Minimally Processed Meat and Fish Products - Minimally Processed Foods - page 199

developed in ohmically cooked meat products. Ohmic cooking effectively inhibits
microbial growth by providing uniform temperature distribution in the product and
cooks the product extremely fast.

10.2.2 Minimal Processing with Non-thermal Methods

10.2.2.1 High Pressure Processing

Among the novel non-thermal food processing methods, the application of high pres-
sure (HP) has been the most successful so far. High-pressure processing (HPP) treats
product statically at or above 100 MPa by means of a liquid transmitter. According to
Patterson ( 2005 ), it is common to use pressure from 500 to 900 MPa. High-pressure
processing has various advantages over other non-thermal technologies. Food can be
processed at ambient or even at lower temperatures. It is the isostatic transmission of
pressure; the processed material experiences the pressure instantaneously with no
gradient, resulting in uniform treatment irrespective of the size and geometry of the
material. High-pressure modifi es only non-covalent bonds like hydrogen, ionic and
hydrophobic bonds and does not affect small molecules such as fl avour compounds
and vitamins. Therefore, high-pressure processing leads to less degradation in the
overall quality of processed foods as compared to heat treated foods. In addition,
high pressure processing takes lower time and energy (Simonin et al. 2012 ).

Application in raw products : In raw meat so far HPP has been used for increasing
tenderness with improved functionality and food safety. The pressurisation infl u-
ences the physicochemical and functional properties of meat and muscle proteins
such as gelation and water binding capacity (Jiménez Colmenero 2002 ; Sun and
Holley 2010 ) in addition to the destruction of spoilage and pathogenic microorgan-
isms. High pressure processing also causes an immediate drop in pH of pre-rigor
muscle as a result of accelerated glycolysis. Application of more than 200 MPa to
fresh meat results in myofi brillar protein denaturation, but stromal proteins such as
collagen remains stable. Tenderness values are generally higher in pre-rigor meat
subjected to HPP processing as compared to controls. Myofi brillar protein solubil-
ity of post-rigor muscle is increased when subjected to HPP (Souza et al. 2011 ).
HPP can change the molecular composition of meat, enhance the stability of meat
gels and modify the textural properties of biopolymers such as proteins and polysac-
charides yielding gel-type products. This allows lower salt levels to be used and
achieves high water binding capacity with improved texture in processed meat prod-
ucts (Chen et al. 2006 ; Chattong et al. 2007 ; Sikes et al. 2009 ). In seafood pastes,
which generally show low gel-setting abilities, HPP resulted smoother gels with
fi ner texture (i.e. more elastic than those produced by heat alone) (Hwang et al.
2007 ). These effects could be resulted from greater ionic, hydrogen bonding and
hydrophobic interactions. Moreover, the pressure is thought to protect proteins
against subsequent heat-induced denaturation (Uresti et al. 2005 ). Several workers
have attempted HPP in raw meat and fi sh and observed its benefi cial effects on
selected quality parameters (Table 10.3 ).