Transcript Enzymes

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
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]
Carbohydrasesbreak 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