proteins - home ec

• The basic chemical structure of an amino acid includes a carboxyl group, an amino group, and a central carbon atom with various side chains attached.
• An essential amino acid cannot be manufactured in the body and must be obtained from food sources such as Valine, Lysine, and Leucine.
• Gluten, Myosin, and Albumin are examples of proteins found in food sources like wheat, meat fibres, and eggs respectively.
• Consumer trends in meat consumption suggest that people are becoming more conscious of the health benefits of plant-based proteins and are reducing their meat intake.
• Two proteins present in meat are Myosin and Gluten.
• High biological protein and essential amino acid are key factors to consider when purchasing protein foods.
• Protein can be denatured through the application of heat, which causes coagulation, and through the application of acids, which lower pH.
• Beans on toast is an example of proteins supplementing or complenamenting each other.
• Beans are high in lysine but low in methionine.
• Bread (Wheat) is low in lysine but high in methionine.
• A peptide bond forms when amino acids join together, involving the loss of a water molecule in a condensation reaction.
• The NH2 group (alkaline) of one amino acid reacts with the COOH group (acidic) of another amino acid.
• The NH2 group loses a hydrogen atom and the COOH group loses an OH group.
• The hydrogen atom and the OH group join together to form a molecule of water, resulting in a CONH bond.
• Two amino acids join to form a dipeptide (one bond) and many amino acids join to form a polypeptide (many bonds).
• The main type of protein found in fish is Myosin, in eggs is Albumin, and in wheat is Gluten.
• Deamination is the process of using protein as a source of energy.
• Excess protein not required for growth and repair is deaminated in the liver.
• The NH2 group is removed, converted to ammonia and then urea and is excreted by the kidneys.
• The COOH group is oxidised to produce heat and energy.
• Casein is found in cheese, Actin in fish, and Albumin in eggs.
• Amino acids are the building blocks of protein.
• Essential amino acids cannot be manufactured in the body, they must be obtained from food examples include Valine, Lysine, and Leucine.
• Non-essential amino acids can be manufactured in the body for example Glycine, Serine, and Alanine.
• A peptide bond forms when amino acids join together, this reaction involves the loss of a water molecule, it's a condensation reaction.
• The NH2 group (alkaline) of one amino acid reacts with the COOH group (acidic) of another amino acid.
• The NH2 group loses a hydrogen atom, the COOH group loses an OH group, the hydrogen atom and the OH group join together to form a molecule of water, the resulting bond is a CONH bond.
• Two amino acids join to form a dipeptide (one bond), many amino acids join to form a polypeptide (many bonds).
• Eating two low-biological value protein foods together can ensure that all the essential amino acids are obtained, this is very important in vegetarian diets where no animal proteins are eaten.
• Essential amino acid


  Cannot be manufactured in the body, must be obtained from food
• Essential amino acids


  • Valine
  • Lysine
  • Leucine
• Primary structure


  The sequence/order and the number of amino acids in a chain
• Secondary structure


  In a protein molecule, a polypeptide chain can be interlinked, creating a coiled or spiral shape. These links are known as crosslinks or bridges and give proteins their properties.
• Coagulation


  Heat causes coagulation, for example the albumin in egg hardens/coagulates upon heating
• Culinary application of heat

  Moist heat such as boiling changes collagen to gelatine
• Acid


  Lowers pH, for example milk souring bacteria change lactose to lactic acid which causes caseinogen in milk to coagulate
• Culinary application of acids


  Vinegar (acetic acid) in a marinade denatures protein which tenderises meat
• Foam formation


  The trapping of air bubbles when egg whites are whisked, whisking unravels the globular protein in the egg white and creates heat coagulate the ovalbumin around the air bubbles creating a foam
• • gel formation

  When collagen is heated, it is converted to gelatine.Gelatine can absorb large amounts of water when heated, as protein chains uncoil, and water becomes trapped. This forms a sol. On cooling a sol forms a gel, a semi solid viscous solution that has a 3D protein matrix/mixture in which water molecules become trapped.
• foam formation is the trapping of air bubbles  when egg whites are whisked ,whisking unravels the globular protein in the egg white and creates heat coagulate the ovalbumin around the air bubbles creating a form