Transcript Functions of Lipids PowerPoint

FUNCTIONS of
LIPIDS
Presentation prepared by
Alice F. Mullis
February 2011
1.
4.
TRANSFER
HEAT
ENHANCE
FLAVOR
2.
5.
FUNCTIONS OF
LIPIDS
TENDERIZE
LUBRICATE
3.
6.
AERATE
LIQUIDS in
EMULSIONS
LIPIDS TRANSFER HEAT
• Fats are an excellent heat medium.
• Transfer heat from cooking utensils to
food quickly, evenly and at very high
temperatures.
• Temperature will continue to increase as
heat is added; heat cannot be added
indefinitely.
“When You’re HOT You’re HOT”
1971 hit song by Jerry Reed
LIPIDS &
SMOKING POINT
• Every lipid has a temperature point when the
fatty acids begin to break apart and produce
smoke…..called the “smoking point”.
• Fatty acids combine with oxygen and form
new compounds that have strong and
unpleasant odors.
• Once the oil begins to smoke, breakdown has
occurred and the oil should be discarded.
LIPIDS &
FLASH POINT
• The flash point is the temperature at
which lipids will burn and form a flame.
• Heated oil should be monitored at all times
or a grease fire may occur.
LIPIDS as Tenderizers
• Fats are used to tenderize baked products.
• Fat shortens long strands of protein in flour
used in baked goods. (“shortening”)
• Solid fats coat flour particles, making the
dough slippery thus preventing long strands
from forming.
LIPIDS as AERATERS
• Aeration is the addition of air into a batter.
• Saturated fats allow tiny air pockets to form
when batters are sufficiently beaten.
• Often cake recipe directions call for fat and
sugar to be “creamed” together.
LIPIDS as AERATERS
• Whipped margarines and butter products are
made more spreadable by adding air.
• Unwhipped butter or margarine is packaged
with 4 sticks per container.
• Whipped butter or margarine is packaged
with 6 sticks per container.
• Extra volume in whipped product is due to
trapped air.
LIPIDS as AERATERS
• 1 stick of whipped
butter is not the same
as 1 stick of butter.
Whipped butter would
not make a good
substitute for butter in
a recipe because its
proportions are not
the same.
ENHANCE FLAVORS
• Lipids provide a lot of flavor to food:
- Spreading butter on bread
- Bacon Fat added to vegetables
- Cook onions, garlic, celery, peppers in
fat as first step in food preparation
• Lipids dissolve and disperse flavor compounds in
foods such as vegetables or salad dressings.
• Exception to the rule – Cottonseed Oil is used to
make potato chips because it is most flavorless of
the oils.
LIPIDS as LUBRICANTS
• Marbling makes meat easier to chew (small
flecks of fat distributed throughout meat) .
• Greasy texture gives a slick feel to mouth and
tongue causing food to seem moister.
• Butter, margarine and mayonnaise are popular
spreads for breads and rolls; make foods seem
moist and not soggy.
• Frequently asked questions about butter:
http://www.landolakes.com/TestKitchen/TipsAndTechniques/FAQ/Butter.aspx
http://www.wisegeek.com/what-is-whipped-butter.htm
LIPIDS & EMULSIONS
• Lipids are usually one
of the two liquids in
an emulsion (a
mixture that contains
a lipid and a waterbased liquid).
• Examples are
mayonnaise, butter,
milk and bottled salad
dressings.
RESOURCES
Principles of Food Science, Glencoe, 2007. Janet Ward. Chapter 10, pages 216-240.
http://www.bigoven.com/glossary/shortening
http://en.wikipedia.org/wiki/Shortening
http://en.wikipedia.org/wiki/When_You're_Hot,_You're_Hot
http://www.youtube.com/watch?v=Bzewk-FMgS0
http://www.landolakes.com/Products/Butter/
http://www.landolakes.com/TestKitchen/TipsAndTechniques/FAQ/Butter.aspx
http://www.wisegeek.com/what-is-whipped-butter.htm
http://en.wikipedia.org/wiki/Mayonnaise
http://www.brooklynfarmhouse.com/basic-techniques/how-to-make-mayonnaise/
http://www.ask.com/wiki/Condiment
http://en.wikipedia.org/wiki/Biochemistry
http://www.biochemweb.org/lipids_membranes.shtml
http://www.encyclopedia.com/topic/lipids.aspx