FATS AND LIPIDS
What is Lipids?
Lipids are a type of organic compound that are formed as a solid or liquid and come in forms of either oils, fats, waxes or sterols (Biology-Online, 2015). They are a diverse group of molecules and share the properties of being carbon based and essential for living alongside carbohydrates, proteins and water.
Lipids have various function within an animal’s body and are composed of both fatty acids and glycerol. They store energy, help to insulate the body and cushion and protect many bodily organs (Bailey, 2014).
A lipid is a non-soluble molecular compound which is comprised of hydrogen and carbon, they are of crucial importance for energy storage and cell membrane development (Lipids, 2015).
Fats and oils are both defined as lipids and are known as complex organic products which occur in two forms:
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Single lipids
These are short, medium and long chain fatty acids and esters of fatty acids with glycerol of which the triglycerides (three fatty acids + glycerol) are most commonly associated with food.
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Conjugated lipids
These lipids are combined with other products e.g. phospholipids and lipo-proteins (Agar, 2001).
Glycerol is a simple sugar which means it is easy to break down and is also used to create Adenosine Triphosphate (usually referred to as ATP) which is the body’s natural energy source, especially for animals. Fatty acids are used to aid the growth and development of the cell member structures within the body (Fitday, 2015).
Chemical and physical properties...
Chemical properties:
Lipids are important within the food science industry and are a major source impact for the dietary energy but also affect the nutritional value, taste and texture of feed stuffs (Veloz, 2015). They fall into two categories; Saturated fats and unsaturated fats both which will identify the bonding of carboxylic chains (Desko, 2015). With lipids they are similar to carbohydrates which contain carbon, hydrogen and oxygen, however the proportion of oxygen in lipids is much lower. In addition to this, phosphorus is also found in some of the more complex lipids (Admin, 2009)
There are approximately forty naturally occurring fatty acids. The fatty acids without carbon-carbon double bonds are classified as saturated and those that contain carbon-carbon double bonds are classified as unsaturated (Chemistry, 2015)
Inside lipids are molecules, these molecules determine their function e.g. insoluble triacylglycerides are used as the predominant storage form of chemical energy within the body. In comparison to polysaccharides (glycogen) the C structure in the chains of the triacylglyceride are at a more reduced state.
Animal’s bodies are obtained through oxidising the carbon-based molecules to carbon dioxide and water (Lipid structure, 2013).
Fatty acids are the buildings block of triacylglyceride which is the most common molecule found in both fats and oils. In each triacylglyceride, there is a glycerol molecule which has three fatty acids attached to it by ester bonds. The fatty acids are long chains of hydrocarbons with polar ends (opposite). When the carbon chain is hydrogenated, this is when the fatty acid is referred to be a saturated fatty acid as an unsaturated fatty acid contains double bonds along the carbon chain. The more saturated fatty acids are, the higher the melting points; fats that contain a higher percentage of unsaturated fatty acids have lower melting points and are liquid (oil) at room temperature (Carbprin, 2015).
Physical properties:
Lipids are considered of being hydrophobic or insoluble in water. The physical properties of lipids have given them an essential role of the texture, appearance and healthfulness of different foods eaten by an animal (Veloz, 2015).
In relation to their physical properties they are known as a diverse group of molecules. Some lipids are long chain hydrocarbons which have polar ends (fatty acids) and others are mixed combinations of porphyrin rings (cholesterol). The majority of lipids are insoluble in water. When comparing fats and oil, they can be differentiated by the physical state whilst at room temperature. Fats which consist mainly of saturated fatty acids are solid at room temperature and oils are liquid at room temperature. This is because they are made up of a long chain of unsaturated fatty acids (Carbprin, 2015).
Please see diagram below of example:
Sources of lipids:
Fats occur in both animal and plants foods, e.g. pork fat and sunflower oil.
Common sources of lipids include omega-3 fatty acids such as fish oils (salmon, herring) also omega-6 fatty acid sources which include, pork fat, chicken fat, safflower and sunflower oils also corn and vegetable oils (soybean) (PetMD, 2015).
carbon-carbon double bonds
(Google Images, 2016)
Triglyceride
(Google Images, 2016)
Fat-Solid Oil-Liquid
Fats within the diet are necessary in order to maintain the animal’s body. The dietary fats exist mainly in the form of triglycerides and are classified as high-energy food. Consumption of greater amounts of saturated fats is related to higher levels of cholesterol in the blood which means that animals may be at a great risk of heart disease (Chemistry, 2015).
Essential fatty acids (EFA) are fatty acids which that the animal cannot synthesize themselves and so therefore it is essential for the animal to be provided with these in their diet. An example of an essential fatty acid in a dog and cat may include; Linolenic acid and Arachidonic acid (Admin, 2009).
The uses and functions of lipids are important to understand for an animal’s diet as the lipids have several biological functions, these include;
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Serve as a source for fat soluble vitamins e.g. A, D, E, K.
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The layers of fat within the subcutaneous (under the skin) layer provides insulation and protection
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Lipids are storage compounds, triglycerides serve as reserve energy of the animals body – major energy source
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Regulators for membrane permeability
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It has improved palatability of food for animals
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Protection for internal organs (e.g. offer fat shields for the kidneys)