Additives Flashcards
additives
substances that aren’t normally consumed as food itself but are added to food intentionally for a technological purpose.
Why are additives needed?
- Protect from spoilage
- Reduce nutrient loss
- Obtain sensory properties
Origins of food additives
- Natural – beetroot extract
- Natural identical (manmade) – vanilla essence
- Synthetic – aspartame
Preservatives
- Prevent growth by interference with cell membranes, genetics, enzymatic activity
- Give extra shelf life
- Nitrate and Nitrites used in meat products, fish and cheese
- Nitrites inhibit growth of gram negative bacteria
- Salt preserves by osmatic effect, change of pH
antioxidants
- Prevents oxidative reactions
- Vitamin C
- Seasonings such as basil or rosemary
Rancidity
- Physio-chemical change of fat leafing to the development of off-odour, off-flavour or abnormal colour
- Saturated fats resist rancidity more than unsat fats that have double bonds
- Controlling rancidity – add antioxidants, limiting factors that accelerate oxidation
hydrolytic rancidity
caused by enzymes, lipases.
Fat is decomposed to fatty acids and glycerol.
Affects products with fat and water – butter
oxidative rancidity
oxygen binds to unsat fatty acids
aldehydes and ketones giving off flavour.
Enzymes, metal ions speed up reaction.
Plant and fish oils susceptible
ketonic rancidity
produces floral off flavours.
Affects short and medium sized fatty acids (milk and coconut)
catalysed by enzymes and oxidation.
Stabilisers
preserve physio-chemical properties, protects from colour change, increase binding capacity.
Emulsifiers
creates emulsion, slows down staling
Example applications of emulsifiers
- Bread – softer crumb structure
- Chocolate – lecithin
- Ice cream – smoother texture – lecithin
- Margarine – disperse the water
- Gelling agents – pectin to make jam
