cooking with vegetable oils l.o: to understand why people cook foods in oil and how they can be...

Cooking with Vegetable OilsCooking with Vegetable Oils

L.O: To understand why people cook foods in oil and how they can be turned into vegetable spreads

• Chip pan fire – the oil is really hot!

AnagramsAnagrams

• nkalea• eatatsdur• iilsttioladn• onoremm• uoisantrnatu• plmeroy• uredaanstut• droanbroych• nkgricca

• Alkane• Saturated• Distillation• Monomer• Unsaturation• Polymer• Unsaturated• Hydrocarbon• Cracking

What should you cook What should you cook potatoes in? oil or water?potatoes in? oil or water?

• The difference is that oil is at a much higher temperature - the molecules in oils are much bigger so the forces between molecules are much larger, making it boil at a higher temperature.

• During cooking permanent chemical reactions occur in the food this is why the taste changes

Why does frying cook potatoes and other foods quicker than boiling them?

What is the impact of oils on What is the impact of oils on your diet?your diet?

Clogged ArteriesClogged Arteries

Supersize vs superskinny

http://www.youtube.com/watch?v=y4jHNrg9KYU&feature=relmfu

Which would be the best fat to Which would be the best fat to use in food?use in food?

Oil Melting point (˚C)

Volume of bromine water reacted (cm3)

1 2 3

Olive -5 22.6 22.4 22.2

Palm 34 14.7 15.3 15

Sunflower -16 34.6 34.5 34.7

rapeseed -11 27.1 27.5 26.7

a. Calculate the mean volume of bromine water reacted for each oil

b. Explain which oil is the most unsaturatedc. Explain the relationship between amount of unsaturation and

its melting pointd. Coconut oil reacted with 3.2cm3 of bromine water in a similar

experiment. Predict giving reasons, the state of this oil at room temperature

Making margarineMaking margarine

• Unsaturated vegetable oils are usually liquid at room temperature:

Can you explain why?

the carbon-carbon double bonds stop the chains fitting together very well.

Removing some of the double bonds and adding hydrogen increases the melting point. This is called hydrogenation.

Can you explain why butter is more solid at room temperature than margarine?

Turning unsaturates into Turning unsaturates into saturatessaturates

The unsaturated fat is hardened by “hydrogenation”. Hydrogenated oils have a higher melting point and so are solid at room temperature.

600C, Nickel catalyst

Trans-fatsTrans-fats

• What are trans fats?• How are trans-fats made?• What are the health problems

associated with trans-fats?• Do modern margarines contain

trans-fats?

What is this?What is this?