 |
| Microbiological test to compare the new material (right) and the wood multilayer (left) |
by Dr Simona Digiuni, PhD - Postdoctoral Researcher at the Department of Industrial Engineering, University of Parma, Italy and Emanuele Bigna, Plant Production Manager and R&D Manager, Ocrim s.p.a, Italy.
When cereals arrive to the milling plant,
they carry a series of contaminations that can be divided into three main
classes: physical, chemical and biological. The third class of biological
contaminations may contain human pathogen microorganisms like E.coli,
Salmonella and mycotoxin producing fungi. These organisms are naturally present
in the environment where the cereals grow and several factors can increase
their concentration leading to a threat to human health.
The
first step of the milling process is actually the elimination of these
contaminations. The cleaning of cereal prior to milling is therefore an
essential step of the flour production. In time, many machines have been
developed to remove physical contaminations from cereals like stones and straws
or other biological contaminants like insects and seeds from other plants.
However, when it comes to microorganisms, due to their size, it is more
difficult to detect and remove them. Moreover, as said before, the amount of
microorganisms on the surface of the cereals can differ between batches. This
phenomenon can lead to cross contamination effects inside the mill, because it
is impossible to clean the plant every time a new lot is used.
How to solve contamination
The problem of microorganism contamination
can be approached from different angles. One is to remove them mechanically
from the surface by peeling or debranning during the cleaning. Another method
is to reduce drastically their number with high temperature, chemicals (e.g.
ozone, chlorine) or irradiation at different stages of the milling process.
The
third approach is to reduce cross contaminations by avoiding the formation of
new source of inoculation in the mill. The R&D team of OCRIM, in
collaboration with the University of Parma, has investigated the last one in
order to develop an innovative product for the mill.
The 70 years of experience in building and
maintaining mills all over the world have shown OCRIM that certain spots in the
mill create an optimal environment for mould formation.
Although in theory, the
water activity in the milling plant is not optimal for the growth of
microorganisms, certain conditions may create ideal microenvironments for their
development.
The objective of the R&D team was to counteract the formation
of these microenvironments thus block mould formation and bacterial
propagation.
In the food industry, the use of materials
with antimicrobial characteristics in strategic zones of the plants is largely
diffused (e.g. packaging area). Thus, the idea was to transfer this technology
to the flour milling industry. This research first identified the plansifters
as one of the areas of the mill where microorganisms can develop and
contaminate new batches of flour. This contamination can occur for a long period
of time, until the growing moulds are physically removed from the machines.
Therefore, OCRIM considered the possibility to build sieves containing an
antimicrobial compound that could prevent mould and bacterial formation. A fundamental
step of the research was to find the appropriate material to build the sieves
that bring together antimicrobial activity and three others main features:
compatibility with food usage, durability and mechanical reliability.
OCRIM R&D team succeeded in finding a
new composite material certified as food grade that contains an antimicrobial
ingredient that can be used in milling plants. This substance is trapped inside
the material; therefore, the antimicrobial is not released in the flour during
sifting. This has the great advantage that it will not interfere with the
rheological and backing characteristics of the flour.
Nonetheless, the
antimicrobial is active on the surface of the sieves blocking the development
of moulds and bacteria in the plansifter. Moreover, having a component that is
incorporated in the material gives the benefit that it does not consume over
time and the antimicrobial effect is present and stable for the whole life of
the sieves.
The Global Miller
This blog is maintained by The Global Miller staff and is supported by the magazine Milling and Grain
which is published by Perendale Publishers Limited.
For additional daily news from milling around the world: global-milling.com
No comments:
Post a Comment