Here´s a useful and complete presentation about a chapter of the book "el cocinero científico" of Diego Golombek. We hope you enjoy it.

1. Biology practical work:
“El cocinero científico”
Group members: Ignacio Duran, Victoria Gonzalez, Juan
Germano, María Jachno, Clara Halvorsen, Sebastian
Salinas, Andrea Gambarte, Juan Hevia.

2. We are of meat
 The meats have a special place in the Occidental World diet, especially in
Argentina.
Interest in meat attracted the attention of specialists from different
affiliations.
 Meat comes from the latin "caro".
 The meat itself is the muscular tissue of animals, whose function is to move
the animal from one place to another.
 With the arrival of the Homo erectus an omnivorous diet that includes
fruits, roots and meat was introduced.
What is the advantage of eating meat?
Animal tissue generally have a proportion number of
amino acids similar to those of humans. One
advantage of the meat is that it provides B12 vitamin
and that has a high protein content.

3. In general, everytime we say ¨meat¨, we mean every eatable part of
the animal. But meat really means the muscular tissues, which allow
the animal to move from one place to another.
•Why do we eat meat? What is the advantage of eating
meat?
One possible explanation is that we eat meat because animals are
similar to us and so their chemical compounds. Animal tissues, in
contrast with plants, have a similar proportion and number of
aminoacids. This is why vegetarians ought to be more careful about
their diet. The other advantage is the high level of proteins meat has.

4. Types of meat
In vertebrates, there are three types of meat:
Smooth muscle (located around organs and
blood vessels)
Cardiac muscle (consisting on the meat
related to the heart)
 Skeletal muscle (The muscles responsible
of locomotion)

5. Which is the reason for
meat´s color?
Mainly, its caused by myoglobin, proteins
which contain groups of atoms called heme
(containing iron), used to store oxygen or to
use it.
Both the concentrarion (Which varies from
one animal to the other)and the state of the
molecule afects the color.

6. When myoglobin stores oxygen, its color is
red. After the animal is dead, its reverts to its
deoxygenated form and turns purple
Once the meat is cut, it is exposed to oxygen
again, obtaining once again the red color.
Now, due to the fact that oxygen difuses with
dificulties through meat, if the meat is exposed
to a low oxygen concentration the myoglobin
turns into metmyoglobin, which´s color is a
dark brown.

7. This process speeds up for other factors as
well:
 Due to microbes
 Extreme temperatures (including when its cooked)
 And a big concentration of salts
This process is imposible to revert, and the
older the meat, the darker the brown
Brown meat Good quality
meat

8. Animal From To
The more oxygen Pig 40 150
the muscle
requires, the more Cow 280 500
myoglobin it
has, and it has a Lamb 250
darker red color.
Horse 800
Whale 910
Concentation of myoglobin per 100 g
of fresh muscle.

9. Cow meat
In Europe and America, the most widespread
bovine species is the Bos taurus.
Brangus
Hereford
Red angus
However, there are other bovine species, like the Bos
indicus
Which includes the cebu

10. Meat´s composition
Water
Proteins
Fats, carbohydrat
es and minerals
Muscles contain groups of The fibers are located This connective
tissue is composed
microscopic fibers formed in semitransparent
by a minor quantity
by proteins (miosine and tubes of connective of cells and much
actine) tissue extracellular tissue
Connective tissue is responsible for the toughness of the meat. Therefore, with more
movement of the animal, greater development of connective tissue, which results in a tougher
meat
•Thus, bovines raised in open fields will have tougher meat, as the
connective tissue is more developed
For example, japanese breeders give their cows
massages to relax the muscles and prevent them
from exercising

11. Cow cuts
Generally, an animal uses some muscles more than
others. Among the muscles with greater
development of connective tissue we found the
muscles of the limbs, the tail and the neck.
Thus, these parts are the toughest cuts of a bovine.
In contrast, the muscles that suffer less exercise are
the softer ones.
Another matter about meat toughness is the age of the cow, as
older animals will be able to move more. Moreover, growth also
causes the connective tissue to become stronger, contributing to
the toughness of the meat.

12. Connective tissue collagen
2 components
(proteins) elastin
Collagen When sorrounded by heat and moist (the conditions of
boiling water for example), it transforms in a jelly-like
substance, making the meat softer.
Elastin In contrast with collagen, it doesn´t softens in the
presence of heat and moist
However, heat and a longer Nonetheless, the effect of
process of cooking results softening overwhelms the
in a strenghtening of the negative effects on the fiber
muscular tissues

13. With a quieter animal, better quality of meat…
• Any stress before the moment of the death produces negative effects on the
animal
Unwanted
When the muscles are music…
active, they consume energy In 1979, a
(glycogen) and produce lactic slaughterhouse in
acid. Finland forced a
group of musicians
to leave the area
because their
When the animal dies, the music disturbed
muscles keep working for some their cows and
time, while the blood flow stops affected the
and causes an accumulation of quality of their
lactic acid meats.
In consequence, the meat results
gum-like and runs off faster, as
acid concentration drops
allowing bacteria and fungi to
grow.

