Filetype PDF | Posted on 14 Sep 2022 | 3 years ago
Authentication
digital resources
169x Filetype PDF File size 0.15 MB Source: www.ijcmas.com
Int.J.Curr.Microbiol.App.Sci (2018) 7(3): 2833-2838
International Journal of Current Microbiology and Applied Sciences
ISSN: 2319-7706 Volume 7 Number 03 (2018)
Journal homepage: http://www.ijcmas.com
Review Article https://doi.org/10.20546/ijcmas.2018.703.326
Microbial Behavior against Newer Methods of Food Processing and
Preservation: A Review
1* 2 1
Sucheta , Panvi Ahuja and Rakesh Gehlot
1
Centre of Food Science and Technology, CCS Haryana Agricultural University, Hisar, India
2MCM D.A.V. College for Women, Chandigarh, India
*Corresponding author
A B S T R A C T
There has been a great advancement in food processing methods over the
Keywords years from traditional thermal processing to various non-thermal
Food processing, processings like high-pressure, electric field and radiations based methods.
Thermal processing,
These methods have been found more effective and less damaging to food
Preservation
quality. This review describes the mechanism of inactivation of microbes
Article Info
due to these newer methods of food processing. These methods kill
vegetative microbes but fail to effectively kill spores, but a combination of
Accepted:
methods can be used to achieve the objective. These methods, however, can
24 February 2018
Available Online: meet the demands of consumers for safe, nutritious, improved taste, texture
10 March 2018 and ready-to-eat food products.
Introduction browning, protein and fat deterioration, loss
of certain nutrients etc. The alternative
Food Processing is the conversion of raw technologies are non-thermal as these do not
materials or ingredients to a final product. employ heating of food directly, thus,
According to Connor (1988) food processing minimizing the damaging effects on food
is that branch of manufacturing that starts quality. The newer methods includes High
with raw animal, plant or marine materials hydrostatic pressure (technique that destroys
and transforms them into intermediate the microorganisms with the intense pressure
foodstuffs or edible products through the in the range 100-1000 MPa), Pulse electric
application of labor, machinery, energy and field (delivery of pulses at high electric field
scientific knowledge. Thermal pasteurization intensity 5-55 kV/cm for a few milliseconds),
and sterilization had been in use in the food gamma radiations also known as cold
industry for a long time for their efficacy and sterilization (employs doses of 2-10 kGy),
product safety record. Excessive heat used in ultraviolet radiations (germicidal properties at
these processes, may, however, cause wavelengths in the range of 200- 280 nm),
undesirable quality changes in food like ultrasound (20 to 100 kHz; which is referred
2833
Int.J.Curr.Microbiol.App.Sci (2018) 7(3): 2833-2838
to as ‘‘power ultrasound’’, has the ability to by the high pressure treatment which
cause cavitation, which has uses in food ultimately disturbs the internal
processing to inactivate microbes) (Zhang et physiochemical balance of the cell. The lethal
al., 1995; Kuo et al., 1997; Piyasena et al., pressure is approximately above 180 MPa
2003; Gervilla et al., 2001). These methods after which there is observed loss of cell
employ different mechanisms of inactivation viability and the rate of inactivation increases
of microbes. Very few of these new exponentially as the pressure increases. HHP
preservation methods are until now inactivation seems to be multitarget in nature.
implemented by the food industry. The aim of Membrane is a key target, but in some cases
this article is to reflect the mechanisms of additional damaging events occur such as:-
inactivation of these newer methods and
lighting up the research efforts made in Extensive solute loss during pressurization,
direction of use of such less food damaging
techniques. Protein coagulation,
High Hydrostatic pressure Key enzyme inactivation and ribosome
conformational changes, together with
Certes, in 1883, was the one who succeeded impaired recovery mechanisms, seem also
in relating the effects of high pressure on needed to kill bacteria.
