Can I do crude fibre estimation of a defatted sample which I have dried at 105 degrees C after defatting it?
Hi Babita,
I have determined total dietary fibre in legume-based dishes using the total dietary fibre assay kit by Sigma. All of my samples were initially dried at 105 oC and then defatted with petroleum ether, since the fat content was >10%. Following defatting, the samples were dried for another hour at 105 oC. I believe that you should determine the dietary fibre content in your samples and not crude fibre, because crude fibre measurements underestimate the actual dietary fibre in a food. You may also want to see the method that I used by following the link.
https://www.sigmaaldrich.com/content/dam/sigma-aldrich/docs/Sigma/Bulletin/1/tdf100a_tdfc10_en.pdf
Yes Babit you can .In crude fibre analysis you are mainly estimating cellulose and lignin. You can employ an elimination method in defatted samples with digestion with dilute acid and alkali. If the fat content in food material is more than 1% you need to eliminate fat with ether prior to digestion. This temperature wont harm cellulose and lignin since anyway you are using boiling temperatures for acid and alkali digestion.
Then simple answer is, yes. Crude fiber does recommend defatting of the sample before analysis. With your pre-drying step you will determine crude fiber on a dry matter basis. Take a look at the analytical procedure found at: https://www.ankom.com/sites/default/files/document-files/Method_1_Crude_Fiber_A2000.pdf
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