14. Fish Meat
Muscles: short fiber segments separated by transverse connective tissue layers.
Only 3 per cent of the animals weight
Meat: white color Slow muscle fibers form a thin layer which is located on the
periphery of the animal under the skin Myoglobin as a reservoir of oxygen, which is needed to
burn fat to obtain energy for muscular activity reddish layer. Furthermore, the cells of fast fibers
used mainly carbohydrates: do not require Oxygen and have little myoglobin, so color is white.
Molecules called amines: formed by the nitrogen group (amino-group). They are very small
and highly volatile. This is the reason we smell them easily.
In the presence of acid, the next reaction takes place:
R-NH2 + H+ R-NH3+ Positive Charge
amine proton
Charged Molecule
Easily dissolved due to water and thus smell do not reach our noses. This is why people
put water and lemon on their fingers before eating fish.

15. Flesh on Flesh
• Effect over cooking meat: the proteins are denatured by heat
and are easily attacked by enzymes of the digestive system.
First, the proteins of meat loose the shape due to heat. They begin to form
solid masses with consequences
the passage of light is
prevented, that´s why it looks
opaque, and juice begins to
appear, due to the water which
was between the fibers.

16. • Heat produces the typical flavor of cooked
meat, in two ways.
By damaging the cells, the heat makes all
the compounds, the intra and extracellular,
get into contact, which promotes reactions between
amino acids, sugars, minerals, fats and enzymes.
The intense heat favors reactions called pardas (brown color), where the sugars and amino acids
of the meat can be linked with each other and create many types of compounds, some of them
tasty, others with toasted color and smell.

17. Its the way it feels to the touch; how easily
it can be shredded by a knife or by the teeth.
As seen before, it can be changed. For
example, it can be made softer by
heating, cutting, hitting it and other ways.

18. Tenderizers
Another way of softening the meat is with a
tenderizer, which unwinds and cuts proteins.
Tenderizers can also be found in nature, in the form
of bromelain in pineapples and in pawpaw in the form
of papain ,to give some examples.

19. Storage of meat
tors that affect the edibility of the meat:
Action of light and O2
Enzymes and microorganisms present in the meat
It depends on the type of meat:
 Mammals and birds: Enzymes
ns which accelerate the work at relatively high and
cal reactions of and constant temperatures you
ism. The low temperatures of must put the meat in the fridge
nzymes are good because they to slow the activity down
he food not degrade  Fishes: Their temperature is
similar to the enviroment. So
the cooling can not stop their
activity.
n problems nowadays with the storage of meat are: FUNGI AND BACTERIAS.
of fungi and bacteria which can affect the meat:

20. Cold Storage
Refrigeration is the most popular method to
preserve meat.
The aim of this method is to reduce the working of bacteria and enzymes.
• What happen during freezing?
The more salts the water has the lower the temperature at which it freezes.
Another important fact is that the concentration of salts within the cell is higher
than outside the cell. Finally, the ice is less dense than water, that is when liquid
water is transformed into ice, it occupies more volume.
When to thaw again raise the temperature, the meat loses much fluid and
becomes drier, and therefore harder than it should
As the temperature of the meat reaches the freezing point, some ice crystals
begin to form between the muscle cells. These crystals burst into the cell
membranes and cause them holes, thereby exposing achieved muscle proteins
external fluid.So, that´s why is convenient to freeze the meat very fast.

21. WARMING
ackaging first appeared when in 1810 Nicolas Appert
iscovered that by sealing food while warming it, it would
ot rot.
In pasteurization, food In sterilization, all
is warmed while trying to organisms are destroyed
cause the least harm to it. regardless of its effects over
food.

22. SMOKED
Smoked is a preservation technique that consists in a type of slow cooking
and at low temperature.
Smoke is formed by:
 Alcohols
 Acids
 Phenols
 Several Toxics
Toxics Inhibit the growth of microbes, Phenols hold up the oxidation of fats
and this whole process gives meat that flavor characteristic of burnt wood.
This proccess is often combined with curing to minimize the fat
oxidation produced by it

23. Curing is a process which uses salt mixed with sugar and other species to
obtain a type of meat that differs from other meat-based products because
of it´s texture, smell, flavour, and because of a resistant- to- cooking colour.
The salt takes out the water from inside the cells; but it also causes the
destruction of many proteins, which makes the the meat have more fat.
Curing has an influence on the colour of the meat. Salty meats keep their
red-pink colour even after cooked. This is due to a chemical compound
present in the salt called nitrite. This reacts with the purple pigment to form
a molecule of nitrosomyoglobin, which is pink. This compound is very stable
to changes in temperature, but is sensible to oxygen and light. For this
reason, cured meat is usually vacuum packed and not exposed to light.
•Nitrite is a very efective antibacterial agent wich slows down oxidation and
contributes to the flavour of the meat.