microorganisms (Knorr, 1995). The principle
demonstrates that food product is compressed The technology was first used and
under uniform pressure in every direction and commercialized in 1990 in Japan. The initial
regains it’s original shape as the pressure is products processed include juices, jellies,
released (Yordanov and Angelova, 2014). jams, meats, fishes etc. as reported by
High pressure processing is comprised of the Augustin et al., (2016). This is an emerging
following units: a) pressure vessel b) pressure technology with a great future scope in food
generating device c) material handing system industry.
d) temperature controls. The food package is
loaded onto vessel and the top of vessel is Pulse electric field processing
closed. The pressure medium (generally
water) is allowed to pump into the vessel Pulse electric field (PEF) is one of the
from the bottom. As the desired pressure is promising non-thermal food processing
reached, pumping is stopped. The valves are technology. It involves use of short pulses of
closed and pressure is maintained. The high electric voltage (upto 5-50 kV/cm) for
pressure was applied in an isostatic manner so microseconds to milliseconds which
that all the food in the container experiences a decontaminates the food followed by aseptic
uniform pressure throughout (Mertens, B. packaging and refrigeration (Wouters et al.,
1995; Doona and Feeherry, 2008). 2001). The pulse electric field system is
composed of three units: a treatment chamber
High pressure has a lethal effect on vegetative (consist of a set of electrodes), a high voltage
microorganisms and that is the result of pulse generator, a control system for
numerous changes that take place in the monitoring the process (Loeffler, 2006). The
membrane of a microbial cell. The membrane food is placed between the electrodes in a
is the most probable site of disruption in a treatment chamber which is exposed to short
microbial cell. The active and passive pulses of high electric voltage. The two
transport functions of membrane are altered electrodes are connected to non-conductive
2834
Int.J.Curr.Microbiol.App.Sci (2018) 7(3): 2833-2838
material to prevent the electric flow from one Ultrasound
to another. The food product experiences a
force as electric field, which is responsible for Ultrasound waves have a frequency that is
the cell membrane breakdown in above 16 KHz and cannot be detected by the
microorganisms and causes inactivation of human ear. It can be further divided into two
microorganisms. (Fernandez-diaz, 2000) The categories: a) low energy; b) high energy. The
process is majorly equipped for pasteurisation low energy ultrasound frequency is higher
of food products including eggs, juices, milk, than 100KHz with intensity lower than
soups and yogurt (Bendicho, 2003). 1W/cm2. The high energy ultrasound
frequency ranges 20-500 KHz at the intensity
The efficiency of PEF technology for higher than 1W/cm2 (Chemat et al., 2011).
inactivation of microbes depends largely on The commonly applied frequency for
the microbial characteristics including type of ultrasound technology by researchers ranges
microbe, species and strain (Macgregor, between 20KHz - 500 MHz (Yusaf and Al-
2000). Compared to yeast cells, gram positive Juboori, 2014). Ultrasonics is one of the
and gram negative bacteria are found to be fastest growing non-thermal food processing
more resistant to PEF technology. In like methods that have been devised to meet the
manner, bacterial and mold spores are consumer demands and provide minimum
asserted to be defiant to PEF processing processed, high quality and healthy product
(Katsuki, 2000). (Knorr et al., 2011).
The mode of action of pulse electric field Cavitation phenomenon is responsible for the
mainly focuses on reduction of microbial load lethal effects of ultrasound. In ultrasonics,
to produce safe quality foods. The basic electrical energy is converted to mechanical
mechanism of pulse electric field technology energy or vibrational energy which is passed
involves induction of electric field which on to the sonicated liquid system. Partial input
leads to electromechanical compression. This energy is lost in the form of heat and partial
further causes formation of pores in the can cause cavitation producing effects
microbial membrane, known as (O’Sullivan, 2017). The bubbles so generated
electroporation. Electroporation can be as a result of cavitation implodes under an
defined as the formation of pores in cells and intense ultrasonic field, free radicals are
organelles. When it ruptures membrane and generated which inactivates microbial cells.
