Question about food scale

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knelson095
knelson095 Posts: 254 Member
in Food and Nutrition
So I did a little test with my coconut milk today...I measured out the 1 cup serving and poured it in a mug on my scale. The label says one cup or 240 ml, but when weighed, my cup was only 215 ml. I went with the higher one, but I was just curious as to which you guys feel is more accurate?

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  • JeffBrown3
    JeffBrown3 Posts: 161 Member
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    240 ml is one cup. I'd go with 240 for sure but how did you measure the milk before you weighed it? A measuring cup?
  • knelson095
    knelson095 Posts: 254 Member
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    Yes a measuring cup.
  • JeffBrown3
    JeffBrown3 Posts: 161 Member
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    Hmmmm that's odd. You got me there, I don't know why that happened lol. I do know measuring cups are not too accurate. I have several sets and some hold differing amounts of liquid. I always go by what the scale says. My suspicion is that the measuring cups are incorrect.

    A while back, I was not losing weight and figured out the culprit was measuring spoons and cups. Once I started weighing everything instead I started to lose again.
  • seska422
    seska422 Posts: 3,217 Member
    edited October 2015
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    Only solids can be weighed for serving purposes. Their nutritional information is given in grams, which is a weight.

    For liquids other than water, the only accurate thing to do is to use measuring cups and spoons. Liquids have variable densities. Water is 1 gram per milliliter but other liquids can be more or less dense than water. Somewhere in your scale instructions it probably says that the ml measurement can only be used with water and things with nearly that same density. All the scale is doing is measuring grams but labeling it as milliliters. Volumes cannot actually be weighed.

    For liquids that you use often, you can make a note of the actual difference to use for reference. So, for dressing, you might take 15 ml and weigh that and get 13 g. After that, you can just weigh out 13 g and know that you are getting 15 ml and that 26 g would be 30 ml.

    Having said this, I pick my battles. I use so little dressing that I call it close enough and just weigh it. Something like ice cream with a lot of air in it, that gets measured with a scoop rather than weighed.
  • saphin
    saphin Posts: 246 Member
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    Liquids are weighable, but you have to account for the specific gravity of the liquid you are weighing. Simply put, water typically has a specific gravity of 1; other liquids will vary. Lower specific gravity liquids would float on water (eg, olive oil) and higher specific gravity Iiquids would sink in water.
    http://www.aqua-calc.com/mobile/page/density-table/substance/nuts-coma-and-blank-coconut-blank-water-blank--op-liquid-blank-from-blank-coconuts-cp-
    Is a good reference guide
  • kailyw05
    kailyw05 Posts: 80 Member
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    You shouldn't be able to weigh in mL... Were you weighing in grams? 240 mL is a volume, not a weight. I would imagine the weight in grams would not match the volume in mL for the same reasons above: specific gravity.

    It's also probably hard to measure exactly to the 1 cup line on a measuring cup due to the meniscus of the liquid. You have to get down to eye level and check that the bottom of the meniscus is at the line to get an accurate measurement, and even then there will be a margin of error.
  • seska422
    seska422 Posts: 3,217 Member
    edited October 2015
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    kailyw05 wrote: »
    You shouldn't be able to weigh in mL... Were you weighing in grams? 240 mL is a volume, not a weight. I would imagine the weight in grams would not match the volume in mL for the same reasons above: specific gravity.
    Many food scales these days have a ml measurement option. I guess because people have asked for it so they can use it with the nutritional info on labels. It's misleading because it give the impression that you can directly weigh a volume. If I switch between g and ml while I'm weighing, they are always exactly the same because the scale is measuring grams but slapping a "ml" label on it.

    There's a disclaimer in the instructions that it's only accurate for water and things with the density of water but that's easy to miss if you don't go looking for it.

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