Transcript TECHNOLOGY 9th 3 px

TECHNOLOGY
9TH GRADE
3RD PARTIAL
Content
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Ways of cooking
Food spoilage
Food preservation
Processing milk
Additives
Grasses
Tubers - roots
evaluation
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Investigation
Jelly -video
Cooking lab
Cooking lab
Mural
Quiz
Exam
10
20
15
5
10
10
30
• Solar cooker
• A solar cooker, or solar oven, is a device which
uses the energy of direct sun rays (which is the
heat from the sun) to heat, cook or food or drink.
The majority of solar cookers are relatively cheap
devices. Because they use no fuel and cost
nothing to operate, many nonprofit organizations
are promoting their use worldwide in order to
help reduce fuel costs (for low-income people)
and air pollution, and to slow down
the DEFORESTATION caused by gathering
firewood for cooking. Solar cooking is a form
of outdoor cooking.
Factors
• Concentrating sunlight: A reflective mirror of
polished glass or metal concentrates light and
heat from the sun on a small cooking area.
• Converting light to heat: A black or
low reflectivity surface on a food container or
the inside of a solar cooker improves the
effectiveness of turning light into heat.
• Trapping heat: It is important to
reduce convection by isolating the air inside the
cooker from the air outside the cooker. A plastic
bag or tightly sealed glass cover traps the hot air
inside.
• Green House Effect: Glass transmits visible light
but blocks infrared thermal radiation from
escaping. This amplifies the heat trapping effect.
• Box cookers
Box cookers cook at moderate to high
temperatures and often accommodate
multiple pots
• Panel cookers
• Panel cookers incorporate elements
• of box and curved concentrator
• cookers. They are simple and
• relatively inexpensive to buy or
• produce
Underground cooking
• This is one of the most ancient ways of cooking
• and has been used almost worldwide.
A whole is digged in the ground and wood is
added.This can be any type of wood because certain
ones can give out an undesirable smell or taste. Then
porous rocks of the size of a fist are added on top.
These rocks retain the heat . The wood is lighted and
heats the pit and the rocks.The food is added and and
on top of it leaves and grass.Then it is covered with the
soil from the pit.
FOOD SPOILAGE
• Fermentation is the convertion of a carbohydrate such as sugar into an
acid or an alcohol. Yeasts,molds and bacteria are types of
fermentation.
• Yeasts are microscopic fungi found in the air ,soil, and of surface of
fruit.Some tolerate high acidity ,salt and sugar concentration and can
grow without presence of oxygen.
There are 3 types of yeasts:
• BENEFICIAL YEAST: baker’s yeast,for beers and wine
• SPOILAGE YEAST: in foods and beverages
• PATHOGENIC YEAST –causes diseases:oral and vaginal infections.
• MOLDS
Are microscopic fungi .They grow in tiny spores that float in
the air When spores fall into a piece of damp food then it
grows into mold. There are thousands known species of
molds.
They grow on dead organic matter everywhere in nature
and their presence is only visible when mold colonies
grow.
• BACTERIA:
Are microscopic organisms round, spiral,or rod shaped
that cause spoilage in food . Bacteria generally prefer low
acid foods like vegetables and meats.
It grows in warmth and in moisture.
putrefaction
• Is the process in which organic material is
broken down into simpler forms of matter –
poisonous substances , with the formation of
foul smelling and tasting products. It is caused
by bacteria ,fungi,oxygen and moisture.
Rancidity
• Is the chemical decomposition of fats,oils,and
other lipids. Oxygen molecules interact with
the structure of food in a way that can change
the odor,taste,and its safety for consumption.
• “””””””STUDY UP TO HERE””””””””
Food preservation
Advantages:
Extends the life of food
Maintains as much as possible nutritional quality.
Avoids growth of unwanted micro-organisms
SALTING
Food is preserved with salt. Salt inhibits the growth of
microorganisms by taking out water of cells through osmosis.
Most bacteria,fungi,and other pathogenic organisms can’t
survive in a highly salted environment.
One of the oldest methods for preserving food.
DRY SALTING : meat or fish are buried in salt.
BRINE-CURING : Meat is put in strong salt water.
Dehydration
• Dehydration
• Process of removing water from foods
inhibiting growth of bacteria.
• It is done open air and also with special
devices.
• Also done with sun.
• Ancient way of preservation
• Drying
• Drying is one of the oldest techniques used to
hamper the decomposition of food products.
As early as 12,000 B.C., Middle Eastern and
Oriental cultures were drying foods using the
power of the sun.
• Vegetables and fruit are naturally dried by the
sun and wind,
• Refrigeration
preserves foods by slowing down the growth
and reproduction of micro-organisms and the
action of enzymes that cause food to rot.
• Freezing
is also one of the most commonly used
processes, both commercially and
domestically, for preserving a very wide range
of foods, including prepared foods
• Can be done in vinegar ,a strong acid in which
few bacteria can survive.
• It can also be done in a salt brine to encourage
fermentation.Here the growth of good
bacteria makes food less vulnerable to
spoilage –causing bacteria.
