Extraction of oil from hemp seed using scCO2 and pressurized n-propane with high yield.
New experimental data of phase transition to the system n-propane (1) / hemp seed oil (2) were measured.
High antioxidant contents in oil extracted using pressurized n-propane.
Hemp seed oil with ratio of ω6/ω3 between 2.5 and 5.0 and solvent free, ratio deal for the consumption of fatty acids.
Hemp (Cannabis sativa L.) seeds are composed of a high oil content rich in polyunsaturated fatty acids and antioxidants such as tocopherols and carotenes, resulting in an interesting nutritional aspect. Oil from hemp seeds extracted using supercritical carbon dioxide (scCO2) as the solvent preserves the qualities described above. However, the high operating pressures and the low solubility of the oil in scCO2 significantly increase operating costs. Generally, the use of pressurized n-propane as a solvent for extraction of vegetable oils is an alternative to overcome these challenges without changing their nutritional qualities. The main objective of this work was to study the extraction of the oil from dehulled hemp seeds using scCO2, pressurized n-propane and organic solvents at atmosphere conditions, to compare some physicochemical properties of the extracts. The extraction conditions using scCO2 as the solvent were 40 and 60 °C and 30 and 40 MPa. These operating conditions of extraction are similar to those available in the literature. For pressurized n-propane used as a solvent, temperatures of 40, 50 and 60 °C and pressures of 6, 8 and 10 MPa were used. The values of the extraction pressures with n-propane were defined from the knowledge of the phase behavior measured for the system n-propane (1) / hemp seed oil (2). The values of the mass percentage yields were similar for both pressurized solvents. However, the solubility of the oil in n-propane was higher than in scCO2. The kinetics of the extractions were satisfactorily using the Sovová modeling.
Cold-pressing may be the most healthy, but it is definitely not the most efficient. Some oil remains in the pulp, which means the economics of oil per yield suffers. A recent (January 2015) article in the Chemical and Biochemical Quarterly reports on an experiment to optimize the oil yield through cold-pressing.
A January 2019 article in the Journal of Cleaner Production reports on an experiment conducted in the Indian Institute of Technology, Roorkee, India. The purpose of this experiment was to identify the most economical method of hemp seed oil extraction for industrial use.
The extraction process can cause differences in the physical and chemical composition of the oil derived. Differences in the extraction process also lead to variations in the economics of the yield.
Adding CO2 to Extract Remnant Oil
Threshing and winnowing the seeds manually or mechanically is highly important to ensure that no plant matter sticks to the seeds. The presence of plant matter can alter the chemical composition of the oil.
The hemp seed oil has several industrial uses, in addition to being a nutritious dietary supplement with amazing health benefits. There are several processes of extracting oil from hemp seeds. The process of extraction often depends on the intended use.
In fact, one of the issues with expeller screw machines is that they can get overheated when pressing harder seeds or nuts. Some companies use coolants to deal with this problem. The quality of seeds also affects the quality of the oil extracted and so does the actual pressing method.
Different types of screws are necessary for different seeds and nuts. A mistake there will affect the operation. Adjusting the distance between the press head and the screw end is another important factor. The tip size, the speed – all of these need to be just right.
In a nutshell, an experienced operator is critical to maintain the quality of the oil produced in the cold-press method.
Refined hemp seed oil is almost colorless and has no flavor. Cold-pressed organic hemp seed oil is the most nutritious as it retains most of the nutrients present in the seeds. Some of the defining characteristics of hemp seed oil are:
Comparisons were conducted in terms of physical, chemical & economic aspects.
SFE, Soxhlet, percolation, sonication, pyrolysis & treated processes were compared.
Different processes were compared for the extraction of hemp oil.
Central composite design was used to optimize the SFE & sonication parameters.