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What distinguishes fats from fixed oils in terms of physical state at normal temperatures?
What distinguishes fats from fixed oils in terms of physical state at normal temperatures?
Which of the following is a characteristic physical property of fixed oils and fats?
Which of the following is a characteristic physical property of fixed oils and fats?
What type of lipid contains sulfur in its structure?
What type of lipid contains sulfur in its structure?
How are animal fats typically separated from other tissues?
How are animal fats typically separated from other tissues?
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Which statement about glycerides of fatty acids is true?
Which statement about glycerides of fatty acids is true?
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What distinguishes 'cold-pressed oil' from 'hot-pressed oil'?
What distinguishes 'cold-pressed oil' from 'hot-pressed oil'?
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What is the primary function of lipids such as fixed oils and fats?
What is the primary function of lipids such as fixed oils and fats?
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Which type of lipid is characterized by containing carbohydrates in its structure?
Which type of lipid is characterized by containing carbohydrates in its structure?
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What is the primary source of carbon units in the biosynthesis of fatty acids?
What is the primary source of carbon units in the biosynthesis of fatty acids?
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What is indicated by the acid value of fixed oils?
What is indicated by the acid value of fixed oils?
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What effect does hydrogenation have on the chemical properties of fats?
What effect does hydrogenation have on the chemical properties of fats?
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Which type of rancidity is primarily caused by the action of the enzyme lipase?
Which type of rancidity is primarily caused by the action of the enzyme lipase?
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Which type of oil is characterized by a high content of oleic acid glycerides and does not dry upon exposure to air?
Which type of oil is characterized by a high content of oleic acid glycerides and does not dry upon exposure to air?
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Which test can be used to determine the degree of unsaturation in fixed oils?
Which test can be used to determine the degree of unsaturation in fixed oils?
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What effect does hydrogenation have on fixed oils?
What effect does hydrogenation have on fixed oils?
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During the polymerization of oils, what effect does prolonged heating in an inert atmosphere have?
During the polymerization of oils, what effect does prolonged heating in an inert atmosphere have?
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Which of the following oils is typically involved in the hydrogenation process to produce solid cooking fats?
Which of the following oils is typically involved in the hydrogenation process to produce solid cooking fats?
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What is a significant result of oxidative rancidity in fixed oils?
What is a significant result of oxidative rancidity in fixed oils?
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What is the process called that allows unsaturated fixed oils to add hydrogen to their double bonds?
What is the process called that allows unsaturated fixed oils to add hydrogen to their double bonds?
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Which physical constant is NOT typically used to identify or evaluate the quality of fixed oils?
Which physical constant is NOT typically used to identify or evaluate the quality of fixed oils?
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Which of the following is an emollient property of fixed oils utilized in pharmaceutical formulations?
Which of the following is an emollient property of fixed oils utilized in pharmaceutical formulations?
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What is the result of the reaction between malonyl-CoA and butyryl-CoA in the biosynthesis of fatty acids?
What is the result of the reaction between malonyl-CoA and butyryl-CoA in the biosynthesis of fatty acids?
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What must be controlled to prevent hydrolytic rancidity effectively?
What must be controlled to prevent hydrolytic rancidity effectively?
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Why is fat hardening a significant process in the fat industry?
Why is fat hardening a significant process in the fat industry?
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Which of the following best describes castor oil?
Which of the following best describes castor oil?
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What is a primary use of linseed oil?
What is a primary use of linseed oil?
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What characterizes cottonseed oil in pharmaceutical applications?
What characterizes cottonseed oil in pharmaceutical applications?
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Which oil is referred to as cacao butter?
Which oil is referred to as cacao butter?
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What is a significant property of sesame oil?
What is a significant property of sesame oil?
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Lard is mainly recognized for which of the following uses?
Lard is mainly recognized for which of the following uses?
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Which statement about lanolin is true?
Which statement about lanolin is true?
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Higly molecular weight esters are commonly known as?
Higly molecular weight esters are commonly known as?
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What is a primary therapeutic property of castor oil?
What is a primary therapeutic property of castor oil?
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What primarily distinguishes fixed oils from fats based on their physical properties?
What primarily distinguishes fixed oils from fats based on their physical properties?
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In which of the following applications is olive oil NOT typically used?
In which of the following applications is olive oil NOT typically used?
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Which type of lipids are classified as having fatty acids combined with glycerol and containing other functional groups?
Which type of lipids are classified as having fatty acids combined with glycerol and containing other functional groups?
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Which of the following is a common use for cottonseed oil?
Which of the following is a common use for cottonseed oil?
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What is the primary method for obtaining fixed oils and fats of vegetable origin?
What is the primary method for obtaining fixed oils and fats of vegetable origin?
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Which property of sesame oil makes it suitable for pharmaceuticals?
Which property of sesame oil makes it suitable for pharmaceuticals?
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Which property describes fixed oils and fats in relation to water?
Which property describes fixed oils and fats in relation to water?
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What is a primary characteristic of lanolin?
