27.1 Waxes, Fats, and Oils
3 min read•may 7, 2024
, , and are lipids with unique chemical compositions. Waxes are of long-chain and alcohols, while fats and oils are of and . Their structures determine their properties and behaviors in various applications.
Fatty acids can be saturated or unsaturated, affecting their melting points and physical states. of alters their properties, increasing melting points and stability. Understanding lipid behavior is crucial for industries like food production and cosmetics.
Chemical Composition and Properties of Waxes, Fats, and Oils
Chemical composition of lipids
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- Waxes composed of esters formed from long-chain fatty acids and long-chain alcohols
- Carbon chains in waxes range from 12 to 34 carbon atoms in length
- Common examples include , , and
- Fats and oils are triesters of glycerol (a trihydric alcohol) and fatty acids
- Fatty acids are long-chain carboxylic acids typically containing 12 to 18 carbon atoms
- Fats are solid at room temperature (butter), while oils are liquid at room temperature (olive oil)
- structure consists of a glycerol backbone with three fatty acid chains attached via
Properties of fatty acids
- contain only single bonds between carbon atoms in the hydrocarbon chain
- Examples include (C16:0) and (C18:0)
- Exhibit higher melting points due to the ability to pack closely together, resulting in stronger intermolecular forces
- Typically solid at room temperature (coconut oil)
- contain one or more double bonds between carbon atoms in the hydrocarbon chain
- Examples include (C18:1, one double bond) and (C18:2, two double bonds)
- Exhibit lower melting points due to the presence of double bonds, which create kinks in the hydrocarbon chain and prevent close packing
- Typically liquid at room temperature (canola oil)
- The degree of unsaturation determines the and physical state of a fatty acid
- The more double bonds present, the lower the melting point and the more likely it is to be liquid at room temperature
Hydrogenation of vegetable oils
- Hydrogenation process involves adding hydrogen atoms to unsaturated fatty acids, converting double bonds to single bonds
- Carried out in the presence of a (typically nickel) at high temperatures and pressures
- results in some double bonds remaining, while others are converted to single bonds
- converts all double bonds to single bonds
- Consequences of hydrogenation include:
- Increased melting point of the fat, making it more solid at room temperature (margarine)
- Improved shelf life and stability of the fat, as saturated fats are less susceptible to oxidation and
- Formation of in partially hydrogenated fats, which are associated with negative health effects
- Trans fatty acids have a linear configuration, similar to saturated fatty acids, despite the presence of double bonds
- Trans fats are known to increase (bad) cholesterol and decrease (good) cholesterol, increasing the risk of heart disease (fried foods, baked goods)
Lipid Behavior and Reactions
- : The process of hydrolyzing triglycerides with a strong base to produce soap and glycerol
- Rancidity: The oxidation of unsaturated fatty acids in fats and oils, leading to unpleasant odors and flavors
- : The process of dispersing one liquid in another immiscible liquid, often stabilized by amphipathic molecules (e.g., lecithin in mayonnaise)
- Lipid bilayers: Self-assembled structures formed by phospholipids in cell membranes, with hydrophilic heads facing the aqueous environment and hydrophobic tails facing inward
Key Terms to Review (35)
Beeswax: Beeswax is a natural wax produced by honey bees that is used for a variety of purposes, including the construction of honeycomb and as a sealant and waterproofing agent. It is a key component in the context of waxes, fats, and oils discussed in this chapter.
Carnauba Wax: Carnauba wax is a natural wax obtained from the leaves of the carnauba palm tree, native to northeastern Brazil. It is known for its hardness, high melting point, and versatile applications in various industries.
Emulsification: Emulsification is the process of dispersing one immiscible liquid (such as oil or fat) into another (such as water) to create a stable, homogeneous mixture called an emulsion. This process is crucial in various contexts, including the formation of waxes, fats, oils, and soap.
Ester Linkages: An ester linkage, also known as an ester bond, is a chemical bond formed between a carboxylic acid and an alcohol, resulting in the creation of an ester compound. This type of linkage is crucial in the context of waxes, fats, and oils, as it is the fundamental structural component that gives these substances their unique properties and functions.
