Agriculture Reference
In-Depth Information
Thermocouple
Sample
holder
High
pressure
vessel
Data acquisition
system
High pressure
transducer
Water bath
High pressure
pump
High pressure
fluid
Recirculating
pump
Figure 5.1.
Schematic of high-pressure processing technology (source: Adapted from Patazca et al., 2007).
operating worldwide, with the volumes of the HPP equip-
ment varying from 35 to 360 liters (Tonello-Samson, 2007).
Furthermore, additional parameters are incorporated with
the basic equipment to broaden the scope of the technol-
ogy. Pressure-shift freezing is another form of use of high-
pressure technology. In Japan, the Meidi-ya company is
manufacturing jams, jellies, and sauces using products pre-
filled into flexible plastic containers which are subsequently
loaded into a vessel for pressure treatment. Other manu-
facturing configurations consist of either direct or indirect
pressurization of pumpable foods or drinks and subsequent
aseptic or clean packaging (Earnshaw, 1996).
Schematics for HPP technology and commercial high-
pressure equipment are illustrated in Figs. 5.1 and 5.2, re-
spectively. Liquid foods can be compressed directly in a
pressure vessel. The food material packed in flexible pack-
aging material is placed in the pressure vessel and closed;
the pressure transmitting medium is applied after the de-
gassing of the vessel, and pressure is applied through a HP
pump. The resulting volume change due to compression
is about 4% at 100 MPa at room temperature and 15% at
600 MPa. The food remains under pressure for specified
treatment time, and then the chamber is decompressed, and
treated food is taken out.
Effect of high-pressure treatment on quality
HPP has extensively been used on fruits purees, juices,
jams, or many other fruit products for pasteurization
or high-pressure freezing. Some HPP fruit products are
already on the market. However, the technology has not
Figure 5.2.
Commercial high-pressure processing
equipment (courtesy of Avure Technology).
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