Meaning and mechanism
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.
Relationships and conditions
(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.
What to observe in the food simulation
Divide residue C−A by sample mass B−A. B−C is mass lost, not the ash numerator.
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.
Key relationships and symbols
Ash (%) = (C − A)/(B − A) × 100
| Symbol | Meaning | Unit |
|---|---|---|
| A | Mass of empty crucible at constant mass | g |
| B | Mass including crucible before ashing | g |
| C | Cooled mass including crucible after ashing | g |
Worked food-analysis example
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.
Common misconceptions
- Crude ash is not necessarily the original sum of inorganic element masses or a specific mineral content.