24. Jerky
Curing: food preservation Linked to Latin American independence
Dry meat jerky (or charqui in Spanish)
Cut in slices Quechua
Jerky
Salted to preserve it origin:
ch´arqui
Can be crashed by a mortar
From english verb
“to jerk”
Indigenous
peoples from
the South
With ñandu and Charqui, also
guanaco meat called cecina

25. Meat preparation
1) Cutting it into large thin slices
(separating the fat). Sometimes the meat
is partially frozen so as to cut it more
easily.
2) Salt is added and meat is dried slowly.
Nowadays in stead of being dried by the
sun, ovens are used. The optimum
temperature is 120 -130 °C. A well dried
meat can be maintained in an hermetic
box for 1 or 2 months.
“Ojo al charqui”
English translation: “having an eye on the jerky”. This is a common
expression which means to pay attention and take care of a loved
possession, something you don’t want to lose.
• Mixture of smells
Jerky • Smelled before being eaten
• Gives a strong taste to potatoes

26. The jerky and the crossing of the Andes
Jose de San Martin, unknowingly, used a gastronomic strategy, very useful for
refrigeration in those days: curing. Part of the success in the crossing of the Andes
was thanks to jerky.
Towards the end of 1815, months before the declaration of independence, San Martin
announced his intention for crossing the Andes to Chile and fighting the Spaniards
there. 700 slaves between 16 and 30 years old were incorporated to the army (not
those who worked in agriculture or trade).
To feed the troops, San Luis provided San Martin with cattle. Jerky and charquicán
(an seasoned version of charqui), were prepared.

27. A pasta composed by dry meat flavoured
Charquicán with fat and hot pepper. This together with
corn flour meant an economic and
nutritive meal.
Cattle went together whit the troops for feeding and more cattle
would be sent as soon as they reached Chile.
Food wasn’t only meat. They had other supplies too such as
biscuits, toasted corn flour and water.
Jerky Not only nutritive, hygienic and highly
concentrated. It also meant less weight to
carry, as it was dehydrated meat. Meat is
70% water and a litre of water meant 1
kilogram. Therefore, meat severely
reduced its weight.

28. Spaghettis, Vermicellis and the Campanelli
 Pasta became popular in the 18th century.
 The base for pasta is water and wheat or semoline flour.
 If semoline flour is used, less water is required because it
has less starch and the resulting noodles are a bit more
fragile than if they are done with wheat flour.
 Part of the water can be replaced by fresh eggs, which
gives them more color and taste.
 Pasta is sold dry, with 10% of water. Pasta sold in the
supermarket is often dried-up over a day in the fabric.
 When pasta dries up, you have to be careful: moving it too
much may lead to a break up of pasta but leaving it
untouched gives bacteria the chance to start acting over
the dough.

29. Cooking Pasta
 The starch of the dough releases a starch when it is
cooked, which is gelatinized when it cools.
 If oil is added to water, it floats and is not in touch with the
pasta but keeps the water from escaping.
 Once the pasta is done, oil or butter used cover the
gluten and starch of the surface and avoid the pasta from
being “sticky”.
 By cooking pasta with a lot of water, pasta swells and
starch solution will be more diluted and that is why
noodles will be less sticky.
 It is important to add salt to the water while cooking it
because it will give it a better taste than if added before
straining the pasta.

30. A GRAIN OF RICE
 Since Alexander the Great brought the rice from Asia to Europe, has become the most famous food
worldwide. Nowadays, there are approximately 250,000 different varieties, in places where there is is goo
soil and plenty of water.
 Rice grains undergo a long process before reaching the pan. The shell is removed and then the
rice is mechanically polished. Sometimes sugar is added to brighten it and almost always a vitamin
solution is added to fortify the grain.
 The Indian rice is precooked with vapor (preboil), thus the nutrients are set in the grain.
 Wild rice: it is one of the most expensive types of rice. It comes from North
America and the excuse of its cost is that it is harvested by hand. However, since
the middle 20th century it has lost much of its savagery, as it is cultivated and
harvested in factories. Once harvested, it is fermented to give a particular taste and
heated to gelatinize the starch thus giving it a brown colour.
 Brown rice: every rice comes wrapped in a shell, which, when it dries up,
leaves a light brown rice, wrapped in layers of bran. Bran is then polished until the
grain is completely white.
 Chinese rice: it is fairly polished, and has a high content of glycogen.
Therefore, it absorbs a lot of water during cooking. When cooked, the rice
becomes sticky due to the high quantity of water and glycogen that it contains.
 Basmati rice: known as the “queen of fragrances”,original of India and
Pakistan, this rice is aged so that the water is lost and, as a result, the smell and
flavor stronger.
 The secret of a good rice is in the amount of water that is added. However, this also depends on the
type of rice.

31. Wild rice Basmati rice
Chinese rice