Starch #2

Starch constitutes the nutritive reserves of many plants. During the growing season, the green leaves collect energy from the sun. In potatoes this energy is transported as a sugar solution down to the tubers, and it is down there that the sugar is converted to starch in the form of tiny granules occupying most of the cell interior.The conversion of sugar to starch takes place by means of enzymes. Then next spring, enzymes are also responsible for the re-conversion of starch to sugar - transported upwards as energy for the growing plant.THE BASIS FOR STARCH QUALITY IS LAID IN THE POTATO CLAMP.In the field or stored in clamps during winter, the tubers stay alive and need some air for respiration and life activity.Potatoes consume a small amount of their own starch during winter to maintain life functions until spring. This requires fresh air and the respiration causes generation of heat.If the surrounding temperature falls with a risk of frost, the tubers try to save their skin by extensive conversion of starch to sugar in order to lower the freezing point in the cell juice. If this does not suffice, the tubers die. Potatoes therefore must be adequately covered when stored.If the potatoes get warm, respiration increases, raising the temperature further. A lot of starch is used for the respiration and the tubers will die of heat.Unfavourable storage conditions cause starch losses and, in the worst case, dead and smashed potatoes, which are disruptive for the process.Supplies of bad potatoes have to be rejected.Damage during transport also causes quality problems. Every single blow damages cells, with starch losses and a dead spot on the tuber as a result. It is therefore of utmost importance to handle the potatoes during transport as carefully as possible with the techniques and equipment available.REFINING BEGINS ALREADY DURING RAW MATERIAL INTAKE.Drop damper for initial filling of empty store.During unloading at the factory, damage can be reduced by covering buffer silos with rubber and minimising drop impact with rubber curtains. Smashed potatoes loose a lot of juice, causing foam and unnecessary problems in the washing station.Loose dirt, sand and gravel are removed on a rotating screen before the potatoes are deposited in the store - the better the dirt removal, the lesser the problems with stones and sand in the fluming channels later. The soil also contains considerable quantities of nutrients, which will dissolve in the washing water and contribute to the environmental effect caused by the effluent.The potato store is a necessity to secure the supply of potatoes overnight. Supplies for the weekend may also be required because of restrictions on heavy road transport outside ordinary working hours.The ideal situation is to reach the bottom of the potato store every morning, because the potatoes suffer during long storage in thick layers without adequate ventilation.EFFICIENT WASHING MAKES REFINING EASIER.Soil and dirt not removed in the washing station give problems later. The washing is therefore very important. The washing is a counter current process, with fresh water added through pressure nozzles in the final step.The potatoes are flumed by water in channels - passing a stone trap - to the washing station. The stone trap utilises the difference in specific weights between stones and potatoes - an upstream water flow carries the potatoes over the stone trap, while the heavier stones are trapped and collected on a stone conveyor. The water level in the washing drum has to be kept low so that the potatoes do not float. The drum is not merely a conveyor, but also ensures that the potatoes rub vigorously against each other. The rubbing is essential for the removal of fungi, rotten spots, skin and dirt from the surface. The floating water may be recycled after settling of sand in pools.A high standard of washing improves refining because many impurities resemble starch in specific density and size, so washing the potatoes is the only way to get rid of them.The quantity of impurities adhering to the potatoes on delivery depends to a great extent on weather conditions and on the soil where the potatoes are cultivated.The quantity of water used for fluming and washing is identical with the quantity of clean water applied in the final high-pressure spray. RASPING.Rasping is the first step in the starch extraction. The goal is to open the tuber cells and release the starch granules. The slurry obtained can be considered as a mixture of pulp (cell walls), fruit juice and starch. With modern high-speed raspers, rasping is a one-pass operation only.USE OF SULPHUR.The cell juice is rich in sugar and protein. When opening the cells the juice is instantly exposed to air and reacts with the oxygen, forming coloured components, which may adhere to the starch.Sulphur dioxide gas or sodium-bisulphite-solution therefore has to be added. A considerable reduction potential of the sulphur compounds prevents discoloration. Sufficient sulphur has to be added to maintain the juice and pulp light yellow.EXTRACTION. Powerful washing is needed to flush the starch granules out from the cells - the cells are torn apart in the rasper and form a filtering mat that tries to retain the starch. Water has previously been used for the extraction, but today extraction takes place in closed systems allowing the use of the potato juice itself. It has the advantage that the juice can later be recovered in concentrated and undiluted form, reducing transport costs for its use as a fertiliser.The flushed-out starch discharges from the extraction sieves along with the fruit juice, and the cell walls (pulp) are pumped to the pulp dewatering sieves. The pulp leaves the dewatering sieves as drip- dry - i.e. approximately 13% dry matter. The extraction takes place on rotating conical sieves, where centrifugal power increases the capacity per unit of area. The high efficiency makes it feasible to utilise high quality sieve plates made of stainless steel, which will withstand abrasion and CIP-chemicals. The sieve plates have long perforations only 125 microns across. Operating Principle of a Starch Extractor.The extraction is a counter current process in which the pulp-dewatering screen is actually the last step. If the pulp is required in almost dry form, the number of spray nozzles with washing water is reduced. Instead continuous back spraying is maintained to ensure that the dry pulp will slide down the screen.CONCENTRATING THE CRUDE STARCH SLURRY.On hydrocyclone unit as much juice is excreted as possible. The starch leaves the concentrator as pumpable slurry of approximately 19 oBe.The concentrating stage typically consists of a unit with hydrocyclone blocks for defoaming, concentrating and starch recovering arranged in series.REFININGIt now remains to purify the crude starch milk (suspension) and remove residual fruit juice and impurities. The way it is done is more or less based on the same principles used when removing soap water from the laundry - you wring and soak in clean water again and again. Everyone doing laundry realises how often it is necessary to wring before the rinsing water is completely clear and that the harder you wring the fewer rinsing steps are required.In the same way, the starch slurry is diluted and concentrated again and again. To save rinsing water the wash is done counter currently - i.e. the incoming fresh water is used on the very last step and the overflow is recycled for dilution on the previous step and so on.HYDROCYCLONES

