Evaluation of the efficiency of Lactic acid and
Buffered Lactic acid on naturally contaminated
pork carcasses during the slaughtering process.
ICOSMT 2008
Le Roux A., Minvielle B., Gault E.
IFIP – French institute for pig and pork industry La Motte au Vicomte, BP 35104, 35561 Le Rheu Cedex, France.
[email protected]
The aim of this study was to evaluate the efficiency of Lactic acid (LA) and Buffered Lactic Acid (BLA) as a single treatment onto pork
carcasses at the end of the slaughter line. In our normal processing conditions, Lactic acid efficiency appeared to be limited for naturally contaminated carcasses.
INTRODUCTION
This on-site study measured the bacterial and commercial efficiency of spraying carcasses at the end of slaughter, just before chilling, at
different concentrations (1 and 2% of LA, and 2% BLA) and temperatures (10 and 40°C) after 24h and 48h of storage. According to literature,
a bacterial reduction up to 3 log can be achieved, but the highest reductions are generally observed with artificial contamination.
METHOD
For each treatment, i.e. the combination of different concentrations (1 and 2% of LA, and 2% BLA) and temperatures (10 and 40°C), 15 carcasses were tested in 3 periods.
Sampling for bacteriological examination was:
Excision of 5 cm2 tissue samples from 4 sites for the outside (Rind) and 3 sites for the inside (Meat) of each carcass.
Aerobic colony counts (ACC) and Enterobacteriaceae (ENT) were enumerated on pooled samples from Rind
and Meat of each carcass.
Carcasses were visually inspected by skilled person, and commercial acceptance was scored (satisfactory, acceptable, unsatisfactory).
Means of bacterial reductions (log10 CFU/cm2) were calculated at 24h and 48h post each treatment from initial
contamination ; the bacterial reduction of untreated carcasses being also taken into account. Statistical analysis were conducted using
the GLM procedure (SAS Institute, USA).
RESULTS
The levels of initial contamination for ACC and ENT were respectively : 5.3 and 2.1 log10 CFU/cm2 for Rind, and 3.9 and 1.4 log10 CFU/cm2
for Meat.
The tables 1 and 2 present the efficiency of treatments for the two bacteria respectively on Rind and on Meat.
LA 1%
LA 2%
BLA 2%
ACC
0-24h
10°C
0.54
0.28
-0.11*
ENT
0-48h
40°C 10°C
0.38 0.26
0.35 0.52
0.03 -0.05*
40°C
0.52
0.48
0.26
* the negative sign notices growth of bacteria
0-24h
10°C
0.49
0.26
0.39
40°C
0.87
0.96
0.26
0-48h
10°C
0.22
0.44
0.43
40°C
0.19
0.66
0.23
Table 2: Evolution (log10 CFU/cm2) of bacterial contamination
on pork meat according to LA treatments.
Treatment
Treatment
Table 1: Evolution (log10 CFU/cm2) of bacterial contamination
on pork rind according to LA treatments.
LA 1%
LA 2%
BLA 2%
ACC
0-24h
10°C
1.04
0.86
0.58
40°C
0.08
0.47
0.25
ENT
0-48h
10°C
0.74
0.68
0.26
0-24h
40°C 10°C 40°C
0.46 0.46 0.03
0.40 -0.01* 0.42
0.69 0.01 0.16
0-48h
10°C
0.24
0.23
0.17
40°C
0.31
0.76
0.53
* the negative sign notices growth of bacteria
Conclusion
Higher temperature nor concentration did not clearly improve efficiency of LA, but reduced colour acceptability. The use of BLA
improved colour acceptability of treatment, but reduced its efficiency.
The best compromise between bacterial reduction and visual acceptability was achieved with LA sprayed at 2% and 10°C.
In our normal processing conditions, Lactic acid efficiency appeared to be rather limited ( < 1 log10 CFU/cm2) for naturally contaminated carcasses. However, the optimization of use conditions has to be studied.
Validation of Steam-Vacuum
process as corrective measure for visible faecal
contamination on carcasses.
