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Food Process Technology
Fichas del conjunto (12)
- 1MEAT PROCESSINGCAUSES OF MEAT DEFECTS AFTER SLAUGHTER
- 21. DFD DEFECT (DARK, FIRM, DRY) CONDITION IN RED MEAT WHERE THE PH 45 MINUTES AFTER SLAUGHTER IS 6.5-6.8THE CAUSES - ANIMALS THAT ARE EXPOSED TO CHRONIC OR LONG TERM STRESS BEFORE SLAUGHTERING
THE STRESS BEFORE SLAUGHTER LEADS TO DEPLETION OF STORED GLYCOGEN AS A RESULT THERE IS LESS GLYCOGEN POST-MORTEM AFFECTING THE PROCESS OF ACIDIFICATION AND LEAVING THE PH OF THE MEAT HIGH - 3GLYCOLYSIS CEASES WHEN PH REACHES 5.5, IF THE ANIMAL HAS BEEN STARVED BEFORE SLAUGHTER THE GLYCOGEN RESERVES ARE ALREADY DEPLETED BEFORE SUFFICIENT LATIC ACID HAS BEEN FORMED TO BRING THE PH DOWN TO 5.5DFD IS A CONDITION IN WHICH HIGH PH RESULTS IN LITTLE DENATURE OF THE PROTEINS THE WATER IS TIGHTLY BOUND AND LITTLE OR NO EXUDATES ARE FORMED RESULTING IN A FIRM PRODUCT
- 41. MEATS TRANSMIT MORE LIGHT INTO ITS DEPTH LEADING TO THE FORMATION OF DARK COLOUR 2. SMALL EXTRACELLULAR SPACE LEADING TO HIGH WATER HOLDING CAPACITY (FORMING A DRY PRODUCT) 3. AMINO ACIDS ARE UTILISED DUE TO GLUCOSE DEPLETION AND SPOILAGE ODOUR IS PRODUCED AT AN EARLY STAGEREASONS FOR DFD
CHRONIC OR LONG TERM STRESS BEFORE SLAUGHTER INCLUDE:
1. TRANSPORTATION OF ANIMALS OVER LONG DISTANCES
2. LONG HOURS OF FOOD DEPRIVATION AND OVERCROWDING OF ANIMALS IN THE LAIRAGE OVER A LONG PERIOD OF TIME - 5PSE DEFECT (PALE, SOFT, EXUDATIVE)DEFECT MAINLY AFFECTING PORK AND IS A CONDITION WHERE THE MEAT PH AFTER 2 HOURS OF SLAUGHTER REACHES A PH AROUND 5.2
- 6CAUSESANIMALS EXPOSED TO ACUTE STRESS PRIOR TO SLAUGHTERING CAUSES PSE.
ACIDIFICATION OCCURS IN MUSCLES POST MORTEM DUE TO THE BREAKDOWN OF GLYCOGEN TO LACTIC ACID - 7PSE OCCURS BECAUSE THE RATE OF ACIDIFICATION AFTER SLAUGHTER IS ACCERERATED AND LOWER PH VALUES ARE REACHED IN THE MUSCLE WHEN THE TEMPERATURE OF THE CARCASS IS STILL HIGH THE COMBINATION OF LOW PH AND HIGH TEMPERATURE IN PSE MEAT CAUSES THE DENATUREATION OF SOME MUSCLE PROTEINS LEADING TO THE FORMATION OF SOFT MEAT TISSUEDUE TO HIGH PROTEIN DENATURATION A LARGE EXTRACELLULAR SPACE IS CREATED RESULTING IN POOR WATER HOLDING CAPACITY OF THE MUSCLE AND THE PRODUCTION OF A LARGE AMOUNT OF EXUDATES
- 8SHRINKAGE OF THE MYOFILLAMENT INCREASES THE AMOUNT OF LIGHT REFLECTED FROM THE MEAT IN ADDITION TO DENATURATION OF MYOGLOBIN DUE TO LOW PH. AS A RESULT PSE MEAT IS LESS RED AND MORE YELLOW AND PALEEXAMPLES OF ACUTE OR SHORT TERM STRESS INCLUDE:
USE OF ELECTRIC GOADS, FIGHTING AMONG ANIMALS JUST BEFORE STICKING, BEATING OF ANIMALS PRIOR TO SLAUGHTERING AND OVERCROWDING IN THE LAIRAGE - 9THE PREVENTION OF PSE AND DFD IN MEATS RELAYS MAINLY ON MEASURES TO AVOID STRESS IN THE ANIMALS PRIOR TO SLAUGHTER. STRESSES INCLUDE 1. REMOVAL FROM THE HOME 2. ENVIRONMENT, 3. LOADING AND UNLOADING INTO VEHICLES, 4. FEED AND 5. WATER DEPRIVATION DURING 6. TRANSPORTATION, 7. HOLDING INTO UNFAMILIAR SURROUNDINGS 8. MIXING WITH STRANGE ANIMALS 9. BAD ODOUR 10. HIGH TEMP AND NOISE PRODUCED BY MOVING VEHICLESANIMALS AWAITING SLAUGHTER ARE STRESSED BY FACTORS SUCH AS RESTRAINT, HANDLING, NOVELTY OF THE PRE- SLAUGHTER ENVIRONMENT, ADVERSE WEATHER CONDITIONS, HUNGER, THIRST, AND FATIGUE.
