2 Industrial Plant Oil Extraction
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is about 14.18%. Through theoretical calculation and the one-dimensional pressing
device, the conditions of cold pressing process and performances of fruits from
Swida wilsoniana had been studied. The results show that Swida wilsoniana fruits
dried through natural weather are more suitable for direct pressing, which guarantees
a higher quality of oils. The volume of fruits fed into pressing device had little effect
on pressures of oil squeezed out, fruits crushed, and critical compression, and the
value of those pressures were 55.7, 71.5, and 80 MPa individually. At the critical
pressure of 80 MPa and the compression ratio of 3.14, residual oil of meal is 6.5%.
The fruits oil has about 72% unsaturated fatty acids, of which approximately oleic
acid is 29.83%, linoleic acid is 39.15%, and linolenic acid is 2.59%.
2.6.3.1 Main Contents of Swida wilsoniana Fruits and the Theoretical
Basis of Direct Pressing
Oilseeds mainly consist of fat, protein, cellulose and water, and these substances
affect the physical strength of oilseeds. Swida wilsoniana fruits from different habitats and species are collected and measured by conventional chemical analysis methods for contents of crude oil, moisture, crude protein, and cellulose. The main contents
of fruits from Swida wilsoniana were analyzed through chemical means using 46
samples from different areas. The fruits have an average moisture content of about
8.19% after they are naturally dried. The oil content is about 28.02% (dry basis) or
more. The protein content is 7.25% (dry basis) and the cellulose content is about
14.18%.
For oilseeds, moisture content is a convenient adjustment factor, whose change
will directly lead to changes of contents in oil, protein, cellulose, and other indicators.
Besides, physical strength will be changed. Therefore, control of moisture content
of Swida wilsoniana fruits is an important means to regulate conditions of the cold
pressing process. Changes of moisture content generally follow the rule that high
temperature is suitable for low moisture content while low temperature is suitable
for high moisture, and the relation between moisture content and temperature can be
calculated according to the N.B. empirical formula, which is as follows:
c = (14 − 0.1 ∗ T ) ∗ k
(2.7)
In the above formula, C (%) stands for oil content; T (°C) stands for pressing
temperature; k stands for correction factor, which can be expressed by the formula k
= (100-M)/55, in which M (%) stands for the oil content of oilseeds.
Taking a low temperature of 70–80 °C, we can get the best conditioned fruits
whose moisture content ranges from 7.85 to 9.16%, which is just similar to the
natural moisture content of fruits. So, it is suitable for Swida wilsoniana fruits to be
directly fed into the press, and it provides theoretical support for us to focus on the
direct pressing process.
83
is about 14.18%. Through theoretical calculation and the one-dimensional pressing
device, the conditions of cold pressing process and performances of fruits from
Swida wilsoniana had been studied. The results show that Swida wilsoniana fruits
dried through natural weather are more suitable for direct pressing, which guarantees
a higher quality of oils. The volume of fruits fed into pressing device had little effect
on pressures of oil squeezed out, fruits crushed, and critical compression, and the
value of those pressures were 55.7, 71.5, and 80 MPa individually. At the critical
pressure of 80 MPa and the compression ratio of 3.14, residual oil of meal is 6.5%.
The fruits oil has about 72% unsaturated fatty acids, of which approximately oleic
acid is 29.83%, linoleic acid is 39.15%, and linolenic acid is 2.59%.
2.6.3.1 Main Contents of Swida wilsoniana Fruits and the Theoretical
Basis of Direct Pressing
Oilseeds mainly consist of fat, protein, cellulose and water, and these substances
affect the physical strength of oilseeds. Swida wilsoniana fruits from different habitats and species are collected and measured by conventional chemical analysis methods for contents of crude oil, moisture, crude protein, and cellulose. The main contents
of fruits from Swida wilsoniana were analyzed through chemical means using 46
samples from different areas. The fruits have an average moisture content of about
8.19% after they are naturally dried. The oil content is about 28.02% (dry basis) or
more. The protein content is 7.25% (dry basis) and the cellulose content is about
14.18%.
For oilseeds, moisture content is a convenient adjustment factor, whose change
will directly lead to changes of contents in oil, protein, cellulose, and other indicators.
Besides, physical strength will be changed. Therefore, control of moisture content
of Swida wilsoniana fruits is an important means to regulate conditions of the cold
pressing process. Changes of moisture content generally follow the rule that high
temperature is suitable for low moisture content while low temperature is suitable
for high moisture, and the relation between moisture content and temperature can be
calculated according to the N.B. empirical formula, which is as follows:
c = (14 − 0.1 ∗ T ) ∗ k
(2.7)
In the above formula, C (%) stands for oil content; T (°C) stands for pressing
temperature; k stands for correction factor, which can be expressed by the formula k
= (100-M)/55, in which M (%) stands for the oil content of oilseeds.
Taking a low temperature of 70–80 °C, we can get the best conditioned fruits
whose moisture content ranges from 7.85 to 9.16%, which is just similar to the
natural moisture content of fruits. So, it is suitable for Swida wilsoniana fruits to be
directly fed into the press, and it provides theoretical support for us to focus on the
direct pressing process.