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53-560: Many manufactured goods come in powder form, such as flour , sugar , ground coffee , powdered milk , copy machine toner , gunpowder , cosmetic powders, and some pharmaceuticals . In nature, dust , fine sand and snow , volcanic ash , and the top layer of the lunar regolith are also examples. Because of their importance to industry, medicine and earth science, powders have been studied in great detail by chemical engineers , mechanical engineers , chemists , physicists , geologists , and researchers in other disciplines. Typically,

106-548: A Natufian hunter-gatherer site more than 14,000 years old in northwest Jordan. The Romans were the first to grind seeds on cone mills . In 1786, at the beginning of the Industrial Era , the first steam-powered flour mill, Albion Mills, Southwark , was completed in London . In the 1930s, some flour began to be enriched with iron, niacin, thiamine and riboflavin. In the 1940s, mills started to enrich flour and folic acid

159-471: A 14% moisture content. Thus, a US flour with 0.48% ash would approximate a French Type 55. Other measurable properties of flour as used in baking can be determined using a variety of specialized instruments, such as the farinograph . Flour dust suspended in air is explosive —as is any mixture of a finely powdered flammable substance with air ( see dust explosion ). Some devastating explosions have occurred at flour mills, including an explosion in 1878 at

212-650: A bit more strength than cakes, but still produce flaky crusts rather than hard or crispy ones. All-purpose, or "AP flour", or plain flour is medium in gluten protein content at 9.5–11.5% (10–12% from second source ) protein content. It has adequate protein content for many bread and pizza bases, though bread flour and special 00 grade Italian flour are often preferred for these purposes, respectively, especially by artisan bakers. Some biscuits are also prepared using this type of flour. "Plain" refers not only to AP flour's middling gluten content but also to its lack of any added leavening agent (as in self-rising flour). Bread flour

265-624: A dominant effect on the bulk behavior of the material. Only when the grains are very small and lightweight does the Van der Waals force become predominant, causing the material to clump like a powder. The cross-oversize between flow conditions and stick conditions can be determined by simple experimentation. Many other powder behaviors are common to all granular materials. These include segregation, stratification, jamming and unjamming, fragility , loss of kinetic energy , frictional shearing, compaction and Reynolds' dilatancy . Powders are transported in

318-403: 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 (known as plain outside North America), self-rising flour, and cake flour (including bleached flour). The higher the protein content the harder and stronger the flour, and the more it will produce crispy or chewy breads. The lower

371-636: A number of mechanical toys operated by air, water, and steam under pressure." Though no documents written by Ctesibius survive, he is thought to have heavily influenced Philo of Byzantium while writing his work, Mechanical Syntaxis , as well as Vitruvius in De architectura . In the first century BC, the ancient Greek mathematician Hero of Alexandria compiled recipes for dozens of contraptions in his work, Pneumatics. It has been speculated that much of this work can be attributed to Ctesibius. The pneumatic experiments described in these ancient documents later inspired

424-402: A powder arises because of the molecular Van der Waals force that causes individual grains to cling to one another. This force is present not just in powders, but in sand and gravel, too. However, in such coarse granular materials the weight and the inertia of the individual grains are much larger than the very weak Van der Waals forces, and therefore the tiny clinging between grains does not have

477-399: A powder can be compacted or loosened into a vastly larger range of bulk densities than can a coarser granular material. When deposited by sprinkling, a powder may be very light and fluffy. When vibrated or compressed it may become very dense and even lose its ability to flow. The bulk density of coarse sand, on the other hand, does not vary over an appreciable range. The clumping behavior of

530-450: A small quantity of oil is added at the compressor to prevent corrosion and lubricate mechanical components. Factory-plumbed pneumatic-power users need not worry about poisonous leakage, as the gas is usually just air. Any compressed gas other than air is an asphyxiation hazard—including nitrogen, which makes up 78% of air. Compressed oxygen (approx. 21% of air) would not asphyxiate, but is not used in pneumatically-powered devices because it

