Starch production is an isolation of starch from plant sources. It takes place in starch plants. Starch industry is a part of food processing which is using starch as a starting material for production of starch derivatives, hydrolysates,

dextrin Dextrins are a group of low-molecular-weight carbohydrates produced by the hydrolysis of starch and glycogen. Dextrins are mixtures of polymers of D-glucose units linked by α-(1→4) or α-(1→6) glycosidic bonds. Dextrins can be produced from ...

s. At first, the raw material for the preparation of the starch was wheat. Currently main starch sources are: *

maize Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...

(in America, China and Europe) – 70%, *

potato The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae. Wild potato species can be found from the southern Unit ...

es (in Europe) – 12%, *

wheat Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...

- 8% (in Europe and Australia), *

tapioca Tapioca (; ) is a starch extracted from the storage roots of the cassava plant (''Manihot esculenta,'' also known as manioc), a species native to the North and Northeast regions of Brazil, but whose use is now spread throughout South America ...

- 9% (South East Asia and South America), *

rice Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesticat ...

, sorghum and other - 1%.

Potato starch production

The production of

potato starch Potato starch is starch extracted from potatoes. The cells of the root tubers of the potato plant contain leucoplasts (starch grains). To extract the starch, the potatoes are crushed, and the starch grains are released from the destroyed cells. T ...

comprises the steps such as delivery and unloading potatoes, cleaning, rasping of

tubers Tubers are a type of enlarged structure used as storage organs for nutrients in some plants. They are used for the plant's perennation (survival of the winter or dry months), to provide energy and nutrients for regrowth during the next growing s ...

, potato juice separation, starch extraction, starch milk refination, dewatering of refined starch milk and starch

drying Drying is a mass transfer process consisting of the removal of water or another solvent by evaporation from a solid, semi-solid or liquid. This process is often used as a final production step before selling or packaging products. To be consider ...

. The potato starch production supply chain varies significantly by region. For example, potato starch in Europe is produced from potatoes grown specifically for this purpose. However, in the US, potatoes are not grown for starch production and manufacturers must source raw material from food processor waste streams. The characteristics of these waste streams can vary significantly and require further processing by the US potato starch manufacturer to ensure the end-product functionality and specifications are acceptable.

Delivery and unloading potatoes

Potatoes are delivered to the starch plants via

road A road is a linear way for the conveyance of traffic that mostly has an improved surface for use by vehicles (motorized and non-motorized) and pedestrians. Unlike streets, the main function of roads is transportation. There are many types of ...

rail transport Rail transport (also known as train transport) is a means of transport that transfers passengers and goods on wheeled vehicles running on rails, which are incorporated in tracks. In contrast to road transport, where the vehicles run on a p ...

. Unloading of potatoes could be done in two ways: # dry - using elevators and tippers, # wet - using strong jet of water.

Cleaning

Coarsely cleaning of potatoes takes place during the transport of potatoes to the scrubber by channel. In addition, before the scrubber, straw and

stone In geology, rock (or stone) is any naturally occurring solid mass or aggregate of minerals or mineraloid matter. It is categorized by the minerals included, its Chemical compound, chemical composition, and the way in which it is formed. Rocks ...

s separators are installed. The main cleaning is conducted in scrubber (different kinds of high specialized machines are used). The remaining stones,

sludge Sludge is a semi-solid slurry that can be produced from a range of industrial processes, from water treatment, wastewater treatment or on-site sanitation systems. For example, it can be produced as a settled suspension obtained from conventional ...

and light

waste Waste (or wastes) are unwanted or unusable materials. Waste is any substance discarded after primary use, or is worthless, defective and of no use. A by-product, by contrast is a joint product of relatively minor economic value. A waste prod ...

s are removed at this step.

Water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...

used for washing is then purified and recycled back into the process.

Rasping of tubers

Most often the rasping of potato tubers is carried out with a rotary

grater A grater, also known as a shredder, is a kitchen utensil used to grate foods into fine pieces. Uses Food preparation Several types of graters feature different sizes of grating slots, and can therefore aid in the preparation of a variety of ...

. The purpose of this stage is disruption of cell walls, which therefore release the starch. In practice, potato cells are not entirely destroyed and part of the starch remains in the mash. Potato pulp rapidly turns dark, because

tyrosine -Tyrosine or tyrosine (symbol Tyr or Y) or 4-hydroxyphenylalanine is one of the 20 standard amino acids that are used by cells to synthesize proteins. It is a non-essential amino acid with a polar side group. The word "tyrosine" is from the G ...

presented in the potato is

oxidised Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a d ...

polyphenol oxidase Polyphenol oxidase (PPO; also polyphenol oxidase i, chloroplastic), an enzyme involved in fruit browning, is a tetramer that contains four atoms of copper per molecule. PPO may accept monophenols and/or ''o''-diphenols as substrates. The ...

