I have recently adapted the OPA degree of hydrolysis quantification method from Nielsen 2001. I have gotten absorbance readings for standards and hydrolyzed soy proteins that make sense, but I am having trouble calculating the degree of hydrolysis from the absorbance values given the formulas provided in the paper.
Serine-NH2 = ODsample - ODblank/ODstandard - ODblank* 0.9516 meqv/L *0.1 * 100/ X * P
h = (Serine-NH2 - B) / a meqv/ g protein
% DH = h/ htot
My main questions are: Where should the parenthesis go in the first equation? Are the only values I need to input in the second equation the Serine-NH2 and a and B for soy protein? If anyone could provide a resource with a sample calculation that would be much appreciated.
I believe I have worked out the correct equation. The first equation should read:
Serine-NH2 = [(ODsample - ODblank)/(ODstandard - ODblank)]* 0.9516 meqv/L *0.1 * [100/ (X*P)]
Salam
This article may be help you
https://www.ingentaconnect.com/content/aoac/jaoac/2010/00000093/00000005/art00023
Hi Terrence did you use the alpha and beta values proposed by Nielsen too?
Because for alpha then it gives a unit "meqv/g protein" so I don't know if we should calculate alpha according to the gramms of protein we have in the sample... Thank you!
Mariana Ventura, as far as I understand you can use the alpha values in this paper as long as they correspond to your system. I had to find alternate values as I am using different proteins. The units should work out as the quantity of protein you are working in is factored into the initial equation I asked about with the X and P values. Hope that helps
How do you determine the values of alpha and beta values for a new system that uses proteins which are not listed by Nielsen. How are the alpha and beta values estimated or derived. Please help
Dennis Panashe Chakawa and Terrence Dent did either of you find what you were looking for? I am also developing an DH method using the Nielson article and would like double check that I am using the formulas correctly and I am working with protein other than soy and will need different value constants.
Please can someone explain, what is this meqv/gprotein. Why in the equation meqv associated with alpha constant and not in Beta constant.
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