583-444: A stationary stone wheel, vertically or horizontally with the grain in between. Roller mills soon replaced stone grist mills as the production of flour has historically driven technological development, as attempts to make gristmills more productive and less labor-intensive led to the watermill and windmill . These terms are now applied more broadly to uses of water and wind power for purposes other than milling. More recently,

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636-496: A type of rock. For comparison, the Moon has neither wind nor water, and so its regolith contains dust but no mudstone. The cohesive forces between the particles tend to resist their becoming airborne, and the motion of wind across the surface is less likely to disturb a low-lying dust particle than a larger sand grain that protrudes higher into the wind. Mechanical agitation such as vehicle traffic, digging or passing herds of animals

689-597: A very high surface area, they can combust with explosive force once ignited. Facilities such as flour mills can be vulnerable to such explosions without proper dust mitigation efforts. Some metals become especially dangerous in powdered form, notably titanium . A paste or gel might become a powder after it has been thoroughly dried, but is not considered a powder when it is wet because it does not flow freely. Substances like dried clay , although dry bulk solids composed of very fine particles, are not powders unless they are crushed because they have too much cohesion between

742-607: Is a powder made by grinding raw grains , roots , beans , nuts , or seeds . Flours are used to make many different foods . Cereal flour, particularly wheat flour , is the main ingredient of bread , which is a staple food for many cultures. Corn flour has been important in Mesoamerican cuisine since ancient times and remains a staple in the Americas. Rye flour is a constituent of bread in both Central Europe and Northern Europe . Cereal flour consists either of

795-550: Is a fire hazard, more expensive, and offers no performance advantage over air. Smaller or stand-alone systems can use other compressed gases that present an asphyxiation hazard, such as nitrogen—often referred to as OFN (oxygen-free nitrogen) when supplied in cylinders. Portable pneumatic tools and small vehicles, such as Robot Wars machines and other hobbyist applications are often powered by compressed carbon dioxide , because containers designed to hold it such as SodaStream canisters and fire extinguishers are readily available, and

848-597: Is a principal ingredient used to thicken many puddings or desserts, and is the main ingredient in packaged custard. Pneumatics Pneumatics (from Greek πνεῦμα pneuma 'wind, breath') is the use of gas or pressurized air in mechanical systems. Pneumatic systems used in industry are commonly powered by compressed air or compressed inert gases . A centrally located and electrically-powered compressor powers cylinders , air motors , pneumatic actuators , and other pneumatic devices. A pneumatic system controlled through manual or automatic solenoid valves

901-400: Is a theoretically possible protein content ). This flour may be used where a recipe adds ingredients that require the dough to be extra strong to hold together in their presence, or when strength is needed for constructions of bread (e.g., some centerpiece displays). Gluten flour is refined gluten protein, or a theoretical 100% protein (though practical refining never achieves a full 100%). It

954-453: Is more effective than a steady wind at stirring up a powder. The aerodynamic properties of powders are often used to transport them in industrial applications. Pneumatic conveying is the transport of powders or grains through a pipe by blowing gas. A gas fluidized bed is a container filled with a powder or granular substance that is fluffed up by blowing gas upwardly through it. This is used for fluidized bed combustion , chemically reacting

1007-517: Is no codified dividing line. The CDC has cautioned not to eat raw flour doughs or batters. Raw flour can contain bacteria like E. coli and needs to be cooked like other foods. The English word flour is originally a variant of the word flower , and both words derive from the Old French fleur or flour , which had the literal meaning "blossom", and a figurative meaning "the finest". The phrase fleur de farine meant "the finest part of

1060-416: Is often referred to as "white flour". Bleached flour is artificially aged using a "bleaching" agent, a "maturing" agent, or both. A bleaching agent affects the carotenoids responsible for the natural colour of the flour; a "maturing" agent also affects gluten development. A maturing agent may either strengthen or weaken gluten development. The four most common additives used as bleaching/maturing agents in

1113-402: Is relatively little hazardous dust in the natural environment. Once aloft, the dust is very likely to stay aloft until it meets water in the form of rain or a body of water. Then it sticks and is washed downstream to settle as mud deposits in a quiet lake or sea. When geological changes later re-expose these deposits to the atmosphere, they may have already cemented together to become mudstone ,

