Chemistry
Fats and Oils
Fats and oils are organic compounds composed of fatty acids and glycerol. They are a type of lipid and are essential for energy storage, insulation, and cell membrane structure. Fats are solid at room temperature, while oils are liquid. Both fats and oils are important in the human diet and are used in cooking and food preparation.
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11 Key excerpts on "Fats and Oils"
eBook - PDF- Stephen G Rees-Jones(Author)
- 1987(Publication Date)
- Elsevier Science(Publisher)
3 Oils and fats Oils and fats are familiar materials forming, as they do, an important part of the normal human diet. In addition to their use as food they have been used, since antiquity, as illuminants, a base for perfumes, and in ointments for medical and cosmetic purposes. Materials for religious ritual and burial practices would also often incorporate fatty matter. Thus, they are often encountered in an archaeological context as residues in vessels and on sherds. The subgroup formed by the drying oils is of basic importance to coatings technology in general and to western painting in particular. The chemistry of fats, while simple in essence, becomes more complicated and less precise when the question of 'drying', or polymerization is entered into. 3.1 Composition There is no essential difference between oils and fats except that, at normal temperatures, the former are usually liquid and the latter solid. It should be remembered though that the animal fats, which we think of as solids, will be liquid at the body temperature of the animal. Chemically the fats are defined as mixtures of mixed triglycérides, that is to say esters of the trihydric alcohol glycerol with a range of possible long chain fatty acids. Fats form the major subgroup of the larger class of fatty acid esters known as lipids, the definition of which sometimes extends to include other fat-soluble compounds also. The physical and chemical properties of individual fats are determined by the kinds and proportions of the fatty acids which enter into the triglycéride composition. 3.1.1 The fatty acids While the range of fatty acids which can be found in fats is large, most triglycérides are made up from relatively few of them, more especially the straight chain acids with eighteen carbon atoms. The series of saturated straight chain acids has already been shown in Table 1.3 (page 10).
- Michael EJ Lean(Author)
- 2006(Publication Date)
- CRC Press(Publisher)
Fats, oils and lipids The term lipid is a general one that is used to describe a large group of naturally occurring fat-like sub-stances. They form a diverse group of compounds that have little in common except that they are sol-uble in organic solvents such as chloroform and alco-hols but are not soluble in water. Lipids are essential, structural and functional components of all mem-branes. Indeed, the appearance of lipids was essential to the emergence of life. Lipids in plants, animals and foods also provide a base in which other ‘lipid-soluble’ compounds can dissolve. They are organic compounds which all contain carbon, hydrogen and a small amount of oxygen. Many lipids are derivatives of fatty acids. Fatty acids are essentially acid groups attached to chains of carbon atoms, with two hydro-gen atoms added to each like the inorganic paraffin oils. Oils and fats, waxes and phospholipids are examples of lipids that are fatty acid derivatives. Steroids are also classified as lipids, though they are not direct fatty acid derivatives and they are dissimi-lar in structure to the rest of the group. Oils and fats are of major importance in food and nutrition. Chemically they belong to a class of sub-stances known as esters, which result from the reac-tion of ‘fatty’ acids with alcohols, which in turn result from the hydrolysis of fatty acids. Fats are esters of the trihydric alcohol glycerol. The three hydroxyl groups of the glycerol molecule can each combine with a fatty acid molecule and the resulting ester is called a triglyceride. The simplest type of triglyceride results when the three acid molecules are all the same.
eBook - PDFHow Baking Works
Exploring the Fundamentals of Baking Science
- Paula I. Figoni(Author)
- 2010(Publication Date)
- Wiley(Publisher)
The term fat is also commonly used to refer to any lipid, whether fat, oil, or emulsifier. For example, the amount of fat listed on food labels includes the amount of solid fat, liquid oil, and emulsi- fier present in the food product (Figure 9.1). Oils are lipids that are liquid at room temperature. Oils are typically from vegetable sources such as soy- bean, cottonseed, canola, and corn. Tropical oils such as coconut, palm, and palm kernel oil are solid at room temperature (70°F/21°C), but they melt quickly in a warm room. Emulsifiers can be either liquid or solid, just like Fats and Oils. There are many different emulsifiers, but they all have one thing in common: part of the molecule is attracted to, and dissolves in, water, while another part of the molecule is attracted to, and dissolves in, Fats and Oils. By dissolving in both water and fats/oils, emulsi- fiers hold the two together as an emulsion. This ability to hold oil and water together is one of the most impor- tant functions of emulsifiers in baked goods. Chemically speaking, Fats and Oils—but not emul- sifiers—are triglycerides. Triglycerides consist of three (tri-) fatty acids attached to a three-carbon glycerol (glycerine) molecule. Figure 9.2 is a simplified repre- sentation of a fat or oil molecule with its three fatty acids. Fatty acids are made of carbon chains that have anywhere from four to twenty-two carbon atoms. Because they are important to the makeup of Fats and Oils, it is worthwhile to study the chemistry of fatty Nutrition Facts Serving Size 1 Tablespoon (14g) Servings Per Container 64 Calories 120 Vitamin A 0% *Percent Daily Values are based on a 2,000 calories diet.
