Food Technology

Question 1

What is food technology?

Answer 1

The study of how different foods can be used snd made into food products from production to consumption

Question 2

What is the aim of food technology?

Answer 2

To minimise growth of micro-organisms during storage
(promote longer shelf-life)
(reduce hazards from eating food)

Question 3

Role of vet in food technology

Answer 3

Inspection of animal origin food establishments (Abattoirs)
Microbiological testing
Legislation

Question 4

Intrinsic factors affecting microbial behaviour in foods

Answer 4

Nutrient content
Natural antimicrobial substances
pH and buffering capacity
O/R potential
Water activity
Mechanical barriers e.g. skin

Question 5

Extrinsic factors affecting microbial behaviour in foods

Answer 5

Temperature
Relative humidity
Atmospheric gases
Time

Question 6

How nutrient content affect microbial activity in food

Answer 6

Water is required for all microorganisms
*Higher requirement of water for moulds
Need a source of energy
* Sugars, alcohols, amino acids, starch, cellulose, fats
Source of nitrogen
* Amino acids

Question 7

Natural antimicrobial substances in foods

Answer 7

Essential oils in some plant spp.
* Eugenol in cloves
* Allicin in garlic
Cows milk contains:
* Lactoferrin
* Conglutinin
* Lactoperoxidase
Lysozyme in eggs and milk

Question 8

pH change and buffering capacity

Answer 8

Most microorganisms grow around pH 7.0
Very few grow < 4.5
Buffered foods resist changes in pH
* Meats are more buffered than veg
Moulds and yeasts can grow at lowest pH

Question 9

Redox Potential

Answer 9

Ease of which the substrate gains of loses e-
(OiL RiG)
Potential difference is expressed as mV
Aerobic organisms require oxidation (+ve Eh values)
Anaerobic organisms require reduction (-ve Eh values)

Question 10

What determines O/R

Answer 10

Redox potential of original food
Poising capacity
Oxygen tension of atmosphere

Question 11

Water activity

Answer 11

How efficiently water can take part in chemical reactions
Reducing available water can preserve food
Most pathogens stop growing at 0.9aw

Question 12

Psychrotroph temperatures

Answer 12

Can grow <7
Optimum is 20-30

Question 13

Psychrophile temperatures

Answer 13

Optimum < 15

Question 14

Mesophile temperatures

Answer 14

Can grow 20-45
Optimum 30-40

Question 15

Thermophile temperatures

Answer 15

Can grow >45
Optimum 55-65

Question 16

What is the D value?

Answer 16

Decimal Reduction Time
Time for population to deplete by 90% at a specific temperature
E.g. D121 - Time required to kill 90% of population at 121 degrees

Question 17

1D = ?
2D = ?
3D = ?

Answer 17

90% of original population
99% of original population
99.9% of original population

Question 18

What is the Z value?

Answer 18

Temperature change required for D value to change by a factor of 10

Question 19

What is the most important gas for microbial activity in food?

Answer 19

CO2
Ozone is also important - strong oxidising agent

Question 20

How does ozone affect high lipid food?

Answer 20

Increases rancidity due to fat oxidisation

Question 21

How doe relative humidity affect microbial behaviour?

Answer 21

High temp = Low RH
Low temp = High RH
Foods that undergo spoilage from moulds and yeasts should be stored in low RH

Question 22

Reasons for rejecting food as spoiled

Answer 22

Organoleptic changes
Chemical changes
Physical damage
Freezer burn
Staling
Ripening foreign bodies
Chemical contamination - often cleaning chemicals

Question 23

Organoleptic changes

Answer 23

Most common cause of spoilage
Acts on sensory organs
Causes unacceptable changes in:
Taste
Texture
Odour
Appearance

Yoghurt is a spoiled food that is safe to eat

Question 24

Chemical changes

Answer 24

Rancidity from chemical oxidation of fats
Browning of fruits and veg in air
Meat rejected due to colour change
* Dark colour due to further oxidation from myoglobin to oxymyoglobin to metmyoglobin

Question 25

Physical damage

Answer 25

Caused by improper handling of goods
could be related to biological risk

Question 26

Freezer burn

Answer 26

Caused by poor wrapping during freezing
Leads to loss of moisture

Question 27

Staling

Answer 27

Process by which bread reduces in palatability by loss of water

Question 28

In what products does over ripening occur?

Answer 28

Fermented meats
Fruits and veg
Cheeses