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Feb 20, 2013 (4 years and 3 months ago)

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Shelf
-
life extension of

cooked meat
products by

high hydrostatic pressure

treatment combined with
natural preservatives

Vercammen Anne
1
, Van Oirbeek, K. G. A.
1
, Steen, L.
3
, Goemaere, O.
3
,
Szczepaniak, S
.
3
,
Paelinck
,

H.
3
,
Hendrickx
,

M.
2
, Aertsen, A.
1

and
Michiels
,

C.W
.
1

1
Laboratory of Food Microbiology,
2
Laboratory of Food Technology, and Leuven Food Science and Nutrition
Research Centre (LFoRCe), Department of Microbial and Molecular Systems (M
2
S), Katholieke Universiteit
Leuven, Kasteelpark Arenberg 22,
3001 Leuven, Belgium

3
Research group for Technology and Quality of Animal Products

and Leuven Food Science and Nutrition
Research Centre (LFoRCe),
KaHo Sint
-
Lieven
-

Technologiecampus Gent
, Gebroeders Desmetstraat 1, 9000
Gent, Belgium


Introduction

Cooked meat products like cooked ham are often sliced and MAP packaged before distribution.
These manipulations unavoidably result in

recontamination, and this
reduces

the shelf
-
life and compromise
s

the
safety of the product. HHP can be used for
the in
-
pac
k treatment of such sliced

meat products
[1,2]
.
In this
context, we conducted a study on the extension of the microbiological shelf
-
life of sliced and modified
atmosphere packaged
cooked ham
by

high hydrostatic pressure
treatment and ‚natural‘ preservative
s.


Materials and methods
Cooked ham
and cooked ham model product
:

Commercial packages of sliced cooked
ham
(~100g)
were
provided by an industrial company
. Cooked ham model

product was prepared by KaHo Sint
-
Lieven (Ghent,
Belgi
um) and contained 2.5
%
Purasal
O
pti
Form
PD Plus

(72.8% potassium
lactate
, 5.2% sodium
diacetate)

(Purac Biochem, Gori
nchem, The Netherlands) or 0.15%
caprylic acid (Sigma

Aldrich
, Germany) and
was sliced. Both products were MAP packaged (
70% N
2

and 30% CO
2
).
High pressure proces
sing
: Samples
were treated with an 55L
pressure unit (
W
ave 6000/55, NC Hyperbaric, Burgos, Spain)
. Pressurisation
was
performed at 450 or 600 MPa (
10 minutes
, 10°C)
.
Sample storage and microbi
o
l
ogical

analyses
: After high

pressure processing samples were stored at 7°C for 12 weeks. At selected tim
es,
packages were aseptically
opened and the content
was transferred to a sterile stomacher bag. The meat (~100g ) was
homogenized

in 200
ml potassium

p
h
osphate buffer (10 mM, pH
7.0) in a stomacher and
t
he following microbi
ological

parameters
were determined

by plating
:
mesophilic

aerobic
count

(P
late
C
ount
A
gar
,

30°C, 2 days), lactic acid bacteria
(
de
Man Rogosa Sharp
agar,
30°C,

5 days), mesophilic anaerobic count

(
Reinforced Cl
ostridium Agar
,

37°C, 2
days),
Brochot
h
rix

spp.
(
Streptomycin Thallium Acetate Agar
,

22 °C, 2 days).

Shelf
-
life was defined as the
storage time until the mesophilic aerobic count exceeded 10exp7 cfu/g.

Results and discussion
T
he shelf
-
life of the commercial cooked ham could be extended
from 14
to 61 days after
a pressure treatment at 600 MPa (10°C, 10 minutes). The shelf
-
life of the
unpressurized
cooked ham model

product
was only extended marginally by the

addition of purasal

o
r caprylic acid,

approximately
40 days

to 45
days
.
After

pressure treatment

(600 MPa,
10°C, 10 minutes)
, the bacterial counts in
the cooked ham model

product without additives
remained unchanged for about 40 days, and the shelf
-
life was exceeded after 68 d
ays.

I
n the pressure treated cooked ham model

product with caprylic acid or purasal
, not any bacterial outgrowth was
observed during the entire storage period.
We conclude that
the combination of

pressure treatment
(
600 M
P
a
)
and caprylic acid or purasal synergistically
extend
s

the shelf
-
life of cooked ham.

References
[1] Diez A. M. et al. (2008).
International Journal of Food Microbiology 123: 246
-
253
.

[
2
]

Patterson M.F. et al.
(2010). Food Microbiology 27 (2):266
-
273.