ContentsIntroductionMethods of flayinga) Large ruminant 1.Combined Horizontal & vertical method 2.Vertical methodb) Small ruminant 1.Combined Horizontal & vertical method 2.Vertical method Advantages of combined horizontal & vertical method Disadvantages of combined horizontal & vertical method Advantages of vertical method Disadvantages of vertical method Definitions
Introduction:Stunning of the animal is done by mechanical, electrical orchemical method followed by sticking/bleeding of the animal andthen flaying/skining is done.Flaying is defined as removal of a skin/hide from a carcass ofslaughtered or dead animal.Hide is one of the precious product obtained from the slaughterof animal used for the preparation of leather goods.Price of hide depends upon the quality of hide.To obtain quality product specific scientific methods areproposed to avoid unnecessary cuts in hide which reduces thequality of hide.
Flaying/skinning should be done within a few hours of theanimals death as the skin will peel off especially easily.Make sure the knives used are sharp. Methods of flaying1. Combined Horizontal & vertical method2. Vertical method
Combined horizontal & vertical methodsHead: After bleeding, while theanimal is still hanging from theshackling chain, the horns areremoved and the head is skinned.The head is detached by cuttingthrough the neck muscles andthe occipital joint.Hang the head on a hook.
Legs.Remove skin and the legsat the carpal (foreleg) andtarsal (hind leg) joints.The forelegs should not beskinned or removed beforethe carcass is lowered on tothe dressing cradle or the cutsurfaces will becontaminated.The hooves may be leftattached to the hide. Fig. Correct line of cutting for hide removal
Clear the skin carefullyfrom around the vent(anus) avoiding puncturingit and cut the abdominalwall carefully around therectum.Skin the tail avoidingcontamination of theskinned surface with thehide.Raise the carcass free ofthe floor and finish flaying.
Vertical methodsHigh-throughput plants have overheadrails which convey the carcass from thesticking point to the chills.Hide removal is carried out on thehanging carcass.The operations are as in the combinedhorizontal/vertical method, but as it isnot possible to reach the hide fromground level more than one operator isneeded.A single operator may work with ahydraulic platform which is raised and Fig. Pneumatically operatedlowered as required. rotating knives (flayers) speed the removal of the hide from the flanks
Automatic hide pullers are used inhigh-throughput slaughterhouses.Some types pull the hide down fromthe hind, others from the shouldersupwards toward the rump.Automation of hide removal reducescontamination since there is lesshandling of the carcass and less useof knives.Moving overhead rails also improvehygiene by reducing carcass contactwith operators, equipment such as Fig. Flaying knives aredressing cradles and with each other used for the more intricate parts of hidesince carcasses are evenly spaced. removal
FLAYING/SKINNING GOAT/SHEEP Ripping is the process of tearing theskin to start the skinning process.Steps in the ripping: One long and straight incision fromthe jaw to the anus along the center lineof the belly. Four circular cuts around the shanksat the level of the knee and hock joint. Two cuts on the inside of the forelegs,knees to the breast bone. Two cuts on the back of each hockjoint to a point mid-way between theanus and scrotum.
Combined horizontal/vertical methodThe animal is turned on its back and cuts aremade from the knuckles down the forelegs.The neck, cheeks and shoulders are skinned.The throat is opened up and the gullet (food-pipe) is tied off.The skin on the hind legs is cut from theknuckles down to the tail root.The legs are skinned and the goat/sheep ishoisted by a gambrel inserted into the Achillestendons.The pelt is then pulled down over thebackbone to the head.
Moving cratch and rail system.The hanging carcass is lowered on to a horizontal conveyormade up of a series of horizontal steel plates, bowed slightlyand divided into sets large enough to cradle a single animal.Two operators usually work together on each lambperforming the legging operations and opening the skin tothe stage where it can be pulled off the back. When thegambrel is inserted into the hind legs it is hoisted on to adressing rail.
Vertical MethodFlaying/ skinning of sheep and goatscan be started by making a smallincision on the inside of one of the hindlegs.The hind legs, including a smallportion of the skin covering theabdomen and edges of the butt roundthe rump, can be flayed with a knifeand fist while on the floor.The carcass should then be hoisted.
