HPP is now on a growing
scale commercially utilised in food industry in order to satisfy customers’
demand for minimal processed food. This is because the covalent bonds related
to dietary and organoleptic properties cannot be broken down throughout HPP.
The processed fruit or vegetable products freshness will be better retained.
Furthermore, with microorganisms and endogenous enzymes inactivation, during
shelf of life the microbial spoilage and high-quality deterioration can be
minimised. This kind of method commonly used for frozen food to make sure any
microorganism and bacteria remove in order to keep the frozen food long
lasting.
1. Type
of process
In industrial production, there are three types of
system of processing which are batch, continuous and semi continuous. Typically
for HPP method use batch system to process their food. In batch system there
are consists of pump, pressurization fluid, pressure vessel, and intensifier.
This system can operates in liquid and solid products while semi continuous can
only processing for liquid product (Elamin, Endan, Yosuf, Shamsudin, & Ahmedov, 2015). So that batch
system has more advantages rather than semi continuous system. Alternatively,
the pressure vessel can additionally be designed as a pressure intensifier. The
pressure vessel is constructed to resist a certain amount of pressure and
temperature, and incorporates the packaged food product and pressurization
fluid. Pressure vessel sizes are described through the volume of fluid that the
vessel can keep. The pressurization fluid is commonly water, and is delivered
to the pressure vessel to get rid of air pockets between the packages of food.
2. Effect
of pressure
According to Ginsau, 2015 the suitable pressure for
HPP method had been discovered by Hite in year 1899. He found that
microorganism can be obstructed by using HPP and at the same time it can
increase the period of realistic of usability. He tried if milk treated with
different levels of pressure remained sweet for a more drawn out period than
unpressurized milk did. It was appeared utilizing a pressure of over 463 MPa
for one hour normally decelerates the souring of milk for not less than twenty
four hours. Typical pressures applied to foods range from 300 – 800 MPa. Heat
may also be applied, however, the majority of high pressure processes are conducted
at refrigerated temperatures, relying mainly on pressure to process the food.
It is important to note that some temperature increase does occur naturally
during a typical HPP treatment due to adiabatic heating, which is dependent on
the target pressure and food composition.
3. Effect
on protein and enzyme
The processing conditions are depended on the
stimulation of the enzymatic activity. Protein have not been previously
modified by other process for example drying or fermentation because proteins in
HPP method are partially denatured in products. The electrostatic interactions
and hydrophobic bond will affected by the pressures. At pressure more than 200
MPa denaturation commonly irreversible that caused pressure denaturation become
complex.
4. Food
quality
In avoiding the excessive thermal
treatments or chemical preservation, HPP method are applied to provide a means
for retaining food quality. Storage temperatures and the barrier properties of
the packaging rather than by the high pressure treatments to maintain the
quality throughout shelf-life is influenced more by subsequent distribution
(Yordanov, 2014). In keeping good nutrients and food quality HPP method played
its role in food preservation in order to making food safer to eat by the
consumer. During pressure treatment, due to physical compression and returns
back to its initial value upon decompression the temperature of different food
materials will increases quickly. This condition can be lead to higher
compression of fatty foods heating due to their higher compressibility with
long-chain unsaturated fatty acids.
5. Applications
In the past 25 years, high pressure processing has
stimulated from being a laboratory preservation method to become an
economically useful technology. To enhance the efficiency of the process and
expand new knowledge in this promising field high pressure processing of foods
method has been used globally. For example, meat of application of HPP reduced
the activity of calpain compared with the controlling (Zhang, 2018).
Generally HPP method are used for,
·
Spoilage control – HPP
may be used to extend shelf-life by increasing the period over which the food
can be marketed by reducing the foods microbial load.
·
Pathogen control – By
elimination or reduction to safe levels pathogens of concern.
·
Product reformulation –
The use of HPP for enhancing the characteristics of reformulated products.
·
Product forming – By
subjecting food products such as reformed meats to the very high pressures used
in HPP, the cohesion of many small pieces of meat into one larger piece will be
become easier.
During HPP, pressure is
uniformly applied around and throughout the food product. Pressure additionally
gives a completely unique possibility to create and manage novel food textures
in protein-based or starch-based foods. In a few instances, pressure can be
used to form protein gels and increase viscosity without the use of heat. HPP
machines are broadly utilized for the processing of meat, dairy, seafood,
fruits and vegetable items, and different beverages.
High pressure
processing at low and high temperatures in foods and beverages packaged in
flexible packaging can likely bring about modifications within the useful
properties of packaging, specifically in structures with organic coatings
including metallization and structures laminated with aluminium foil that may
be extensively affected by processing. Finding the right temperature and
pressure combination is vital to using the equipment correctly but the most
important is in maintaining the quality of the food is a concern. HPP
has ability as a phyto sanitary remedy to control quarantine insect pests in
fresh or minimum processed fruits and vegetables to increase their shelf-life
