Unit 1: Chapter 6 - Plant Oils Flashcards
Extracting Vegetable Oil
From the process of photosynthesis, plants produce useful chemicals, such as vegetable oils in the SEEDS of a plant.
Farmers collect these seeds and crushed and pressed to extract their oil. Impurities are then removed and then processed to make useful products. One example would be of rapeseed oil.
Alternatively, we can extract vegetable oils using STEAM. One example is through DISTILLATION. The plants are put in boiling water. As the mixture evaporates together, they are collected by condensing them. The water and other impurities are removed to give pure oil. One example would be of Lavender plants.
VEGETABLE OILS AS FOODS AND FUELS
Veg oils are very important as they provide important nutrients and provide a great deal of energy. This makes them great sources of food and bio-fuels.
All oils contain carbon atoms with hydrogen atoms, however veg oils contain carbon-carbon double bonds (C=C). We can detect unsaturated oils in bromine water where is will go clear.
Cooking with Vegetable Oils
WATER VS. OIL
Oils cook quicker than water.
The outside becomes crispier and colours more.
The inside should be softer if you don’t cook it for too long.
When cooking oils, the food absorbs some of it. The content of energy of fried food is much higher than that of boiled food.
HARDENING UNSATURATED OILS
- NICKEL CATALYST
- Reacting with HYDROGEN GAS
- 60C
The adds more hydrogen atoms to the molecule and will allow the oil to set at room temperature. The unsaturated oils will also lose the carbon-carbon double bond. These are also called HYDROGENATED OILS.
Everyday Emulsions
Because oils and water have different densities, it does not mix together as one. You have to use an EMULSIFIER to blend the mixture together. A good example of an emulsion is milk. Mayonnaise is also an emulsion
Another popular emulsion is ice-cream. If the ice-cream melts, the emulsion separates and when you freeze the ice-cream again, it will be crunchy. This is because the water freezes separately.
Lotions, cosmetics and lipsticks are also types of emulsions.
Water-based paints can be emulsified with oil droplets for indoor plaster.
HOW DOES AN EMULSIFIER WORK?
An emulsifier consists of two parts:
- Hydrophilic
- Hydrophobic
The head (negative charge) hydrophilic part an connects to the water.
The tail is hydrophobic and thus connects to the oil, instead of the water.
The oil droplets repel each other and spread out instead of separating into two different layers.
Food Issues
Saturated oils are bad for you, whereas unsaturated oils can be actually good for you. They reduce the chances of receiving heart disease. Consuming vegetable oil will lower you ‘bad’ cholesterol levels.