• JELLY
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MARMALADE
SYRUP
JAM
additives
These are substances added to foods with certain purposes.
They maintain nutritious quality so as taste, appearance and endurance. Additives
need to be controlled under certain rules and must have a especial permission to be
used. Excess of these can be dangerous.
These are the functions of additives:
Preservant: against putrefaction,chemical deterioation,
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Nutritious supplement:vitamins,aminoacids,minerals, calories
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Color modifier
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Taste agents:synthetic, natural,extenders of flavor
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To control humidity
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To stop certain processes
Selection and preparation of meats
WE EAT MEATS FROM DIFFERENT TYPES OF ANIMALS.IT ALL DEPENDS ON THE AREA
OR COUNTRY YOU LIVE.
COLD MEATS ARE:
HAM, SAUSAGE, BOLOGNE,hotdogs,salami,etc. ETC.
ANIMALS ORGANS ARE:
KIDNEY, HEART, BRAIN, TONGUE, LIVER.
TYPES OF MEAT:
MEAT CAN BE RED OR WHITE DEPENDING ON THE ANIMAL. RED MEAT ARE BEEF, AND
PORK. WHITE MEATS ARE FISH, SEA FOOD, CHICKEN, AND TURKEY.
WHITE MEATS ARE SOFTER THAN RED. REDS HAVE MORE CHOLESTEROL AND FATS.
THATS WHY IT IS RECOMMENDED TO BE EATEN IN SMALL QUANTITIES TO AVOID
HEART DISEASES.
COLD MEATS
MEAT CHARACTERISTICS
• COLOR: TELLS US THE AMOUNT OF FAT A MEAT HAS.ALSO
INDICATES ANIMA’LS AGE. THE LIGHTER THE TONE THE
YOUNGER THE ANIMAL IS.
• SMELL: IT INDICATES IF THE MEAT IS FRESH OR IT IS BAD.
• CONSISTENCY: AFTER THE ANIMAL IS KILLED THE MUSCLES
ARE VERY RIGID BUT FEW HOURS LATER IT GETS SOFT.
MUSCLE FUNCTION; THE MUSCLES THAT DO MORE WORK
ARE HARDER LIKE LEGS AND NECK. OLD ANIMAL MEAT IS
VERY HARD.
• NUTRITIOUS VALUE: MEATS ARE AN EXELLENT SOURCE OF
PROTEINS SINCE THEY HAVE ALL THE ESSENTIAL
AMINOACIDS FOR HUMANS. SOME ARE A RICH SOURCE OF
IRON AND VITAMIN A. MEATS WITH LESS FAT ARE
EXCELLENT SOURCE OF IRON AND PHOSPHORUS.
MILK
Types of milk
In our country we get milk from cows ,donkeys and goats
but mostly from cows.Liquid milk can be modified in
several ways to preserve it.
• Whole milk:it has all its elements
• Pasteurized Milk:Pasteurization is the only
technique that destroys microorganism which make
people sick.
• Fortified milk: Vitamins A and D are added to help
in the nourishment of certain groups of people like sick
people, babies and toddlers.
• Skim milk:It doesn’t have fats nor vitamin A nor D
• CURD MILK: Microorganisms are added to
it to make it clot. We get
cuajada,yogurt,cottage cheese.It has
tiamine,protein and riboflavine as the original
but with less vitamin A.
• People that can’t tolerate lacthose in milk can
eat these products.
Evaporated milk
It is usually found in cans and lasts a long period of time. 1/3 of its
water content has been removed. The heating process in this milk
eliminates its vitamins C and B,it changes its proteins so as its flavor.
CONDENSED MILK
Most part of its water has been removed and lots of sugar have been
added increasing its energetic value and stopping the development of
microorganisms
POWDERED MILK
Its water content has been removed totally.Its storage and handling
makes it cheaper .Since its microorganisms can’t reproduce without
water this type of milk lasts so much longer than the others.But
because of all the process this milk takes its price is higher.
DONKEY’S MILK
CEREALS
• These are grasses grown for edible components
of their grains that are a rich source of nutrients
like: corn,wheat,rye,rice,barley and oat.
Among their products we find:
• Flours,precooked cereals,corn flakes,oils and
starches.
Since they have lots of carbohydrates they are an
excellent source of energy.
LEGUMES
• These are plants that grow in pods.The grains are
eaten fresh or dried.Some are eaten with shell like
the green chinese bean.They are a protein source
and have calcium,phosphorus,and iron .Legumes
provide lots of fiber.Like cereals ,they give energy and
are low in fats.Some grow underground ,others are
runners and some grow in trees.
• peas,beans,lentils,peanuts,soy.
ROOTS AND TUBERS
• These are roots or underground stems used as
foods.Malanga and yuca are roots while
potatoe and sweet potatoe are tubers.All
these are rich in carbohydrates since they are
starch.They are an important energy source
but are poor in proteins,minerals,fats and in
vitamins.
• Roots and tubers have more water and
vitamin C than cereals and legumes.