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 matchfriction---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

biological protein

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