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1166-442: Is selected when it provides a lower cost, more flexible, or safer alternative to electric motors , and hydraulic actuators . Pneumatics also has applications in dentistry , construction , mining , and other areas. Pneumatic systems in fixed installations, such as factories, use compressed air because a sustainable supply can be made by compressing atmospheric air {{ Citation needed }}. The air usually has moisture removed, and

1219-457: Is treated either with benzoyl peroxide or chlorine gas, but no way exists to tell which process has been used when buying the flour at the grocery store. The old method of procuring white or "bleached" flour did not entail the use of chemical agents at all. Rather, the wheat kernels were moistened with water long enough for the outer kernels of the wheat which contained the bran to soften and, eventually, fall off while grinding. In some places,

1272-555: Is typically made from hard red winter wheat planted in the fall and harvested in the spring. Hard wheat is high in gluten, a protein that makes dough stretchy. Hard wheat is 11.5–13.5% (12–14% from second source ) protein. The increased protein binds to the flour to entrap carbon dioxide released by the yeast fermentation process, resulting in a better rise and chewier texture. Hard is a general term for flours with high gluten protein content, commonly refers to extra strong flour, with 13.5–16% (or 14–15% from some sources) protein (16%

1325-474: Is used to strengthen flour as needed. For example, adding approximately one teaspoon per cup of AP flour gives the resulting mix the protein content of bread flour. It is commonly added to whole grain flour recipes to overcome the tendency of greater fiber content to interfere with gluten development, needed to give the bread better rising (gas holding) qualities and chew. Unbleached flour is simply flour that has not undergone bleaching and therefore does not have

1378-494: The Unifine mill , an impact-type mill, was developed in the mid-20th century. Modern farm equipment allows livestock farmers to do some or all of their own milling when it comes time to convert their own grain crops to coarse meal for livestock feed . This capability is economically important because the profit margins are often thin enough in commercial farming that saving expenses is vital to staying in business. Flour contains

1431-588: The Washburn "A" Mill in Minneapolis that killed 22 people. The CDC has cautioned not to eat raw flour doughs or batters. Raw flour can contain bacteria like E. coli and needs to be cooked like other foods. Bread , pasta , crackers , many cakes , and many other foods are made using flour. Wheat flour is also used to make a roux as a base for thickening gravy and sauces. It can also be used as an ingredient in papier-mâché glue . Cornstarch

1484-400: The endosperm , germ , and bran together (whole-grain flour) or of the endosperm alone (refined flour). Meal is either differentiable from flour as having slightly coarser particle size (degree of comminution ) or is synonymous with flour; the word is used both ways. For example, the word cornmeal often connotes a grittier texture whereas corn flour connotes fine powder, although there

1537-426: The phase change between liquid and gas makes it possible to obtain a larger volume of compressed gas from a lighter container than compressed air requires. Carbon dioxide is an asphyxiant and can be a freezing hazard if vented improperly. Although the early history of pneumatics is murky, the field's founder is traditionally traced back to Ctesibius of Alexandria "who worked in the early 3rd century BCE and invented

1590-530: The Renaissance inventors of the thermoscope and the air thermometer , devices which relied upon the heating and cooling of air to move a column of water up and down a tube. German physicist Otto von Guericke (1602-1686) invented the vacuum pump, a device that can draw out air or gas from the attached vessel. He demonstrated the vacuum pump to separate the pairs of copper hemispheres using air pressures. The field of pneumatics has changed considerably over

1643-541: The US are: Some other chemicals used as flour treatment agents to modify color and baking properties include: Common preservatives in commercial flour include: All bleaching and maturing agents (with the possible exception of ascorbic acid) have been banned in the United Kingdom. Bromination of flour in the US has fallen out of favor, and while it is not yet actually banned anywhere, few retail flours available to

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1696-427: The ash mass is only rarely given on the label by flour manufacturers. However, the legally required standard nutrition label specifies the protein content of the flour, which is also a way for comparing the extraction rates of different available flour types. In general, as the extraction rate of the flour increases, so do both the protein and the ash content. However, as the extraction rate approaches 100% (whole meal),

