Title of page

Proteins form an important fraction in most foods. In this section you will refresh your knowledge on the structure and function of proteins.

Proteins rich in glutamine, arginine, lysine and asparagine do have a higher nitrogen contents than proteins low in these amino acids.

The nitrogen contents of proteins depends on the amino acid composition.

The nitrogen contents of all amino acids is the same.

Food proteins normally contain more than 30 amino acids. The proteins and amino acids are present in a complex matrix also containing water, fats, carbohydrates and some minor components, all of which might interfere during the analysis of proteins in foods.'

Structure of proteins:

Knowledge on the structure of proteins and amino acids is essential to understand the methods for analysing protein contents in foods which are covered in the next section of this case.

Proteins are polymers of amino acids. Twenty different amino acids occur naturally in proteins (click Learn More for an overview). Their chemical variety comes from the side chain that is attached to the α-carbon. The amino acids are joined head-to-tail in a long chain (polypeptide) which is folded into a three-dimensional structure unique to each type of protein. > http://www.learner.org/

Not right. You have selected a statement that is not true. Note that not all amino acids have the same number of nitrogen atoms.

Not right. There are more statements that are true. Study the structure of the different amino acids carefully.

Right! So the nitrogen contents of proteins depend on their amino acids composition.

Which statements are true?

a
b
c