Esters: Esters are a class of organic compounds formed by the reaction between a carboxylic acid and an alcohol, resulting in the replacement of the hydroxyl group (-OH) of the acid with an alkoxy group (-OR). Esters are ubiquitous in nature and play a crucial role in various chemical processes and applications.
Fats: Fats are a class of macronutrients that are essential for various physiological functions in the body. They serve as a concentrated source of energy, insulate and protect vital organs, and play crucial roles in cellular structure and signaling. Fats are a key component of the topics covered in Chapter 27.1: Waxes, Fats, and Oils.
Fatty acids: Fatty acids are long-chain hydrocarbons with a carboxylic acid group at one end, essential components of lipids such as waxes, fats, and oils. They can be saturated or unsaturated based on the presence of double bonds between carbon atoms.
Fatty Acids: Fatty acids are long-chain carboxylic acids that are the primary components of fats and oils. They play a crucial role in various biological processes, including energy storage, cell membrane structure, and signaling pathways, which are relevant to the topics of waxes, fats, and oils, soap, metabolism, and the catabolism of triacylglycerols.
Full Hydrogenation: Full hydrogenation is a chemical process that completely saturates the carbon-carbon double bonds in unsaturated fats and oils, converting them into fully saturated fatty acids. This transformation results in the conversion of liquid oils into solid or semi-solid fats, altering their physical and chemical properties.
Glycerol: Glycerol, also known as glycerin, is a simple sugar alcohol that plays a crucial role in various biochemical processes related to fats, oils, and energy metabolism. This three-carbon compound is a key component in the structure of triacylglycerols, the primary storage form of lipids in the body, and is also involved in the production and utilization of energy through its participation in metabolic pathways.
HDL: HDL, or High-Density Lipoprotein, is a type of lipoprotein that plays a crucial role in the transport and metabolism of lipids, particularly cholesterol, within the body. As a key component of the lipid profile, HDL is often referred to as the 'good' cholesterol due to its beneficial effects on cardiovascular health.
Heat of hydrogenation: The heat of hydrogenation is the amount of energy released when a double bond in an alkene reacts with hydrogen gas to form a single bond, turning it into an alkane. This process is exothermic, indicating that energy is given off during the conversion.
Hydrogenation: Hydrogenation is a chemical reaction in which hydrogen gas (H2) is added to an organic compound, typically an alkene or alkyne, to produce a more saturated compound. This process is commonly used in the food industry to convert unsaturated fats into more stable, saturated fats.
LDL: LDL, or low-density lipoprotein, is a type of lipoprotein that transports cholesterol and other fats throughout the body. It is often referred to as the 'bad' cholesterol because high levels of LDL can contribute to the buildup of plaque in the arteries, increasing the risk of heart disease and stroke.
Linoleic Acid: Linoleic acid is an essential polyunsaturated fatty acid that plays a crucial role in various aspects of waxes, fats, and oils. As a member of the omega-6 fatty acid family, it is involved in the structure and function of cell membranes, hormone production, and energy metabolism.
Lipid Bilayer: The lipid bilayer is the fundamental structure that forms the cell membrane, serving as a barrier to regulate the movement of molecules in and out of the cell. It is composed of two layers of lipid molecules arranged in a specific orientation, creating a semipermeable barrier that is essential for cellular function and homeostasis.
Melting Point: Melting point is the temperature at which a solid substance transitions into a liquid state. It is a fundamental physical property that reflects the intermolecular forces and crystal structure of a material, and is an important consideration in the study of waxes, fats, and oils.
Metal Catalyst: A metal catalyst is a metallic substance that facilitates or accelerates a chemical reaction without being consumed or altered itself. It works by providing an alternative pathway for the reaction, lowering the activation energy required and increasing the rate of the reaction.
Oils: Oils are a class of lipids that are liquid at room temperature, composed primarily of triglycerides. They are a vital component of many biological processes and have a wide range of applications in various industries, from cooking to personal care products.