ICOSMT 2008
Le Roux A., Minvielle B., Gault E.
IFIP – French institute for pig and pork industry La Motte au Vicomte, BP 35104, 35561 Le Rheu Cedex, France.
[email protected]
The aim of this study was to evaluate the efficiency of steam vacuum systems applied onto pork carcasses with visible faecal contamination. Steam-vacuum removed visible faecal contamination and reduced bacterial contamination to a normal level on the rind
and meat surfaces of the carcass.
INTRODUCTION
According to EU regulation, visible faecal contamination on carcasses must be removed by trimming or alternative means having an
equivalent effect. Existing steam-vacuum systems, developed an used in USA or Denmark, need to be tested and validated as an alternative to traditional knife-trimming.
METHOD
In order to evaluate the efficiency of both methods, evisceration accidents were simulated on
45 carcasses. The inside (Meat) and outside (Rind) surfaces of belly area, for the both sides of carcasses, were sponged with a pooled of 5 pigs caecal content. After 10 minutes of contact time,
one half of the carcass was knife-trimmed and the other one was treated by the steam vacuum
system.
Steam-vacuum
Knife-trimming
For each carcass one 25cm2 sample tissue was excised from Rind and Meat, prior (contaminated) and
after treatments. On the slaughter line, 45 carcasses were also sampled, to be used as control of bacterial contamination. Aerobic colony counts
(ACC) and Enterobacteriaceae (ENT) were enumerated from Rind and Meat of each carcass, and a Salmonella presence Test performed.
RESULTS
Most of the bacterial counts were below the enumeration threshold ; these results were thus replaced by the value of the threshold. The table 1 presents the average levels of bacterial contamination. The counts of contaminated carcasses were logically higher compared to control
(+ 2 log10CFU/cm2 for ACC and + 3 log10CFU/cm2).
Table 1: Means of contamination (log10CFU/cm2) between
treated carcasses and control carcasses.
Rind
Table 2: Efficacy (log10CFU/cm2) of treatments
on faecal contaminated pork carcasses.
Rind
Meat
Meat
ACC
ENT
ACC
ENT
ACC
ENT
ACC
ENT
Contaminated carcasses
5.49
4.93
5.24
4.22
Trimming
2.69
3.39
2.27
2.60
Trimming
2.80
1.54
2.97
1.61
Steam vacuum
2.82
3.59
2.10
2.53
Steam vacuum
2.67
1.34
3.15
1.78
Control carcasses
3.26
1.90
3.06
1.00
Bacterial contamination after both treatments was significantly reduced to the level of control carcasses.
Whereas the efficiency of treatments (Table 2) was underestimated by substitution of counts below the enumeration threshold with the value
of the threshold, steam-vacuum treatment for ACC on Rind was significantly superior of knife-trimming. Therefore, on Meat, both treatments
were not significantly different. The presence of Salmonella was respectively about 4% (2/45) and 13% (6/45) on Rind and Meat of fecally
contaminated carcasses. After treatments, only one sample was positive for salmonella (0/45 for trimming 1/45 for steam-vacuum).
After both treatments, surfaces were free of any visible faecal contamination. All the contaminated rind surface and a large part of sparerib
surface was removed by knife-trimming, reducing the carcass commercial value. With steam-vacuum treatment, the Rind was preserved and
the Meat side needed only a slight trimming due to surface heat damage.
Conclusion
The results of this study show than both treatments reduced the bacterial contamination to the level of control carcass. The steamvacuum system had an equivalent decontamination effect (>2 log10CFU/cm2), with a lower reduction of the commercial value of
the carcass. Steam-vacuum system should be thus considered by meat industry as a good alternative to traditional knife-trimming
for pork carcasses with visible faecal contamination.
On-site validation of thermal treatments
used as corrective actions
on pork carcasses and cuts.
ICOSMT 2008
Le Roux A., Minvielle B., Vallée A.
IFIP – French institute for pig and pork industry La Motte au Vicomte, BP 35104, 35561 Le Rheu Cedex, France.
