Methods of slaughtering, processing & postmortem changes and ageing of meat
- 1. WELCOME TO MY PRESENTATION Presented by: Mahabub Alam MS student in Animal Science Department of Animal Science and Nutrition Chittagong Veterinary and Animal Sciences University, Khulshi, Chittagong -4202 CVASU 1
- 2. Contents Slaughtering of animals Processing of animals after slaughter Postmortem changes and ageing of meat 2 CVASU
- 3. Slaughtering of animals Slaughter: The act of killing or butchering of animals in a "correct" way especially for food. 3 Essentials of Slaughter 1. Suffering should be minimum 2. Perfect bleeding should be ensured CVASU
- 4. Treatment of Animal prior to slaughter Resting Watering Feeding Fasting 4 CVASU
- 5. Resting Keeping quality of meat reduced without adequate resting due to: Incomplete development of acidity Invasion of microbes from intestine Period of rest: Depending on species, age, sex & breed Usually 12-24 hours 5 CVASU
- 6. Watering Essential for: Reduce microbes load in intestine Facilitated skinning Electrical stunning is more efficient 6 CVASU
- 7. Feeding Importance: Deposition of muscle glycogen Development of acidity- Increase keeping quality of meat Good appearance, taste & tenderness of meat 7 CVASU
- 8. Fasting Should stop feeding few hours before slaughter Importance: Good bleeding carcass Minimize migration of microbes from intestine 8 CVASU
- 9. Slaughtering practices and techniques A. The Humane Method & Conventional Techniques of Slaughter & B. Traditional and Ritualistic Slaughter 9 a. African Traditional Slaughter b. Jewish Method/Shechita c. Muslim method of slaughter d. Jhakta (Sikh) method CVASU
- 10. A. The Humane Method & Conventional Techniques Complete state of unconsciousness -mechanical, electrical or chemical means (Stunning) Stunning- Painless, Motionless, eliminating excitement and cruelty 10 CVASU
- 11. Steps of Humane Method 1. Stunning: Make unconscious prior to slaughter 2. Bleeding: vertical hanging position (Head down), - knife through the neck behind the jaw bone and below the first neck bone - sever the blood vessels of the neck and let out blood - bleeding should be as complete as possible 11 Vertical Hanging CVASU
- 12. Steps of Humane Method (Cont.) 3. Skinning: Removing of skin from the body 4. Eviscerating: open the animal body to dislodge the contents and produce the carcass 5. Postmortem Inspection: Carried out by professional veterinarians 6. Special Measures: Stamped as – INSPECTED/ PASSED/ CONDEMNED 12 CVASU
- 13. Humane Method Advantages: Painlessness (Stunning) Eliminating excitement and possible cruelty. Disadvantages: Disallowed by rituals and established traditions 13 CVASU
- 14. Stunning in humane Method Stunning: Make unconscious prior to slaughter Methods of stunning: Direct blow to skull using a club- sheep & goats Free bullet fired from a pistol into the skull – cattle & Horse (unsafe) Captive-bolt pistols – Cattle & horse (safe) Electrical stunning- 60–80 V for few seconds Carbon dioxide stunning- 85% for 45s, used in pig 14 CVASU
- 15. 15 Captive-bolt pistol Electric stunner Aiming point for stunning cattle Head tongs are also suitable for stunning pigs CVASU
- 16. Traditional and Ritualistic Slaughter Defer from Humane Method by: Interpretation of the basic tenets governing them The animals must be in a state of consciousness at the time they are bled The bleeding must also be complete. 16 CVASU
- 17. African Traditional Slaughter Sheep or goat is first securely held on its back on the ground by two or three men while the mouth is grabbed tight and drawn backwards to stretch the neck The slaughterer then cuts the throat transversely with a series of strokes half- way deep into the neck Blood is allowed to drain off until the animal (still tightly held) is motionless or dies. The head is then severed off completely. 17 CVASU
- 18. Jewish Method/Shechita Formulated by following the religious taboos Kosher: meat - right fulfilling the requirement of Jewish law-specified in the Talmud Shochet: person appointed for slaughtering Shomer: person appointed for limbs and meat processing and seal. 18 CVASU
