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Subject:
From:
Anders Møller <[log in to unmask]>
Reply To:
Date:
Mon, 11 May 2015 19:23:30 +0200
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Dear Ruth and Jessica,

 

I am a little confused about Ruth’s answer – Ruth’s answer is sort of right,
but mixes up weight (actually mass) and volume, and especially, I am
confused about Ruth’s comment about recording your altitude.

It is true that you weigh less on the top of Mount Everest than at the
bottom of Death Valley, but - in connection with food density - is that
something a normal kitchen scale can measure – I doubt it.

The boiling point of liquids is influenced by the altitude and the
differences are measurable, but that is a completely different story.

 

Density is mass per volume and always has a unit (g/cm3, kg/m3, kg/litre,
tonnes/m3, etc.).

You can use ordinary standard, household measures, cup, teaspoon,
decilitre/litre  measures, etc.

 

I think that what Ruth is trying to say is that you can actually use any
glass or container – and I would say the bigger the better to minimize
errors in measuring.

 

1.       Weigh the container without anything in it.



2.       Top fill the container with water from fridge or just cold tap
water (in my country it is ground water and always 8 degrees).



3.       Weigh the water+container – the difference in mass water+container
minus mass of container is a measure of the volume of water as the density
of water is about 1 g/cm3, i.e. if you find that the mass of water in the
container is 526 gram, then the volume is (about) 526 cm3.



4.       Then fill the container to the top with the food in question and
weigh it. The mass of the food is the mass of container+food minus the mass
of the container.

 

The density can then be calculated as mass of food divided by the volume of
the container, e.g. if the mass of food is 428 g and the volume of the
container is 526 cm3, the density of you food is 428 g divided by 526 cm3
which equals 0.814 g/cm3 or 814 g/litre or 0.814 kg/litre.

 

All the best,

Anders

 

PS.  Just as a precaution, please do not mix up density and specific gravity
(which is without unit) – see earlier posts in the group. 

 

 

Anders Møller

Danish Food Informatics

Borgediget 12

DK-4000 Roskilde, Denmark

 

 

From: Food Composition Discussion Group
[mailto:[log in to unmask]] On Behalf Of Charrondiere,
Ruth (ESN)
Sent: 11 May 2015 16:43
To: [log in to unmask]
Subject: Re: Best Practices for Calculating Density Conversion Factors

 

Dear Jessica,

you take a laboratory scale, put an empty glass or other container on it,
weigh it. Then fill it up with water coming from the fridge. weigh it.
Record the difference in weight which is your volume. Then weigh all foods
in this container and divide it by the volume. Describe the food well, e.g.
fish powder, loose; raw eggplant without skin in 1 cm cubes. Record your
location (altitude). I would be happy to include your data in our next
version of the FAO/INFOODS density database

 

Best wishes

Ruth

 

P.S. Anyone else willing to contribute data are most welcome

  _____  

From: Food Composition Discussion Group
[[log in to unmask]] On Behalf Of Raneri, Jessica
(Bioversity) [[log in to unmask]]
Sent: Monday, May 11, 2015 2:12 PM
To: [log in to unmask]
Subject: Best Practices for Calculating Density Conversion Factors

Dear Infoods Members,

 

We’re currently attempting to identify the density conversion factors of
some unique foods in Vietnam in order to analyse 24hr recall data. Is anyone
aware of guidelines or best-practices manual on how to calculate these
densities? We would like to eventually make the data publically available.

 

Many thanks in advance.

 

Jessica Raneri, MSc
Nutritionist,  Research Support Officer

Nutrition and Marketing Diversity Programme, 

 <http://www.bioversityinternational.org/> Bioversity International 
Via dei Tre Denari, 472/a 
00057 Maccarese (Fiumicino) 
Rome, Italy 

 

P Please consider the environment before printing this e-mail

 

 

 

 

  _____  

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