Food Marketing & Technology - India June 2019 | Page 50

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MODERN TECHNIQUES TRENDING
IN FOOD MICROBIOLOGY
BY: ADITI RUNGTA *
T
he journey of food microbiology
initially started with the
discovery of canning by Nicolas
Appert in 1810 followed by Louis
Pasteur’s conclusive demonstration of
the relation between food spoilage and
microorganisms, some 50 years later,
now known as Pasteurisation. This led
to a cascade of events which ultimately
established the food microbiology as
we know of today. Food is the source
of nutrients for microorganisms which
makes it vulnerable to spoilage and
also may have an impact on the health
of the person ingesting spoilt food.
Food microbiology is dynamic and has
evolved a lot over the past 200 years
and also various new technologies
have emerged. Not only the technology
has undergone evolution, but the
microorganisms have become deadlier
and more resistant. The emergence
of these microorganisms such as: E.
Coli O157H7 (Shiga toxin producing
strain); Vibrio vulnificus; Cyclospora
cayetanensis; etc. leads to a need for
rapid detection of these food borne
pathogens to prevent outbreaks.
Advancements in Microbiology
There have been a lot of advancements
in the areas of isolation, detection
and enumeration of microorganisms.
When we talk about the area of sample
preparation for any microbiological
experiments Stomacher and Pulsifiers,
which homogenize the samples inside
a sterile disposable bag, are the most
widely used instruments. Dilution is
another tedious and laborious task
to be done after sample preparation.
Gravimetric diluters which inject the
appropriate amount of diluents in the
samples are available for this purpose.
Spiral Plating Systems are being
increasingly employed for plating a
fixed amount of sample on solidified
agar plates for determination of total
viable counts.
Identification and Detection of
Microorganisms
Detection Kits: For identification
and detection of microorganisms,
scientists have been working on the
development of miniaturised kits to
reduce the volumes being used. One of
the most successful detection kits being
used is the VITEK kits which comprise
of 30 tiny wells in which reagents are
added. The addition of culture changes
colour and the colour scheme can be
used for identification of the culture.
Several such detection kits have been
developed for the detection of specific
microorganisms.
Immunology: This is an upcoming
field using antigen-antibody reactions
as a microbial detection technique.
Food Marketing & Technology
50
June 2019
Any
antigen
associated
with
microorganisms when introduced into
an animal’s body generates antibodies
which are isolated from them. This
forms the basis for immunological
tests. Sandwiched ELISA is the most
commonly used test.
Lateral Flow Technology: It is another
technology being used to detect food
borne pathogens by incubating the
food overnight which changes colour
on detecting the presence of any
pathogenic microorganism.
Instrumental Analysis: Instruments
are also being used to analyse
microbial growth kinetics such as
pH, ATP changes, turbidity, colour
etc. of a microbial population. These
parameters are directly related to the
viable cell count which makes the
detection easier. Liquid and semi-solid
samples can be analysed in such a way.
The detection time will depend on the
growth rate of microorganisms.
DNA Bar-coding System: This can
also be used for detection of the kind
of microorganisms contaminating the
food. This comprises of a 100-1000
base pair (bp) long DNA fragment
representative of the microorganism
which is amplified using Polymerase
Chain Reaction and is matched with
the DNA fragment extracted from the
food.
Biosensor: Biosensor is a group of
biological molecules attached to a
signal recognition material. When