- 19. The rules of Jewish ritual slaughter * Must be alive, healthy & have suffered no injury * Stunning- forbidden * Diseased or lesion in meat (Terefa)- unfit for consumption * Animals that lie & cannot be made to rise must not be slaughtered * Slaughter the animals with a single deliberate swift action of razor sharp knife. * Structures severed: including the CA& JV * Neck incision-complete, without pause, pressure, stabbing, slanting or tearing * Post mortem examination by Shochet making an incision posterior to the xiphoid process inserting the arm to detect any adhesion in the thoracic cavity. * Kosher -must be sold out within 3 days. 19 CVASU
- 20. Jewish Method/Shechita Advantages: No cruelty respiratory activity, struggle> oxyhemoglobin > good color meat Disadvantages: Animal remainconscious for a considerable time No stunning- Inhuman (many people) Economic loss 20 CVASU
- 21. Muslim method of slaughter (Halal method) Most widespread Laws are derived from the Koran welfare of the animals is a major consideration (Jewish faith also apply to Muslims) Death animals, consumptions of blood and swine is forbidden. 21 CVASU
- 22. Rules of halal method Uttered - “bismillahi Allahu Akbar'' Done by - adult sensible Muslim Stunning - allowed Should done quickly Casting- laid on its back Neck vessels and passages (oesphagus and trachea) are severed by a single slash of a sharp knife must not - in the sight of the beast Prior to killing – should feed water 22 CVASU
- 23. Halal method (cont.) Advantages Same as Jewish Struggling & cardiac action- efficient bleeding Disadvantage contamination by contents of the stomach -waste of blood 23 CVASU
- 24. Jhakta/Sikh method Instant decapitation process Sikh, Hindu in the India follows this method. Limited to only to sheep and goats By only one blow head is separated 24 CVASU
- 25. Jhakta/Sikh method (cont.) Advantages Easy and quick method Disadvantages Imperfect bleeding 25 CVASU
- 27. Processing includes: Skinning Evisceration Splitting Washing Dressing of carcasses & Refrigeration 27 CVASU
- 28. Skinning of animals Precautions: Outer side of the skin must never touch the skinned surface Operators must not touch the skinned surface with the hand 28 CVASU
- 29. Skinning of Cattle Combined horizontal/vertical methods Head: horn- remove, head- skinned, Detached head- cutting through occipital joint, Hang head- on a hook (Hanging animal) Lower the carcass on its back- dressing cradle Legs: Skin & remove the legs at carpal & tarsal Hooves may be left attached to the hide Forelegs should skinned after carcass is lowered on to the dressing cradle – to avoid 29 CVASU
- 30. Combined methods (cont.) Flaying: Cut skin-along middle line from sticking wound to tail Skin brisket & flanks, working backwards toward the round – with long strokes & keeping knife up to prevent cuts Skin udders-without puncturing glandular tissue Raise the carcass: half-hoist position shoulders resting on cradle & rump at good height. Anal region: Clear skin carefully from around anus avoiding puncturing it Cut abdominal wall carefully around rectum Tie off with twine to seal it Skin the tail, raise carcass free of floor & finish flaying 30 CVASU
- 31. Vertical methods Modern plants have overhead rails- Hide removal is carried out on the hanging carcass Operations are similar to combined method It is not possible to reach the hide from ground level more than one operator is needed Single operator-work with hydraulic platform Automatic hide pullers - high-throughput 31 CVASU
- 32. 32 Fig: Correct cutting lines for hide removal Fig: Combined method of skinning CVASU
- 33. 33Fig: Cattle are on hanging rail (Vertical method) CVASU
- 34. Evisceration In all species care must be taken not to puncture the viscera 34 Fig: Evisceration of cattle CVASU
- 35. Evisceration of cattle 35 combined horizontal/ vertical system brisket is sawn along midline when the carcass on cradle raised to half-hoist position and abdominal cavity is cut carefully along middle line. carcass is then fully hoisted to hang so that the viscera fall out under their own weight Separated into thoracic viscera, paunch & intestines Vertical system Carcass is cut along midline through brisket & abdomen Viscera will come out as the carcass in hanging position Stomachs or intestines if use for consumption they should tie separately. CVASU
