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From:
Ian Unwin <[log in to unmask]>
Reply To:
Ian Unwin <[log in to unmask]>
Date:
Tue, 28 Jan 2014 10:07:18 -0000
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Dear Susanne and Anders

 

In September, I prepared a presentation on organic acids and polyols that
may be a useful starting point for discussing the components that might
contribute to the totals used in energy calculation.  It is online at:

http://www.eurofir.org/wp-content/uploads/thesauri/discussion/2013/OrgAcids
<http://www.eurofir.org/wp-content/uploads/thesauri/discussion/2013/OrgAcids
&Polyols-Sep2013.pdf> &Polyols-Sep2013.pdf

This includes some suggestions on which acids might be included in Total
Organic Acids (tagname OA), if this is intended to represent the total
energy-contributing “organic acids”.  Incidentally, as shown on slide 3, the
tagname for propionic acid is PROPAC.  Propanoic acid (the IUPAC name)
should be added as a synonym in both the INFOODS tagname list and the
EuroFIR Component Thesaurus.

 

F4:0 occurs in triglycerides in dairy products and seems the natural lower
limit for the definition of “fatty acids”.  On the other hand, the term
“organic acid” includes various other carboxylic acids (and their salts? –
as these presumably also contribute energy) that occur naturally, such as
substituted short chain monocarboxylic acids, dicarboxylic acids, etc., as
well as some food additives.  However, as Anders indicates, there is no
definition of “organic acid” that is well formulated; any compositional
value for Total Organic Acids (tagname OA) needs to be documented in respect
of the contributing acids.

 

With regard to Chebi, EuroFIR is not currently inputting information to the
database or to its curators.  Chebi provides a collection of information on
the structure, nomenclature, identifiers and chemical relationships of
Chemical Entities of Biological Interest.  It supplements the basic
information available in the EuroFIR Component Thesaurus, which as you know
contains links to the corresponding Chebi entries.  Chebi also connects to
the citation network that is part of the Europe PubMed Central service,
formerly CiteXplore.  Note that the definitions for component groups in
Chebi do not necessarily agree with food composition conventions.  For
example, the term “long-chain fatty acid” is described as “A fatty acid with
a chain length ranging from C13 to C22”.  However, Chebi is an important
source of information on food components that it would be impractical to
maintain as part of the EuroFIR Component Thesaurus or the INFOODS tagname
documentation.

 

Hope these comments are useful,

 

Best wishes

Ian

 

Ian D Unwin Food Information Consultancy

 <mailto:[log in to unmask]> [log in to unmask]

 

 

From: Food Composition Discussion Group
[mailto:[log in to unmask]] On Behalf Of Anders Møller
Sent: 24 January 2014 11:50
To: [log in to unmask]
Subject: Re: energy factor for acetic acid and other organic or fatty acids

 

Dear Susanne,

 

We may be “on dangerous grounds” here J

Please note that we are trying to be very precise in our definitions (but
with some overlaps and maybe with wrong terminology)  – which is fine –
however, we need to keep in mind that the energy factors used in the
different systems are very, very rough averages.

As Rakesh indicated, all compounds differ in their measure for heat of
combustions, the longer the chain the larger the heat of combustion (energy
factor).

In addition, some Chebi definitions may come from us (EuroFIR) – Ian Unwin
will know that.

 

I think that you should stick to the IUPAC definitions for fatty acids
(http://goldbook.iupac.org/F02330.html), which says

“Aliphatic monocarboxylic acids derived from or contained in esterified form
in an animal or vegetable fat, oil or wax. Natural fatty acids commonly have
a chain of 4 to 28 carbons (usually unbranched and even-numbered), which may
be saturated or unsaturated. By extension, the term is sometimes used to
embrace all acyclic aliphatic  <http://goldbook.iupac.org/C00852.html>
carboxylic acids.”

 

The definition’s extension include some of the “organic acids”, the very
short chain carboxylic acids (F2:0 and F3:0), but there are quite a lot of
other “organic acids” (carboxylic acids), which are not necessarily “usually
unbranched and even-numbered”.

Please also note that the term “organic acid” is not defined in the IUPAC
system – the correct term is carboxylic acid - I may get into trouble here J

 

In the explanation of the Atwater system  by Merrill and Watt, a few
“organic acids” are listed (USDA AH 74, one of the USDA classics,
http://www.ars.usda.gov/SP2UserFiles/Place/12354500/Data/Classics/ah74.pdf):

 

cid:image001.png@01CF1B44.0305C6B0

 

and we could add other “organic acids” like propionic/propanoic acid, sorbic
acid, etc., commonly appearing in foods both naturally and as food
additives.

And yes, you see vitamin C (ascorbic acid) among the “organic acids”, and if
you want to be very precise, you should count the energy from the ascorbic
acid too.