What is a primary characteristic of lanolin?
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What type of alcohol is predominantly found in the structure of fixed oils and fats?
What type of alcohol is predominantly found in the structure of fixed oils and fats?
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Which type of oil is primarily used in the manufacture of ointments due to its emollient properties?
Which type of oil is primarily used in the manufacture of ointments due to its emollient properties?
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What distinguishes cold-pressed oils from those that are hot-pressed?
What distinguishes cold-pressed oils from those that are hot-pressed?
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What is the main use of Theobroma oil?
What is the main use of Theobroma oil?
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Which type of lipid contains nitrogen in its structure?
Which type of lipid contains nitrogen in its structure?
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Which oil is often referred to as sweet oil and is also a nutrient?
Which oil is often referred to as sweet oil and is also a nutrient?
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What is the main characteristic of glycerides made from saturated fatty acids?
What is the main characteristic of glycerides made from saturated fatty acids?
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What does the saponification value indicate in fixed oils and fats?
What does the saponification value indicate in fixed oils and fats?
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Which type of rancidity results from the action of the enzyme lipase?
Which type of rancidity results from the action of the enzyme lipase?
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What does the iodine number in fixed oils indicate?
What does the iodine number in fixed oils indicate?
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Which of the following is a strategy to prevent oxidative rancidity in fixed oils?
Which of the following is a strategy to prevent oxidative rancidity in fixed oils?
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Which of the following tests evaluates the presence of free fatty acids in fixed oils?
Which of the following tests evaluates the presence of free fatty acids in fixed oils?
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Rancidity in fixed oils is primarily due to the formation of which harmful compounds?
Rancidity in fixed oils is primarily due to the formation of which harmful compounds?
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To what does the term 'hydrogenation' refer in the context of fixed oils?
To what does the term 'hydrogenation' refer in the context of fixed oils?
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Which of the following factors can influence the rancidity of fixed oils during storage?
Which of the following factors can influence the rancidity of fixed oils during storage?
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What compound is formed when acetate reacts with CoA in the biosynthesis of lipids?
What compound is formed when acetate reacts with CoA in the biosynthesis of lipids?
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Which type of oils are classified as nondrying oils?
Which type of oils are classified as nondrying oils?
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What is the primary benefit of fat hardening in the fat industry?
What is the primary benefit of fat hardening in the fat industry?
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What happens to the unsaturated components of oils during fat polymerization?
What happens to the unsaturated components of oils during fat polymerization?
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How does the malonyl portion of malonyl-CoA contribute to fatty acid biosynthesis?
How does the malonyl portion of malonyl-CoA contribute to fatty acid biosynthesis?
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Why do hydrogenated fats become rancid less readily than non-hydrogenated oils?
Why do hydrogenated fats become rancid less readily than non-hydrogenated oils?
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What type of reaction leads to the formation of a cyclic structure during fat polymerization?
What type of reaction leads to the formation of a cyclic structure during fat polymerization?
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Study Notes
Lipids (Fixed Oils, Fats, and Waxes)
- Lipids are esters of long-chain fatty acids and alcohols.
- The main difference between fixed oils and fats, and waxes is the type of alcohol.
- In fixed oils and fats, glycerol alcohol (C3H8O3) combines with fatty acids (forming glycerides).
- In waxes, the alcohol has a higher molecular weight, such as cetyl alcohol (C16H34O).
- Fats and waxes can be from plants (like olive oil, peanut oil) or animals (like lard).
- Their primary function is energy storage.
- Fixed oils and fats are important in pharmaceuticals, industry, and nutrition.
Classification of Lipids
- Simple lipids: Esters of fatty acids with alcohol (e.g., fixed oils, fats, waxes).
- Compound lipids: Esters of fatty acids with alcohol containing another group (e.g., phospholipids).
Examples of Compound Lipids
- 1- Phospholipids: Compounds of fatty acids with glycerol and phosphoric acid.
- 2- Glucolipids: Compounds of fatty acids with glycerol and carbohydrates.
- 3- Sulpholipids: Contain sulfur.
- 4- Aminolipids: Contain nitrogen.
Fixed Oils and Fats
- Fixed oils and fats differ only in their melting point.
- Liquids at normal temperatures are fixed oils.
- Semisolid or solid at ordinary temperatures are fats.
- Vegetable fixed oils and fats are obtained by compression.
- If the compression is carried out in the cold, the oil is known as a "virgin oil" or "cold-pressed oil".
- If the compression is carried out in heat, the oil is known as a "hot-pressed oil."
- Animal fats are separated from other tissues by rendering with steam, with or without pressure.
- The heat melts the fat, which rises to the top and can be separated by decantation.
Chemical Properties
- Chemically, fixed oils and fats are glycerides of fatty acids.
- Glycerides of unsaturated fatty acids are liquid.
- Glycerides of saturated fatty acids with sufficient chain length are solid.
Physical Properties
- Fixed oils and fats are lighter than water and insoluble in water.