Cont…..To hang a sheep/goat by its back legs, find the large tendonthat connects the lowest leg segment with the rest of the leg.Poke a hole in between that tendon and the leg bone at hockjoint.Use your fingers to feel the lump that is created by thedouble jointed bone.Then sever the lower leg at the lower of the two joints.Cut skin and tendons around the joint, and then snap it overleg.
CONT…..Skinning is a straight forward activity if one follows the bodysbuilt in guidelines because the skin and muscle tissue arenaturally separated from one another by protectivemembranes.The skin easily separates from the meat along thesemembranes when you pull it.After getting a clean start, there is little risk of tearing the skinor the meat.Sometimes, the belly skin is removed using a knife leaving thesurface of the carcass with close serrated scores.
Cont….When we use a knife to slice the skinfrom the animal we inevitably violatethese layers and make the whole jobharder.Once you cut into the meat, we are nolonger working with the natural divisionbetween meat and skin.We usually end up removing largechunks of meat, as well as putting cutsand holes in the skin.These cuts (also called scores) andholes open up and enlargeeasily, increasing the amount of work atevery stage of the tanning process lateron.
The butcher must take care tofrequently wash his hands and arms andnot touch the dirty outside of the animal’sskin while removing the skin this way.An alternative to fisting is the use ofcompressed air. If facilities areavailable, a compressed air pipe isintroduced between the skin and carcasssurface and the air pressure graduallydetaches the skin.The air must pass through a filter inorder to reduce the micro-organismspresent in the air, which otherwise canconstitute a source of contamination.Blowing air into the cut in the hind leg isa traditional practice in many areas whenthe skin, usually goat skin, is required asa water bag
A knife should not be used in the final phase. The flayer uses hisweight with downward pressure to remove the skin especiallyfrom the tail area, the neck and forelegs.After the skin is separated, remove any meat and/or fat from theskin. Wash flesh side if contaminated with blood and/or gutcontents. Then immediately cure with common salt or by airdrying to prevent putrefaction. Removal of fat and flesh Salting Frame drying
Advantages of Combined horizontal & vertical method 1. Less chance of contamination of meat with skin during flaying. 2. Less mechanisation required as during finishing of flaying animal is brought in horizontal position. 3. More efficient, less time consuming, less labour required.Disadvantages of combined horizontal & vertical methodAs it is combination of both the position horizontal and verticalcarcass is interchanged as and when required hence have nopractical disadvantage.It is more complicated to practice.
Advantages of vertical method:Hoisting the animal makes it easy to use one’s body weightto pull the skin off.It also assures that the meat will stay clean.The slaughtered animal can either be hanging from theneck or from the legs.Knifing is not required, fisting is sufficient and better optionto avoid scores.Fisting is hygienically critical.
Disadvantages of vertical method:It is not possible to reach the hide from ground level morethan one operator is needed.A single operator may work with a hydraulic platformwhich is raised and lowered as required.Automatic hide pullers, dressing cradles and moremechanization required.
DEFINITIONS:Curing: The treatment of skins with common salt or by air drying toprevent putrefaction.Defatting: The removal of unwanted fatty (adipose) tissue from theflesh side of a fresh skin during fleshing.Flay cuts: Damage caused by careless use of a knife duringflaying, sometimes cutting through the skin.Flaying (skinning): The removal of a skin from a carcass.Flaying knife: The knife used to sever the subcutaneous tissueswhen removing the skin from the carcass.Flesh side: The inner side of a skin next to the body of an animalin life.
Fleshing: The removal of the residual connective andadipose tissues from the flesh side of a skin after flaying.Gouges: Knife damage to the skin during flaying, takingout scooped portions of the corium.Grain layer: The top portion of the dermis.Pattern: The pattern of skin when laid out flat.Putrefaction: Bacterial and enzymatic breakdown, rotting.Scores: Knife damage to skins during flaying by cuts thatdo not fully penetrate through the skin.Trimming: Removal of unwanted portion of a skin.