A food can be
preserved (under refrigerated or nonrefrigerated con-ditions) by several
methods.
1.
lowering of its water activity (by dehydration,
cooling,or addition of salt/sugar),
2.
removal of air/oxygen,
3.
fermentation, and
4.
removal/inhibition/inactivation of
microorganisms.
The properties of
importance in thermal processing of foods are
1.
physical (density, viscosity, and glass
transition temperature),
2.
thermal (thermal conductivity and specific heat
for conventional heating),
3.
electrical (electrical conductivity for ohmic
heating), and
4.
dielectric(dielectric constant and loss factor
for microwave and radiofrequencyheating).
Thermal processing of
foods.
1.
steam injection,
2.
steam in-fusion,
3.
tubular heat exchangers,
4.
shell and tube heat exchangers,
5.
plate heat exchangers,
6.
scraped surface heat exchangers,
7.
extruders,
8.
ohmic heaters,
9.
infrared heaters,
10.
adiofrequency heaters,
11.
microwave
12.
heaters,
13.
variations/combinations of these
Microorganisms are
classified as
1.
aerobes and anaerobes
2.
psychrotrophs,mesophiles , or thermophiles
3.
obligate or facultative
persamaan yang berlaku pada mikroorganisme:
N=No*10^(-t/D,T)
D,T=D,ref*10^[(T,ref - T)/z]
k=Ae^(-E,a/RT)
Process safety and
product quality
1.
making sure that theFvalue is at least the minimum
value --> F=
2.
minimizing the Cv alue of the critical quality --> C=10^[(T,ref - T)/z,c]*t
