Week 3 - Fat & Oil processing

Question 1

Natural sources: rich in lipids

Answer 1

Coconut, palm, kernel, sunflower, rapeseed (highest output UK) , marine, animal

Question 2

Plant: Oils/fats

Answer 2

1. Oil seeds - Rapeseed, coconut, kernel, sunflower, soybean

2. Fruit Pulp - Olives, palm fruit

Question 3

Animals & Fish: oils/fats

Answer 3

1. Lard - Pig kidney, fatback and caul
2. Tallow - Sheep fat
3. Marine oils - fish/whales

Question 4

Milk: Fats/oils

Answer 4

1. Butter from whole milk/cream.

Agitation separates butterfat (solid) and buttermilk (liquid)

Question 5

Lipid extraction from fruit

Answer 5

1. Grind to paste
2. Pressing
3. Seperate (decant or centrifuge)
4. Heating / solvent extraction

Question 6

Virgin oil extraction

Answer 6

Physical means

1. Pressed from fruit pulp
2. Has a superior flavour
3. Green colour because pure. Other oils are refined and lighter in colour

Question 7

Lipid extraction from seeds: Milling

Answer 7

1. Clean
2. Break
3. Cook 70-100C
4. Expell
5. Solvent extraction

Question 8

Lipid extraction from animals: Rendering

Answer 8

1. Wet rendering - Lard
   - Tissue heated with steam, lipid separated through decanting or centrifuging
   - White lipid / neutral flavour
2. Dry rendering - Soap
   - High heat
   - Brown lipid/ strong flavour

Question 9

Refining

Answer 9

1. Chemical / caustic refining
2. Physical refining

Improves:
Flavour
Colour
Stability
No toxicants (aflatoxins-peanut) (gossypol- cotton)

Removes:
Free fatty acids, Phospholipids, Coloured compounds, Pro-oxidants, Pesticides, Off flavours

• Bottled oil should last at least a year

Question 10

Chemical refining steps

Answer 10

1. Degumming: remove phospholipids and some protein
   - 2-3% water added + agitation at ~50 oC. Water phase removed after phase separation
2. Neutralisation: remove free FAs
   - Caustic soda added to heated fat. Aqueous solution (soap stock) removed. Washed with hot water
3. Bleaching: remove colour and pro-oxidants
   - Heated to 85 oC and absorbents added (fullers earth or activated carbons)The bleaching earth removed by filtration
4. Deodarisation: remove volatile compounds and flavours
   - Steam distillation-steam passed through oil under reduced pressure. Citric acid is often added to sequester metals

Result: refined oil/ pure foods

Question 11

Physical refining

Answer 11

1. Degumming: remove phospholipids and some protein
2. Steam distillation under high vacuum: remove free FAs and deodorisation
3. Bleaching: remove color and pro-oxidants

Result: refined oil