, which is located in the cellular juice. Therefore, cellular juice must be separated as soon as possible.

Potato juice separation

This allows the recovery full-value

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

from juice and reduces the onerousness of water juice as a sludge.

Starch extraction

After separation of potato juice the pulp is directed to the washing starch station, to isolate the starch. Most used are stream-oriented washers. In these machines pulp diluted with water is washed with a strong stream of water to flush out the milk starch. The mash smuggling with water is a waste product – dewatered potato

pulp Pulp may refer to: * Pulp (fruit), the inner flesh of fruit Engineering * Dissolving pulp, highly purified cellulose used in fibre and film manufacture * Pulp (paper), the fibrous material used to make paper * Molded pulp, a packaging material ...

. Starch milk is contaminated by small fiber particles (potato tissue fragments) and the remaining components of the potato juice – that is why it is called raw starch milk.

Starch milk raffination

Raw starch milk is purified in the refining process. This involves the removal of small fibers from the starch milk and then the removal of juice water and starch milk condensation. For this purpose, the screens and

hydrocyclone Hydrocyclones are a type of cyclonic separators that separate product phases mainly on basis of differences in gravity with aqueous solutions as the primary feed fluid. As opposed to dry or dust cyclones, which separate solids from gasses, hydrocy ...

s are commonly used. Hydrocyclones due to the low output (approximately 0.3 cubic meter per hour) are connected in parallel and works as multihydrocyclones. For the starch milk desanding bihydrocyclones are used. In order to prevent enzymatic darkening of potato juice the chemical refining of starch is carried out using sulfurous acid. Refined starch milk has a

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

of about 22° Be, which is about 38% of starch.

Dewatering of refined starch milk and starch drying

It is a

suspension Suspension or suspended may refer to: Science and engineering * Suspension (topology), in mathematics * Suspension (dynamical systems), in mathematics * Suspension of a ring, in mathematics * Suspension (chemistry), small solid particles suspende ...

of starch in water, which needs dewatering up to 20% of

moisture Moisture is the presence of a liquid, especially water, often in trace amounts. Small amounts of water may be found, for example, in the air (humidity), in foods, and in some commercial products. Moisture also refers to the amount of water vapo ...

. This is equivalent to the moisture content of commercial starch when stored. High temperatures cannot be used in this process because of the danger of starch gelatinization which destroys granular structure. It may result in significant changes of the functional starch properties. Therefore, removal of excess water from milk shall be done only under conditions that prevent the gelatinization of starch. Dewatering of refined starch milk is carried out in two stages. In the first stage the excess water is removed by means of a rotary vacuum filter. Secondly moist starch is dried, without starch pasting. For this purpose a pneumatic dryer is used. In this device moist starch (with water content 36 – 40%) is floating in strong and hot (160 °C) air flow and then dried during 2 – 3 seconds. Then, the starch is separated from hot air in cyclones. Due to short time of high temperature drying and intensive water evaporation from the starch granules, its surface is heated only to 40 °C. Dried starch contains about 21% of water. During the pneumatic transport starch loses additional 1% of water. Received starch is storing separately in silos, in jute bags (100 kg) or

paper bag A paper bag is a bag made of paper, usually kraft paper. Paper bags can be made either with virgin or recycled fibres to meet customers’ demands. Paper bags are commonly used as shopping carrier bags and for packaging of some consumer go ...

s (50 kg). There are three kinds of starch: superior extra, superior and prima. Different sorts of starch depend on degree of

purity Purity may refer to: Books * ''Pureza'' (novel), a 1937 Brazilian novel by José Lins do Rego * ''Purity'' (novel), a 2015 novel by Jonathan Franzen ** ''Purity'' (TV series), a TV series based on the novel *''Purity'', a 2012 novel by Jackson P ...

and whiteness. The differences between them are in an

acidity In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a ...

and content of

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. (2 ...

substances. Table 1. Potato starch production characteristic. The water which is used in starch production (dirty water) for transportation and cleaning does not have to be totally clean. That is why clarifier usage enables application of closed cycle which noticeably reduces amount of cleaning water that is needed. On the other hand, requirements for quality of technological water are the same as for

drinking water Drinking water is water that is used in drink or food preparation; potable water is water that is safe to be used as drinking water. The amount of drinking water required to maintain good health varies, and depends on physical activity level, a ...

