Dry Fractionation, in many ways, are considered to be an art. It is a combination of two subsequent steps, Crystallisation and filtration.
Dry fractionation, in short, is the physical method of separating the olein ( liquid portion of the oil) and the stearin ( solid portion of the oil) by means of a crystalliser and a filter. No chemical is used in this process, hence dry fractionation are a preferred fractionation method in many countries when it comes to vegetable oils.
Crystallisation is a separation process that consists of a slurry in which the oil which has higher IV precipitate in the form of crystals. It is the initial step in a solids processing sequence that subsequently includes solid-liquid separation and drying equipment. The slurry is being cool against a temperature gradient of cooling water flowing the the cooling pipes in the crystalliser, in which then the crystals starts to form.
Fats are made up of a large number of triglyceride each of which has its own melting point. As the temperature is reduced the different triglyceride become crystalline progressively and the fat acquires a semi-solid consistency.
In the production of RBD palm olein or any kind of oil, crystallisation is one of the crucial steps. It involves precise control of the temperature gradient of the oil and good knowledge of crystallisation.
Insoftek Sdn Bhd have vast and knowledgeable experience in the field of crystallisation and we can ensure a good crystallisation process that meets the product specification and that the desired yield is achieved.
Filtration is a separation process by which the solid is being separated from the liquid portion via a means of filter.
The filtration step is a crucial step to ensure that all the desired crystals that are formed in the crystallisation step is throughly filtered so that the desired specification of both the olein and the stearine can be achieved. These demands the user to know how to manipulate the membrane filter press well, and high knowledge in the field of filtration.
Insoftek’s Membrane filter Press will be explained in more detail here.
Process of a Filtration Cycle
The mixed pack of membrane plates and chamber plates are covered with membrane filter clothes and pressurized by the hydraulic cylinder and the feeding pressure, forcing the olein to flow through the filter cloth and to be collected in the olein tank.
Squeezing medium are used to pressurized the slurry between the plates so the yield of olein will be higher and the stearine cake will be dryer.
Once the filtration process is finish, the hydraulic cylinder will then be relieved of its pressure and the MFP will open, and allow the remaining stearine which is trapped in between the plates to drop into the stearine tank below.