GLUPOR 12 - 12nd International Meeting of the Portuguese Carbohydrate Chemistry GroupDue
to
an
increase
in
fish
consumption
over
the
past
years
, in comb
ination
with
the
perishable
nature
of
fish
, the
fish
industry
has
given
an
added
focus
on
the
improvement
of
the
currently
used
fish
preservation
techniques.
Chitosan
coatings
may
add
improvements
to
the
traditional
water
glazing
, name
ly
in
physical
and
ant
i- microbial
protection
,
allowing
for
shelf
life
extension.
Nevertheless
, during
retail
storage
, frozen
fish
products
can
suffer
temperature
variations
that
lead
to
a decrease
in
quality.
These
temperature
var
iations
can
be
caused
by
a multitude
of
reasons
,
some
of
which
are
easy
to
control
,
while
others
are
due
to
unforeseen
circumstances
.
In
either
case
, thermal
stress
can
often
affect
frozen
fish
products
and
this
effect
is
of
considerable
importance
.
This
work
was
meant
to
determ
ine
the
influence
of
chitosan coatings
in
the
organoleptic
characteristics
of
salmon
as
well
as
report
a strategy
to
help
mitigate
the
effects
of
thermal
stress
of
frozen
fish
samples
.A 15
g/L
chitosan
solution
was
applied
on
frozen
salmon
samples through
dipping
at
a temperature
of
8
°C,
wi
th
a dipping
time
of
10
s; water
glazing
was
applied
as
blank
treatment
at
0.5 °C,
with
a dipping
time
of
40
s.
Some
of
the
samples
were
submitted
to
retail-
simulated
thermal
stress
conditions
(i.
e. a temperature
variation
of
-15
°C
to
-5
°C
was
enforced
),
and
studied
during
a
70-days
long
experiment
,
while
others
were
used
to
assess
the
sensory
properties
of
chitosan
coat
ings
on
Atlantic
salmon
(Sa/mo
salar)
and
were
compared
with
uncoated
and
water
glazed
samples
over
a six-month
storage
period
at
-18
°C.
Retail
simulation
samples
were
tested
for
variations
in
pH
, coat
i
ng
loss
and
color
,
while
samples
used
for
sensory
analys
is
were
evaluated
by
a sensory
panel
(frozen
, frozen+thawed
and
frozen
+thawed+cooked
samples
were
assessed
,) regarding
its
organolept
ic properties
, and
textural
analysis
, by
means
of
a TPA
(texture
profile
analys
is
).
Samples
analys
is common
to
both
exper
iments
were
microbiological
stabi
lity, assessed
through
TVC
(ISO
4833-1
:2013
standard)
, and
chemical
stability
, determined
as
TVB-N
(N
P
2930
:2009
standard
).
Through
coating
loss,
it
was
possible
to
verify
that
chitosan
coatings
offer
better
protect
ion,
with
water
glazed
samples
becoming
virtually
unprotected
after
the
evaluation
period,
with
losses
of
more
than
80
%
of
its
glazing
,
while
chitosan
coated
samples
maintained
50
%
of
its
coating.
Extrapolat
i
ng
this
data
to
complete
loss
of
water
glazing
shows
an
increase
in
shel
f life
of
at
le
ast
26
%
in
chitosan
coated
samples.
No
significant
changes
between
samples
were
obtained
in
the
other
parameters
assessed
. The
anti-m
icrobial
effect
of
chitosan
was
confirmed
through
TVC
which
showed
a reduction
in
microbial
counts
in
chitosan
coated
samp
les
,
whi
le
while
TVB-N
results
showed
to
remain
stable
, for
both
experiments
. The
proven
anti
-
microbial
effect
of
chitosan
coated
samples
in
conjunction
with
a slower
coating
loss
leads
to
an
expected
increase
in
shelf
life ,
even
in
unforeseen
circumstances
of
temperature
change
in
retail
transportation.
Textural
results
from
the
TPA
analysis
showed
no
significant
differences
between
different
coatings.
Results
of
the
trained
panel
indicated
that
for
frozen
samples
ch
itosan
was
the
preferred
choice
,
while
no
significant
differences
existed
between
chitosan
-coated
and
glazed
samples
in
thawed
and
cooked
samples.
Flavor
diffu
sion
from
the
chitosan
coating
to
the
samples
was
assessed
by
Principal
Component
Analysis
and
no
correlation
between
coating
type
and
sample
flavor
could
be
established
, meaning
that
no
chitosan
flavor
was
detected
by
the
panellists.Portuguese Foundation for Science and Technology (FCT) under
the scope of the strategic funding of UID/BIO/044691/2013
unit and COMPETE 2020 (POCl-01-0145-FEDER-006684) and BioTecNorte
operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under
the
scope
of
Norte2020
-
Programa
Operacional
Regional
do
Norteinfo:eu-repo/semantics/publishedVersio