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Natural casings
and food safety:
an up-to-date
Valerio Giacconce
School of Veterinary Medicine – University of Padua (Italy)
Who I am
My name is Valerio Giaccone
Full professor of “Meat Hygiene
and Food Inspection”
Who I am
My Collegues say
I am …
… the “Food detective”
Who I am
I would like to be called …
… the “Food Doctor”
As Doctor …
… I should make everything
to keep the food “safe” …
… and keep away
every possible “hazard”
Arguments
What we know on casings
What we should better
understand
What we should discover
What
we know on
natural casings?
We know that …
… natural casings are
worldwide used as “skin” …
… for various kind of sausages
and other foods
We know that …
… the commercial trade of
natural casings on the world …
… plays a considerable
economic role
Houben (2005)
“In 2002 the total EU foreign
trade in natural casings …
… was about 1.4 billion dollars”
Koolmees (2004)
He reports that the trade
of natural casings …
… is estimated in 2.5 billion
dollars per year
We know that …
… the 60% of natural casings
used for sausages …
… comes from the small
intestine of sheep
Natural casings …
… are drawn from the
submucosa of animal gut …
… by desliming and stripping
off their mucous and muscular
layers
Natural casings …
… are usually prepared
by salting, curing and drying …
… various part of animal gut
Hazards
for human health
First
HAZARD and RISK …
… ARE NOT THE SAME THING
An hazard …
… is a physical, chemical
or biological agent …
… which can be dangerous
for human health
An hazard …
… is always an hazard …
… aside from the food
For example
Ice cream contains a lot of air
(and of Oxygen)
Clostridium botulinum grows
only in strict anaerobiosis
For example
Clostridium botulinum
is an hazard for ice cream ?
YES, because it
can cause botulism in humans
Nevertheless …
… the probability
that C. botulinum grows
in ice cream …
… is very low, because the
presence of too much oxygen
The risk
A risk is
the mathematical
probability …
… that an hazard can occurr
Microbial pathogens
Kind of
hazard
Chemical residues
Bacteria
Microbial
hazards
Toxigenic
moulds
Viruses
Natural
contaminants
Chemical
hazards
Xenobiotic
contaminants
Microbial pathogen
Salmonella enterica
Campylobacter
Listeria monocytogenes
Escherichia coli VTEC
Chemical residues
Heavy metals
Antibiotics & chemoterapics
Pesticides
Mycotoxins (ochratoxin)
Microbial pathogen
In 2009 in European Union
occurred more than …
… 190.000 cases of human
foodborne campylobacteriosis
Microbial pathogen
In 2009 in European Union
occurred more than …
… 108.000 cases of human
foodborne salmonellosis
Microbial pathogen
In 2009 in European Union
occurred …
… 1.645 cases of foodborne
human listeriosis
Foodborne diseases 2009
The EU Summary Report
“Trends and Sources of Zoonoses
and Zoonotic Agents and
Food-borne Outbreaks in 2009”
What we know
Natural casings are not
a substantial source …
… of foodborne pathogens
for sausages
As consequence
Natural casings are
microbiologically
fully acceptable …
… if they are adequately
dry-salted
What we know
Very rarely natural casings
harbor Salmonella, …
… Listeria monocytogenes
or other microbial pathogens
Why ?
Because their production
process and …
… because the antimicrobial
action of salting and curing
The pathogens
They are normally harbored
in gut of animals, so they …
… could pass to natural casing
in the first production steps
But … …
… by salting, curing and drying
the gut for at least 30 days …
… it is very rare that
Salmonellae and other
pathogens can survive
Clostridia
Sulphite-reducing Clostridium
are sometimes detected
in natural casings
They produce high resistant
“spores” which survive in salt
Bacillus
The same risk can occorr
with spores of Bacillus cereus …
… another cause
of foodborne intoxication
Nevertheless …
… the risk for sausages …
… comes from the alive
clostridia, NOT from spores
We know that …
… the alive Clostridia CAN NOT
grow in natural casings …
… because their salt content
An experience
of challenge test
Aim of the study
Inspired by Bailocom, we have
performed a challenge test …
… to study the behaviour
of Clostridia in natural casing
The numbers
We have analysed 120 samples
of natural casings …
… looking for the charge
of sulphite-reducing Clostridium
The numbers
The 30 casing in which
we found the most high charges
of Clostridium …
… were then used to produce
raw seasoned sausages
The tests
21 sausages at the begin
of seasoning and other …
… 21 sausages at the end
of seasoning were analysed
The results
In all samples tested we have
found charges of Clostridium …
… always below 10 cfu/g of meat
What does it means?
Natural casing can contain low
charges of Clostridium spores …
… but the spores have no real
significance for the sausage
What we should
better understand
Viruses
Certain viruses, pathogenic for
breeding animals, may persist …
… in adequately salted casings
Viruses
Cattle and sheep’s gut can
harbor infectious viruses …
… of Foot and Mouth disease
Viruses
Pig gut can harbor
infectious viruses of …
… Classical Swine Pest Virus
(Hog cholera virus)
It is possible …
… to treat natural casings
with anti-viral compounds
These treatments can inactivate
the pathogenic viruses
Treatments
They are based on lactic acid
or citric acid …
… and also on orthophosphates
Effectiveness
At today it seems that these
treatments are effective …
… to inactivate
pathogenic viruses, but …
… but …
… we must take high care
to the rinsing of casings …
… after the treatment
The rinsing
It is probable that
a rinsing of only 3 hours …
… it is not sufficient to wash
away all residues of additives
Instead …
… a rinsing of 16 hours
seems to be sufficient …
… to wash away all residues
of acid or basic additives
TSE risk
In bovine and sheep gut could
be present prions of …
… transmissible spongiforme
encephalopathies (BSE/scrapie)
TSE risk
In the EU no casings are
made from native-born cattle …
… because cattle intestine is
a specified risk material (SRM)
TSE risk
Natural casings derived from
sheep and goats can harbor .…
… the causative agent of scrapie
We know that …
… most TSE infectivity resides
in the mucosa …
… particularly in the lymphoid
nodules (s.c. Peyer’s patches)
Lymphoid nodule (Peyer’s patch)
Natural casings
Because the severe process
of desliming and stripping …
… they ARE NOT particularly
at risk to harbor TSE prions
What we should
discover on
natural casings?
Chemical residues
They are a real “black hole”
There is a quite complete
lack of scientifica data
Chemical residues
Pharmacological treatments
are regularly performed …
… in reared animals
(antibiotics, chemotherapics …)
Chemical residues
Other chemical residues can be
present in gut content …
… because they come from feed
and environment (heavy metals)
In theory …
… residues of all these
contaminants could be present …
… also in natural casings
In literature
We have only a report about
the persistance of residues …
… in natural casings
At today …
… we DO NOT have scientific
data about the real amount …
… of antibiotics, heavy metals
and/or pesticides in casings
Personally …
… in this last month I began
to perform some analysis …
… looking for heavy metals and
ochratoxins in natural casings
I hope …
… You will substain my effort …
… to obtains sufficient
scientific data in this research
In conclusion
Remember that …
… an hazard is always an hazard
What is important is the RISK,
i.e. the probability of an hazard
In conclusion
It is quite probable that natural
casing are products …
… with a very low risk
for human health, but …
… but …
… it needs to demonstrate
this low risk …
… from a scientific point of view