2- Food technology 1 Flashcards
Define Food Technology
Study of how different foods can be used & made into food products from production to consumption
Goal of food preservation
Minimise growth of microorganism during storage period thus promoting longer shelf life & reduced hazard
Name the important nutrients microorganism require
Water
Source of energy
Source of nitrogen
Vitamins & related growth factors
Minerals
What pH do most microorganism grow best at?
Values around 7
The Oxidation/Reduction potential of a substrate may be defined generally as …
The ease with which the substrate looses or gains electrons
Loose electrons = oxidised
Gains electrons = Reduced
What determines O/R potential?
Poising capacity = Resistance to change
Oxygen tension of atmosphere around food
Access that the atmosphere has to food
Microorganism
What is the oxidation-reduction potential (Eh) dependendent on?
pH of the susbtrate (rH value)
What is water activity?
Measure of how efficiently the water present can take part in chemical reaction
Difference between Psychotrophys & Thermophiles
Psychotrophs grow well at or below 7 degrees but have an optimum temp of 20-30 degrees
Thermophiles grow well at or above 45 degrees optimum is 55-65 degrees
What temp is optimum for psycrophiles
15 degrees or lower
What is a D value?
The time required to kill 90% of bacterial population at a certain temp
What is the Z value?
Temperature change that is required to change D value by a factor of 10
What gas is the most important gas used to control microorganism in food?
Carbon dioxide
Oxygenation of myoglobin to oxymyoglobin and mletmyoglobin produces what colours in meat
Oxymyoglobin = Bright red Metmyoglobin = Brown
List 4 processes of food spoilages
Freezer burn
Chemical change
Ripening
Staling
