Foods and Nutrition 1021 Lecture Notes - Lecture 5: Peanut Butter, Peanut Oil, Monounsaturated Fat
11 Jun 2018
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Chapter 5
The Lipids
Lipids: organic (carbon-containing) compounds
◦ soluble in organic solvents
◦ not soluble in water
◦ Most are a mixture of SAFA, MUFA, PUFA
Fats: lipids that are solid at room temperature (25o C or 70o F)
Oils: lipids that are liquid at room temp.
Three types of lipids in the body/food
◦ triglycerides, phospholipids, sterols
Triglycerides/Triacylglycerol
Chief form of fat in foods & human body (95%)
3 units of fatty acids attached to 1 unit of glycerol
◦ fatty acids differ in chain length & in degree of saturation
Types of Fat and Our Health
Saturated Fats & Health- carries maximum possible number of H atoms (no points of
unsaturation),
Many contribute to elevated LDL cholesterol (bad cholesterol) in the blood which
predicts diseases of the heart & arteries
Known to elevate risk of HD = lauric, myristic & palmitic acids
Monounsaturated FA & Health- MUFAs– contain 1 point of unsaturation
May help to lower LDL cholesterol (bad cholesterol)
Does not lower HDL
Fairly resistant to damaging oxidation
Examples- canola oil,
olive oil, & peanut oil
Examples: Coconut&
oils; butter, lard, meat
fat
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Polyunsaturated FA & Health- - f.a. with 2 or more points of unsaturation
Essential Fatty Acids (EFAs): Omega-3 and Omega-6
Provide raw materials for eicosanoids
Eicosanoids: biologically active; hormone-like functions - muscle relaxation or
contraction, blood vessel dilation or constriction, blood clot formation, blood lipid
regulation(positive effect for lower LDL), immune response.
Structural & functional parts of cell membranes
Contribute lipids to the brain & nerves
Promote normal growth & vision
Assist in gene regulation- cancer prevention
Maintain outer structures of skin, protecting against water loss
Help regulate genetic activities affecting metabolism
Support immune cell functions
Omega 3- a-linolenic acid
◦ used to make EPA (eicosapentanoic acid) & DHA (docosahexanoic acid) (also
available in fish oils)
Vulnerable to oxidation & free radical formation
◦ Careful with high heats!
May enhance immune system functioning
May improve rheumatoid arthritis & some skin disorders
May help prevent cataracts
Exert an anticancer effect
May assist in preventing and treating some neurological and behavioral disorders
Modulating effect on heart functions; reduced tendency of blood to clot (risk of bleeding
in excessive doses); lowered BP, lower total cholesterol & LDL, high HDL
Omega 6 - EFA; linoleic acid
◦ Used by the body to make arachidonic acid
Used to make hormone-like substances prominent in brain & retina of eye
Neutral or beneficial effect on blood lipids related to HD, except when intakes are high
Many lower HDL, a negative effect
When substituted for SAFA in the diet, they can reduce HD risks
Points of unsaturation – vulnerable to damaging oxidation & free radical formation
thought to initiate HD or CA
Food Sources of Essential Fatty Acids-
Linolenic acid (omega-3) – oils (canola, flaxseed, soybean, walnut), nuts & seeds,
soybeans, flaxseed
Linoleic acid (omega-6) – leafy veg, nuts (walnuts) & seeds (pumpkin, sunflower), grains,
veg oils (corn, sesame, soybean, sunflower)
EPA & DHA – human milk, omega-3 milks/eggs, fatty coldwater fish (mackerel, salmon,
tuna, sardines)
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Trans FA & health
Novel fatty acids formed during hydrogenation of unsaturated fats; hydrogen introduced
into the liquid oil
Found in stick margarines, tub butters, chips, baked goods, fast foods
Contribute energy equal to other fats
May be equal to or greater than SAFA in negative heart health effects
Raises LDL-C, lowers HDL-C, may produce inflammation
Other health effects are unknown
Why are Fats Hydrogenated?
Makes fats stay fresh longer
◦ Usaturated poits are oidized akig oil raid, with off taste
Higher smoking point (suitable for deep-fat frying)
◦ More resistant to damage from oxidation or breakdown from high cooking temp
Makes fats harder, more stable & spreadable
Alternative – keep them refrigerated; antioxidant BHA (butylated hydroxyanisole) & BHT
(butylated hydroxytoluene) used as additives
Phospholipids
Similar to triglycerides, but have a phosphorus-containing acid in place of one of the f.a.
Soluble in water (d/t phosphorus molecule)
Soluble in fat (d/t fatty acids)
Function
◦ Emulsifier: disperse fat in water
◦ Key roles in cell membranes
Lecithin (a phospholipid)
Manufactured by the liver, found in many foods
Plays key role in the structure of cell membranes
Helps fat travel across lipid-containing membranes of cells into the watery fluids
Lecithin in egg yolks keep the emulsified substance stable (e.g., mayonnaise)
Lecithin supplements – have no special ability to promote health; body can manufacture
all the lecithin it needs
Sterols
Large molecules: Interconnected rings of C atoms with side chains of C, H, O attached
Play important roles as part of vit. D, sex & steroid hormones
Example: lecithin
Examples: cholesterol (in animal
products); phytosterols (from plants)
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find more resources at oneclass.com
Document Summary
Lipids: organic (carbon-containing) compounds soluble in organic solvents: not soluble in water, most are a mixture of safa, mufa, pufa. Fats: lipids that are solid at room temperature (25o c or 70o f) Oils: lipids that are liquid at room temp. Three types of lipids in the body/food triglycerides, phospholipids, sterols. Chief form of fat in foods & human body (95%) 3 units of fatty acids attached to 1 unit of glycerol fatty acids differ in chain length & in degree of saturation. Saturated fats & health- carries maximum possible number of h atoms (no points of unsaturation), Many contribute to elevated ldl cholesterol (bad cholesterol) in the blood which predicts diseases of the heart & arteries. Known to elevate risk of hd = lauric, myristic & palmitic acids. Monounsaturated fa & health- mufas contain 1 point of unsaturation. May help to lower ldl cholesterol (bad cholesterol) Examples- canola oil, olive oil, & peanut oil.