But “being precise” and  “energy calculation” is a contradiction J

 

Be pragmatic:

fatty acids are carboxylic acids with “a chain of 4 to 28 carbons” - fat
energy factor 37kJ/g (9 kcal/g) in EU regulation – the rest – among these
F2:0 and F3:0 (although pion means fat in Greek (from Wikipedia)) - are
currently “organic acids” with energy factor 13 kJ/g (3 kcal/g) in EU
regulation.

 

All the best,

Anders  

 

 

Anders Møller

Danish Food Informatics

Borgediget 12

DK-4000 Roskilde, Denmark

 

Websites:  Danish Food Informatics (http://www.danfood.info
<http://www.danfood.info/> )

                      SciName Finder™ (http://www.sciname.info
<http://www.sciname.info/> )

                      LanguaL™ (http://www.langual.org
<http://www.langual.org/> )

                      

 

 

From: Food Composition Discussion Group
[mailto:[log in to unmask]] On Behalf Of Susanne
Westenbrink
Sent: 24 January 2014 10:48
To: [log in to unmask]
Subject: energy factor for acetic acid and other organic or fatty acids

 

Dear all, 

Many thanks to Esther, Erling, Anders, Rakesh and Paul for replying to our
question. This has helped to get things clearer. 
We do use the European legislation to calculate energy in foods, which means
that we apply specific factors for e.g. organic acids and polyols. My main
question was about where to put acetic acid, as this compount is both
indicated as organic acid and fatty acid F2;0. So far we only have zero
values in our database, so any change will not have an inpact on energy
values. When adding an acetic acid value for vinegar and related foods we
need to apply the correct approach. 

From the discussion we have concluded that acetic acid (F2:0) must be
treated as an organic acid and not as fatty acid. Acetic acid it is a
building block of natural fatty acids but, unlike them, does not occur in
natural triglycerides (Chebi). And with the usual analytical methods, they
do not turn up in the value for fat/fatty acids. You need special analytical
methods to determine the amount of organic acids, as indicated by Anders. In
the NEVO database we will attribute ~3 kcal /g organic acids, and not
include acetic acid in the sum of saturated fatty acids. 

To continue the discussion: 
Following this, the next question pops up for other short chain fatty
acids/organic acids. On internet
<http://www.cyberlipid.org/fa/acid0001.htm#1>
(http://www.cyberlipid.org/fa/acid0001.htm#1) I found information that
stated that short chain fatty acids (below 4- 6 Carbons) should/could be
regarded as organic acids. Up to 6 (or 4) carbon atoms, organic acids are
considered "short-chain organic acids", they have substantial solubility in
water. Furthermore, they do not behave physiologically like other fatty
acids since they are more rapidly digested and absorbed in the intestinal
tract and have unique properties in regulating sodium and water absorption
through the mucosal epithelium. Biochemically, they are more closely related
to carbohydrates than to fats. However I am not sure how reliable this
website is. 

Propanoic acid is listed as organic acid in the EuroFIR component thesaurus
and as fatty acid by Chebi (I could not find it in the INFOODS tagnames). Is
this measured through fatty acid analyses methods? Is it a relevant
component in food?  If available in a food comp database, should 3 or 9 kcal
be calculated for energy? 
What is your opinion on this? 

Butyric acid (F4:0) is classified as fatty acid in both the EuroFIR
component thesaurus and the Chebi database. I know this is measured in fatty
acid analyses, we have several values. My conclusion would be that F4:0 must
be treated as a fatty acid, yielding ~ 9 kcal/g. (This what we have been
doing all the time). 
Do you agree on this conclusion for  butyric acid? 


EuroFIR component thesaurus: 
Acetic acid classified as organic acid, with synonym F2;0 
Propanoic acid: classified as organic acid with synonym F3;0 


Butyric acid classified as saturated fatty acids (F4:0)


Chebi database: 


Acetic acid F2:0 Chebi 15366: building block of natural fatty acids which,
unlike them, does not occur in natural triglycerides. 
Propanoic acid F3:0 chebi 30768: The smallest H(CH2)nCOOH acid that exhibits
the properties of the other fatty cids. 
Butyric acid F4:0 Chebi 30772: four carbon straight-chain saturated fatty
acid 

Looking forward to your reaction, 
with best wishes, 
Susanne and Martine


Susanne Westenbrink
Rijksinstituut voor Volksgezondheid en Milieu (RIVM) / National Institute
for Public Health and the Environment
Centrum voor Voeding, Preventie en Zorg / Centre for Nutrition, Prevention
and Health Services
PO Box 1
3720 BA Bilthoven
The Netherlands
tel:  +31 (0) 30 274 2448
fax: +31 (0) 30 274 4466
e-mail: [log in to unmask]
for more information on  the Dutch food composition database see 
 <http://www.rivm.nl/nevo> http://www.rivm.nl/nevo
 <http://nevo-online.rivm.nl/> http://nevo-online.rivm.nl



 <http://www.rivm.nl/Proclaimer> 
Proclaimer RIVM http://www.rivm.nl/Proclaimer 

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