Industrial pressing of oilseeds is realized using continuous screw presses. The presses are fed with crude or pre-treated seeds. Types of pre-treatments (thermal pre-treatment, size reduction, mechanical sieving, etc.) differ for various seed species (Carr 1997). Each type of seed pre-treatment provides its own advantages.
Does screw pressing increase oil yield?
Screw pressing of entire seeds leads to higher oil yields (maximum 85.7 % for entire seeds and maximum 72.01 % for dehulled seeds). Behavior according to moisture content is also different; for entire seeds, oil yield decreases with increasing moisture content whereas an optimum oil yield can be found for dehulled seeds.
At what temperature should peanut oil be pressed?
Before pressing, it is necessary to dry the peanuts repeatedly with a hot air drier to control the water content within the range of 5¨C6% and then bring down the temperature of the oil quickly with cool air to a temperature below 40°C.
What is the production flow of cold pressing peanut oil?
The production flow of the cold pressing process of peanut oil is shown in Fig. 3.3. The temperature rises from 60 to 90°C during the process, and the oil/residual oil ratio of the system decreases gradually, reaching 4.5% at 90°C (as shown in Fig. 3.4).