HP processing Flashcards
What are the SI and imperial units for pressure?
SI: kPa
Imperial: PSI
HP has mostly been studied as a replacement for:
What are other major applications? (2)
replacement for thermal processing
inactivate enzymes
drying
HP will mostly affect: ___ molecules, such as:
bio molecules
organisms
enzymes
molecules in food (proteins, etc)
True/False: HP will result in nutrient loss
False; nutrients largely unaffected
HP will not affect ____ bonds, but will affect ______.
This results in:
covalent
secondary, tertiary structure
CHANGE IN FUNCTIONAL PROPERTIES
how do fruits and veggies survive the extremely high pressure without being crushed?
equal pressure exerted on all sides: does not allow for deformation
Can HP be used to kill microorganisms?
Yes; but spores more resistant
the 2 principles of HP:
- Iso-static principle: application of pressure is UNIFORM, and INSTANTANEOUS
- LeChatelier’s: rxn that would cause volume decrease will be ACCELERATED by pressure
(rxn causing volume increase will be slowed)
Pressure will increase ____ and _____ of molecules.
A combination of temp and pressure will _____ kinetics.
degree of ordering
kinetic energy
accelerate
How can HP affect texture/structure of food?
high mechanical stress
can cause tissue/cell rupture
Advantages of HP: (5)
short time, instant response
lower temp
independent of size/shape (uniform pressure)
preserve quality (color, flavor, nutrients)
waste free, save energy
Can HP be used for sterilizing low acid foods?
yes, both high and low acid foods
How can HP be used as a texture modification aid?
gelatinize starch at lower temp
coagulate proteins
enhance protein abilities (due to slight denaturation, sites exposed)
What HP process has been well studied already?
HP pasteurization; guidelines have been developed by FDA
The guidelines established by ____ for HP processing dictate that:
USDA - FDA
must be 5 log reduction in PRESSURE RESISTANT PATHOGENS (E Coli, Salmonella, etc)
How could HP processing be beneficial for cheese production? (2)
Could allow for safe, “raw” milk quality cheese
(kill pathogens but not inactivate native enzymes for ripening)
improves firmness
if pressure is too high, what issue might occur?
discoloration due to denatured proteins (fish, eggs)
Sterilization with HP is still considered a _____. Why might there be concerns?
need sufficient data; normal temp destruction kinetics may not apply. (pressure sensitive vs temp sensitive microbes)
The 2 types of HP sterilization processing:
Which one is established as a method, and which one is still considered novel?
TAPS - temp assisted pressure sterilization
PATS - pressure assisted temp sterilization
(TAPS novel)
(PATS is accepted; since using temperature to kill)
compression causes temperature (increase/decrease), through ____ ____. This is a very (rapid/slow) process. Why?
increase
adiabatic heating
very rapid heat/cooling - does not involve energy transfer
How does PATS work? Why would PATS be advantageous to normal temperature sterilization?
use HP to quickly achieve necessary temperature - hold for necessary time - rapid cooling
faster, don’t need CUT since almost instantaneous, preserve quality better
What happens to freezing point as pressure is increased?
depressed
How can HP be used for freezing?
HP -> FP depressed -> water is supercooled (below 0, but still liquid) -> pressure released -> very rapid freezing -> continue cooling and allow for some crystal growth
HP freezing is advantageous because:
very rapid -> lot of nucleation -> many tiny fine ice crystals (preserve better texture)
