TECHNOLOGY

9TH GRADE 3RD PARTIAL

Content

• Ways of cooking• Food spoilage• Food preservation• Processing milk• Additives• Grasses• Tubers - roots

evaluation

• Investigation 10• Jelly -video 20• Cooking lab 15• Cooking lab 5• Mural 10• Quiz 10• Exam 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.

• MOLDSAre 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 foodMaintains as much as possible nutritional quality.Avoids growth of unwanted micro-organismsSALTINGFood 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,

• Refrigerationpreserves 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• MARMALADE• SYRUP• JAM

additivesThese 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,

• Nutritious supplement:vitamins,aminoacids,minerals, calories

• Color modifier

• Taste agents:synthetic, natural,extenders of flavor

• To control humidity

• To stop certain processes

Selection and preparation of meatsWE 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 MILKMost 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 MILKIts 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.