food products and processing systems Flashcards
1
Q
food processing techniques are used to control the performance of food
temperature – heat, cold
A
- when food is heated enzymatic action increases and micro-organisms are activated
- when the optimum temperature for each is reached metabolism slows and the heat destroys them
- cooking or canning or pasteurisation use heat to sterilise or preserve food
- freezing is a preservation method that involves the storage of food at below -18 °C
- reducing enzymatic or microbial activity
- micro-organisms can survive freezing and multiply when
2
Q
exposure to air
A
- Some proteins undergo oxidative reactions. The surface of red meat turns brown when exposed to air for a long time.
- Lipids undergo ‘oxidative rancidity’ if exposed to air for a long time, especially in high temperatures. Oils are more likely to go rancid than fats.
- Fruits and vegetables are susceptible to oxidative reactions because when cut, their enzymes are exposed and react easily with air, causing the surface to brown.
- If frozen food is not properly wrapped to keep out the cold, dry air, the air will remove water from the exposed surface, resulting in freezer burn.
3
Q
pH level
A
- acids cause proteins to denature sour cream or yoghurt or vinegar are acidic ingredients that can be added to meat marinades
- the acids act as a tenderiser by breaking down the connective tissue and converting collagen to gelatin
- acids decrease the ability of starch to thicken
- acids break down the starch grains into smaller particles
- acids should be added to starch mixtures after gelatinisation has occurred
- vinegar added to the water for poaching eggs will speed up the coagulation process by lowering the temperature at which coagulation occurs
- egg white will coagulate quickly
- sensory properties are improved
- the setting of jam relies on the correct proportions of acid, sugar and pectin
- acid from the fruit is responsible for the smooth texture of jam
- acid helps prevent crystallisation during storage
- some fruits or vegetables will oxidise when cut
- enzymes in fruit or vegetables oxidise when exposed to oxygen
- an acid such as lemon juice will delay enzymic browning
- bicarbonate of soda which is an alkali which when added to an acid in the presence of water produces carbon dioxide
- it can be combined with cream or tartar
- when heated the carbon dioxide expands and causes mixture to rise
- Salt denatures and coagulates proteins.
4
Q
addition of chemicals – salt, sugar
A
- salt preserves food by drawing moisture from food cells
- salt dissolves in this moisture raising the salinity levels
- bacteria cannot multiply in this environment
- brine is a solution of salt and water
- during osmosis brine passes though the cell walls of food
- food can be preserved using brine as it inhibits bacterial growth
- strong concentrations of sugar will inhibit the growth of micro-organisms
- sugar has a dehydrating effect similar to salt
- in jam making the natural sugar level of the fruit is increased to prevent microbial growth
- sugar helps retain the colour of fruit in jam making
- this is due to its capacity to attract and hold water
- sugar prevents the fruit from absorbing water which would cause colour loss due to dilution
5
Q
removal of moisture
A
- dehydration is a process used to remove all moisture
- enzymes and microbes need water to be active dehydration is used to preserve food, evaporation removes most of the water from foods they still contain a high moisture content
- this makes them susceptible to mould growth
6
Q
manipulation
A
- Denaturation occurs when egg whites are beaten into a foam.
- Mechanical action during processing causes the proteins to stretch.
- Too much mixing or beating stretches the protein strands until they break and denature the protein.
- The greater the rate of agitation the greater the volume of foam produced.
- Agitation is essential for the creation of a smooth, gelatinised sauce.
- Stirring sugar solutions encourages crystals to develop. If a sugar solution is stirred while hot, crystallisation starts too soon.
- Some products such as fudge require beating to develop their characteristic textures. When fudge is made commercially, beating is done by machines to achieve a better product.
- Creaming butter and sugar together when preparing cake batters- the texture of the mixture becomes light and fluffy and the colour of the fat changes. As the sugar crystals are pressed into the fat.
- Rubbing in introduces air into a mixture
- Whipping cream to form a foam.
7
Q
recipe adaptation
commodities
A
8
Q
recipe adaptation
nutrition
A
9
Q
recipe adaptation
processing techniques
A
10
Q
recipe adaptation
cost
A
11
Q
product proposal
consumer profile
A
12
Q
product proposal
product purpose
A
13
Q
analysis of food product
product’s compliance with the proposal
A
- does the product comply with the product proposal
- product developers must know the product specifications
14
Q
analysis of food product
product’s sensory properties
A
- qualitative analysis such as taste testing or consumer testing is carried out during the product development
- this will determine the appeal of the product to consumers
15
Q
analysis of food product
effectiveness of the processing techniques selected
A
- quantitative tests are used to measure physical properties or size or weight or nutrient content or shelf life
- these provide a benchmark against which the product can be compared
