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{{open access}}
 
[[Image:B981.jpg|right|Cover]]
 
[[Image:B981.jpg|right|Cover]]
 
=[[Small Scale Vegetable Oil Extraction]] (NRI, 1995, 105 p.)=
 
=[[Small Scale Vegetable Oil Extraction]] (NRI, 1995, 105 p.)=
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== Chapter 1 - Oilseed composition ==
 
== Chapter 1 - Oilseed composition ==
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This section is intended to provide the reader with a basic understanding of the composition of oils and fats, and to define many of the terms used in their processing. A complete understanding of its content, although desirable, is not essential.
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Oilseeds can be thought of as mixtures of oil, meal and water. Processing removes the bulk of the oil and the product remaining is called oil-cake. Oil-cake contains the residual oil, all of the meal and some water. Since the meal is mainly composed of protein, carbohydrate and fibre, oilseed-cakes in general are excellent materials for animal feeds. Table 1 shows the composition of copra (dried coconut kernel) by weight and weight percentage terms at various levels of moisture content.
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This section is intended to provide the reader with a basic understanding of the composition of oils and [[fats]], and to define many of the terms used in their processing. A complete understanding of its content, although desirable, is not essential.
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Oilseeds can be thought of as mixtures of oil, meal and [[water]]. Processing removes the bulk of the oil and the product remaining is called oil-cake. Oil-cake contains the residual oil, all of the meal and some water. Since the meal is mainly composed of protein, carbohydrate and fibre, oilseed-cakes in general are excellent materials for animal feeds. Table 1 shows the composition of copra (dried coconut kernel) by weight and weight percentage terms at various levels of moisture content.
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Copra is usually considered to be dry when its moisture content is 6%. A typical oil content of dry copra is 65%, leaving a balance of 29% for the meal content.
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Copra is usually considered to be dry when its moisture content is 6%. A typical oil content of dry copra is 65%, leaving a balance of 29% for the meal contenttokkemanna kadu1 show the changes in oil and moisture content as a sample of copra dries out. The figures are composed so that the weight of 'dry' copra is 100 parts. Thus, 117.5 kg of wet copra containing 55.3% oil and 20% water will dry down to 100 kg of 'dry' copra containing 65% oil and 6% water. In other words, 100 kg of copra at 20% moisture only contains 55.3 kg of oil whereas 100 kg of 'dry' copra will contain 65 kg.
 
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The figures is Table 1 show the changes in oil and moisture content as a sample of copra dries out. The figures are composed so that the weight of 'dry' copra is 100 parts. Thus, 117.5 kg of wet copra containing 55.3% oil and 20% water will dry down to 100 kg of 'dry' copra containing 65% oil and 6% water. In other words, 100 kg of copra at 20% moisture only contains 55.3 kg of oil whereas 100 kg of 'dry' copra will contain 65 kg.
      
Because of the variation of oil content with moisture content, comparisons of oil contents are always made on a dry weight or 'moisture free basis' (MFB). The oil content of copra (MFB) in Table 1 is 69.1%. The following formula may be used to convert oil content (MFB) to oil content at any given moisture content:
 
Because of the variation of oil content with moisture content, comparisons of oil contents are always made on a dry weight or 'moisture free basis' (MFB). The oil content of copra (MFB) in Table 1 is 69.1%. The following formula may be used to convert oil content (MFB) to oil content at any given moisture content:
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50 x (100-10) / 100 =45%
 
50 x (100-10) / 100 =45%
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=== Extraction efficiency ===
 
=== Extraction efficiency ===
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Extraction efficiency tends to be related to the oil content of the seed. It is difficult to achieve high levels of efficiency with seed of low oil content. However, in general, large-scale processing operates with an EE of over 90%, whereas in small-scale processing, EE is usually in the range 60-65% and rarely exceeds 80%.
 
Extraction efficiency tends to be related to the oil content of the seed. It is difficult to achieve high levels of efficiency with seed of low oil content. However, in general, large-scale processing operates with an EE of over 90%, whereas in small-scale processing, EE is usually in the range 60-65% and rarely exceeds 80%.
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=== Oils and fats - origin and definition ===
 
=== Oils and fats - origin and definition ===
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Oils and fats are basically similar in composition. They are substances used by plants and animals mainly as an energy store. Some of their components are essential to metabolic processes. Many seeds are rich in fats which act as a food supply to the young seedling. The difference between an oil and a fat is that an oil is usually liquid at ambient temperature while a fat is solid. However, this simple definition can result in anomalies; coconut oil, for example, which has a melting range of 22-24°C, is usually a liquid oil in the tropics but a solid fat in temperate climates.
 
Oils and fats are basically similar in composition. They are substances used by plants and animals mainly as an energy store. Some of their components are essential to metabolic processes. Many seeds are rich in fats which act as a food supply to the young seedling. The difference between an oil and a fat is that an oil is usually liquid at ambient temperature while a fat is solid. However, this simple definition can result in anomalies; coconut oil, for example, which has a melting range of 22-24°C, is usually a liquid oil in the tropics but a solid fat in temperate climates.
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=== Triglycerides and fatty acids ===
 
=== Triglycerides and fatty acids ===
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The authors wish to thank Peerless Food Products, a division of Pura Food Products Ltd, UK, for permission to use their pictorial concept of triglyceride structure in this publication.
 
The authors wish to thank Peerless Food Products, a division of Pura Food Products Ltd, UK, for permission to use their pictorial concept of triglyceride structure in this publication.
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[[Category: CD3WD]]
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[[Category:CD3WD]]
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[[Category:Vegetable oils]]

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