Component ranges and limits

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Component numerical ranges

The total for a set of related components such as fatty acids may be defined as a numerical range, for example in terms of the length of the carbon chain.  Thus the existing EuroFIR term for a total of short-chain saturated fatty acids is "fatty acids 4:0 – 10:0", code F4-10:0.  In INFOODS tagnames, the hyphen (-) is used at the end of tagnames to indicate that unknown or mixed methods were used to determine the compositional value, but method information is not incorporated into the EuroFIR component identifier. 

In discussions on the harmonisation of component codes, INFOODS have suggested that identifiers for component ranges should specify the components at each end of the range, separated by the string "_TO_", e.g. "fatty acids 4:0 – 10:0" would have the tagname F4D0_TO_F10D0.  However, if the use of an internal hyphen were to be agreed, this would provide more concise codes and make clear the part of the identifier forming the range, and indeed allow double ranges such as F20-24D2-3 (with the corresponding EuroFIR identifier F20-24:2-3).

Component numerical limits

Similarly, a set of related components may be defined by a numerical limit, for example saturated fatty acids with chains longer or shorter than C18.  The first EuroFIR discussion in this area (in terms of monounsaturated C18 isomers, e.g. “F18:1 (n>12)t”) is reported on page 13 of EuroFIR NoE deliverable D1.8.33.  This proposed use of the character "A" to represent ‘and Above’ and "B" for ‘and Below’, thus specifying the start of the range.  For example, the set of fatty acids represented by ">C18 saturated" would have the EuroFIR identifier F19A:0 ( "C19 and Above"), which is perhaps clearer than using F18A:0 to represent "Above C18".  INFOODS have proposed F19D0_GT (corresponding to F19:0_GT) for ">C18 saturated", but the acronym GT is conventionally used for "greater than", so again there is potential for misunderstanding.  The conventional acronym for "greater than or equal to" is GE and this might be the better option, i.e. F19D0_GE and F19:0_GE.  Analogous arguments apply to the "less than" case, for which the corresponding acronyms are LT and LE.  Thus it is proposed that "<C18 saturated" is represented by the codes F17D0_LE and F17:0_LE.

Please post your comments to the alternative proposals for identifying component totals that use ranges or limits as soon as possible so that EuroFIR can discuss the issues further with INFOODS and finalise the rules as part of the work on updates to the Component Thesaurus.

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