Oils and fats Flashcards
How much lipid is in seeds or fruits?
20-50% by weight
What is oil?
The energy reserve for germination
What can the residue from oil seeds be used for?
Animal feed as it is high in protein
Why are seeds easily transported and stored?
Because they have a low moisture content and won’t go off
What are the 2 methods for oil extraction from soya beans?
Direct solvent extraction and mechanical extraction
How can omega 3, 6 and 9 be identified in fatty acids?
Depending on where the double bond is on the carbon chain
What is the structure of erucic acid?
22 carbons with one double bond (22:1) at the 9th carbon (omega 9)
What are triacylglycerol’s?
Fats consisting of 3 fatty acids (2 right, 1 left) and a glycerol backbone
What are phospholipids?
Cause foaming during cooking and draw water into oil leading to hydrolysis and TAG molecules
How are phospholipids removed?
A process called degumming where they are hydrated and oil and water are separated using centrifugation
What is lecithin?
A hydratable phosphate used in the food and pharma industries
Why are fats and oils processed?
- Shelf life
- Eating quality
- Appearance
- Safety
What are the processes for fats and oils?
- Rendering
- Wet screw pressing
- High pressure screw pressing
- Pre-pressing solvent extraction
- Direct solvent extraction
At what temperature does sterilization and digestion occur at in wet screw pressing?
Sterilization: 132°C
Digestion: 90°C
What is the process for soya bean extraction?
- Beans are tempered at 24°C for 7-10 days
- Cracking and dehulling reduces the impurities and increases protein
- Conditioning at 60-80°C for 30-60 mins weakens the cell wall, reduces viscosity, coagulates proteins and sterilises seeds
Why is storage of crude oil important?
Because leaking, mixing and moisture can lead to rust or lipolysis
Why is oil refined?
- Removes contaminants
- Maintains vitamin E
What are the 3 processes for refining palm oil?
Pre-treatment (degumming), bleaching filtration and deodorization
Emulsions
A mixture of one liquid with another which it cannot normally combine smoothly with
2 examples of emulsions
Oil in water (mayonnaise) or water in oil (margarine)
What is hydrophilic lipophilic balance (HLB)?
Value of a surfactant molecule
How can HLB be calculated?
HLB= 20 x Mh/M
Mh=molecular mass of the hydrophilic portion of the molecule
M=molecular mass of the whole molecule
How many carbons are in water soluble substances?
10 or more
How many carbons are in water dispersible substances?
6-10
How many carbons are in oil soluble substances?
6 or less
What has a HLB value of 2.8-3.8?
Monoglycerides and diglycerides
What is the HLB value of lecithin?
4-10
What is the HLB value of triglycerides?
8-10
Structure of fatty acids
R group and carboxylic group
How is an ester made?
Carboxylic acid reacts with alcohol in a condensation reaction
What are stereoisomers?
Isomers with the same bonded atoms but with different forms in space
What are conformational isomers?
Stereoisomers which easily change forms around a single bond
What are configurational isomers?
Stereoisomers which can’t change forms due to double bonds
Cis vs trans isomers
Cis- 1 and 4 carbons on the same side of double bond
Trans- 1 and 4 carbons on different sides of double bond
How do double bonds effect melting point?
More double bonds the lower the melting point as chain gets shorter
