C1b Oils, Earth and Atmosphere Oils from Plants

Solar powered Plants use energy from the sun: energy from sun 6CO2 + 6H20 C6H1206 + 6O2 Plants turn glucose into other chemicals Can be useful to us

Vegetable oils Rapeseed – vegetable oil Collect seeds after plant has flowered Crushed, pressed to extract oil Impurities removed Important food stuff Extraction using steam Lavender oil - distillation Plants boiled in water Steam contains oil Collected, water and impurities removed

Oils as foods Contain loads of energy Hydrocarbon molecules May be saturated or unsaturated Tested with bromine water Food/oil Energy in 100g (Kj) Vegetable oil 3900 Sugar 1700 Animal protein (meat) 110

Cooking with veg oils: Boiling point Temperature depends on forces between molecules Bigger force = higher boiling temperature Molecules in veg. oils are much larger than water molecules Bigger forces Higher boiling point Higher temperatures = different reactions Food cooks differently

Soak it up Why can too much fried food be bad for you? Food absorbs some of the oil it’s cooked in Veg oils very high in energy Increases the energy content of the food Needs to be used

Hydrogenated oils Unsaturated oils are liquid at RToC Double bond stops molecules fitting together well Reduces the forces between molecules Boiling point can be increased Adding hydrogen, replacing double bonds Molecules fit together better Increased forces = higher boiling point

Hydrogenated oils Higher melting point – solid at RToC “Hardening” of vegetable oils Hydrogenated oils Can be used to make spreads, margarine etc.

Smooth operator Texture of food is very important Ice cream, mayonnaise etc. Mixture of oil and water – don’t mix! Can be persuaded Very small droplets of oil Spread throughout water Emulsion Milk is an everyday example

Emulsifiers Encourages oil and water to stay mixed Egg yolk in mayonnaise Gives a thick texture

Emulsion paint Emulsion paint is NOT an emulsion! It is a powder suspended in a liquid Colloid

Preservation Need to make food last longer – preserve it Salt (remove water) Vinegar (pickling) Alcohol (kill microbes) Knowledge of chemistry Also use chemistry to improve flavours or appearance

Food additives Substance added to a food Approved for use in Europe Given an ‘E’ number Identify them rather than name them Eg.E102 is tartrazine (yellow colouring) E220 is sulphur dioxide (preservative) Six types of additive

Food additives E number Additive What it does Example E1xx Colours Improve the appearance of food. Can be natural, brownings or additives E150 – caramel colour E2xx Preservatives Helps food last longer = less wastage E211 – sodium benzoate E3xx antioxidants Help stop food reacting with oxygen E300 – vitamin C E4xx Emulsifiers, stabilisers and thickeners Help improve the texture of food E440 – pectin E5xx Acidity regulator Helps control pH and taste E501 – potassium carbonate E6xx Flavourings Blends flavours of food – sweet, sour, bitter, salt and savory E621 – monosodium glutamate

Detecting additives Food scientists – investigate what has been added Complicated versions of simple techniques Chromatography How well something dissolves in a solvent Solubility determines how far they move across a surface Separation technique

Fuels from plants Biodiesel - Name given to fuel made from vegetable oil Oil is treated to remove unwanted chemicals Used on its own Mixed with diesel refined from crude oil Other by-products: Solid material = high energy cattle feed Glycerine = used in soap

Benefits and advantages Biodiesel gives off carbon dioxide when burnt Biodiesel is grown Crops used absorb carbon dioxide as they grow C02 produced is absorbed by plants Carbon neutral No greenhouse gases Very clean in terms of pollution Very little sulphur dioxide Not harmful to animal and plant life If spilled, breaks down much faster than ‘normal’ diesel

Other bio-fuels Ethanol (alcohol) Gives off CO2 when burnt Fermenting sugar from sugar cane Used in Brazil a lot – added to normal petrol Gives off CO2 when burnt Absorbed by plants during photosynthesis Ethanol can also be made from ethene C2H4 + H20  C2H5OH Not carbon neutral