eBook - PDF- Chavan, U D(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
when each of these three -OH groups reacts with a fatty acid. The resulting fats are called triglycerides. Because of their preponderant aliphatic structure, fats are hydrophobic, generally soluble in organic solvents but generally insoluble in water. Fats made up of shorter chain fatty acids are usually liquid at room temperature, whereas the longer chain fats will be solid. Some ambiguity in terminology arises because the words “oil”, “fat”, and “lipid” are often used interchangeably. Of these lipid is the general term, because a lipid is not necessarily a triglyceride. Oil is the term usually used to refer to fats that are liquids at normal room temperature, while fat is usually used to refer to fats that are solids at normal room temperature. Fat is important foodstuff for many forms of life and fats serve both structural and metabolic functions. They are necessary part of the diet of most heterotrophs (including humans). Some fatty acids that are set free by the digestion of fats are called essential because they cannot be synthesized in the body from simpler constituents. There are two essential fatty acids (EFAs) in human nutrition: alpha-linolenic acid (an omega-3 fatty acid) and linoleic acid (an omega-6 fatty acid). Other lipids needed by the body can be synthesized from these and other fats. Fats and other lipids are broken down in the body by enzymes called lipases produced in the pancreas. Fats and Oils are categorized according to the number and bonding of the carbon atoms in the aliphatic chain. Fats that are saturated fats have no double bonds between the carbons in the chain. Unsaturated fats have one or more double bonded carbons in the chain. The nomenclature is based on the non-acid (non-carbonyl) end of the chain. This end is called the omega end or the n-end. Thus alpha-linolenic acid is called anomega-3 fatty acid because the 3rd carbon from that end is the first double bonded carbon in the chain counting from that end.
- Viduranga Waisundara(Author)
- 2018(Publication Date)
- IntechOpen(Publisher)
1 Section 1 Biochemistry of Fatty Acids 3 Chapter 1 Introductory Chapter: Fatty Acids in Modern Times Viduranga Y. Waisundara 1. Introduction to lipids and fatty acids Before going into the chemical structure and properties of fatty acids, it is important to mention that they are merely one component of the major nutri-ent group commonly known as lipids. Lipids are biological compounds, which are soluble only in nonpolar solvents. They are typically known as Fats and Oils as well. However, fats and oil differ from each other based on their physical characteristics. The term “fats” is used to refer solid lipids at room temperature such as lard and butter, while “oils” are liquid lipids at room temperature such as sunflower oil, olive oil, etc. The classification of lipids is shown in Figure 1 . Fatty acids appear under “triglycerides” since it is a component of this particular category of lipids. To provide a brief introduction on fatty acids at a very basic level, they are the building blocks of the fat, which is physiologically present and obtained from the food we eat. During digestion, the body breaks down fats in the food products into fatty acids, which are subsequently absorbed into the blood. Upon absorption, fatty acid molecules are typically joined in groups of three, forming a molecule called a triglyceride. It has to be noted in this instance that triglycerides can even be made up from the carbohydrates in the food that we consume. There are several important functions of fatty acids in the body, including being a medium of storing energy and being involved in the cellular composition in the forms of phospholipids and Figure 1. Major types of lipids: fatty acids come under triglycerides according to this classification. Biochemistry and Health Benefits of Fatty Acids 4 cholesterol esters. When glucose is unavailable for generation of energy in the cel-lular mechanism, the body uses fatty acids as fuel instead.
eBook - PDF- Sharma, Dipiti(Authors)
- 2021(Publication Date)
- Daya Publishing House(Publisher)
6 Lipids 6.0 Introduction General Characteristics Lipids that are solid at room temperature are called as fats (for example butter) and those that are liquid are called oils (for example vegetable oil). Lipids have following features: They are organic compounds made up of carbon, hydrogen and oxygen. Lipids as a class also have a lower ratio of oxygen to carbon compared with carbohydrate, proteins or alcohols. They rarely occur in on organism in free state, but are usually combined with proteins (lipoproteins) or with carbohydrate as glycolipids. They provide 9 kcal/g energy i.e. they supply more energy than carbohydrate, proteins. Lipids do not have repeating monomeric units i.e. they are not polymeric in nature. Although lipids form a diverse group even then they share two main characteristics: 1. They dissolve in organic solvents such as chloroform, This ebook is exclusively for this university only. Cannot be resold/distributed. benzene and ether etc. 2. They are not readily soluble in water. Fatty acids are long chain hydrocarbon containing a terminal carboxyl group and are found in most lipids in the body and in the lipids in food. Fatty acid is an organic acid composed of a chain of carbon atoms with attached hydrogen atoms; it has an acid group at one end and methyl group at the other end. These are normally found as esters in natural Fats and Oils, however they do occur in unesterified form when fatty acids bound to certain proteins. Fatty acids with lesser number of carbon atoms (4 to 8) are present in milk fats, whereas those of intermediate chain length (10 to 14) and between 16 to 20 carbon atoms are found in most of the animal and vegetable fats.
