Technology education - Essay Example

The following table shows the basic food preparation techniques. Table 7. 1 shows the basic and advanced food preparation techniques Advanced food preparation techniques Basic food preparation techniques by with the use of time- and labor-saving hand Different blades in the food processor can Cutting, shredding, slicing, dicing, do different Jobs. E. G. Hopping blade, mincing, chopping, crushing, peeling and slicing blade, meat grinder, sausage coring stuffer, Juice extractor Crisis cross cut Defining with automatic debaters Roll cut Shredding Shredding with automatic food shredder Grating Grating with industrial graters for large reduction Mixing Extruding the dough into thick sheets Chinese dough making by using rice flour, for making pasta and wrappings for glutinous rice flour, tang flour dumplings Pastry making: short crust pastry, puff Pastry making pastry, flaky pastry and choux pastry Cake making: whisking method, creaming method, rubbing-in method and melting Cake decoration, piping method Apart from using kitchen utensils, time- and labor-saving devices can be used in food preparation and processing to save time and energy. They are being used in both domestic and industrial levels, which should have the following features to perform their functions: They should have the power and capacity to do a wide range of Jobs. Should be easy for cleaning. They They should be made of durable materials.

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The accessories of the machines should be easy to be attached for use and detached for cleaning. Electric beaters are usually used in mixing. It can be used to mix different solids, liquids or even a mixture of solids and liquids. Some electric beaters use blades to create a movement or current to mix solids and liquids. Some electric beaters such as those used by bar tenders may make use of vigorous vertical movements for mixing different liquids. A number of purposes can be achieved by equipping the eater with different attachments. For example, using balloon whisk for whipping cream and egg white; using a flat beater for mixing batters; and a dough hook for kneading.

Electric beaters can be divided into two types: (A) Hand-held beater Its basic structure consists of a handle mounted over a large enclosure containing the motor, which drives one or two beaters. The beaters are immersed in the food to be mixed. (B) Heavy-duty stand beater Stand beater is mounted on a stand which bears the weight of the device. They typically consist of a special bowl that is locked in place while the beater is operating. Comparing with hand-held beaters, stand beaters are larger and have more powerful motors. Heavy duty commercial models of stand beaters have large bowl capacities for mass production. Mince’s are ideal for mincing meats. Liquidness are electrically powered mixers with whirling blades that mix or chop or liquefy foods. Beans, butter, herbs, nuts etc.

Blender can be used in various Jobs, for example, making purr©e, fruit Juice, soybean milk, mixing batters, mayonnaise, salad dressings, and chopping nuts, herbs. In recent years, dry blenders are very popular for crushing hard food ingredients into powder. Normally, the cup of a dry blender is smaller than a wet blender or mixer for controlling the volume of food to be processed. Mixers can do various Jobs by using different attachments including dough hook, electric can-opener, minced, potato peeler and Juice extractor etc. (A) A food processor is a multi-purpose machinery. It can do a wide range of Jobs by using different attachment or blades.

Some food processors can even do all the Jobs that can be done by mixers and blenders. Apart from mixing and blending, a food processor is usually used for making pastry, mincing meat, grating cheese and slicing ND shredding fruits, vegetables and herbs. (B) The cautions of using food processor include: Extra care must be taken when handling the blades of food processors since some of them have sharp edges. The food processor must be switched off before changing any parts of the processor. The blade should not be used alone without the bowl provided. Keep the blades and cups clean, since micro-organisms may grow on the surface especially inside the small gaps.

Household ice-cream maker Conventionally, the production of ice-cream involves the mixing of ingredients, homogeneities, postulation, ageing and rapid freezing. During the freezing process, vigorous agitation is applied for incorporating air bubbles into the ice-cream mixture and allowing the formation of fine ice crystals. This results in a desirable soft and smooth texture of the products. A household ice-cream maker is a scraped- surface heat exchanger that contains a dasher driving scraper blades and a heat exchanging bowl including cryogenic (coolant). The bowl is frozen overnight to ensure mixture is poured into the pre-frozen bowl, ice-cream starts to freeze on the inner- surface of the bowl.

The scraper blades will scrape off the frozen ice-cream on the reface followed by the immediate formation of a new layer of frozen ice-cream. In addition, the rotation of the scraper blades also plays the function of incorporating air bubbles into the ice-cream mixture. Soft-serve ice-cream can be formed after 1-2 hours in a household ice-cream maker. Figure 7. 2 Household Ice-cream Maker 7. 3. 1 Scientific principles and types of heat transference When we talk about heat transfer, we must know the relationship between temperature and molecules. The higher the temperature, the faster is the rate of the vibration of molecules in a matter. Therefore, heat transfer is a process of changing he vibration rate of molecules. A) Conduction Conduction occurs when two matters with different temperature come in contact each other and the kinetic energy of the molecules in the matter higher in temperature transfers to the other matter. Figure 7. 3 shows two different spaces representing two matters in different temperatures. The molecules in the space higher in temperature move faster than that in the space lower in temperature. When the barrier between the two spaces is removed, the molecules collide with each other and kinetic energy is transferred from the faster molecules to the lower lessees. This type of transferring of kinetic energy is called conduction. Figure 7. Systematic representation of conduction (Length of arrow represents the magnitude of the vibration of the molecules) (B) Convection Convection involves a bulk movement of molecules from a hot region to a cold region. This type of heat transfer occurs only in a fluid like air or liquid. Figure 7. 4 shows the flow of matters in convection. When a local area is heated up, its density decreases. The molecules in the cooler area, which is higher in density, will move into the area with lower density. This creates a convection current that can be found when water is heated until boiling. 6 Figure 7. 4 Convection current in boiling water (C) Radiation Radiation or electromagnetic radiation (no matter visible or invisible light) is one of the other forms of heat transfer. Heat and radiation are forms of energy which can be interchanged to a certain extent.

