| ||Updated 2015-08-15|
| Components in Food Composition Databases|
The components in food composition databases are the descriptors (identifiers) that are used to identify the
chemical sustances, compounds or physico-chemical properties to which the reported values relate.
The components are typically defined with a more or less complete
description and are typically held in a simple list or in a more complex
thesaurus (or ontology) in a database or printed form.
The list or thesaurus entry normally includes the descriptor and its corresponding component name, a scope note to define usage of the term and additional information.
A few typical examples of these lists or thesauri ("systems") are in
Several of the listed examples cross-link to other component lists,
e.g. ChEBI links to CAS Numbers and IUPAC names, the EuroFIR Thesaurus
link to ChEBI identifiers and INFOODS food component identifiers, etc.
Although there is an ongoing discussion of which system is best or to
use, it is evident the use of a "system" must match its purpose. As the
different "systems" are constructed for specific and/or different
purposes, the food composition data compiler is often in the situation
that there is a need for applying several of the systems in parallel.
This is especially the cases when the food composition database contains
information from several different component groups, e.g. nutrient,
heavy metals, pesticides, food additives, etc., which is most likely the
case in modern laboratory information management systems (LIMS).
The typical component thesaurus is organised into a hierarchy that uses group headings that are not used to identify components for individual compositional values. A term or group heading may be linked to more than one parent term in the hierarchy
(a poly-hierarchy), e.g. L-Ascorbic acid can be both a naturally
occuring nutient (vitamin) and a food additive (antioxidant).
A component thesaurus also includes descriptors for measurable properties such as density,
pH, edible proportion, etc. so that their values can also be reported using the Value entity.