(microbiological and chemical

contamination Contamination is the presence of a constituent, impurity, or some other undesirable element that spoils, corrupts, infects, makes unfit, or makes inferior a material, physical body, natural environment, workplace, etc. Types of contamination ...

). In addition, this type of water should contain low amounts of metals such as: Ca, Mg, Fe, Mn; which has bad influence on starch properties.

Waste products

- Potato juice is a liquid waste product separated from the potatoes pulp after the rasping, using

centrifuge A centrifuge is a device that uses centrifugal force to separate various components of a fluid. This is achieved by spinning the fluid at high speed within a container, thereby separating fluids of different densities (e.g. cream from milk) or ...

s or decanters. It contains about 5% of dry substance, including about 2% valuable protein of the potato of high nutritional value,

vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutrie ...

s and other. Modern starch plants separate the juice from the mash. - Potato protein can be extracted from the juice by

coagulation Coagulation, also known as clotting, is the process by which blood changes from a liquid to a gel, forming a blood clot. It potentially results in hemostasis, the cessation of blood loss from a damaged vessel, followed by repair. The mechanis ...

with heat at low pH. About 600 kg of coagulated protein from each 1000 kg of potato protein can be recovered this way. The coagulated protein product contains about 80% protein (with the digestibility of about 90%), 2.5% minerals, 1.5% fat, 6%

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

-free substances and 10% water. Because of the full range of the

exogenic In a variety of contexts, exogeny or exogeneity () is the fact of an action or object originating externally. It contrasts with endogeneity or endogeny, the fact of being influenced within a system. Economics In an economic model, an exogeno ...

amino acid Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...

s the formulation is a valuable protein feed. The remaining potato juice is used as

fertilizer A fertilizer (American English) or fertiliser (British English; see spelling differences) is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply plant nutrients. Fertilizers may be distinct from ...

. - Potato pulp is a side product of washing the starch from the mash. It contains all non-starchy substances insoluble in water (fragments of wall of cells) fibres and bounded starch which cannot be mechanically separated from the blended parties of potato. The dry substance of the pulp contains 30% of starch, which makes it a good source for animal feed for

cow Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult ma ...

s. The pulp contains a lot of water, dry solids about 16%, which is inconvenient in

transportation Transport (in British English), or transportation (in American English), is the intentional movement of humans, animals, and goods from one location to another. Modes of transport include air, land (rail and road), water, cable, pipeline, ...

and storage. That is why it is really often dried and

dehydrated In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...

. - Juicy water is a liquid side product obtained after refining of starch milk. It is ten times diluted potato juice. As it is a

and it cannot be discharged to open water. It must be treated as waste water or is used as fertilizer.
International Starch Institute Aarhus Denmark Potato starch effluents

Application of potato starch

The usage of raw starch is relatively small. Starch is mainly used as material both in the manufacture of food and non-food products. In food processing a lot of starch is converted to starch hydrolysates. Also it is used to receive puddings, jellies, desserts, caramel and other food products. In addition, starch is processed to modified starch in order to change material properties. The modified starches have a wide range of applications in many industries. Applications of starch in non-food sectors include: production of

and adhesives,

drilling fluid In geotechnical engineering, drilling fluid, also called drilling mud, is used to aid the drilling of boreholes into the earth. Often used while drilling oil and natural gas wells and on exploration drilling rigs, drilling fluids are als ...

s, biodegradable plastics,

gypsum Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula . It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard or sidewalk chalk, and drywal ...

binders and many other. In addition

modified starch Modified starch, also called starch derivatives, are prepared by physically, enzymatically, or chemically treating native starch to change its properties. Modified starches are used in practically all starch applications, such as in food produ ...

es are used as

emulsion An emulsion is a mixture of two or more liquids that are normally immiscible (unmixable or unblendable) owing to liquid-liquid phase separation. Emulsions are part of a more general class of two-phase systems of matter called colloids. Altho ...

stabilizers. Other important fields of starch application are

textile sizing Sizing or size is a substance that is applied to, or incorporated into, other materials—especially papers and textiles—to act as a protective filler or glaze. Sizing is used in papermaking and textile manufacturing to change the absorption ...

agents,

excipient An excipient is a substance formulated alongside the active ingredient of a medication, included for the purpose of long-term stabilization, bulking up solid formulations that contain potent active ingredients in small amounts (thus often referred ...

in tablets for pharmaceuticals.

References

Mieczysław Pałasiński, 2005. Technology of Carbohydrate Processing (in Polish). Polish Society of Food Technologists, Małopolska Branch, Kraków, p. 63 - 76. {{DEFAULTSORT:Potato Starch Starch Food science Food technology