this is about the ash estimation and sample preparation for acid insoluble mineral analysis of food sample. in very belief with pictorial form thank you

1. Take fresh sample for the determination.
Ignite the dried material in the dish left after the determination of moisture with the flame of a
burner till charred.
Transfer to a muffle furnace maintained at 550 – 600°C and continue ignition till grey ash is
obtained.
Cool in a desiccator and weigh.
Repeat the process of heating, cooling and weighing at half hour intervals till the difference in
weight in two consecutive weighing’s is less than 1 mg.
Note the lowest weight.
If ash still contains black particles add 2-3 drops of preheated water at 60°C.
Break the ash and evaporate to dryness at 100-110°C. Re-Ash at 550°C. Until ash is white or
slightly grey.
Calculation:
Total ash on dry basis (% by weight) =
(𝑊3−𝑊1)
(𝑊2−𝑊1)
X 100
TOTAL ASH WAS DETERMINED BY AOAC (1986)
METHOD

2. Where,
W3 = Weight in gm of the dish with the ash
W1 = Weight in gm of empty dish
W2 = Weight in gm of the dish with the sample taken for test
SAMPLE Ignition Muffle furnace CALCULATION

3. SAMPLE FOR MINERAL ANALYSIS (acid Insoluble)
After taking weight of ash, cover the dish with watch glass and gently add 40-50ml of 50% dil.
HCl with the help of pipette.
The watch glass is used to prevent spattering.
Heat over a water bath for 30 mins. Remove the cover and rinse.
Continue heating for another 30 mins to dehydrate silica.
Add another 10 ml of HCl (50%) and the water to dissolve soluble salts.
Filter into 100 ml volumetric flask using whatmann number 44 filter paper.
Wash the residue into basein once or twice using dil. HCl and make up vol. to 100 ml with water.
Return the filter paper to the dish ignite, place in muffle furnace for 1 hr. at 450°C, cool and
weigh.
The mineral solution so prepared can be used for further analysis of minerals.

4. WATER BATH
MAKE UP WITH
DW
100 ML READY
SAMPLE FOR
MINERAL ANALYSIS
ANALYSIS