How to Determine Crude Fiber in Feed Mill Quality Control Lab?

Crude Fiber Test is one of the most important test in feed quality control laboratory. So let’s first find out-

What is Crude Fiber?

There are basically two types of fiber โ€“

  1. Dietary fiber  
  2. Crude fiber

Of these, dietary fiber is all types of digestible-indigestible or soluble-insoluble or digestible-indigestible fiber. Crude fiber, on the other hand, is a type of dietary fiber that is largely indigestible or indigestible or insoluble fiber such as cellulose, pentosone, lignin, etc. Basically, the amount of indigestible fiber that remains after digesting the sample between acid and alkali is crude fiber. That is, “All crude fiber is dietary fiber; But not all dietary fiber is crude fiber! โ€

Lab Test – Crude Fiber

Necessary equipment and chemicals
  • Samples
  • Blender machine
  • Analytical balance
  • Heater and steer machine
  • Glass disorder
  • Muslin cloth
  • Plastic jars
  • Crucible
  • Hot air oven
  • Desiccator
  • Sulfuric acid solution (1.25%) – 200 ml
  • Sodium hydroxide solution (1.25%) – 200 ml
Solution Preparation:
  • Preparation of 1.25% sulfuric acid solution: Mix 1.8 ml sulfuric acid well in 1 liter of distilled water to make 1.25% sulfuric acid solution.
  • 1.25% Sodium Hydroxide Preparation: 1.25% sodium hydroxide solution should be prepared by mixing 12.5 g of sodium hydroxide well in 1 liter of distilled water.

Crude Fiber Test method:

  1. The first sample to be tested is to be finely grinded in a blender machine and measured with a sample analytical balance of 2 – 2.5 grams per 500 ml.
  2. Then add 200 ml 1.25% sulfuric acid to the beaker and hit.
  3. Then the heater should be turned off when the solution comes close to 200 ml to 150 ml.
  4. After that, the sample has to be cut with a muslin cloth and only the sample has to be collected and then the sample has to be taken again.
  5. Then add 200 ml 1.25% sodium hydroxide to that beaker and hit again.
  6. The heater should then be turned off when the solution reaches 200 ml to 150 ml.
  7. Then the sample should be cut with a muslin cloth and just collected the sample and taken to a pre-weighed crucible.
  8. Then the crucible with the sample should be heated in the oven at 135 degree Celsius for 2 – 2.5 hours, cooled in desiccator for 30 minutes and then weighed again according to the formula.
  9. Calculation: Crude Fiber = {(Dry wt. With Crucible) – (Crucible wt.) / Sample weight} x 100%

(In the next article I will discuss on ” How to Determine Crude Fat or Ether Extract or EE Test”)

Dr. Srabon Hasan Sajal



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