- 36. Evisceration of small ruminants 36 A small cut is made in the abdominal cavity wall just above the brisket Fingers of the other hand are inserted to lift the body wall away from the viscera cut is continued to within about 5 cm of the udder The omentum is withdrawn & viscera taken out breastbone is split down the middle & thoracic organs then removed Hind quarterCVASU
- 37. Carcass splitting in cattle Work facing the back of the carcass Split the carcass down the backbone (chine) with a saw or cleaver from the pelvis to the neck If a cleaver is used, it may be necessary to saw through the rump and loin in older animals The saw and cleaver should be sterilized in hot (82°C) water between carcasses 37 Splitting carcass down the vertebral column CVASU
- 38. Carcass splitting in small ruminant Generally sold entire Can be split by saw or cleaver Saw will probably be necessary for older animals 38 CVASU
- 39. Carcass splitting in pig Split down the backbone as for cattle But the head is generally left intact 39 CVASU
- 40. Carcass washing Objectives: Remove visible soiling & blood stains Improve appearance after chilling • Recommendations : Water must be clean Soiled carcasses should be sprayed immediately before the soiling material dries Remove stains from the skinned surface, internal surface, sticking wound & pelvic region. 40 CVASU
- 41. Carcass dressing Objectives: Remove all damaged or contaminated parts Standardize the presentation of carcasses Recommendations: Inspection should be done by veterinarian Signs of disease/damage - entire carcass/offal may be condemned Factory personnel must not remove any diseased parts until they have been seen by the inspector otherwise they may mask a general condition which should result in the whole carcass being condemned. Any instructions from the inspector to remove and destroy certain parts must be obeyed. 41 CVASU
- 42. Refrigeration of carcasses Objectives: Retard bacterial growth & extend the shelf-life Recommendations: Chilling meat after postmortem down to 0°C & keeping it cold will give a shelf-life of up to three weeks Must be placed in the cooler immediately Must hang on rails & never touch the floor deep muscle temperature of 6–7° C should be achieved within: 28 to 36 hours in beef 12 to 16 hours for pork 24 to 30 hours for mutton 42 CVASU
- 43. Refrigeration (cont.) Humidity and Air current of cooler: High air speeds (AS)-rapid cooling but- evaporating wt losses High RH- condensation on the carcass surface favouring mould and bacteria growth Optimum RH=90% & AS=0.5m/s Cooler-thoroughly washed before refilling Personnel handling - should follow the strictest hygiene 43 CVASU
- 44. 44 Stunning Bleedingon bleedingrail Loweringon skinning cradle,start flaying,cut feet,head&tail Graduallylifting uptodressing rail,continue flaying Completionof flaying,cut breastbone Evisceratio n Splitting Sequence of operation (combined method) CVASU
- 45. Sequence of operation (vertical method) 45 Stunning Bleeding Transferfrom bleedingrailto dressingrail Mechanical hidepulling Evisceratio n Splitting CVASU
- 46. SCALDING AND DEHAIRING OF PIGS 46 CVASU
- 47. SCALDING (pig) Scalding in 60°C for about six minutes Low temperature: hair will not be loosened high a temperature: skin cooked and the hair difficult to remove simplest equipment consists of a tank of hot water into which the pig is lowered by a hoist To reduce contamination, scalding water should be changed frequently Effectiveness scald-hair comes away easily in rubbing with thumb Thermostatic controls and timers 47 CVASU
- 48. DEHAIRING (pig) Done by bell scraper or knife/ Dip the pig in a bath containing a hot resin adhesive: The pig is removed from the bath when resin is about to set Require less & produces a very clean skin 48Fig: Machine contain both hot water bath & scraper Water bath Scrap er CVASU
- 49. Postmortem changes and ageing of meat These includes: Acidification of the muscle after animal the animal is killed The development of rigor mortis The resolution of rigor and The tenderization of meat (due to ageing) 49
