Enzymes

Enzymes- are special proteins responsible for certain chemical reactions. They aid in digestion. Activation energy- the energy that supplies the force needed for a reaction

eg. Strike a match friction---enough energy--- burst into flame

When a chemical reaction occurs between 2 substances Chemical reaction Bonds break New ones form New product

Catalyst Speeds up the rate of reactions without being changed itself. Allows the cells to survive. Able to be used over and over. catalyst faster Lower temperature

Enzymes act as catalysts. Enzyme names end in – ase Maltase- breaks down maltose Amylase- breaks down amylose catalyst biologicalprotein

22 digestive enzymes Amylase- starches, CHO Protease- proteins Lipase- fats [ lipids] Lactase- milk [ lactose]

Substrates Enzymes act on specific molecules or sets of molecules called substrates They fit into an area of the enzyme called an active site.

Enzymes hold the substrate until the reaction occurs. After the reaction the enzyme releases the product and then can be reused.

Coenzyme Sometimes an enzyme needs a partner to help the enzyme work. One that is heat stable with organic molecules. It helps shape the enzyme to fit better. Influences the active site. LOCK + KEY + OIL

Enzymes and digestion Needed for many aspects of digestion to happen. MOUTH- saliva contains amylase breaks down amylose [ starch in bread] To the sugar maltose

STOMACH Enzymes work on the acid in the stomach Rennin- curdles the milk protein Pepsin- denatures protein Stomach enzymes are the only ones not destroyed by the acid.

Small Intestine Proteases- breaks down protein Lipases- break down fats [ lipids] Carbohydrases- break down carbohydrates

Enzymes are vital to good health. They metabolize [ digest] food. Nutrients are now available in useable forms.

Things that affect enzyme activity. Temperature pH balance Water All these things affect how we treat food to preserve it.

Enzymatic Browning Enzymes cause some foods- fruits- to turn brown when cut exposing them to the air. 1. substance 2. enzyme 3. oxygen Must limit one of the above to stop this browning.

Heat- slows this happening Lower the pH- add an acid

Eg. Fruit- sugar + water - ascorbic acid [ vitamin C ]

Eg vegetables – soak in salt water

Yeast Contains maltase Stops when bread baked as the heat kills the yeast maltase Breaks down maltose Releases CO2 Cause bread to rise

Meat Meat tenderizers are enzymes that break down the connective tissue in meat. Fruit juices [Pineapple juice] Vinegar Wine Marinate-use an acid

M.S.G.-breaks down connective tissue

Papain-enzyme found in papaya

Uses of enzymes Food scientists have learned to use enzymes to aid in preservation. Chocolates- used in centers to keep them soft..

Apple/ grape juice- enzymes used – juice appears less cloudy

Tomatoes- enzymes- enhance flavor - give longer shelf life