AT THE ABATTOIR STAGE ANIMALS SHOULD BE RESTED ENOUGH TO RECOVER FROM STRESS BEFORE SLAUGHTERING. - 10COLD SHORTENING--- AFTER SLAUGHTERING AEROBIC RESPIRATION CEASES, BLOOD FLOW STOPS, MUSCLES ARE NO LONGER SUPPLIED WITH OXYGEN --- ANAEROBIC CONDITIONS PREVAIL AND GLYCOLYSIS STARTS
---WHEN GLYCOLYSIS STOPS AND ALL SUPPLYS OF ATP IS DEPLETED, THE ACTOMYOCIN CROSS LINKS HAVE FORMED AND THE ANIMAL NOW HAS ENTERED RIGOR MORTIS - 11--- IF THE MEAT IS COOLED BELOW 10 DEGREES CELCIUS BEFORE RIGOR MORTIS HAS OCCURS, COLD SHORTENING CAN OCCUR WHICH CAUSES THE FORMATION OF TOUGH DARK MEAT WHICH PREVENTS TENDERISATION DURING AGING. --- HOWEVER BECAUSE THE PERIOD BETWEEN SALUGHTER AND RIGOUR MORTIS CAN BE AS MUCH AS 6 HOURS IN SOME ANIMAL SPECIES THE CARCASS MUST BE STORED AT TEMPS BELOW 10 DEGREES CELCIUS TO PREVENT MICROBIAL GROWTH COLD SHORTENING CAN OCCURONE OF THE SOLUTIONS TO THIS PROBLEM IS THE APPLICATION OF ELECTRIC STIMULATION, AN ELECTRICAL CURRENT IS APPLIED TO THE CARCASS FOLLOWING SLAUGHTER WHICH CAUSES FASTER DEPLETION OF ATP SO THE PH DROPS AND A RESULT IS THE HASTENING THE ONSET OF RIGOR MORTIS SO THAT THE PERIOD THAT THE CARCASS STAYS OUT OF CHILL TEMPERATURE IS REDUCED
- 12RIGOR MORTIS ONSET 6-12 HOURS FOR BEEF AND LAMB 30 MINUTES- 3 HOURS FOR PORKRIGOR IS COMPLETED IN CATTLE AFTER 12-24 HOURS AND IS RESOLVED BY PERIODS THAT DEPEND ON THE TEMPERATURE 10-13 DAYS AT 0 DEGREES CELCUIS
4-5 DAYS AT 10 DEGREES CELCIUS
30-40 HOURS AT 20 DEGREES CELCIUS
10-11 HOURS AT 30 DEGREES CELCIUS
THE PROCESS IS TWICE AS FAST IN PORK AS BEEF OR LAMB AND IS FASTER IN YOUNG ANIMALS
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- Fichas sobre Food Process Technology, creado por sarah darby el 24/07/2015.
- Creado por
- sarah darby · jul 2015
- Actualizado
- 19 feb 2016
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