Process for the preparation of granular cold water-soluble starch

1. A process for preparing granular cold water-soluble starch comprising the steps of: preparing a slurry of initially cold water insoluble starch granules and a liquid phase including water and a polyhydric alcohol, said slurry having a starch:water weight ratio of from about 1:0.6 to 1:3, and a starch:polyhydric alcohol weight ratio of from about 1:2 to 1:10, both of the foregoing ratios being on a dry starch basis; heating said slurry to a temperature of from about 80°-130° C. for a period of from about 3-30 minutes to convert the crystalline structure of said starch granules to cold water-soluble V-type single helix crystalline structure or an amorphous structurel while substantially maintaining the granular integrity of the starch and yielding birefringent starch granules having a cold water solubility of at least about 70%; and separating the birefringent, converted, cold water-soluble starch granules or fragments thereof from said liquid phase.

2. The process of claim 1, said starch being selected from the group consisting of cereal, tuber, root and legume starches.

3. The process of claim 2, said starch being selected from the group consisting of native wheat, corn, potato, sweet potato, tapioca, mung bean, waxy barley, and waxy corn starches, and cross-linked and substituted wheat, corn, waxy corn, potato and tapioca starches, and cross-linked waxy corn starch.

4. The process of claim 1 said polyhydric alcohol being selected from the group consisting of, 1,2- and 1,3-propanediols, all positional isomers of butanediol and glycerol.

5. The process of claim 1, said starch:water ratio being from about 1,0:1.0 to 3 and said starch:polyhydric alcohol ratio being from about 1.0:2 to 7.

6. The process of claim 1, said temperature being from about 85° to 127°.

7. The process of claim 1, said time being from about 10 to 15 minutes.

8. The process of claim 1, said heating step being carried out at substantially atmospheric pressure. 9. The process of claim 1, said separating step comprising the steps of adding an excess of volatile solvent to said slurry which is miscible with water and polyhydric alcohol, and volatilizing said solvent. 10. The process of claim 9, said solvent being selected from the group consisting of edible alcohols. 11. The process of claim 10, said solvent being selected from the group consisting of ethanol, methanol, and iso-propanol. 12. The process of claim 1, said converted, cold water-soluble starch granules having a cold water-solubility of at least about 80%.

Pea starch used as edible film with antimicrobial activity

Pea starch used as edible film with antimicrobial activity

Pea starch, which has inherently good gel strength, was used as the source material for manufacturing a biodegradable and bioactive packaging material.

Extrudates containing 99% pea starch and 1% lysozyme were produced under various extrusion conditions.

The expansion of extrudates increased with an increase in die temperature, whereas increasing moisture content had the opposite effect.

Extrudate densities decreased as extrusion temperature increased, whereas lower moisture content in the extrudate dough decreased extrudate densities.

The elastic modulus and fracture strengths were highly correlated in a power-law fashion to relative density, showing that the mechanical properties of extrudates were dependent on solid density and foam structure. Up to 48% of the initial lysozyme activity was recovered from the extruded pea starch matrix.

