The Science Behind How Popcorn Pops

The Science Behind How Popcorn Pops Popcorn has been a popular snack for thousands of years. Remnants of the tasty treat have been found in Mexico dating back to 3600 BC. Popcorn pops because each popcorn kernel is special. Heres a look at what makes popcorn different from other seeds and how popcorn pops. Why It Pops Popcorn kernels contain oil and water with starch, surrounded by a hard and strong outer coating. When popcorn is heated, the water inside the kernel tries to expand into steam, but it cannot escape through the seed coat (the popcorn hull or pericarp). The hot oil and steam gelatinizes the starch inside the popcorn kernel, making it softer and more pliable. When the popcorn reaches a temperature of 180 C (356 F),  the pressure inside the kernel is around 135 psi (930 kPa), which is sufficient pressure to rupture the popcorn hull, essentially turning the kernel inside-out. The pressure inside the kernel is released very quickly, expanding the proteins and starch inside the popcorn kernel into a foam, which cools and sets into the familiar popcorn puff. A popped piece of corn is about 20 to 50 times larger than the original kernel. If popcorn is heated too slowly, it wont pop because steam leaks out of the tender tip of the kernel. If popcorn is heated too quickly, it will pop, but the center of each kernel will be hard because the starch hasnt had time to gelatinize and form a foam. How Microwave Popcorn Works Originally, popcorn was made by directly heating the kernels. Bags of microwave popcorn are a bit different because the energy comes from microwaves rather than infrared radiation. The energy from the microwaves makes the water molecules in each kernel move faster, exerting more pressure on the hull until the kernel explodes. The bag that microwave popcorn comes in helps trap the steam and moisture so the corn can pop more quickly. Each bag is lined with flavors so when a kernel pops, it strikes the side of the bag and gets coated. Some microwave popcorn presents a health risk not encountered with regular popcorn because the flavorings are also affected by the microwave and get into the air. Does all corn pop? Popcorn that you buy at the store or grow as popcorn for a garden is a special variety of corn. The commonly cultivated strain is Zea mays everta, which is a type of flint corn. Some wild or heritage strains of corn will also pop. The most common types of popcorn have white or yellow pearl-type  kernels, although white, yellow, mauve, red, purple, and variegated colors are available in both pearl and rice shapes. Even the right strain of corn wont pop unless its moisture content has a moisture content around 14 to 15%. Freshly harvested corn pops, but the resulting popcorn will be chewy and dense. Sweet Corn and Field Corn Two other common types of corn are sweet corn and field corn. If these types of corn are dried so they have the right moisture content, a small number of kernels will pop. However, the corn that pops wont be as fluffy as regular popcorn and will have a different flavor. Attempting to pop field corn using oil is more likely to produce a snack more like Corn Nuts, where the corn kernels expand but dont break apart. Do other grains pop? Popcorn is not the only grain that pops! Sorghum, quinoa, millet, and amaranth grain all puff up when heated as the pressure from expanding steam breaks open the seed coat.

