Food Chemistry

Topics: Fatty acid, Nutrition, Fat Pages: 14 (4556 words) Published: October 31, 2014
Food Chemistry: Option F
Food Groups: F.1
Food & Nutrients
Food: any substance, whether processed, semi-processed or raw, which is intended for human consumption, and includes drinks, chewing gum and any substance which has been used in the manufacture, preparation or treatment of “food” but does not include cosmetics or tobacco or substances used only as drugs. Nutrients: any substance obtained from food and used by the body to provide energy, to regulate growth, and to maintain and repair the body’s tissues. These include proteins, fats and oils, carbohydrates, vitamins, minerals and water(2cm3).

Lipids (fats and oils: 10%-20%)
Soluble in non-polar solvents. Fats, which are made from the elements carbon, hydrogen and oxygen, provide a more concentrated energy source than carbohydrates. The carbon atoms are less oxidized as the molecules have fewer oxygen atoms in their molecules and so more energy is released when the molecules are completely oxidized to carbon dioxide and water. The fat stored in adipose tissue provides insulation, which regulates the temperature of the body, and protective covering for some parts of the body.

Esters of propane-1,2,3-triol (glycerol) and long chain carboxylic acids, called fatty acids form lipids as follows.

If the three fatty acids in a triglyceride are the same, it is called a simple glyceride; if they are different, it is called a mixed glyceride.The chemical and physical properties of the fat depend on the nature of the fatty acid group R.Fats, which are animal in origin, are solid at room temperature and have saturated R chains with no carbon–carbon double bonds. Oils, which derive from plants and fish, have unsaturated R chains and are liquid at room temperature.

Carbohydrates (60%)
Carbohydrates have the empirical formula Cm(H2O)n.The main function of carbohydrates in our bodies is as an energy source.
Plants are the main source of dietary carbohydrates, which are produced from carbon dioxide and water by photosynthesis: 6CO2 + 6H2O → C6H12O6 + 6O2.Light supplies the energy needed for photosynthesis. Plants are able to synthesize a large number of different carbohydrates.

Sugars are low-molar-mass carbohydrates, which are crystalline solids and dissolve in water to give sweet solutions.
Monosaccharides
The simplest carbohydrates are called monosaccharides, with the empirical formula CH2O. They are either aldehydes (aldose) or ketones (ketose), with one carbonyl group (C=O) and at least two hydroxyl (—OH) groups. Pentoses have five carbon atoms and hexoses have six carbon atoms. Examples of monosaccharides include glucose, fructose and ribose. They are soluble in water as the hydroxyl (OH) functional groups are able to form hydrogen bonds with the water molecules. Monosaccharides are the building blocks of disaccharides and polysaccharides.

D-glucose is the most important monosaccharide as it is

necessary for cellular respiration.It has the straight chain

formula shown below. The carbon atoms are numbered,

starting with 1 at the top in the carbonyl group and ending

with 6 at the bottom.

Disaccharides
Disaccharides are formed in condensation reactions by the elimination of one water molecule from two monosaccharides. There are many disaccharides known, but those important to the food industry are maltose, lactose and sucrose. Polysaccharides

Polysaccharides are condensation polymers formed from monosaccharides with the elimination of water molecules. Glucose is the most important monomer of the naturally occurring polysaccharides.Polysaccharides act as energy stores. Starch is the polysaccharide in which glucose is stored in plants and glycogen is used as an energy store in animal cells.

Cellulose, a polysaccharide made from glucose molecules, is a major component of plant cell walls. As humans do not have the necessary enzymes to break the links between the glucose...
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