Solvent extraction of soybean
- Basic principles and elements of solvent extraction
Oil extraction is to extract the oil from the embryo by wetting and infiltration, molecular diffusion and convective diffusion with solvent which can dissolve the oil. The mixture of solvent and fat is then separated to recover the solvent to obtain the crude oil. It is also necessary to recover the solvent in the soybean meal and obtain the solvent extracted meal. In this process, the basic elements are solvent and material embryo, and the solvent extraction methods and technological parameters that determine the extraction effect.
- Process of solvent extraction
Solvent extraction is the main process of oil extraction.In the extraction process, the full contact between the solvent and the embryo of the material is realized through a specific extraction device and a reasonable extraction mode, so as to achieve the purpose of fully dissolving oil and extracting oil.
（1）The way of extraction refers to the contact mode between solvent and material embryo in the process of oil extraction.Here’s three modes:
- Immersion:The material embryo is always soaked in solvent (or dilute mixed oil) to complete the extraction process.In this way, the extraction time is short, the mixed oil content is large, but the concentration is thinner, that is, the oil content in the mixed oil is less, and the residue content in the mixed oil is more.
- Infiltration:The contact process between solvent and material embryo is always in spray-permeation state. After leaching, the concentrated mixed oil with high oil content can be obtained, and the residue content in the mixed oil is also small. But the extraction time is longer.
- Soaking and spray mixed:At first, soak the material embryo and spray the permeation, which improves the extraction rate and the oil production efficiency, and reduces the leaching time.
（2）Leaching process conditions
The requirement of leaching temperature and leaching time and leaching temperature is consistent with the temperature of the material embryo, and the solvent should be preheated first.
Theoretically speaking, the longer the extraction time is, the better the effect and residual oil rate is.In the actual production, the oil leaching process can be divided into two stages. The first stage is mainly to dissolve the oil in the damaged cells by solvent. The extraction amount is large and the time is short(15~30 minutes), and the total oil content can be extracted from 85% to 90%.In the second stage, solvents are needed to penetrate into the unspoiled cells for a long time with low efficiency. The optimal “economic time” should be considered according to the actual situation.
(3) type of extractor
It is generally divided into continuous type and intermittent type, and then into soaking type, permeating type and mixed type according to leaching method.
Each kind of leaching equipment is divided into many types of structure, among which the single fou and fou group have been gradually eliminated due to the high intensity of labor due to intermittent production.
The leaching efficiency is high and the process is advanced, which has been widely used, but the cost is high.
It is generally divided into continuous type and intermittent type, and then into soaking type, permeating type and mixed type according to leaching method.
Each kind of leaching equipment is divided into many types of structure, among which the single fou and fou group have been gradually eliminated due to the high intensity of labor due to intermittent production.
The leaching efficiency is high and the process is advanced, which has been widely used, but the cost is high.