Oils are closely related to the topics of waxes, fats, and oils, as they share similar chemical structures and properties. Understanding the nature and characteristics of oils is crucial in the context of these topics.
Oleic Acid: Oleic acid is a monounsaturated fatty acid that is a common component in many natural fats and oils. It plays important roles in the structure and function of various biological molecules and processes, including waxes, fats, oils, soap, and phospholipids.
Omega-3 fatty acid: Omega-3 fatty acids are a class of essential polyunsaturated fats found in various types of oils, nuts, and fish, known for their beneficial effects on heart health. These fatty acids cannot be synthesized by the human body and must be obtained through diet.
Palmitic Acid: Palmitic acid is a saturated fatty acid that is commonly found in various lipids, including waxes, fats, and oils. It plays important roles in the formation of soap, the structure of phospholipids, and the metabolic processes of fatty acid catabolism and biosynthesis.
Paraffin Wax: Paraffin wax is a white or colorless solid, derived from petroleum, that is widely used in various applications due to its unique physical and chemical properties. It is a key component in the context of the topics covered in Chapter 27.1: Waxes, Fats, and Oils.
Partial Hydrogenation: Partial hydrogenation is a chemical process that adds hydrogen to unsaturated fatty acids, reducing the number of carbon-carbon double bonds without completely saturating the molecule. This process is commonly used in the production of waxes, fats, and oils to improve their physical and chemical properties.
Polyunsaturated fatty acids: Polyunsaturated fatty acids are a type of fat found in oils from plants and some fish, containing more than one double bond in their hydrocarbon chain. These acids are crucial for human health, influencing inflammation and cell membrane integrity.
Rancidity: Rancidity is the deterioration of fats, oils, and other lipid-containing foods due to oxidation or hydrolysis, resulting in the development of unpleasant odors and flavors. This process is particularly relevant in the context of waxes, fats, and oils, as these lipid-rich substances are susceptible to rancidity over time.
Saponification: Saponification is a chemical reaction that occurs when an ester, such as a fat or oil, is heated with a strong base like sodium hydroxide or potassium hydroxide. This process results in the formation of a salt of a fatty acid, which is the main component of soap.
Saturated Fatty Acids: Saturated fatty acids are a type of fat molecule that have no double bonds between their carbon atoms, resulting in a straight, rigid structure. They are a key component of various lipids, including waxes, fats, and oils, and play important roles in the structure and function of biological membranes.
Stearic Acid: Stearic acid is a long-chain saturated fatty acid that is commonly found in various fats and oils. It plays important roles in the context of functional groups, waxes, fats, and oils, soap, as well as the catabolism of triacylglycerols through β-oxidation.
Trans Fatty Acids: Trans fatty acids, or trans fats, are a type of unsaturated fatty acid that have been chemically altered through an industrial process called hydrogenation. This process converts liquid vegetable oils into solid or semi-solid fats, which can improve the texture, shelf life, and flavor stability of certain foods.
Triesters: Triesters are a class of organic compounds that consist of three ester functional groups. They are commonly found in waxes, fats, and oils, and play a crucial role in their chemical and physical properties.
Triglyceride: A triglyceride is a type of lipid molecule composed of three fatty acid chains attached to a glycerol backbone. Triglycerides are the primary storage form of fat in the body and are an important energy source for many organisms, including humans.
Unsaturated Fatty Acids: Unsaturated fatty acids are a type of fatty acid that contain one or more carbon-carbon double bonds in their hydrocarbon chain. This structural feature distinguishes them from saturated fatty acids, which have no double bonds. Unsaturated fatty acids are an important component of fats, oils, and waxes, and play a crucial role in various biological processes.
Vegetable oils: Vegetable oils are triglycerides extracted from plants, consisting primarily of glycerides of fatty acids. They are commonly used in food preparation and for industrial purposes due to their chemical properties and versatility.
Waxes: Waxes are a class of lipids that are generally solid, waxy substances at room temperature. They are composed of long-chain fatty acids and alcohols and serve a variety of functions in both plants and animals, including providing protection, insulation, and waterproofing.