Dear all
It to clarify any doubts w.r.t. estimating ash and protein in dietary fiber estimatioon.
If we go by protocol you will find we use protease to digest protein and convert it to amino acids and small peptides which are filtered through dried and pre weighed sintered disc cruicbles having celite bed. Hence amount of protein left after this step is very small but that can not be ignored.
Similarly in entire process of dietary fiber estimation we are using buffers (which can increase minerals!! and solublisation of minerals in samples can reduce the minerals!!) hence amount of minerals in residue after digetion by enzymes, precipitation and drying is not the same as was in the sample initially.
Hence it is essential to estimate ash and protein after enzymatic treatments and other steps of dietary fiber estimation. if we will use original protein and ash value it will give erronious results.
One may counter if that is so, we can avoid atleast using protease in dietary fiber estimation, but proteases play vital role in loosening the food matrix and thus helps in compleate extraction of non-fiber components. Moreover, suposidely if one does't uses protease (it will be big deviation from official method) even then we will be loosing soluble proteins to buffers and alcohol and again the ammount of protein will be much less in dietary fiber extraction residue than to initial ammount in sample.
I hope it clarifies the doubts.
Dr. Rakesh Bhardwaj
Senior Scientist (Biochemistry)
Germplasm Evaluation Division
National Bureau of Plant Genetic Resources (NBPGR)
PUSA Campus, New Delhi - 110 012
India
Phone (+91)11-25848074(O),(+91)11-25842495(Fax)
(+91)9560487889 (M), (+91) 9015405449
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On Mon, 5/25/15, Najma Memon <[log in to unmask]> wrote:
Subject: dietary fiber
To: [log in to unmask]
Date: Monday, May 25, 2015, 3:12 AM
Dear
all,
we are working on
determination of dietary fiber by Prosky method. It says
that after enzymatic treatment, weigh the residue and
calculate the difference by subtracting ash and
protein.
Do we need to
determine ash and protein of residue after all enzymatic
treatments or it is fine to subtract protein and ash values
obtained for whole food?
Thank you in
advance.
Dr. Najma
Memon,
Associate
Professor
NCE in Analytical
Chemistry,
University of
Sindh, Jamshoro,
Sindh,
PakistanEditor:
Pakistan Journal of Analytical and Environmental
ChemistryAssociate
Editor: Journal Chemical society of
Pakistan
Tel:
+92(22)9213429
Fax:+92(22)9213431
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