CHILLING OF CARCASSES FROM DOUBLE MUSCLED CATTLE :
TIME-TEMPERATURE EVOLUTION AND PREDICTIVE MODELLING OF GROWTH
OF LISTERIA MONOCYTOGENES AND CLOSTRIDIUM PERFRINGENS
- study the feasibility of complying with chilling recommendations in heaviest carcasses of the Belgian Blue cattle
- predict the potential growth of Listeria monocytogenes on the surface and Clostridium perfringens in the depth of carcasses
Materials and methods
Results and discussion
L. Delhalle, B. Collignon, S. Dehard, P. Imazaki, G. Daube and A. Clinquart
University of Liège, Faculty of Veterinary Medicine Department of Food Science, Sart Tilman, B43bis, 4000 Liège, BelgiumData source of temperature and pH
Predictive microbiology
3 slaughterhouses
4 half carcasses / slaugtherhouse /
day
superficial and core temperature (each min. during 48h) pH (1,2,4,8,48h post mortem)
Secondary growth model (gamma concept)
Primary growth model (linear three-phase primary growth model)
Prediction of the potential growth of Listeria monocytogenes and
Clostridium perfringens 6 days Objectives 5,0 5,5 6,0 6,5 7,0 1 2 4 8 48 p H Time post-mortem (h) electrical stimulation no electrical stimulation
Research financed by Walloon Region (DGO6, Convention n°°°°5713, 2008-2011 ; DGARNE, Project n°°°°D31-1229, 2010-2012)
The observed time-temperature combinations in the selected slaughterhouses comply with recommendations and limit the growth of both pathogens in case of accidental contamination of carcasses.
This study contributes to demonstrate that modeling approach could be used on available environmental data in order to evaluate the risk associated with pathogens. The impact of the variation of environmental conditions can also be evaluated.
Results and discussion
Predicted growth of Listeria monocytogenes on the surface (a) and Clostridium perfringens in the depth(b)of the carcasses
Post-mortem evolution of pH in the longissimus dorsi muscle
Temperature evolution on the surface (a) and in the depth(b)of the carcasses Characteristics of the selected slaughterhouses
and carcasses Conclusions 0,0 0,5 1,0 1,5 2,0 2,5 3,0 0 4 8 12 16 20 24 28 32 36 40 44 48 L o g C F U /c m 2 Time (h) (a) Listeria monocytogenes
potential growth ≤0.7 to 1.4 log at 48h
lower growth due to faster pH evolution 1.0 log cfu/cm² at 0h lag phase = 0h Slaughterhouse A Slaughterhouse B Slaughterhouse C Slaughterhouse A Slaughterhouse B Slaughterhouse C 0,0 0,5 1,0 1,5 2,0 2,5 3,0 0 4 8 12 16 20 24 28 32 36 40 44 48 L o g C F U /g Time (h) (b) Clostridium perfringens potential growth : ≤0.7 log at 48h 1.0 log cfu/g at 0h lag phase = 10h no effect of the pH evolution Slaughterhouse A B C
Electrical stimulation no yes no
Shock chilling 2h30 no 2h30
Carcass weight 494 ± 49 kg 473 ± 32 kg 476 ± 25 kg European
classification
DS2, DS3,
DE2, DE3 DS2, DS3 AS2
0 5 10 15 20 25 30 35 40 45 0 4 8 12 16 20 24 28 32 36 40 44 48 T e m p e ra tu re ( °C ) Time (h) (a) Superficial ≤+7°C at 12h 0 5 10 15 20 25 30 35 40 45 0 4 8 12 16 20 24 28 32 36 40 44 48 T e m p e ra tu re ( °C ) Time (h) (b) In depth ≤+15°C at 24h ≤+7°C at 48h
