shelf life

Question 1

shelf life

Answer 1

period of time during which food will remain safe, retains sensory, chemical, physical microbiological characteristics and apply with nutritional info.

Question 2

Use by

Answer 2

until this date to eat the food. Related to safety.

Question 3

Best before

Answer 3

can eat it after that date but not best quality

Question 4

Growth curve

Answer 4

lag exponential  stationary  death  long term stationary

Question 5

D value

Answer 5

decimal reduction time

Question 6

Z value

Answer 6

microbial thermal death time

Question 7

Extrinsic factors

Answer 7

• Environmental factors that affect the microbiological growth
• Heat treatments cause denaturation of proteins and nucleic acids
• Chilling – affects growth and enzymatic activity
• Freezing – limits availability of water
• Atmosphere around the food product – composition and relative humidity

Question 8

Intrinsic factors

Answer 8

• pH – optimum is 6-8. Most bacteria don’t grow under 4.5.
• nutrient content – amount of water, nitrogen, energy and vitamins available speeds up process
• food structure – presence of intact biological structures which are characterised by: low water activity, deficiency of nutrients and short chain fatty acids
• redox potential - ratio of total oxidising to the total reducing power of the substance. Measure of substance capability to gain or lose electrons.
• Natural antimicrobial substances – present in essential oils. Some enzymes – lysozyme in eggs
• Added antimicrobials