- They feel greasy.
- They leave a permanent translucent stain on paper.
- They don't volatilize when exposed to air.
- They are freely soluble in ether, chloroform, and light petroleum but usually insoluble in alcohol (castor oil is an exception)
Sources of Vegetable Oils
- Vegetable oils and fats are found in various parts of plants, but seeds typically have higher concentrations than other parts.
- Examples include cottonseed oil, linseed oil, sesame oil and castor bean seeds, almonds.
Biosynthesis of Lipids
- Acetate reacts with CoA to form acetyl-CoA.
- Acetyl-CoA is converted to malonyl CoA using carbon dioxide.
- Malonyl CoA reacts with acetyl CoA to form a 5-carbon intermediate.
- The intermediate undergoes reduction and elimination of carbon dioxide to produce butyryl-CoA.
- The process repeats, creating fatty acids with an even number of carbon atoms.
- The malonyl portion of malonyl-CoA acts as the source of the 2-carbon units.
Hardening and Polymerization of Oils
- Unsaturated fixed oils and their glycerides can add hydrogen (H2) to their double bonds in the presence of catalyst.
- This property is used to harden oils in the fat industry.
- Fat hardening process makes fats less susceptible to rancidification.
- Fat polymerization involves heating oils in an inert atmosphere.
- Prolonged heating causes unsaturated components to react and form more saturated or cyclic structures.
- Polymerized oils don't develop rancidity.
- Hydrogenation of cheap oils (like cotton oil, corn oil, soybean oil) converts them from liquid to solid forms, similar to lard or butter.
Drying Properties
- Some fixed oils are classified as drying, semidrying, or nondrying based on their ability to absorb oxygen.
- Oxygen saturates the double bonds, forming oxides that can polymerize and form hard films (drying oils).
- Semidrying oils contain both oleic and linoleic glycerides, while nondrying oils have a high amount of oleic acid in their glycerides.
Evaluation of Fixed Oils and Fats
- The United States Pharmacopeia and the National Formulary include tests to determine the identity, quality, and purity of fixed oils and fats.
- These tests are based on the oils' chemical constitutions.
Testing Methods (Physical Constants)
- Acid value/number: Amount of free fatty acid in the oil (mg of KOH needed for neutralization).
- Saponification value: Amount of KOH needed to saponify completely 1gm of fat or oil (mg of KOH needed to neutralize free acids and saponify esters in 1gm).
- Iodine number: Measures the degree of unsaturation (grams of iodine absorbed by 100 gm of substance).
- Other constants: Melting point, specific gravity, refractive index are used also for identifiying and measuring quality of different fixed oils and fats.
Rancidity
- Rancidity is a transformation in oils and fats during storage where a new compound is formed which often changes the oil's consistency, taste, and smell.
- Rancidity is caused by volatile, bad-smelling acids and aldehydes.
- These compounds result from oxygen attack at reactive allylic positions in the fat molecules.
- Hydrogenation can slow down the development of rancidity. by decreasing the number of double bonds.
- Types of rancidity include hydrolytic (due to enzyme lipase) and oxidative (due to unsaturated fatty acids and polymerization).
Uses of Fixed Oils and Fats
- In pharmaceuticals, fixed oils and fats are used for their emollient properties (e.g., in ointments, creams, and emulsions).
- They are also used as vehicles for other medications.
- In arts and industries, they are used in soap production, drying oil in paints/varnishes, and lubrication.
Specific examples of Fixed Oils (with uses)
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Castor oil: Stimulant cathartic; used in soap manufacturing, sometimes has therapeutic properties.
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Linseed oil: Demulcent and laxative.
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Olive oil: Used in soaps, plasters, also a demulcent, emollient, laxative, and widely used as salad oil.
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Cottonseed oil: Used pharmaceutically as a solvent for injections; also used in soapmaking.
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Sesame oil: Used as a solvent for intramuscular injections also has nutritive, laxative, demulcent, and emollient properties..
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Cocoa butter: Pharmaceutically used as a suppository base.
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Lard: Purified internal fat of abdomen; emollient, used as base for ointment
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Lanolin: Purified, fat-like substance from sheep wool; ingredient in skin creams and cosmetics.
Waxes
- Waxes are esters formed from high-molecular-weight, straight-chain acids and high-molecular-weight, primary, straight chain alcohols.
- In plants, waxes are found on outer cell walls of epidermal tissue, especially in fruits and leaves.
- Waxes protect plants from losing or gaining water.
- Insects also secrete waxes.
- Waxes are used in pharmaceuticals to harden ointments and creams; also for protective coatings.
- Beeswax: A purified wax from bee honeycombs; used as stiffening agent, in yellow ointments, and as a base for plasters; also found in some polishes.
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Description
Explore the fascinating world of lipids, specifically focusing on fixed oils, fats, and waxes. Learn about their structures, functions, and classifications, including simple and compound lipids. This quiz will test your knowledge on the roles of these vital compounds in nutrition and industry.
