Determination of Protein Content Using Kjedahl and Titration
Proteins are polymers. They are the source of dietary amino acids and are used for growth and maintenance of living systems. They are costlier sources of energy compared to carbohydrates and fats and hence the human body utilizes proteins mainly for biosynthesis rather than as an energy source, though the energy yield is 5 kcal/g of protein. Twenty different types of amino acids occur naturally in proteins. Proteins differ from each other according to the type, number and sequence of amino acids that make up the polypeptide backbone. As a result they have different molecular structures, nutritional attributes and physiochemical properties. Typically, proteins are used as gelling agents, emulsifiers, foaming agents and thickeners. Many food proteins are enzymes which are capable of enhancing the rate of certain biochemical reactions. These reactions can have either a favorable or detrimental effect on the overall properties of foods. Food analysts are interested in knowing the total concentration, type, molecular structure and functional properties of proteins in foods.
In this experiment, the methods that are used to determined the protein content which is Kjedahl and titration methods. The Kjeldahl method of nitrogen analysis is the worldwide standard for calculating the protein content in a variety of materials from human and animal food, fertilizer, waste water and fossil fuels. This method is an analytical method to quantitatively determine the nitrogen in certain organic compounds. A food is digested with 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. In the Kjedahl method, there are three principles involved which are digestion, neutralization and titration.
The first step is digestion. The sample to be analyzed is...