eBook - PDF- H. Stephen Stoker(Author)
- 2015(Publication Date)
- Cengage Learning EMEA(Publisher)
Oils are also naturally occur-ring mixtures of triacylglycerol molecules in which there are many different kinds of triacylglycerol molecules present. Given that both are triacylglycerol mixtures, what distinguishes a fat from an oil? The answer is physical state at room temperature. A fat is a triacylglycerol mixture that is a solid or a semi-solid at room temperature (25°C). Generally, fats are obtained from animal sources. An oil is a triacylglycerol mixture that is a liquid at room temperature (25°C). Generally, oils are obtained from plant sources. ◀ Because they are mixtures, no fat or oil can be represented by a single specific chemical formula. Many different fatty acids are present in the tria-cylglycerol molecules found in the mixture. The actual composition of a fat or oil varies even for the species from which it is obtained. Composition depends on both dietary and climatic factors. For example, fat obtained from corn-fed hogs has a dif-ferent overall composition than fat obtained from peanut-fed hogs. Flaxseed grown in warm climates gives oil with a different composition from that obtained from flax-seed grown in colder climates. Additional generalizations and comparisons between Fats and Oils follow. 1. Fats are composed largely of triacylglycerols in which saturated fatty acids pre-dominate, although some unsaturated fatty acids are present. Such triacylglycer-ols can pack closely together because of the “linearity” of their fatty acid chains (Figure 8-7a), thus causing the higher melting points associated with fats. Oils contain triacylglycerols with larger amounts of mono- and polyunsaturated fatty acids than those in fats. Such triacylglycerols cannot pack as tightly together because of “bends” in their fatty acid chains (Figure 8-7b). The result is lower melting points. ◀ 2. Fats are generally obtained from animals; hence the term animal fat.
eBook - PDF- Fatih Yildiz(Author)
- 2009(Publication Date)
- CRC Press(Publisher)
However, the marketing approach of one fat or oil over another stems from the trend toward products offering health claims, such as “heart-healthy”, “may lower cholesterol”, etc. In general, Fats and Oils are both lipids and triglycerides that differ in fatty and other component matters. Thus, saturated fatty acids that make up a triglyceride comprise of those with a full hydrogen atom to the long hydrocarbon chains (palmitic and stearic acids), while unsaturated are similar chains having double bonds and minus the hydrogen atoms. Further, some of these chains can be 188 Advances in Food Biochemistry altered by adding hydrogen atoms through hydrogenation. Technically, a fat may contain some oil and vice versa, but saturated and highly hydrogenated fats are solid at room temperature, while unsaturated fats are liquid. The health implication is that saturated fats lead to fatty deposits in human arteries with athero-sclerosis effects and eventually can lead to heart attacks, while unsaturated fats do not have such effects. Thus, consumers should reduce or replace foods containing saturated fats, although there is evidence that some saturated fats have a neutral effect (e.g., olestra). Unsaturated fatty acids are usually subjected to air oxidation reactions that create rancid taste effects. Therefore, hydrogenation of unsaturated fatty acids reduces these reactions and modifies their functionality. Nevertheless, how can one respond to the critics of hydrogenation who object to it from a health standpoint? Through the years nutrition biochemists have been concerned about the trans fatty acids formed during the hydrogenation process (hydrogen gas is bubbled into oils) that produces artificial trans fatty acids that accumulate in body tissues. These artificial fatty acids cause all kinds of diseases because they are foreign to the human immune system and unnatural.
