the carotenoid content of foods with special reference

Data reported in existing food composition tables were carefully examined as they are
often not original analytical values but imputed, calculated or borrowed from other
sources This is particularly so for data in tables from developing Countries Only
original analytical values and values calculated from these were considered acceptable
for inclusion in the database Where possible, borrowed valIis were traced hack to
their source and, it appropriate, included lowever, many tables do not provide
adequate reference to the source of data A visit was made to the Nutrition Section of
the Ministry of Agriculture, Fisherie,. and Food in London in order to determine
those values in the United Kingdom food composition tables which were derived from
analyses by the UK Laboratory of the Government Chemist For other data, where
informaton iP the publishCd or unpublished material was limited, authors were asked
t, provide additional Ietails, uIsual ly on the analytical method used
Criteria for inclusion of data
As already stated in the Introduction, data presented in the recent publication from
the USDA Nutrient Composition laboratory database (97) was not considered foi
inclsion ais this \kould result In unnecessary duplication of effort even though some
data from de\ eloplng con ntries is InclIded in that database (for example reference
99) From dhe work undertaken, data wkere ,elected from 71 published and 15
uilpublished sources (see Chapters 3 and 7)
Most attention has been given to the carotenoid content ot vegetables and fruits In
addition, there is some data hor meat, fish, fats, eggs, cereals and dairy products.
Since some of the variation in tile reported composition of foods may be attributable
to such factors as varietv, groing conditions and time of harvest, data have not been
aggregated to any great extent It is thought that thils l id make the dat'base more
useful to investigators throughout the ,\)rld Where data have been aggregated (for
example, for different varieties or time, of harvest), this has been denoted in the
database and in the table presented in Chapter 3 )ata for cooked foods have been
included when they meet the e alKnation criteria
Data evaluation
In order to evaluate the quality of the data reported in publications, it is necessary to
establish criteria Data quality depends to a large extent on sampling procedure and
analytical methodology Over the last two decades wth the introduction of highperformance
liqu1id chromatography (IPLC), it has become easier to identify and
quantify many analytes including carotenoid,, However, equipment, reagents and
maintenance are otten too costly and too di fticult to arrange for many laboratories in
deveioping C¢ountries Thus other methods such as ,pectrophotornetry often combined
with open colun chromatography (OCC) and are still commonly used in many
countries for analyzing the carotenoid content of foods
4