Establish constant masses for an empty container and three samples; calculate ash from the final observed masses.
Food Lab · ash determination
An educational model. It does not replace actual test conditions or safety procedures.
Crude ash and residue
Distinguishing loss from residue
Crude ash is the residue remaining under specified ashing conditions as a percentage of sample mass.
Residue mass is C−A: loaded crucible C minus empty crucible A.
Organic matter is removed and residue remains, but some components may volatilize or change chemical form.
(C−A)/(B−A)×100 is ash; (B−C)/(B−A)×100 is mass loss percentage.
Confirm precharring and cooled constant mass. Educational settings and reference links do not imply full verification of current food-specific official conditions.
Crude ash is not necessarily the original sum of inorganic element masses or a specific mineral content.
An independent educational simulation. Not affiliated with or endorsed by HRD Korea, Q-net or MFDS. Virtual results do not establish food safety or guarantee exam success.
Food Lab · Gravimetric analysis / principles and inquiry
Ash determination guide
Distinguish the empty crucible and sample; calculate the mass fraction of residue after ashing.
How does it work?
Divide residue C−A by sample mass B−A. B−C is mass lost, not the ash numerator.
Key relationship
Ash (%) = (C − A)/(B − A) × 100
Try this investigation
Ash, cool and weigh the empty crucible six times; weigh the sample, prechar, then ash.
Process each of three samples to constant mass; retain the last observed C and all cycle records.
Compare normal records with spattering loss or incomplete ashing stopped after two cycles.
Interpreting your results
Can constant-mass checks be skipped when the residue looks gray-white?
No. Check both mass differences in three consecutive cooled readings, not color alone.
Assumptions and limitations
The food-edu-v1 550°C and virtual times are educational. Volatilization, spattering and chemical changes can affect crude ash. Use tongs for hot crucibles.
