Proteins percent nitrogen

Standard method of estimating percent protein from nitrogen content (% N). 

Table B1.2.1 Conversion Factors from Percent Nitrogen to Percent Total Protein for Various Commodities and Their Products...

A nitrogen-to-protein conversion factor (N-factor) of 6.25 is commonly used for animal feeds and other materials. The practice of using 6.25 as an V-factor is based on an incorrect assumption that protein in a given material contains 16 percent nitrogen (100/16 = 6.25).126... 

Protein Determine as directed under Nitrogen Determination, Appendix IIIC, using a 0.25-g sample. Percent nitrogen, N x 6.25, gives the percent of protein in the sample. 

Assay (as Protein) Determine the percent nitrogen as directed under Nitrogen Determination, Appendix IIIC, or by the Protein Nitrogen Combustion Method, AOAC 992.23 or AOCS Ba 4e-93. The percent protein equals percent N x 5.7 and is calculated to exclude added vitamins, minerals, amino acids, and food additives. 

Assay Determine the percent nitrogen as directed under Nitrogen Determination, Appendix mC, and multiply by 6.25 to obtain the percent protein. 

Proteins have high molar masses, ranging from about 5000 g to 1 X 10 g, and yet the percent composition by mass of the elements in proteins is remarkably constant carbon, 50 to 55 percent hydrogen, 7 percent oxygen, 23 percent nitrogen, 16 percent and sulfur, 1 percent. 

What percent nitrogen is contained m a typical protein ... 

Fig, A-21. An automated analysis of digested samples for percent nitrogen or crude protein. (Courtesy, C.W. Cehrke, University of Missouri)... 

PER) was modified in several respects. The diets were calculated on a 10 percent protein level rather than on an isonitrogenous basis. This was done because the nitrogen factors of the various blend components varied appreciably from the 6.25 nitrogen factor assumed in the AOAC procedure. A composite nitrogen factor for each blend was calculated from analytical results by dividing the total amino acid content by the nitrogen content. In this manner,... 

In the net protein ratio (NPR) calculation (17), 15-day growth and protein intake data of animals on the PER diets were used. Nitrogen digestibility (percent of nitrogen intake absorbed) was determined on each animal on pooled data from the 8th through the 15th day of the PER test. 

Titrate the solution in the receiving vessel with the standardized 0.01 N NaOH until there is a color change from pink to light yellow. Calculate the percent protein in the sample as follows. A factor (F) is used to convert the weight of nitrogen to the weight of protein. 

The total nitrogen of orange juices was found to increase with the maturity of the fruit and ranged between. 068 to. 120 g per 100 ml (30). The actual protein values obtained by Clements (31) were about 20 percent of the acetone powder. Nearly 30 percent of the alcohol-insoluble solids of juice and about 20 percent of that of vesicular pulp were found to be protein as determined by the Kjeldahl procedure (32). These values are the actual protein that was precipitated by alcohol and are only a fraction of the total protein values usually reported for orange juice (8). The main source of proteins in citrus juice is probably in the form of enzymes and the plastids. At least 47 different enzymes have been reported to occur in citrus fruits (33). Citrus fruits also contain several phenolic amines (34), some of which such as syn-epherine, may have physiological importance (35). 

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