This document describes the process and equipment used to determine the ash/mineral content of food samples through combustion in a crucible. Key steps include weighing the crucible and food sample before and after burning, then calculating the difference in weight to determine ash content. The goal is to burn off all non-ash material. Results from samples of two dog foods showed ash contents of 2.92% for one brand and 3.89% for the other. While a basic method, more accurate results could be obtained using specialized high-temperature furnaces and controlling for weight variations between crucibles and samples.

2. CRUICABLE
PIPECLAYTRIANGLE
TRIPOD
BUNSEN BURNER
FOOD SAMPLE
HEAT PROOF MAT
TONGS

3.  The aim of this experiment is to obtain the
ASH/Mineral content of food samples

4. Obtain equipment
and PPE
Weight crucible
and record weight
Add food sample
to crucible and
weigh again,
record new weight
Light bunsen
burner and place
crucible on top of
pipe clay triangle
Burn till only ASH
remains
Remove crucible
and weigh
Weighting the crucible
twice is necessary as once
the sample has burned
only ASH will remain and it
will be too difficult to
remove from the crucible
at this stage. So
subtracting the individual
crucible weight form the
combined weight will give
the weight on just the food
sample.

5.  Use only small food sample as this will burn
quicker
 Burn times will differ depending on the
sample used due to its content
 Same scales used
 Same oven is used – same temperature
 Individual weights of each crucible taken to
allow for differences

6. 1, Combined weight of crucible and food sample - Original
weight of crucible = Original Food sample weight
2, Combined weight of crucible and food before burning -
combined weight of both after burning =Weight of food
sample after burning
C = CRUCIBLE
FS = FOOD SAMPLE
CWB = COMBINEDWEIGHT BEFORE
CWA = COMBINED WEIGHT AFTER
FSB = FOOD SAMPLE BEFORE
FSA = FOOD SAMPLE AFTER

7. Ash content is the difference between the food sample end weight (obtained from calculation 2 on previous
slide) and original food weight.
Sample Crucible Food sample CWB CWA DIFFERENCE
(CWB/CWA)
DIFFERENCE
(FSB/ FSA)
Bakers
Puppy
16.5G 2.4G 18.54G 16.21G 2.33G 0.07G
Royal
Canin
19.9G 1.8G 21.7G 20.05G 1.73G 0.07G
Ash content as a percentage = Difference between FSB & FSA divided by the Original food sample multiplied by
100
CombinedWeight before – dish weight
Combined weight after - Dish weight x 100
Bakers puppy = 0.07 / 2.4 x 100 = 2.92 %
Royal Canin = 0.07 / 1.8 x 100 = 3.89 5
There is 2.92 % ASH or mineral content in Bakers puppy and 3.89% in royal canin.

8. This is obviously a very basic method, to achieve
more Accurate results professionals would use a
furnace that would burn at extremely high
temperatures for a longer period of time to
ensure absolutely everything that could burn
away had. It may have been beneficial to burn
the same amount of food sample and possibly to
even use the same crucible as these all had some
slight differences in weight.To check how
accurate the results where they could be
compared to those on the back of the food
labels.