The lysozyme released from extrudates showed an inhibition zone against Brochotrix thermosphacta B2. Extruded pea starch matrix containing lysozyme has potential application as an edible and biodegradable packaging material with antimicrobial activity.

From:Extrusion of Pea Starch Containing Lysozyme and Determination of Antimicrobial ActivityJournal of Food Science.

Starch Definition

From Wikipedia, the free encyclopedia

Starch (CAS# 9005-25-8, chemical formula (C6H10O5)n,[1]) is a mixture of amylose and amylopectin (usually in 20:80 or 30:70 ratios). These are both complex carbohydrate polymers of glucose (chemical formula of glucose C6H12O6), making starch a glucose polymer as well, as seen by the chemical formula for starch, regardless of the ratio of amylose:amylopectin.
The word is derived from Middle English sterchen, meaning to stiffen, which is appropriate since it can be used as a thickening agent when dissolved in water and heated.

Starch in food
In terms of human nutrition, starch is by far the most consumed polysaccharide in the human diet. It constitutes more than half of the carbohydrates even in many affluent diets, and much more in poorer diets. Traditional staple foods such as cereals, roots and tubers are the main source of dietary starch.
Starch (in particular cornstarch) is used in cooking for thickening foods such as sauces. In industry, it is used in the manufacturing of adhesives, paper, textiles and as a mold in the manufacture of sweets such as wine gums and jelly beans. It is a white powder, and depending on the source, may be tasteless and odorless.
Starch is often found in the fruit, seeds, rhizomes or tubers of plants and is the major source of energy in these food items. The major resources for starch production and consumption worldwide are rice, wheat, corn, and potatoes. Cooked foods containing starches include boiled rice, various forms of bread and noodles (including pasta).
As an additive for food processing, arrowroot and tapioca are commonly used as well. Commonly used starches around the world are: arracacha, buckwheat, banana, barley, cassava, kudzu, oca, sago, sorghum, regular household potatoes, sweet potato, taro and yams. Edible beans, such as favas, lentils and peas, are also rich in starch.

When a starch is pre-cooked, it can then be used to thicken cold foods. This is referred to as a pregelatinized starch. Otherwise starch requires heat to thicken, or "gelatinize."[vague]The actual temperature depends on the type of starch.

A modified food starch undergoes one or more chemical modifications, which allow it to function properly under high heat and/or shear frequently encountered during food processing. Food starches are typically used as thickeners and stabilizers in foods such as puddings, custards, soups, sauces, gravies, pie fillings, and salad dressings, but have many other uses.
The modified starches are coded according to the International Numbering System for Food Additives (INS) :

1401 Acid-treated starch
1402 Alkaline treated starch
1403 Bleached starch
1404 Oxidized starch
1405 Starches, enzyme-treated
1410 Monostarch phosphate
1411 Distarch glycerol
1412 Distarch phosphate esterified with sodium trimetaphosphate
1413 Phosphated distarch phosphate
1414 Acetylated distarch phosphate
1420 Starch acetate esterified with acetic anhydride
1421 Starch acetate esterified with vinyl acetate
1422 Acetylated distarch adipate
1423 Acetylated distarch glycerol
1440 Hydroxypropyl starch
1442 Hydroxypropyl distarch phosphate
1443 Hydroxypropyl distarch glycerol
1450 Starch sodium octenyl succinate

Resistant starch is starch that escapes digestion in the small intestine of healthy individuals.
Plants use starch as a way to store excess glucose, and thus also use starch as food during mitochondrial oxidative phosphorylation.

Commercial applications

Starch adhesive
Papermaking is the largest non-food application for starches globally, consuming millions of metric tons annually. In a typical sheet of copy paper for instance, the starch content may be as high as 8%. Both chemically modified and unmodified starches are used in papermaking. In the wet part of the papermaking process, generally called the “wet-end”, starches are chemically modified to contain a cationic or positive charge bound to the starch polymer, and are utilized to associate with the anionic or negatively charged paper fibers and inorganic fillers. Starch also helps get out cleaning stains from dirty washing.

These cationic starches impart the necessary strength properties for the paper web to be formed in the papermaking process (wet strength), and to provide strength to the final paper sheet (dry strength). In the dry end of the papermaking process the paper web is rewetted with a solution of starch paste that has been chemically, or enzymatically depolymerized. The starch paste solutions are applied to the paper web by means of various mechanical presses (size press). The dry end starches impart additional strength to the paper web and additionally provide water hold out or “size” for superior printing properties.

