Oils and fats: Pressing and SOlvent extraction

Mechanical pressing and Solvent Extraction

Where in a cell is oil extracted from?

Oleosomes, oil bodies with a membrane

2 methods of extraction

Pressinng and solvent extraction

Can pressing and solvent extraction be used together for maximum extraction?

yes

What kinds of oilseeds are best for the pressing extraction process?

Oilseeds with a plastic consistency and a relatively high oil content

What does the term ‘Plastic consistency’ mean?

The opposite of elasticity; non-reversible deformability

What is a cheaper method of extraction, Pressing or solvent extraction?

Pressing, because you dont need to pay for expensive solvent

Please outline the steps for mechanical pressing

1. Conditioning

2. Cleaning

3. Crushing

4. Cooking

5. Pressing

What is the conditioning step of pressing

step 1: conditioning: Altering moisture content to improve plasticity and maximise oil extraction

which step of pressing is this?
step 1: Altering moisture content to improve plasticity and maximise oil extraction

Conditioning

What does the cleaning step of extraction entail?

step 2: removing outer particles from the oilseed.

what kind of processes are solvent extraction and mechanical pressing?

extraction processes

what is step 2 of the mechanical pressing process

cleaning

what does crushing in the mechanical pressing process entail?

step 3: no oil is extracted here, only crushing the oilseeds to create more smaller particles for a higher sa.

what is step3 of the mechanical pressing process

crushing

What does the cooking process of mechanical pressing entail?

step 4: heating the crushed oilseeds in a 70C warming pan/oven

what is the purpose of the cooking step in mechanical pressing, and how does it relate to extraction?

Step 4: To denature proteins that would otherwise stabilise water-oil emulsions

Decreases oil viscosity for easier extraction

Coalesces fat droplets

Increases oilseed plasticity

what does it mean when a protein stabilises water-oil emulsions?

essentially prevents water and oil from separating over time, ensuring it remains a mixture.

what is step 4 of the mechanical pressing process?

Cooking

What is step 5 of the mechanical pressing process?

Pressing

What does pressing entail in mechanical pressing

subjecting cooked seeds to high pressure in continuous screw presses or expellers

Several pressings are done.

Here is a typical screw extruder, what step of mechanical pressing is this involved in?

Step 5, the pressing process

Name the object shown in the graph, and label points: E, 1, 2 and 3

Screw extruder
e; entry point for oilseeds

1: filter

2:main body

3: exit for pressured oilseed residue

What kinds of solvents must be used in solvent extraction?

lipophilic or non polar solvents

What kind of oilseed is almost exclusively prepared by solvent extraction?

soya bean

Please outline the solvent extraction process

1: Tempering; seeds are heated to increase plasticity

2; Flaked between rolls to increase surface area

3; treated with non-polar solvent: light petroleum fraction, hexane, alcohol

4; solvent-oil separation by distillation under a vacuum

5; last remnants of solvent removed by injection of slightly superheated steam

What is step one of solvent extraction?

Tempering: seeds are heated to increase plasticity

What is step two of solvent extraction?

seeds are flaked between rolls to increase surface area

What is step three of solvent extraction?

Treat the seeds with a non-polar solvent

What are the most common solvents used in solvent extraction?

light petroleum fraction, alchohol, and hexane

what is step four of solvent extraction

separation of water-oil mixture by diffusion

what is step five of solvent extraction?

Injection of slightly superheated steam to ensure complete removal of solvent