a useful way.

      http://www.ars.usda.gov/Main/docs.ht...6233#copyright
      Is there a copyright on USDA food composition data?

      USDA food composition data is in the public domain and there is no copyright. We would appreciate it if you would list us as the source of the data and when possible we would like to see the product which uses the data or be notified of its use.

      John

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      • #4
        Re: sour cream

        I looked at it again. You can download the whole thing as an Access 2003 database. Unfortunately, I have Access 2000, and don't use it much. I read the descriptions and looked at the ASCII text files, which I think I have figured out. Link for all files:
        http://www.ars.usda.gov/Services/docs.htm?docid=8964

        As a relational database, everything is cross-keyed by reference numbers. The Food Description file contains the word description of each food item and an NBD number which is the primary cross key to other files. For any food, find the NBD number and go to the weight file for density info.

        In the weight file, alpha fields are delimited at both ends by ~, the ^is used as a tab between fields. The important fields are
        *NBD #: The key to the food description
        *Sequence #: Several "amount" choices are offered, this controls the sequence in which they appear
        *Amount: The numerical part of the amount, usually 1 but not always
        *Measure Description: The unit of measure, often with description, eg chopped, melted, diced, etc relating to preparation
        *Gram Weight: Numerical, weight of that amount in grams

        As a human, I can pretty easily reduce each item to a density, but there are a few challenges to automating the process. For each NBD # (food item) examine the various sequence number choices. From amount and measure description, determine the largest volumetric amount (because the data is rounded), and convert it to milliliters. Divide the gram weight by the converted volume. The descriptive part of the measure needs to be retained. The issues are mostly parsing and recognizing (for conversion) all the Customary units.

        For the sour cream, the NBD # is 01056, and the weight data 230 g/cup, or 0.97 g/mL

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