Corrugating glues are the next largest consumer of non-food starches globally. These glues are used in the production of corrugated fiberboard (sometimes called corrugated cardboard), and generally contain a mixture of chemically modified and unmodified starches that have been partially gelatinized to form an opaque paste. This paste is applied to the flute tips of the interior fluted paper to glue the fluted paper to the outside paper in the construction of cardboard boxes. This is then dried under high heat, which provides the box board strength and rigidity.
Another large non-food starch application is in the construction industry where starch is used in the gypsum wall board manufacturing process. Chemically modified or unmodified starches are added to the stucco containing primarily gypsum. Top and bottom heavyweight sheets of paper are applied to the formulation and the process is allowed to heat and cure to form the eventual rigid wall board. The starches act as a glue for the cured gypsum rock with the paper covering and also provide rigidity to the board.

Clothing starch or laundry starch is a liquid that is prepared by mixing a vegetable starch in water (earlier preparations also had to be boiled), and is used in the laundering of clothes. Starch was widely used in Europe in the 16th and 17th centuries to stiffen the wide collars and ruffs of fine linen which surrounded the necks of the well-to-do. During the 19th century and early 20th century, it was stylish to stiffen the collars and sleeves of men's shirts and the ruffles of girls' petticoats by applying starch to them as the clean clothes were being ironed. Aside from the smooth, crisp edges it gave to clothing, it served practical purposes as well. Dirt and sweat from a person's neck and wrists would stick to the starch rather than fibers of the clothing, and would easily wash away along with the starch. After each laundering, the starch would be reapplied. Today the product is sold in aerosol cans for home use.

Starch is also used to make some packing peanuts, and some dropped ceiling tiles.
Printing industry - in the printing industry food grade starch[2] is used in the manufacture of anti-set-off spray powder used to separate printed sheets of paper to avoid wet ink being set off. Starch is also used in the manufacture of glues[3] for book-binding.
Hydrogen production - Starch can be used to produce Hydrogen.[4]
Oil exploration - starch is used as to adjust the viscosity of drilling fluid which is used to lubricate the drill head in (mineral) oil extraction.

Use as a mold
Gummed sweets such as jelly beans and wine gums are not manufactured using a mold in the conventional sense. A tray is filled with starch and leveled. A positive mold is then pressed into the starch leaving an impression of 1000 or so jelly beans. The mix is then poured into the impressions and then put into a stove to set. This method greatly reduces the number of molds that must be manufactured.
Starch can be modified by addition of some chemical forms to be a hard glue for paper work , some of those forms are Borax , Soda Ash , which mixed with the starch solution at 50-70C to gain a very good adhesive, Sodium Silicate can be added to reinforce this formula.

Tests
Iodine solution is used to test for Starch. A bluish-black color indicates the presence of iodine in the starch solution. It is thought that the iodine fits inside the coils of amylose.[5] A 0.3% w/w solution is the standard concentration for a dilute starch indicator solution. It is made by adding 4 grams of soluble starch to 1 litre of heated water; the solution is cooled before use (starch-iodine complex becomes unstable at temperatures above 35 °C). This complex is often used in redox titrations: in presence of an oxidizing agent the solution turns blue, in the presence of reducing agent, the blue color disappears because triiodide (I3−) ions break up into three iodide ions, disassembling the complex.
Under the microscope, starch grains show a distinctive Maltese cross effect (also known as 'extinction cross' and birefringence) under polarized light.

Starch derivatives
Starch can be hydrolyzed into simpler carbohydrates by acids, various enzymes, or a combination of the two. The extent of conversion is typically quantified by dextrose equivalent (DE), which is roughly the fraction of the glycoside bonds in starch that have been broken. Food products made in this way include:
Maltodextrin, a lightly hydrolyzed (DE 10–20) starch product used as a bland-tasting filler and thickener.
Various corn syrups (DE 30–70), viscous solutions used as sweeteners and thickeners in many kinds of processed foods.
Dextrose (DE 100), commercial glucose, prepared by the complete hydrolysis of starch.
High fructose syrup, made by treating dextrose solutions to the enzyme glucose isomerase, until a substantial fraction of the glucose has been converted to fructose. In the United States, high fructose corn syrup is the principal sweetener used in sweetened beverages because fructose tastes sweeter than glucose, and less sweetener may be used.

References
Raven, P.; Evert, R.; Eichhorn, S. (1999) Biology of Plants (6th edition) p. 910 Worth Publishers. ISBN 1-57259-041-6
Spray Powder. - Russell-Webb. Retrieved on 2007-07-05.
Starch based glue. - ICI.
High-Yield Hydrogen Production from Starch and Water by a Synthetic Enzymatic Pathway. PLoS. Retrieved on 2007-07-15.
http://www.bhsu.edu/Portals/0/coartssciences/science/Chemistry/Chemistry107/chem107Lmanual2004.pdf