[email protected]
The aim of this study was to validate the bacterial efficiency of thermal treatments used in slaughterhouses and cutting rooms as
corrective measures. Heat process without flames should be recommended for meat cuts, whereas flames processes should be used
for carcasses.
INTRODUCTION
Since 1993, with the implementation of HACCP principles, pork meat industry have developed some corrective actions. The aim of this
study was an on-site validation of the bacterial efficiency of thermal treatments, already used in some slaughterhouses and cutting rooms
as corrective measures.
METHOD
Three existing heat systems (Photos) were tested in 4 French slaughterhouses. For each system 3 treatments, i.e. couples of distance and duration parameters, were studied (Table 1).
Table 1: Distance and time for each treatment.
Treatment
GB
BT
PB
Carcasses
1
2
3
1
2
3
1
2
3
8/3
15 / 3
20 / 6
15 / 2
20 / 3
25 / 3
Shoulder rind
Shoulder meat
Distance (cm) / Time (s)
15 / 3
5 / 1.5
20 / 6
8/3
15 / 2
20 / 3
20 / 3
5/2
25 / 3
10 / 2
25 / 3
15 / 3
3/5
4/2
3/3
7/4
5/5
7/2
Blowtorch (BT)
Paint burner (PB) Gas burner(GB)
Both samples, before and after treatment, were excided (25 cm2) side by side. Aerobic colony counts (ACC)
and Enterobacteriaceae (ENT) were enumerated.
Means of bacterial reductions (log10 CFU/cm2) for each
treatment were calculated from at least 36 samples
from 2 repetitions. Statistical analysis were conducted
using the GLM procedure (SAS Institute, USA).
Table 2: Reduction of ACC (log10CFU/cm2)
according to equipments and
treatments on carcasses.
Most of the Enterobacteriaceae counts were below the enumeration threshold. However, compa-
RESULTS
rison between results below the threshold prior and following treatment (65% vs. 90%) showed
that the bacterial contamination was significantly lower after heat treatments (Chi-square test;
p≤0.0001).
Treatments
1
2
3
The bacterial reduction for aerobic colony counts (Table 2) was equivalent between the two equipments (1.8 to 2.4 log10CFU/cm2) for carcasses.
* a,b,…LSmeans sharing the same letter
are not different (p>0,05)
The table 3 and 4 present the reduction obtained on rind and on meat surfaces of cuts.
GB treatment had a significantly
lower reduction on the rind and
meat surfaces of cuts than the other
equipments. The efficiency of BT
and PB was about 2 log10CFU/cm2
on rind and 1 log10CFU/cm2 on
meat. The treatments were not significantly different.
Table 3: Reduction of ACC (log10CFU/cm2)
according to equipments and treatments on rind.
Treatments
1
2
3
Shoulders rind
GB
BT
0.5 bc*
2.0 a
0.8 b
2.2 a
0.0 c
2.1 a
PB
2.1 a
2.1 a
1.7 a
Carcasses
GB
BT
1.8 a*
2.4 a
1.9 a
2.3 a
0.8 b
2.4 a
Table 4: Reduction of ACC (log10CFU/cm2)
according to equipments and treatments on meat.
Treatments
1
2
3
Shoulders meat
GB
BT
PB
0.2 ef*
1.5 a
1.0 abc
0.5 cde
0.8 bcd
0.5 cdef
0.0 f
1.4 ab
0.6 cde
* a,b,…LSmeans sharing the same letter are not different (p>0,05)
Conclusion
On carcasses, the efficiency of gas burner and blowtorch was about 2 log10CFU/cm2, they can be alternatively used as corrective
measure. On meat cuts, the gas burner was not efficient. The paint burner had equivalent efficiency than blowtorch (2 log10CFU/
cm2 on rind / 1 log10CFU/cm2 on meat), but its use is safer and better preserves product appearance. This two systems can be use
as corrective measure on meat cuts. All thermal treatments were quick (2-6 s) and easy to use. The information given on each treatment can be used as reference for meat industry.