There are many sources of radiation such as sun, lamp, etc. Matters absorb radiant energy and transfer the energy to different forms including heat, infrared light or visible light. (D) Microwave cooking Microwave vibrates millions of times per second. It penetrates food and makes water molecules vibrating in resonance. As a result strong friction is generated between water molecules and the heat generated warm up the food. Microwave is reflected by metal objects but can penetrate materials such as ceramics, glass and some plastics. Therefore, the container for holding food during microwave cooking should not be made of metal but those that can be penetrated by microwave. E) Induction For induction cooking, heat is not generated directly by the heating source but the cooking vessel itself is a heat generator. In induction cooking, there is an electric coil enervating a high power of electromagnetic field. This electromagnetic field penetrates the iron-made vessel and sets up an electric current which produces heat. The heat in the cooking vessel is then transferred to the contents in the vessel. The heat generated will stop when the vessel is removed from the electromagnetic field or the power for the coil is switched off. For this cooking method, the vessels must contain iron which is important for setting up the magnetic field in the vessels. (A) Moist heat cooking Moist methods of cooking apply a relatively lower heat to food through a medium of quid including water, steam, stock, milk, fruit Juice, wine or beer. (I) Boiling Water evaporates and builds up a pressure over water surface. It is called the vapor pressure increases. When the pressure overcomes the atmospheric pressure, it reaches the state of boiling in which bubbles form and escape. In boiling, liquid is heated to its boiling point (about loco for water) and the heat is then lowered until the liquid is bubbling quickly and evenly. Fish, vegetables, eggs, pasta and rice are foods suitable for boiling. (it) Simmering Simmering is a method whereby food is heated in a more gentle way than boiling to revert losing tenderness or breaking up of food.

Fewer bubbles rise to the surface in simmering and the temperature is Just below the boiling point. (iii) Steaming Steaming is a method using steam instead of water itself as the heating medium. During steaming, food is not immersed in water but is put over the water surface. Food is heated up by the hot steam generated from the boiling water. Fish and dim- sum are usually steamed in Chinese cooking. Food can maintain its original shape after steaming. (iv)Poaching Poaching is a method using a lower temperature (71-ICC) than simmering. It is a very gentle way of cooking. In poaching, food is Just half immersed in the water and heat is applied to the food gently until the food is desirable for consuming.

This method is suitable for foods rich in protein (for example, eggs or fish) which would become tough or curdled at higher temperature. (v) Stewing Stewing is a slow method of cooking similar to boiling but uses a temperature lower than the boiling point of water (< loot). It is carried out in a lidded pan or a covered dish at a low temperature. The food is served with the cooking sauce together. Meat, poultry, root vegetables and fruits are foods suitable for stewing. Food Preparation Technology (vi)Braising Braising is a combination of stewing and roasting. Meat or poultry is heated in very little water in a pot with a well-fitted lid which prevents loss of water while the food is stewed in the pot.

After the food becomes tender, it is browned in a hot oven with the lid off. During braising, the liquid should simmer, but not boil, to prevent the meat from being too tough. In Chinese cooking, the food is usually deep-fried for a minute or two before stewing. Erasure cooking (Vii) the container. The water boils at a higher temperature and the very hot steam is arced through the food so that the food is cooked more rapidly and more energy is saved. Pressure cookers have a pressure gauge, control valve, safety valve, locking lid, separate containers and a trivet. (B) Dry heat cooking (I) Grilling Grilling is the cooking of food by radiation under a gas or electric grill.

Under grilling conditions, the surface of the food is quickly sealed, and the flavor is well developed. In order to prevent drying, the food must be smeared with fat and it is turned over frequently to ensure even cooking. (it) Baking Baking is a cooking process by the convention of air in an oven. Heat is transferred by he movement of air from cool regions to warmer regions of lower density. Cakes, biscuits, pastries, bread, tarts etc. Can be cooked using this method. (iii) Roasting Roasting is a method to cook meat or some vegetables involving basting with hot fat for preventing from drying and for developing brown color and specific flavor, in an oven. There are three kinds of roasting methods.

Searing Searing involves firstly using a very hot oven (about ICC – 24th) for about 20 minutes followed by using a lower temperature. The former step is to sear the outside and develop the flavor of the meat while the latter is to complete the cooking. This method is only suitable for tender Joints of meat such as topside of beef or leg of lamb or pork. 9 Slow roasting For slow roasting, meat is heated up in a pre-heat oven at a relatively low temperature (about 17th) using a cooking time longer than usual cooking time. This method is suitable for cuts such as breast of lamb, belly of pork or brisket of beef. Cold oven method The meat is put into a cold oven gradually rising in temperature up to about 22(HA.

Through this method, the meat is tenderness and its flavor is developed. This is suitable for any cuts of meat, particular for the less tender cuts such as shoulder of iv) Frying Frying is cooking food using fat heated usually to a temperature between 18th and CO’S. It is a quick method of cooking because of the high temperature used. The ways of frying are: Deep fat frying In a deep-fryer or wok, food must be completely covered with sufficient fat or oil and cooked over high or medium heat (between 1 ICC and 20th) until it becomes golden brown. Chinese yeast dough, doughnuts, spring rolls, pork chop, chicken wings, potatoes, onions, fish and prawns are suitable for deep fat frying.

Shallow frying Food is cooked in heated fat covering the bottom of the pan or wok. As the heating of food is done on one side at a time, the food has to be turned to ensure that it gets cooked on both sides. Eggs, fish, steak and pork chop can be fried. Stir frying Food is stirred in a little hot fat in a frying pan.