1749-411: The atmosphere differently from a coarse granular material. For one thing, tiny particles have little inertia compared to the drag force of the gas that surrounds them, and so they tend to go with the flow instead of traveling in straight lines. For this reason, powders may be an inhalation hazard. Larger particles cannot weave through the body's defenses in the nose and sinus, but will strike and stick to

1802-401: The atmosphere for a very long time. Random motion of the air molecules and turbulence provide upward forces that may counteract the downward force of gravity. Coarse granulars, on the other hand, are so heavy that they fall immediately back to the ground. Once disturbed, dust may form huge dust storms that cross continents and oceans before settling back to the surface. This explains why there

1855-432: The bleaching process, nutrients are lost. Some of these nutrients may be replaced during refining – the result is known as enriched flour. Cake flour is the lowest in gluten protein content, with 6–7% (5–8% from second source ) protein to produce minimal binding so the cake "crumbles" easily. Pastry flour has the second-lowest gluten protein content, with 7.5–9.5% (8–9% from second source ) protein to hold together with

1908-502: The color of "white" flour. An example is graham flour , whose namesake, Sylvester Graham , was against using bleaching agents, which he considered unhealthy. In English-speaking countries, self-raising (or self-rising) flour is commercially available with chemical leavening agents already in the mix. In America, it is also likely to be pre-salted; in Britain this is not the case. The added ingredients are evenly distributed throughout

1961-402: The countryside. Heat-processed flour is flour where the germ is first separated from the endosperm and bran, then processed with steam, dry heat or microwave and blended into flour again. Milling of flour is accomplished by grinding grain between stones or steel wheels. Today, "stone-ground" usually means that the grain has been ground in a mill in which a revolving stone wheel turns over

2014-403: The different available flour varieties are labeled according to the ash mass that remains after a sample is incinerated in a laboratory oven (typically at 550 °C (1,022 °F) or 900 °C (1,650 °F), see international standards ISO 2171 and ICC 104/1 ). This is an easily verified indicator for the fraction of the whole grain remains in the flour, because the mineral content of

2067-514: The flour", since flour resulted from the elimination of coarse and unwanted matter from the grain during milling. Maize or corn flour has been important in Mesoamerican cuisine since ancient times and remains a staple in the Americas. Rye flour is a constituent of bread in central and northern Europe. Archaeological evidence for making flour ( wheat seeds crushed between simple millstones ) dates to at least 6000 BC. In 2018, archaeologists reported finding evidence of bread making at Shubayqa 1,

2120-449: The flour, which aids a consistent rise in baked goods. This flour is generally used for preparing sponge cakes, scones, muffins, etc. It was invented by Henry Jones and patented in 1845. If a recipe calls for self-raising flour, and this is not available, the following substitution is possible: Wheat is the grain most commonly used to make flour. Certain varieties may be referred to as "clean" or "white". Flours contain differing levels of

2173-538: The gas with the powder. Some powders may be dustier than others. The tendency of a powder to generate particles in the air under a given energy input is called " dustiness ". It is an important powder property which is relevant to powder aerosolization. It also has implications for human exposure to aerosolized particles and the associated health risks (via skin contact or inhalation) in workplaces. Many common powders made in industry are combustible; particularly metals or organic materials such as flour . Since powders have

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2226-432: The grains, and therefore they do not flow freely like a powder. A liquid flows differently than a powder, because a liquid cannot resist any shear stress and therefore it cannot reside at a tilted angle without flowing (that is, it has zero angle of repose . ) A powder on the other hand is a solid, not a liquid, because it may support shear stresses and therefore may display an angle of repose. Flour Flour

2279-419: The home baker are bromated anymore. Many varieties of flour packaged specifically for commercial bakeries are still bromated. Retail bleached flour marketed to the home baker is now treated mostly with either peroxidation or chlorine gas. Current information from Pillsbury is that their varieties of bleached flour are treated both with benzoyl peroxide and chlorine gas. Gold Medal states that their bleached flour

