Biomedical Engineering Reference
In-Depth Information
resistant to pressure inactivation at their optimal growth temperatures (Escriu and
Mor-Mur
2009
; Campus
2010
). Like responding to other environmental stresses,
bacteria are able to develop resistance to high pressure. Vanlint et al. (
2012
) reported
that, among strains of
Escherichia coli
,
Shigella fl exneri
,
Salmonella enterica
serovars Typhimurium and Enteritidis,
Yersinia enterocolitica
,
Aeromonas hydroph-
ila
,
Pseudomonas aeruginosa
, and
Listeria innocua
tested, some
E. coli
strains
were able to acquire a stable HPP resistant trait that lasted for >80 generations. HPP
has also been studied for potential to inactivate foodborne viruses such as hepatitis
A virus (Kingsley et al.
2002
,
2006
; Grove et al.
2009
), human norovirus (Li et al.
2013
), and enteric viruses (Hirneisen and Kniel
2013
). The high pressure appears to
denature capsid proteins in the virus which render the virus incapable of binding to
the host cells (Kingsley
2013
).
The initial development of HPP focused on pasteurization application that aimed
at inactivating vegetative bacterial cells. As the technology advances, research are
expanding to examine the use of high pressure and higher temperatures for steriliza-
tion application in producing low-acid canned foods which are currently produced
mostly by heat processing. The inactivation of bacterial spores by high pressure
requires the application of higher temperatures (mostly >100 °C) than those used
for inactivating vegetative bacterial cells (Peleg et al.
2012
). Studies have been con-
ducted to examined pressure-assisted sterilization on proteolytic types A and B
strains of
Clostridium botulinum
(Reddy et al.
2013
; Patazca et al.
2013
),
Bacillus
subtilis
,
B. amyloliquefaciens
, and
B. licheniformis
(Margosch et al.
2004
; Rajan
et al.
2006
; Ratphitagsanti et al.
2009
), and
C. botulinum
and
B. amyloliquefaciens
(Margosch et al.
2006
). For example, Ahn et al. (
2007
) reported that a treatment of
700 MPa at 121 °C for 1 min inactivated 7-8 log spores of
C. sporogenes
,
C. tyrobu-
tylicum
,
Thermoanaerobacterium thermosaccharolyticum
,
B. amyloliquefaciens
,
and
B. sphaericus
. The increased sensitivity of bacterial spores to heat under high
pressure is linked to the release of Ca
+2
-dipicolinic acid in the spores (Reineke
et al.
2011
).
Depending on the composition of the foods, the high pressure during HPP
increases the food temperature approximately 3 °C/100 MPa. The heat and pressure
used in HPP generally have no signifi cant effect on the food's fl avor components,
nutrients, and chemical reactions. There has been no evidence that chemical reac-
tions in foods at high pressure and temperatures, e.g., those for pressure-assisted
sterilization, would produce toxin compounds (Bravo et al.
2012
). It would be
expected that furan be produced at high temperatures during HPP from aqueous
solutions of ascorbic acid, simple sugars and fatty acids although the levels of furan
formation will probably be lower due to lower temperature employed for HPP ster-
ilization compared to the thermal conditions without high pressure. Numerous stud-
ies have been conducted to identify the HPP parameters (treatment pressure,
temperature, and time and food factors) for specifi c food products that deliver the
maximum microbiological and sensory quality. The reported HPP parameters and
effects for selected food products have been summarized by Campus (
2010
),
Bajovic et al. (
2012
), and Simonin et al. (
2012
). In addition, mathematical models
that describe the effects of HPP parameters on microbial inactivation have also been