causes permeability known as By causing grievous damage to cell wall, the
electropermeabilization. acoustic cavitation phenomenon can destroy
cell structure and cause impairment of
Electropermiablization may be reversible or functional components causing cell lysis
irreversible depending upon the (Jose, 2016). Ultrasonic has been applied to
organisational change that leads to cell death many liquid foods for inactivation of
(Rowan, 2000). In general, spores are stated microbes. In a study, ultrasonic was applied to
to more resistant to the PEF treatment than apple cider where the levels of E. coli
the vegetative cells (Katsuki, 2000). Bacteria O157:H7 were reduced by 5 log cfu/ml. In the
and yeasts have shown morphological same, study conducted on milk showed
alterations like surface roughness, disruption reduced levels of Listeria monocytogenes by
of organelles, ruptures in the membrane, etc 5 log cfu/ml. A research on ultrasound has
on application of pulse electric field. (Dutreux also reported that microbes having soft and
et al., 2000). thicker capsule are found to be extremely
2835
Int.J.Curr.Microbiol.App.Sci (2018) 7(3): 2833-2838
resistant to the ultrasonic processing. (Gao helix at a close distance (Manas and Pagan,
and Lewis, 2014). The effectiveness of an 2005). Irradiation sources are radioisotopes
ultrasound treatment is dependent on the type (cobalt-60 and cesium- 137) and machine
of bacteria being treated. Microorganisms generated (electron beams and X-rays).
(especially spores) are relatively resistant to Vegetative cells are less resistant to
the effects, thus extended periods of irradiation than spores, whereas moulds have
ultrasonication would be required to render a a susceptibility to irradiation similar to that of
product safe. If ultrasound were to be used in vegetative cells. However some fungi can be
any practical application, it would most likely as resistant as bacterial spores (Farkas, 2006).
have to be used in conjunction with pressure
treatment (manosonication), heat treatment Biopreservation
(thermosonication) or both
(manothermosonication) (Piyasena et al., Biopreservation or biocontrol refers to the use
2003). of natural or controlled microbiota, or its
antibacterial products to extend the shelf life
Irradiation and enhance the safety of foods (Stiles, 1996).
The biopreservation includes bacteriocins
Irradiation being a non-thermal processing which are produced by certain
technology can be used to destroy the microorganisms have antagonistic effect on
microbes and increase the shelf life of a other organisms. Deegan et al., (2006)
product. It can destroy yeasts, molds and classified bacteriocins depending upon their
viable microorganisms (radurization) with a structures as: small peptides (<10kDa;
dosage of 0.4-10 KGy, to destroy non-spore lanthionine containing; nisin, lacticin etc.),
forming food borne pathogens (radicidation) small peptides (<5kDa; non-lanthionine
uses a dosage of 0.1-8 KGy, and to sterilize containing; pediocin, lactococcin etc.), large
the product by killing both vegetative bacteria molecules (like helveticins), and circular
and spores with a dosage of 10-50 KGy peptides (enterocins). The mechanism of
(Fellows, 2000). inactivation is based upon electrostatic
interactions with negatively charged
Irradiation preserves the food by the use of phosphate groups on target cell membranes
ionizing radiation (γ-rays, from electrons and which contribute to the initial binding,
X-rays). The effects of ionizing radiations are forming pores and killing the cells after
classified as direct and indirect. The direct causing lethal damage and autolysin
effects are caused by the absorption of activation to digest the cellular wall (Perez et
radiation energy by target molecules and al., 2015). The established use of nisin as a
indirect effects are caused by hydroxyl preservative is found in processed cheese,
radicals generated from radiolysis of water various pasteurized dairy products and canned
inside the food. The hydroxyl radical OH• is vegetables. Many other bacteriocins from
able to react with the sugar-phosphate lactic acid bacteria have recently been
backbone of the DNA chain giving rise to the characterized. Because of potential usefulness
elimination of hydrogen atoms from the as natural food preservatives, increased
sugar. This causes the scission of the interest has been found on bacteriocins from
phosphate ester bonds and subsequent lactic acid bacteria. Bacteriocin producing
appearance of single strand breaks. Double (Bac+) lactic acid bacteria (LAB) detected in
strand breaks occur when two single strand retail foods indicates that the public is
breaks take place in each chain of the double consuming a wide variety of Bac + LAB. This
2836
no reviews yet
Please Login to review.