Appeasement and the Munich - Smart Custom Writing Samples

Appeasement and the Munich - Smart Custom Writing Heat and TemperatureIn order to understand about heat and temperature, it is of great importance to introduce the meaning of matter as well as the Kinetic Theory of Matter. This is because heat can be seen to exist when its effects are observed on matter. Without matter heat and temperature could not be realized. Matter can be defined as anything that has mass and that can occupy space. Matter is composed of substances, and these can be seen being made up of atoms, ions and molecules. Atoms, ions and molecules are the building blocks of matter; such that the behaviors of different types of substances are determined by these primary particles. The atoms of substances contain minute particles which are referred to as protons and electrons. These subatomic particles are also considered matter since they both have weight and occupy space (Atkins Paula, 2002).   Matter exists in three distinct states namely, solid state, liquid state and gaseous state. The three state of matter are inter-convertible such that one state can be converted into another state by changing the immediate environmental conditions especially temperature. The solid state of matter is characterized by having its own volume as well having a definite shape. Liquid state of matter is characterized by having its own volume but assumes the shape of the container it occupies. Gaseous state of matter does not have both its own volume and shape but occupies entire volume of the container and as well assumes the shape of the container it occupies (Atkins Paula, 2002). Kinetic Theory of Matter states that matter is made up of very many minute particles that are in a constant state of motion. The theory can also be referred to as the Kinetic Molecular Theory of Matter.   The theory forms the basis to explain the behavior that different forms of matter exhibit simply by making simple assumptions, for example, the idea that matter is composed of widely spaced particles which are in a constant motion. The significant areas in this case are transfer or flow of heat as well as the relationship between temperature, pressure, and volume of gases. The Kinetic Theory of matter is a mere prediction regarding the behavior of matter, based on particular approximations and assumptions. These assumptions and approximations are made from experiments and observations, for instance, the fact that objects are made up of atoms or small molecules (Burshtein, 1996).   Heat can be defined as a form of energy that is associated with the motion of molecules or atoms and that can be conveyed through fluid and solid media by the process of conduction, through vacuum by the process of radiation, and through fluid media by convection process.   There are different sources of heat, for instance, heat due to friction, heat due to nuclear reactions, heat due to sun, heat due to burning of fossil fuels, and heat due to electricity. This transmission of energy from one substance to another is determined by a change in phase or a difference in temperature. Therefore temperature can be defined as the measure of the mean kinetic energy of the molecules or atoms in a given sample of matter, and it is usually expressed in degrees or units chosen on a typical scale. The relationship between heat and temperature is depicted from the definitions. Temperatures of substances rise when heat is supplied. Intense heat is characterized by high temperature (Turns, 2006). Now it will be very clear, if in the discussion of converting substances from one state to another immediate state, heat and temperature are involved. From the Kinetic Theory of Matter, it is evident that matter is made up of small particles that are in a constant state of motion. These particles may consist of molecules, ions or atoms which are held together by strong forces of attraction. In the solid state, the particles are closely packed together in fixed positions. The particles cannot move from one position to another but can vigorously vibrate within their fixed positions, and this is because the forces of attraction between the particles are very strong. With the increase in the temperature of a substance in solid state, the particles gain heat energy gradually and the kinetic energy of the particles increases. A point is reached when the particles start to move more vigorous until the forces of attraction between them weakens.   The particles can now move from one place t o another as the substance changes state from solid to liquid. The substance loses its definite shape but it still has its own volume (Atkins Paula, 2002). In the liquid state, the particles are not as closely held together as in the solid states since the forces of attraction between the particles are a bit weaker. The particles are free to move from one place to another within the structure. When the temperature of the substance is increased further, the particles gradually absorb heat energy. The kinetic energy of the particles further increases as the particles move more vigorous. A point reaches when the forces of attraction between the particles are overcome and the particles move far apart from one another. At this point the substance changes its state from liquid to gaseous state (Turns, 2006).   Reduction in temperature reverses the processes, such that the substance in gaseous state changes into liquid state and finally into solid state. This is because, as the temperature reduces, the kinetic energy of the particles goes down and the forces of attraction become stronger. Thus the particles of the substance attract one another. Heat capacity of a substance is defined as a measurable physical quantity that portrays the amount of heat needed to change the temperature of a body by a particular amount. The SI units for heat capacity are joules per Kelvin. In substances heat capacity is determined by various properties for example the amount of matter in the substance expressed in terms of its mass, the type of material of which the substance is composed of, the temperature of the substance, and the atmospheric pressure (White, 1999).  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚  Ã‚     Ã‚   References Atkins, P., Paula, J. (2002). Atkins' Physical Chemistry. Oxford Oxfordshire: Oxford University Press. Burshtein, a., (1996). Introduction to Thermodynamics and Kinetic Theory of Matter.   London: J. Wiley. Turns, S., (2006). Thermal-Fluid Sciences. Cambridge: Cambridge University Press. White, G., (1999). Heat Capacity and Thermal Expansion at Low Temperatures. New York:   Kluwer Academic/Plenum.