Muscle to meat Flashcards
What alters the onset of rigor mortis?
How long ATP production can be sustained as well as ATP consumption rate
What causes the stiffness in rigor mortis
When the ATP supply is exhausted the myosin heads remain locked onto the actin
What three features can be used to asses meat quality?
Water holding capacity - Most proteins in meat lose their charge around 5.1-5.5 which is close to the optimum pH of meat, at this pH the meat releases water
Colour and paleness - Myoglobin blooming in the presence of oxygen is associated with freshness
Succulence/juiciness - fat levels
How can tenderness be objectively assessed
Using myofibrillar fragmentation index and sheering forces
Tenderness of meat depends on:
Age: collagenous tissue increases with age
Type of muscle: White muscle like latissimus dorsi is less tender than red muscle
Amount of sarcomeric shortening during rigorous mortis: the faster the rate of glycolysis the more shortening
Meat maturation: longer chilling leads to more tender meat as there is more proteolysis
How can electrical stimulation be used to tenderise meat?
ES is applied after eviceration and within 1hr of slaughter and speeds up onset of and passing of rigorous mortis
What are the benefits of hanging by the obturator foramen rather than the achilles tendon?
The muscles of the gluteal area will be stretched thus protecting the most expensive cuts of meat from cold shortening
What chemical was can meat tenderness be improved?
Use of proteases: papain (papaya), bromelin (pineapple skin) and fiction (figs)
Marination: NaCl, Polyphosphate CaCl2 and bicarbonate
What causes dark cutting beef or dark firm dry?
Incomplete acidification, the meat has a pH of around 6 caused by depleted muscle glycogen (stress before slaughter) so the meat retains more water and is tougher as the myosin and actin are still locked
What is pale soft exudate?
Accelerated glycolysis after slaughter with a rapid build up of lactic acid
If the pH is less than 6 within 45 min of slaughter PSE is more likely
What causes cold shortening?
When the carcass is chilled below 10’C before rigorous mortis, as is often done to reduce microbial growth
Sheep and cattle - leave 10h before chilling below 10’C and pigs, leave 3h
What causes boar taint?
Sex steroids like androtestosterone
Microbial breakdown of tryptophan in the gut to skatole and indole
Which abattoirs are required to classify carcasses under the BCC scheme?
Abattoirs that slaughter more than 75 adult bovines per week
Do you need a licence to classify beef?
Yes and records must be kept (and animals marked)
Carcasses must be dressed to one of three specifications, what are they?
Standard specification
EC reference specification
UK specification
What does Standard specification require?
Udder fat on Crown fat on Bed fat on Brisket fat on Thin skirt on
What does EC reference spec require?
Udder fat off Crown fat off Bed fat on Brisket fat on Thin skirt on
What does UK Spec require?
Udder fat off Crown fat off Bed fat off Brisket fat off Thin skirt off
What must once consider when classifying beef?
Conformation
Fat cover
What are the conformation classes of beef?
EUROP
Which comes first the conformation or fat cover?
Conformation first eg R4L
What are the beef fat classes?
1 (very lean) to 5 with 4 and 5 being subdivided into H and L
Is sheep carcass classification mandatory?
No
What is used for sheep carcass classification?
The beef classification system
Is pig carcas grading mandatory?
For slaughterhouses doing more than 200 pigs per week (averaged over 12 months) must be registered with the Pig carcase grading scheme
How must pig carcases be dressed?
To EU or UK spec
According to the pig EU spec what must be removed?
Tongue, bristles, hooves, genital organs, flare fat, kidney, diaphragm
According to the UK pig spec what parts can be left in the pig prior to weighing?
Kidneys
Flare fat
Diaphragm
Tongue
When should pig carcases not be weighed?
Not within 45 mins of slaughter
How is cold weight calculated from a warm carcase?
Deduct 2% from the WW
How is pig fatness graded?
Using an optical probe on the latissimus doors 6.5cm from the dorsal midline at the last rib
Use the SEUROP scale
Pig carcasses destined for export must be marked with either:
The appropriate letter from the grading system
The % lean meat
(all letters 2cm high)
