# How is crude protein determined?

## How is crude protein determined?

In animal feeds, crude protein is calculated as mineral nitrogen x 6.25 (the assumption is that proteins of typical animal feeds contain 16% nitrogen in average). The mineral nitrogen value is obtained by the Kjeldahl method, or by a method giving similar results after correction, such as the Dumas method.

### What does the Kjeldahl method measure?

The Kjeldahl method of nitrogen analysis is the worldwide standard for calculating the protein content in a wide variety of materials ranging from human and animal food, fertilizer, waste water and fossil fules.

How is the Kjeldahl method used to determine the amount of protein in a food?

The Kjeldahl method was developed in 1883 by a brewer called Johann Kjeldahl. A food is digested with a strong acid so that it releases nitrogen which can be determined by a suitable titration technique. The amount of protein present is then calculated from the nitrogen concentration of the food.

How do you calculate protein in nitrogen?

On the basis of early determinations, the average nitrogen (N) content of proteins was found to be about 16 percent, which led to use of the calculation N x 6.25 (1/0.16 = 6.25) to convert nitrogen content into protein content.

## What are the applications of Kjeldahl method of protein analysis?

The Kjeldahl method is also used to measure nitrogen in organic and inorganic samples in the chemical industry, the pharmaceutical industry and in environmental samples.

### Why Kjeldahl method is considered as the reference method for protein determination?

The Kjeldahl method is widely used internationally and is still the standard method for comparison against all other methods. Its universality, high precision and good reproducibility have made it the major method for the estimation of protein in foods.

Why Kjeldahl method only measure the quantity of crude protein?

It is usually considered to be the standard method of determining protein concentration. Because the Kjeldahl method does not measure the protein content directly a conversion factor (F) is needed to convert the measured nitrogen concentration to a protein concentration.

What is Kjeldahl nitrogen method?

The Kjeldahl method or Kjeldahl digestion (Danish pronunciation: [ˈkʰelˌtɛˀl]) in analytical chemistry is a method for the quantitative determination of nitrogen contained in organic substances plus the nitrogen contained in the inorganic compounds ammonia and ammonium (NH3/NH4+).

## What is the main advantage of the Kjeldahl method of protein determination?

Advantages. The Kjeldahl method is widely used internationally and is still the standard method for comparison against all other methods. Its universality, high precision and good reproducibility have made it the major method for the estimation of protein in foods.