Ash Determination Flashcards
Ash content
Measure of the total amount of minerals present within a food
Mineral content
Measure of the amount of specific inorganic components within a food
Quality
Quality depends on concentration and type
Taste, texture, appearance, stability
Sample prep
Samples of 1-10 grams
Grind and carefully mix solid foods
Dry foods that are high in moisture
Defat high fat sample with solvents
Dry Ashing
High temp furnace (500-600 C)
Water and other materials are vaporized
Organic substances are burned
Ash db
(Mass Ash/Mass Dry Sample) x 100%
Ash wb
(Mass Ash/Mass Wet Sample) x 100%
Dry ashing advantage
Safe
Few reagents
Analyze multiple samples at 1 time
Not labor intensive
Dry ashing disadvantages
Long analysis time
Furnaces are pricey
Loss of volatiles
Interaction between minerals and crucible
Microwave ashing
Initially remove most of the moisture
Convert sample to ash after
Analysis in less than 1 hour
Wet ashing
Used in preparation of samples that will be analyzed for specific minerals
Dried ground sample weighed into flask
Treat with a strong acid
Heat until the organic matter is digested
Wet ashing advantage
Little loss of volatiles
More rapid than dry ashing
Wet ashing disadvantage
Labor intensive
Dangerous chemicals
Low sample throughput
Microwave wet ashing
Accurate results
Quick
Any type of crucible
Low temp plasma ashing
Samples are placed into chamber
Evacuated with vacuum pump
Oxygen pumped in
Less loss of volatiles
