Fats Flashcards
Which of the following foods is an example of a monounsaturated fat source? A) Butter B) Steak C) Fish D) Olive
D) Olive
Which of the following groups is a good sources of polyunsaturated fatty acids? A) Meat B) Fruit C) Dairy products D) Most vegetable oils
D) Most vegetable oils
Describe three ways lipids differ from carbohydrates
- Lipids are not polymers
lipids do not provide structure to food products
lipids cannot be dissolved in water
30-40% oleic, 25-32% palmitic, 10-15% stearic, 3-5% butyric
Milk fat
30-40% palmitic, stearic
Animal fat
High in long chain polyunsaturated F.A., vitamin A and D
Marine oil
Vegetable fats only, < 20% sat. fat, cotton seed, corn, peanut. olive safflower
Oleic - Linoleic
High in linolenic, considerable oleic, linoleic, soybeans, wheat germ
Linolenic
TRUE or FALSE?
The smoke point of a fat is the temperature at which smoke comes from the surface of the fat when heated. Thus, a fat with lower smoke point is more suitable for frying than a fat with higher smoke point
False
Metals such as iron and copper may be present in trace amount in foods and will encourage the development of oxidative rancidity. Some synergists such as __________ bind or chelate metals and prevent metals from catalyzing the oxidation process
Citric acid
Chelating agents are sometimes called __________
Sequestering agents
TRUE or FALSE?
A winterized oil, usually called salad oil, has a HIGHER melting point, and does not crystallize in refrigerator
FALSE
What is a plastic fat?
Fat that can be molded or pressed into various shapes without breaking (e.g., shortening, butter or margarine)
Why do same fats become rancid more quickly than others?
A) Degree of saturation (more unsaturated, more rancidity)
B) Presence of free fatty acids through “clipping action” of the fatty acid from the glycerol which is caused by: light, heat, moisture, metals or enzymes
Nutritional concerns centre around animal fats, which are highly saturated and contain __________
Cholesterol
Oils used for salad oil should have HIGH/LOW melting point
Low
__________ or __________ oil is used in crackers, where stability to oxidation over a long storage period is vital
Coconut or palm
The solvent extraction process uses __________ to dissolve the oil from the oilseed flakes
Hexane
Mayonnaise is an oil-in-water emulsion. Peanut butter is a(n) __________ emulsion. Margarine is a(n) __________ emulsion
oil-in-water; water-in-oil
Biological catalysts, such as __________, can be used in interesterification reactions
Lipase
__________ is characterized by a sharp melting transition close to body temperature (32-35 degrees Celsius)
Cocoa butter
Quantitatively, the most important food lipids are mono- / di- or triglycerides
Triglycerides
Smoking point is dependent upon the level of free fatty acids in the oil; the higher the free fatty acid levels, the __________ the smoke point
Lower
There are many important roles of lipids in foods. For example, …..
- Carry fat soluble vitamin (A, D, E, K)
- Act as tenderizer in baked products
- Enhance flavour, texture
- Contribute to juiciness of steak
- Act as cooking medium (can be heated to high temperature)
- Provide feeling of satiety (satisfaction)
Fats differ from carbohydrates and proteins in that they are not _________ of repeating molecular units
Polymers
__________ acid is a common fatty acid found in butter
Butyric
Fatty acids differ in __________ and in the number of __________ atoms they contain
Length; hydrogen
The active ingredients in egg yolk stabilizing the emulsion are __________, the best known of which is __________
Phospholipids; lecithin
Fats can exist in more than one crystal form. This means that fats exhibit __________
Polymorphism
Two characteristics that lower the melting range of a fat include
1) Double bond (level of unsaturation)
2) Short carbon chain
What are “plastic” fats?
Fat that are capable of being molded (butter, shortening)
__________ rancidity occur with acyl-glycerols are hydrolyzed to glycerol and free fatty acids
Hydrolytic
__________ is a process that removes the high melting triacylglycerols so that the oil will not solidify in the refrigerator
Winterization
“Synergists” used with antioxidants are more effective in preventing oxidation than either used alone. Citric acid is an effective synergist because it …
binds with copper and iron which promote oxidation
What type of foods are subject to the development of rancidity?
Unsaturated fats and foods that don’t have natural antioxidants
Name two natural and two synthetic antioxidants
NATURAL: Vitamin C and E
SYNTHETIC: BHA and BHT
Define smoke point
Temperature at which fat starts to smoke
What factors decrease the smoke point of a fat?
1) Presence of free fatty acids
2) Presence of mono- and di-glycerides
TRUE or FALSE?
The fat-smoke results from the change of glycerol to “acrolein” which is quite irritating to the eyes and nose
TRUE
