Unformatted text preview: © E.Garcia 2010 FST 1 – Main topics – Lecture 06 Protein reactions Proteins Denaturation: ‐protein unfolds (loss of the three‐dimensional structure)
Proteins help build and maintain body structures, such as muscles, bone, skin, hair, nails, etc. Other functions of proteins in the body are as carriers, as enzymes, antibodies, among many others. Food proteins are source of essential amino acids (see below). Proteins can also be used to provide energy (4 kcal/g). u
In foods, proteins contribute to physical properties of foods, such as in gels, ‐proteins can be denatured by heat, acids, detergents, etc ‐primary sequence is maintained foams, cheese curd, bread dough, and others, such as meat substitutes. ‐protein properties are significantly altered Proteins are organic molecules composed of AMINO ACIDS. Amino acids are Coagulation: ‐ aggregation of denatured protein the building blocks of proteins; all contain C, H, O, and N. Some contain S Ex.: Egg white proteins coagulate during cooking. (sulfur). ◆ Most proteins contain about 20 different amino acids ◆ Based on their nutritional role, amino acids are classified as essential (8 amino acids) and nonessential essential (12 amino acids) Essential amino acids must be obtained from foods (cannot be made by the body) Amino Acids basic structure H I H2N‐C‐COOH I amino group R carboxyl group The R group is called side group. It differs in the 20 amino acids commonly found in proteins. Protein amino acids are joined together by peptide bonds. Protein chains are linear polymers; most are composed of less than 2,000 amino acids. Proteins have up to 4 levels of structure: Primary, Secondary, Tertiary and Quaternary. The Primary structure is the linear sequence of amino acids; it determines the folding of a protein. Note: Topics on Proteins to be completed after MT‐1 Readings 1. McGee p.805‐808 (Proteins) 2. McGee p.691 (Marshmallows) 3. McGee p. 521 (The Basic Structure of Dough, Batters, and Products; Gluten) ...
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- Winter '10
- Amino Acids, essential amino acids