Harmonization of methods for analysis of cholesterol oxides in foods--the first portion of a long road toward standardization: interlaboratory study.
A compilation of literature data on the content of cholesterol oxidation products (COP) in various food products and in blood demonstrates a large variation in content in products or tissues of very similar nature when analyzed in different laboratories according to a large number of methods. The lack of validated, internationally recognized methodology with published accuracy and precision has so far hindered such assessments. Hence an interlaboratory comparision of methodologies of COP analysis was undertaken on egg yolk powders (EYP), whole milk powders (WMP), skim milk powders (SMP), and lard (L). Each product type had one fresh sample (low) and one aged (high) in COP contents. A total of 17 sets of results on WMP, 15 on SMP and EYP, and 13 on L were compared. Overall results (mg/kg sample) varied extensively: Fresh EYP 0.72-265, aged EYP 2.51-361; fresh WMP 0.02-18.1, aged WMP 0.02-26.9; fresh SMP 0.02-6.51, aged SMP <0.01-6.51; fresh L 0.18-97, aged L 4.15-452. Some results were questioned, viz., those from laboratories not indicating substantial differences between samples "low" and "high" in total COP. Others were excluded because of lack of verification of identity of gas chromatographic peaks by mass spectrometry. Then a more narrow range of core results (mg/kg sample) was observed: Fresh EYP 5.69-29.5 sample, aged EYP 11.8-79.0; fresh WMP 0.12-1.76, aged WMP 1.17-13.7; fresh SMP <0.30-<1.21, aged SMP 0.30-2.26; fresh L 0.18-5.07, aged L 94.4-231. At a workshop discussing the results, numerous recommendations were made toward more reliable methodology for determination of COP in foods.
Appelqvist
Lars-Ake
LA
Swedish University of Agricultural Sciences, Department of Food Science, PO Box 7051, SE-750 07 Uppsala, Sweden. Lars-Ake.Appelqvist@lmv.slu.se
Addis
Paul
P
Björkhem
Ingemar
I
Bosset
Jacques Olivier
JO
Caboni
Maria Fiorenza
MF
Dutta
Paresh
P
Grandgirard
Andre
A
Guardiola
Fransesc
F
Hau
Lung-Bin
LB
Nielsen
Jacob Holm
JH
Hugget
Antony
A
Hwang
Lucy Sun
LS
Kumpulainen
Jorma
J
McCluskey
Sinead
S
Ohshima
Toshiaki
T
Przbylski
Roman
R
Sevanian
Alex
A
Yan
Pearlly
P
D002784:Cholesterol / Q000378:metabolism*; D005504:Food Analysis / Q000592:standards*; D007753:Laboratories; D008055:Lipids / Q000032:analysis; D010087:Oxides / Q000032:analysis
D008055:Lipids; D010087:Oxides; D002784:Cholesterol