2332-433: The late 19th century, this process was too short for an industrial production and distribution cycle. As vitamins , micronutrients and amino acids were completely or relatively unknown in the late 19th century, removing the germ was an effective solution. Without the germ, flour cannot become rancid. Degermed flour became standard. Degermation started in densely populated areas and took approximately one generation to reach

2385-399: The leaves of Syrian rue ( Peganum harmala ) were spread in stratified layers between the layers of grain, and left in such a state for several days, until the fumes emitted from the astringent leaves of the plant caused the outer kernels of the wheat to break down and dissolve, leaving a clean and white flour after grinding. During the process of making flour, specifically as a result of

2438-470: The lowest ash residue in the table. The closest is French Type 45. There is no official Chinese name corresponding to the highest ash residue in the table. Usually such products are imported from Japan and the Japanese name zenryufun (全粒粉) is used, or it is called quánmài miànfěn (全麥麵粉). It is possible to determine ash content from some US manufacturers. However, US measurements are based on wheat with

2491-431: The mucous membranes. The body then moves the mucus out of the body to expel the particles. The smaller particles on the other hand can travel all the way to the lungs from which they cannot be expelled. Serious and sometimes fatal diseases such as silicosis are a result from working with certain powders without adequate respiratory protection. Also, if powder particles are sufficiently small, they may become suspended in

2544-681: The protein gluten . "Strong flour" or "hard flour" has a higher gluten content than "weak" or "soft" flour. "Brown" and wholemeal flours may be made of hard or soft wheat. When flours do not contain gluten, they are suitable for people with gluten-related disorders , such as coeliac disease , non-celiac gluten sensitivity or wheat allergy sufferers, among others. Contamination with gluten-containing cereals can occur during grain harvesting, transporting, milling, storing, processing, handling and/or cooking. Flour also can be made from soybeans , arrowroot , taro , cattails , manioc , quinoa , and other non-cereal foodstuffs. In some markets,

2597-408: The protein content drops slightly, while the ash content continues to rise. The following table shows some typical examples of how protein and ash content relate to each other in wheat flour: This table is only a rough guideline for converting bread recipes. Since flour types are not standardized in many countries, the numbers may differ between manufacturers. There is no French type corresponding to

2650-429: The protein the softer the flour, which is better for cakes, cookies, and pie crusts. Cereal flour consists either of the endosperm , germ , and bran together (whole-grain flour) or of the endosperm alone (refined flour). "Bleached flour" is "refined" flour with a chemical whitening (bleaching) agent added. "Refined" flour has had the germ and bran, containing much of the nutritional fibre and vitamins, removed and

2703-487: The starchy endosperm is much lower than that of the outer parts of the grain. Flour made from all parts of the grain ( extraction rate : 100%) leaves about 2 grams (0.071 oz) ash or more per 100 grams (3.5 oz) dry flour. Plain white flour with an extraction rate of 50–60% leaves about 0.4 grams (0.014 oz). In the United States and the United Kingdom, no numbered standardized flour types are defined, and

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2756-808: The years. It has moved from small handheld devices to large machines with multiple parts that serve different functions. Both pneumatics and hydraulics are applications of fluid power . Pneumatics uses an easily compressible gas such as air or a suitable pure gas—while hydraulics uses relatively incompressible liquid media such as oil. Most industrial pneumatic applications use pressures of about 80 to 100 pounds per square inch (550 to 690  kPa ). Hydraulics applications commonly use from 1,000 to 5,000 psi (6.9 to 34.5 MPa), but specialized applications may exceed 10,000 psi (69 MPa). Pneumatic logic systems (sometimes called air logic control ) are sometimes used for controlling industrial processes, consisting of primary logic units like: Pneumatic logic

2809-602: Was added to the list in the 1990s. An important problem of the Industrial Revolution was the preservation of flour. Transportation distances and a relatively slow distribution system collided with natural shelf life . The reason for the limited shelf life is the fatty acids of the germ , which react from the moment they are exposed to oxygen. This occurs when grain is milled; the fatty acids oxidize and flour starts to become rancid . Depending on climate and grain quality, this process takes six to nine months. In

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