all the attributes of eating quality, tenderness is rated
the most important factor affecting beef palatability--
cooked meals are generally easier to make and very cost
effective using cuts of meat that improve in texture and
flavor when cooked for long periods of time at low temperatures.
These tough cuts of meat contain large amounts of collagen
which require long cooking times to break down into a
DOES SLOW COOKING WORK?
you cook, collagen begins to melt at about 160F and turns
to a rich liquid, gelatin. This gives meat a
lot of flavor and a wonderful silky texture. When cooking
it is important to liquify collagen.
Denaturation of the collagen molecule is a
kinetic process, and hence a function of both temperature
and duration of heating. Cooking at low temperatures require
long periods of time to liquify collagen.
--Calpains begin to denature and lose activity till around
105F, cathepsains at 122F. Since enzyme activity increases
up to those temperatures, slow cooking can provide a significant
aging effect during cooking. Meat should however be quickly
seared or blanched first to kill surface microbes.
-- Meat develops a white opacity as heat sensitive
myosin denatures. Coagulation produces large enough clumps
to scatter light. Red meat turns pink.
Meats: 120°F/50°C is the early stages
of juiciness in meats as the the protein myosin,
begins to coagulate . This lends each cell some
solidity and the meat some firmness. As the myosin
molecules bond to each other they begin to squeeze
out water molecules that separated them. Water then
collects around the solidifyed protein core and
is squeezed out of the cell by connective tissue.
At this temperature meat is considered rare and
when sliced juices will break through weak spots
in the connective tissue
-- Red myoglobin begins to denature into tan colored
hemichrome. Meat turns from pink to brown-grey color.
-- Meat suddely releases lots of juice, shrinks noticebly,
and becomes chewy as a result of collagen denaturing which
squeezes out liquids.
-- Well Meats: Collagen shrinks as the meat
tmeperature rises to 140/60 more of the protein
coagulates and cells become more seggregated into
a solid core and surrounding liquid as the meat
gets progressively firmer and moister. At 140-150
the meat suddenly releases lots of juices, shrinks
noticeably and becomes chewier as a result of collagen
shrinkage. Meat served at this temperature is considered
medium and begins to change from juicy to dry.
tissue collagen begins to dissolve to gelatin. Melting
of collagen starts to accelerate at 160F and continues
rapidly up to 180F.
Done Slow Cooked Meats: Falling apart tenderness
collagen turns to gelatin at 160/70. The meat gets
dryer, but at 160F the connective tissues containing
collagen begins to dissolve into gelatin. With time
muscle fibers that had been held tightly together
begin to easily spread apart. Although the fibers
are still very stiff and dry the meat appears more
tender since the gelatins provide succulence.
140°F changes are caused by the denaturing of collagen
in the cells. Meat served at this temperature med-rare
is changing from juicy to dry. At 160°F/ 70°C
connective tissue collagen begins to dissolve to gelatin.
This however is a very lengthy process. The fibers are
still stiff and dry but meat seems more tender. Source:
Harold McGee -- On Food and Cooking
of muscle fiber
muscle is completely enclosed by a thick sheath of
connective tissue (the epimysium) and is divided into
bundles of fibres by a connective tissue network (perimysium).
Individual muscle fibres are bounded by a plasma membrene
surrounded by connective tissue (endomysium) which
consists of a basement membrane surrounded by a reticular
later in which a meshwork of fine collage fibrils
is embedded in a matrix. Tendons are elastic collagenous
among the muscle fibers are fat cells which store energy
for the muscles. Fat is crucial to meat texture. Waxy
when it is cold, fat does not evaporate when you are cooking
as does water. It melts and lubricates the fibers as they
are getting tougher under the heat. Fat is also the source
of much of the flavor in meat. As the animal ages the
flavor compounds build up and get stronger. After the
animal is slaughtered, the fat can turn rancid if stored
improperly or too long.
THE CHALLENGE IN COOKING MEAT
like our meat tender and juicy at the same time...
therefore want our meat to be cooked tender where tough
collagen is converted to gelatin but with a minimum loss
of moisture. The reality is that these methods are contracdictory
and hence the challenge or dilemma to cooking meats. To
minimize moisture loss requires temperatures less than
130F, however .turning collagen into gelatin requires
temperatures above 160F and for extended time periods.
moisture evaporates, the meat begins to shrink. A slab
can lose 20% or more of its weight in cooking due to shrinkage.
Even meat cooked in liquid will dry out although not as
quickly. So we are faced with a dilemma. To liquefy the
collagen we need to cook the meat to 180F and hold it
there for for long periods of time. But by then it is
well past well-done and the muscle fibers can be dryed
out. As a result, we need to add moisture.
to slow loss of moisture
Brining adds a significant amount of moisture,
it helps retain moisture during cooking, contributes noticeable
Another method of adding moisture is to cook
the meat in very high humidity by wrapping it in foil
with a little water or juice. This keeps moisture from
escaping and some vapors penetrate the meat.
or poaching (--low temperatures--). Braising
is a method of cooking by submerging the meat in hot liquid,
but not hot enough to boil. Braising can give you juicy,
tender, and flavorful meat, especially if you use a flavorful
braising liquid. But it tends to pull all the collagen
out and rob the meat of its natural flavor. Flavor the
liquid (water with pickling spices is a nice simple start),
completely submerge the slab, keep the lid off, keep the
temp down to about 160-180F for about 30 minutes, and
let the meat cool in the liquid for 20-30 minutes so it
will absorb some of the water before putting it on the
of collagen covalent links using Acids -- (Tenderizing
meats with acid) -- It
is well known that adding a little vinegar to a stock
will help tenderize meat while cooking. It is also useful
to marinate meat for a few hours using vinegar to tenderize
meat. Offer and Knight (1988) suggested that one of the
mechanisms of pH induced tenderisation of meat could be
a breakage of covalent collagen cross-links and of some
specific peptide bonds.
are tips to keep in mind when slow-low roasting:
Develop a caramelized crust before slow cooking
-- by searing the meat either in a dry pan or
with a small amount of oil or fat.
Place the meat or roast fat side up in the
pan so it self-bastes.
Tenderize your cuts of meat --e..g, pounding
meat, buying aged meats (Note: meats cooked longer
a 120F will age and be more tender), marinading meats
with acids with tenderize the meat.
Tent the resting meat with foil and allow
10 to 15 minutes before cutting it so the meat's
juices will return to the center; slice the meat
against the grain.
APPLIANCES TO AID IN SLOW COOKING
appliances such as Sous Vide Cookers, CVap Ovens
and Combi Ovens are now be used in restaurants
and homes. Reading more about this: What
is Sous Vide Cooking? --- Comparing
Sous Vide to CVap and Combi Ovens, How
is heat transferred in Cooking.
Collagen contribution to meat toughness: Theoretical
aspects Jacques Lepetit ..Meat Science 80 (2008) 960–967
G., & Knight, P. (1988). The structural basis of water-holding
in meat. Part 1: General principles and water uptake
in meat processing. Developments in Meat Science,