High pressure can be applied to inhibit microbial growth in
food. However, many varieties of microorganisms with differing
physiological characteristics exist, and different microorganisms
may have differing pressure-resistant characteristics. Generally,
increases in the processing pressure generate varying levels of
effect on microorganisms, and there has been much research
carried out since then on the response of microorganisms to
pressure. Based on the literature, 50 MPa of pressure can inhibit
protein synthesis in microorganisms and reduce the number of ribosomes. A pressure of 100 MPa can induce partial protein
denaturation, and 200 MPa causes damage to the cell membrane
and internal cell structure. Increasing the pressure to 300 MPa or
more induces irreversible denaturation of enzymes and proteins,
which causes rupturing of the cell membrane and the excretion of
internal substances, resulting in bacterial death (Abe, 2007).
Therefore, the effects that high pressure have on microorganisms
can be categorized primarily as a change to the cell morphology,
an inhibition of metabolic reactions essential for cell maintenance,
and genetic mechanisms. These different cellular targets of
HPP involved in bacterial inactivation are described in the
following sections.