LimsPulse
Food & proximate analysis

Crude fibre analyser

Boils a defatted sample first in dilute acid and then in dilute alkali, filters it in fritted crucibles, and weighs the dried and ashed residue. The organic residue is reported as crude fibre.

  • Animal feed
  • Food & beverage
  • Agriculture
  • Spices
  • Academic research
Illustration of Crude fibre analyser
LEARN & PRACTICE

Test your Fibre analyser knowledge

Multiple-choice questions

Pick an answer to see whether you are right and why.

  1. Q1. Crude fibre is the organic residue left after boiling the sample in:

    basic

  2. Q2. Why is the residue ashed after drying and weighing?

    basic

  3. Q3. Compared with dietary fibre, crude fibre for the same food is usually:

    basic

  4. Q4. Why must reagent strength and boiling time follow the standard exactly?

    intermediate

  5. Q5. Dried residue + crucible weighs 31.2846 g, and after ashing 31.2047 g. The sample weighed 2.0058 g. Crude fibre is:

    intermediate

  6. Q6. Filtration through the crucible frit is very slow. Which is the most likely cause?

    intermediate

  7. Q7. Why are high-fat samples defatted before the acid boil?

    advanced

Viva questions

Think of your answer first, then open it to compare.

  1. 1. Outline the steps of a crude fibre determination on a fibre analyser.

    Grind and weigh the sample into a fritted crucible; defat if needed; boil 30 min in dilute sulphuric acid, filter and wash; boil 30 min in dilute sodium hydroxide, filter and wash; rinse with acetone; dry and weigh; ash at about 500–550 °C and weigh. The loss on ashing as a percentage of the sample is crude fibre.

  2. 2. When would you report dietary fibre instead of crude fibre?

    For nutrition labelling and health claims, regulations normally require dietary fibre measured by an enzymatic-gravimetric method. Crude fibre is reported when a product standard, feed specification or older regulation asks for it.

  3. 3. How do you check the performance of a crude fibre analyser?

    Run a reference or proficiency test material with an assigned crude fibre value through the whole procedure, in duplicate, with a blank crucible. The mean must fall within the assigned range and duplicates within repeatability. Also verify reagent strengths and the drying oven and furnace temperatures.

In LimsPulse · Calibration Management

Keep every Fibre analyser in control: usage logs, calibration and maintenance schedules, and automatic blocking of overdue instruments.

See how