Food preservation Flashcards
Examples of reactions in food
Microbial reactions
Chemical or biological reactions
Browning reactions
How does cooking effect food?
Enhanced digestibility
Increased bioavailability
Removes antinutrients
How can cooking be detrimental?
Loss of nutrients
How does blanching help to preserve foods?
Reduced enzyme activity and reduces microbial numbers
What is the first law of thermodynamics?
Heat is neither created nor destroyed
What is the second law of thermodynamics?
Heat flows from high energy levels to low energy levels (entropy always increases)
What are the 3 types of heat transfer?
Conduction
Convection
Radiation
What is conduction?
Particles transmit kinetic energy to other particles by collision
What is convection?
Heat transfer associated with motion of the medium
What is radiation?
Heat transfer by electromagnetic radiation
What is Fourier’s equation?
Heat flux= Thermal conductivity x Area x Temperature difference / Thickness
What is thermal conductivity?
Measure of the rate a material will conduct heat
What is conductance equal to?
1/Resistance
What is U?
Heat transfer coefficient= Thermal conductivity/Thickness
Why must conductance be converted to resistance to be summed?
Because conductance is limited to its lowest value