- 50. Acidification of the muscle At the death blood circulatory system fails supply of oxygen, glucose & free FA to muscles ceases anaerobic metabolism 50 ATP : regenerated through breakdown of glycogen by glycolysis oxidative decarboxylation & phosphorylation will stop Glycogen broken down in anaerobic condition so LA accumulates (can not remove by circulation) CVASU
- 51. 51 Glycoge n Fructose 1,6-diphosphate Glyceraldehyde 3- phosphate Dihydroxyacetone phosphate Glyceric acid 1,3- diphosphate Glycerol 1,3-diphosphate Glyceric acid 3- phosphate Phosphoenol pyruvte Pyruvate Lactic acid Fig : Pathway of lactic acid production from glycogen in anaerobic condition after circulatory failure (Glycogenolysis). CVASU
- 52. Acidification of the muscle (cont.) The process of acidification normally takes 4–8 h in pigs, 12–24 h in sheep and 15–36 h in cattle Poultry meat the initial pH fall may be relatively rapid- in turkeys breast muscle pH fall to 6 by 10–15 52 CVASU
- 53. 53 Fig: The pHu is inversely proportional to the concentration of the initial glycogen concentration CVASU
- 55. The development of rigor mortis 55Fig: muscle histology CVASU
- 56. Mechanism of muscle contraction 56 ATP interacts with a thick filament head Head to extend into what is called it's "high energy position Release of Ca from sarcoplasmic reticulum Ca attach to actin filaments causing them to change shape so that docking sites for the myosin filament heads appear Myosin filament heads bind to these docking sites (formation of actomyosin) and undergo a change in shape that pulls on the thin filament bringing it closer to the center of the sarcomere Many sarcomeres contract simultaneously their muscle does Again ATP binds to myosin head to start the contraction cycle CVASU
- 57. What happen in rigor mortis? ATP production stop when acidification develop 57 The actinomyosin persist because , ATP require to extend the myosin head to remove binding with actin and start contraction cycle (ATP also require for releale of Ca) Development of rigor mortis Note: Rigor occurs faster in - Animals that have undergone violent exercise at death- quick rigor longer-term preslaughter stress Rigor occurs slower in- cold weather CVASU
- 58. Resolution of rigor and tenderization of meat The myofibrils become fragmented by controlled homogenization of the muscle in aqueous solutions -can be measure by ‘myofibrillar fragmentation index’ Suspensions that are more opalescent indicate smaller particles, reflecting a greater fragmentation 58 CVASU
- 59. The rate of tenderization Varies with temperature %& species faster at higher temperatures 80% tenderness: About 8 h after death of the bird, whereas beef takes 10 days These differences in the rate of tenderization lead to different recommended ‘ageing’ times prior to cooking the meat 59 CVASU
- 60. The process of conditioning Conditioning is the term applied to this natural process of tenderization Two types of process: changes in the connective tissue Components of the meat or weakening of the myofibrils 60
- 61. The mechanism of tenderization Activity of the proteolytic enzymes- Calpains and cathepsins Calpains is more important These are lysosomal and sarcoplasmic enzyme These are activated by Ca, so called calcium-activated sarcoplasmic factor (CASF) The degrade troponin-T, some collagen cross-links and mucopolysaccharides of the CT ground substance They degrade actin and myosin below a 61 CVASU
- 62. DFD meat Color of flesh is darker and drier than normal Occurs in cattle: Pre-slaughter stress Normal animal pH falls to 5.5-5.8 but in stressed animals falls to 7-6.8 Resulting meet are poor keeping quality 62 CVASU
- 63. PSE meat In stress susceptible animals PH falls to 5.8-5.6 when the carcass is warm Found in pork Resulting meat appears pale, soft , exudative and unattractive Occurs due to: High environmental temp. Rough ante mortem handling Fightings 63 CVASU
- 64. References Meat Science An Introductory Text by- P.D. Warriss Meat Hygiene by- J. F. Gracey, D. S. Collins & R. J. Huey FAO official website for slaughtering practices in large animal FAO official website for slaughtering practices in small animal Google wed engine search 64 CVASU