getpdf

Spectrophotometric Method for Determination of Tryptophan in Protein Hydrolysates

Jiaoyan Ren, Mouming Zhao*, Jinshui Wang, Chun Cui and Bao Yang


College of Light Industry and Food Science, South China University of Technology, Guangzhou 510640, Guangdong, PR China


Article history:

Received January 9, 2006

Accepted July 17, 2006


Key words:

protein hydrolysates, tryptophan, spectrophotometry, diphenylamine


Summary:

A novel spectrophotometric method for determination of tryptophan content in protein hydrolysates has been developed. The reagent used is diphenylamine sulphonate which is oxidised to diphenylbenzidine sulphonic acid after reacting with sodium nitrite in the sulphuric acid medium. The unstable oxidation product reacts quickly with sodium nitrite to produce a diazotized intermediate. When the diazotized intermediate is coupled with tryptophan, a pink colour product is developed, which is stable for at least 1 h at the ambient temperature. This coloured product has the absorption maximum at 522 nm and the molar absorptivity is 0.89·104 L/(mol·cm). Beer’s law is obeyed in the range of 0.30–12 µg/mL. The method is applied for the analysis of tryptophan content in grass carp protein hydrolysates. Moreover, it is compared with the reversed-phase high-performance liquid chromatography analysis. There is no significant (p<0.05) difference between the two results. The method is simple, rapid and accurate compared to the previous methods.

 


*Corresponding author:         femmzhao@scut.edu.cn
                                              ++86 208 711 39 14
                                              ++86 208 711 39 14



Search FTB


Follow us


 facebook 1 twitter bird_icon LI In Bug

 

QR Code


qrcode

We use cookies to improve our website and your experience when using it. Cookies used for the essential operation of the site have already been set. To find out more about the cookies we use and how to delete them, see our privacy policy.

I accept cookies from this site.

EU Cookie Directive Module Information