Flour is a powder which is made by grinding cereal grains, or other seeds or roots (like Cassava). It is the main ingredient of bread, which is a staple food for many cultures, making the availability of adequate supplies of flour a major economic and political issue at various times throughout history.
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Wheat flour is one of the most important foods in European, North American, Middle Eastern, Indian and North African cultures, and is the defining ingredient in most of their styles of breads and pastries. While wheat is the most common base for flour, maize flour has been important in Mesoamerican cuisine since ancient times, and remains a staple throughout the Americas. Rye flour is an important constituent of bread in much of central Europe, and rice can also be used in flour, though this is relatively uncommon.
Flour contains a high proportion of starches, which are a subset of complex carbohydrates also known as polysaccharides. The kinds of flour used in cooking include all-purpose flour, self-rising flour (known as self-raising outside North America), and cake flour including bleached flour.
The higher the protein content the harder and stronger the flour, and the more it will produce crusty or chewy breads. The lower the protein the softer the flour, which is better for cakes, cookies, and pie crusts. The Components of Flour:
In addition to the type of grain used, flour also varies depending on what part of the grain is retained during the milling process. This may include the endosperm, bran or germ. Endosperm: This is the starchy center of the grain, which contains carbohydrates, protein and a small amount of oil. Most simple white flours contain only this portion of the grain. Brain: The outer husk of the grain, known as bran, adds texture, color and fiber to flour.
Bran gives whole grain flours their characteristic brown color and rough texture. Germ: The germ is the reproductive epicenter of the grain and is a concentrated source of nutrients. Flour that retains the germ during the milling process will contain more vitamins, minerals and fiber. Gluten: Gluten is a protein found naturally in the endosperm of wheat. It gives strength, elasticity and a characteristic chewy texture to yeast breads, pasta and pizza dough.
Sugar is the generalised name for a class of chemically-related sweet-flavored substances, most of which are used as food. They are carbohydrates, composed of carbon, hydrogen and oxygen. There are various types of sugar derived from different sources. Simple sugars are called monosaccharides and include glucose (also known as dextrose), fructose and galactose.
The table or granulated sugar most customarily used as food is sucrose, a disaccharide (in the body, sucrose hydrolyses into fructose and glucose). Other disaccharides include maltose and lactose. Chemically-different substances may also have a sweet taste, but are not classified as sugars. Some are used as lower-calorie food substitutes for sugar described as artificial sweeteners.
Sugars are found in the tissues of most plants but are only present in sufficient concentrations for efficient extraction in sugarcane and sugar beet. Sugarcane is a giant grass and has been cultivated in tropical climates in the Far East since ancient times.
A great expansion in its production took place in the 18th century with the setting up of sugar plantations in the West Indies and Americas. This was
the first time that sugar became available to the common people who had previously had to rely on honey to sweeten foods.
Sugar beet is a root crop and is cultivated in cooler climates and became a major source of sugar in the 19th century when methods for extracting the sugar became available. Sugar production and trade has changed the course of human history in many ways.
It influenced the formation of colonies, the perpetuation of slavery, the transition to indentured labour, the migration of peoples, wars between sugar trade-controlling nations in the 19th century, and the ethnic composition and political structure of the new world. The world produced about 168 million tonnes of sugar in 2011.
The average person consumes about 24 kilograms of sugar each year (33.1 kg in industrialised countries), equivalent to over 260 food calories per person, per day. Since the latter part of the twentieth century, it has been questioned whether a diet high in sugars, especially refined sugars, is bad for human health.
Sugar has been linked to obesity and suspected of or fully implicated as a cause in the occurrence of diabetes, cardiovascular disease, dementia, macular degeneration and tooth decay. Numerous studies have been undertaken to try to clarify the position but with varying results, mainly because of the difficulty of finding populations for use as controls that do not consume or are largely free of any sugar consumption. Water is a chemical compound with the chemical formula H
2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at standard ambient temperature and pressure, but it often co-exists on Earth with its solid state, ice, and gaseous state (water vapor or steam). Water also exists in a liquid crystal state near hydrophilic surfaces.
Water covers 71% of the Earth’s surface, and is vital for all known forms of life. On Earth, 96.5% of the planet’s water is found in seas and oceans, 1.7% in groundwater, 1.7% in glaciers and the ice caps of Antarctica and Greenland, a small fraction in other large water bodies, and 0.001% in the air as vapor, clouds (formed of solid and liquid water particles suspended in air), and precipitation. Only 2.5% of the Earth’s water is freshwater, and 98.8% of that water is in ice and groundwater.
Less than 0.3% of all freshwater is in rivers, lakes, and the atmosphere, and an even smaller amount of the Earth’s freshwater (0.003%) is contained within biological bodies and manufactured products. Water on Earth moves continually through the water cycle of evaporation and transpiration (evapotranspiration), condensation, precipitation, and runoff, usually reaching the sea.
Evaporation and transpiration contribute to the precipitation over land. Safe drinking water is essential to humans and other lifeforms even though it provides no calories or organic nutrients. Access to safe drinking water has improved over the last decades in almost every part of the world, but approximately one billion people still lack access to safe water and over 2.5 billion lack access to adequate sanitation. There is a clear correlation between access to safe water and GDP per capita.
However, some observers have estimated that by 2025 more than half of the world population will be facing water-based vulnerability. A recent report (November 2009) suggests that by 2030, in some developing regions of the world, water demand will exceed supply by 50%. Water plays an important role in the world economy, as it functions as a solvent for a wide variety of chemical substances and facilitates industrial cooling and transportation.
Approximately 70% of the fresh water used by humans goes to agriculture.