MadSci Network: Biochemistry
Query:

Re: How can you test for iron in beef? How do you do the test?

Date: Wed Jul 7 13:42:28 1999
Posted By: Carl Custer, Staff, Office Public Health & Science, Scientific Research Oversight Staff , USDA FSIS OPHS
Area of science: Biochemistry
ID: 930631908.Bc
Message:

There are several official methods for determining iron in food.  
All of these methods use atomic absorption spectrophotometry on ashed 
samples.  A quick search in a scientific literature base would reveal 
these.   However, the AOAC methods include:  
AOAC 968.08 Iron in feeds
AOAC 990.05 Iron in Oil & fat 
And bioavailability of iron AOAC 974.31
Other methods are mentioned her:   http://www.nal.usda.gov/fnic/foodcomp/Data/SR11/sr11_doc.html
MINERALS: Calcium, iron, magnesium, zinc, copper, and manganese were 
determined by atomic
absorption and plasma emission spectrophotometry. Newer values were 
generally determined by
Inductive Coupled Plasma (ICP). 

Also, here are a few references that cite the methods they used.
AU:   Torelm,-I. 
TI:   Interlaboratory variance in analysis of major nutrients in foods.  
SO:   J-food-compos-anal. Orlando, Fla. : Academic Press. Mar/June 1994. 
v. 7 () p. 2-22.  
DE:   food-analysis. variance-. nutrient-content. food-composition. 
laboratory-methods.  CC:   Q500 
AB:   Variability in analytical results arises through different 
laboratories analyzing a material.  To investigate the magnitude of this 
variance in nutrient analysis in foods, data from annual proficiency tests 
at 20-35 laboratories are compiled.  The test materials are dry powders of 
gruel and dairy products and canned or frozen meat and meat products, and 
the nutrients are moisture, ash, nitrogen, fat, phosphorus, calcium, and 
iron.  The laboratories have used their own routine methods of analysis.  
For all nutrients, plots of the inter- and intralaboratory standard 
deviations in the proficiency tests versus the nutrient concentration of 
the test materials are presented, as are the regression lines and 
equations for the relations.  The magnitude of the inter- and 
intralaboratory standard deviations at the concentration of interest can 
thus be evaluated by consulting the corresponding regression line. In 
moisture analysis, a curved relation of standard deviation to 
concentration seems to be relevant.  For the other nutrients a linear 
relation is found.  In fat analysis, in the investigated range of 
concentration, greater standard deviations are found when analyzing dry 
materials than those found when analyzing moist.   
Record 2 of 4 - AGRICOLA 1992-1997 
 
AU:   Rhee,-K.S.; Ziprin,-Y.A. 
TI:   Modification of the Schricker nonheme iron method to minimize 
pigment effects for red meats.  
SO:   J-Food-Sci. Chicago, Ill. : Institute of Food Technologists. 
Sept/Oct 1987. v. 52 (5) p. 1174-1176.  DE:   meat-. food-composition. 
iron-. pigments-. analytical-methods.  CC:   Q502 
 
AU:   Oellingrath,-I.M.; Slinde,-E. 
TI:   Color, pigment and iron content of meat loaves with blood, blood 
emulsion, or mechanically deboned meat added.  
SO:   J-Food-Sci. Chicago, Ill. : Institute of Food Technologists. Nov/Dec 
1985. v. 50 (6) p. 1551-1555. ill., charts. 
DE:   meat-products. food-quality. color-. blood-. iron-. mechanically-
deboned-meat. hemoglobin-. myoglobin-. food-acceptability.  CC:   Q502 
AB:   Abstract: Meat loaves containing mechanically-deboned meat (MDM) and 
small amounts of blood and blood emulsion were produced, and the effect of 
the pigment and iron (Fe) content of the raw materials on the color of the 
heated products was quantitatively determined. Meat minces containing 
added blood gave lighter meat loaves on heating than meat minces 
containing added blood emulsion or MDM; this was observed even when equal 
amounts of extractable hemoglobin and myoglobin were present in the 
minces. When the same amount of Fe was present, meat minces with added 
blood and MDM produced lighter-colored meat loaves on heating than meat 
minces having added blood emulsion. Definitive spectrometric and 
chromatographic analytical methods were employed.(wz).  




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