Amino Acids in Foods, Feeds, and Nutrition

Abstract

Amino acids are organic compounds which are essential for all living organisms because they play a double role in cells, either connected to each other as building blocks of proteins or free as intermediates in metabolism. This article summarizes the relationship between the structure of the different amino acids and their function and metabolism in living organisms. It deals with the importance of essential amino acids in human and animal nutrition, based on their availability, and their role as taste‐active compounds in food. The amino acid profile and digestibility are important determinants of the quality of dietary proteins. All methods available for the estimation of the nutritional value of food and feed and their amino acids bioavailability are based on the analysis of amino acids, especially the essential ones, or those that are indicators of the nutritional value (reactive lysine or methionine), or possible damages derived from food processing or preservation. Thus, the main methodologies for the analysis of total and free amino acids, which include extraction procedures, deproteinization, protein hydrolysis, derivatization, separation, and quantification of amino acids by means of liquid or gas chromatography or capillary electrophoresis, are discussed.