eBook - PDFFood Lipids
Chemistry, Nutrition and Biotechnology
- Sara Diana Garduno Diaz(Author)
- 2019(Publication Date)
- Delve Publishing(Publisher)
PART I: CHEMISTRY STRUCTURE OF LIPIDS Lipids display extraordinary structural variety as illustrated in Figure 1.1 below, driven by factors such as variable chain length, a multitude of oxidative, reductive, substitutional and ring-forming biochemical transformations as well as alteration with sugar residues and other functional groups of different biosynthetic origin. There are no steadfast estimates of the number of distinct lipid structures in nature, due to the technical challenges of clarifying chemical structures. Estimates in the order of 200,000, based on acyl/alkyl chain and glycan permutations for glycerolipids, glycerophospholipids and sphingolipids are almost certainly on the conservative side (Yetukuri et al., 2008). This number is actually exceeded by the list of known natural products, most of which are of either prenol or polyketide origin (Buckingham, 2010). Because of the importance of these molecules in cell functions and pathology, it is essential to have well-organized databases of lipids with relevant structural information and related features. Fats and Oils consist of about 95% fatty acids. Fatty acids found in edible lipids have long straight hydrocarbon chains of 4–26 carbon atoms in the molecule, and a carboxyl group at the carbon atom 1. The carboxyl group is dissociated only in small degree so that higher fatty acids belong to very week acids. Fatty acids have 18 carbon atoms in most lipids. Even carbon number fatty acids prevail, and the content of odd carbon number fatty acids only rarely exceeds 1%, almost exclusively in milk and fats deposits 1 CHAPTER Food Lipids: Chemistry, Nutrition and Biotechnology 4 of ruminants. Branched-chain fatty acids are only traced components in some animal fats. An exception is cyclic fatty acids, being present as a trace component in rare edible lipids. Fatty acids with a very long hydrocarbon chain are present in most waxes, but their importance in the human diet is minimal.
No longer available |Learn more- Linda DeBruyne, Kathryn Pinna(Authors)
- 2016(Publication Date)
- Cengage Learning EMEA(Publisher)
Fat is a member of the class of compounds called lipids. The lipids in foods and in the human body include triglycerides (Fats and Oils), phospholipids, and sterols. Roles of Body Fat Lipids perform many tasks in the body, but, most importantly, they provide energy. A constant flow of energy is so vital to life that, in a pinch, any other function is sacri- ficed to maintain it. Chapter 3 described one safeguard against such an emergency—the stores of glycogen in the liver that provide glucose to the blood whenever the supply runs short. The body’s stores of glycogen are limited, however. In contrast, the body’s capacity to store fat for energy is virtually unlimited due to the fat-storing cells of the adipose tissue. The fat cells of the adipose tissue readily take up and store fat, grow- ing in size as they do so. Fat cells are more than just storage depots, however; fat cells secrete hormones that help to regulate the appetite and influence other body functions. 1 Figure 4-1 shows a fat cell. The fat stored in fat cells supplies 60 percent of the body’s ongoing energy needs during rest. The fat embedded in muscle tissue shares with muscle glycogen the task of providing energy when the muscles are active. During some types of physical activity or prolonged periods of food deprivation, fat stores may make an even greater energy contribution. The brain and nerves, however, need their lipids: a family of compounds that includes triglycerides (Fats and Oils), phospholipids, and sterols. Lipids are characterized by their insolubility in water. fats: lipids that are solid at room temperature (708F or 218C). oils: lipids that are liquid at room temperature (708F or 218C). adipose tissue: the body’s fat, which consists of masses of fat-storing cells called adipose cells. FIGURE 4-1 A Fat Cell Within the fat, or adipose, cell, lipid is stored in a droplet. This droplet can greatly enlarge, and the fat cell membrane will expand to accommodate its swollen contents.
These discoveries carried out by these two great French chemists were going to become the bases of several sciences, such as analytical chemistry, biochemical synthesis, and lipochemistry. Originally, chemists have considered that these triacylg-lycerol molecules contained only one type of fatty acid. It was necessary to wait more COOH FIGURE 2.16 Rumenic acid ( cis 9, trans 11-18:2). COOH FIGURE 2.17 trans 10, cis 12-Linoleic acid. 18 Lipids: Nutrition and Health than one century, after the development of novel methods, so that the famous German chemist T.P. Hilditch corrected that concept in 1964. Indeed, he showed that natural oils and fats were generally made of mixed triacylglycerol molecules, with two or three types of different fatty acids (Figure 2.18; R1, R2, and R3), saturated or unsaturated. Now, we know that each oil or each fat may contain, thanks to a great number of fatty acid combinations, a great diversity of molecular species. The observed number of these species has been estimated to reach 200 in milk fat. Actually, with a given num-ber of fatty acids, the number of triacylglycerol molecular species observed in natural fats is largely lower than the number of theoretically possible combinations. The use of the two historical names, oils and fats, has risen from the difference in their fatty acid compositions, oils being more unsaturated than fats and are also more liquid at the same temperature. This difference in physical property (melting point) mainly depends on the unsaturation degree of fatty acids themselves, but also on the nature and the variety of the molecular species of the triacylglycerols present in the mixture. Thus, cocoa butter has a melting point slightly lower than 37°C because of the presence of two major molecular species, POS and SOS, combining two saturated fatty acids, palmitic acid (P) and stearic acid (S) with one monounsaturated fatty acid, oleic acid (O).
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