Starches+Group+6

__Starches __
 * Definition: **

Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds. This polysaccharide is produced by all green plants as an energy store. It is the most important carbohydrate in the human diet and is contained in such staple foods as potatoes, wheat, maize (corn), rice, and cassava. Pure starch is a white, tasteless and odorless powder that is insoluble in cold water or alcohol. It consists of two types of molecules: the linear and helical amylose and the branched amylopectin. Depending on the plant, starch generally contains 20 to 25% amylose and 75 to 80% amylopectin. Glycogen, the glucose store of animals, is a more branched version of amylopectin. Starch is processed to produce many of the sugars in processed foods. When dissolved in warm water, it can be used as a thickening, stiffening or gluing agent, giving wheatpaste.


 * Structure: **

Starch molecules arrange themselves in the plant in semi-crystalline granules. Each plant species has a unique starch granular size: rice starch is relatively small (about 2μm) while potato starches have larger granules (up to 100μm). Although in absolute mass only about one quarter of the starch granules in plants consist of amylose, there are about 150 times more amylose molecules than amylopectin molecules. Amylose is a much smaller molecule than amylopectin. Starch becomes soluble in water when heated. The granules swell and burst, the semi-crystalline structure is lost and the smaller amylose molecules start leaching out of the granule, forming a network that holds water and increasing the mixture's viscosity. This process is called starch gelatinization. During cooking the starch becomes a paste and increases further in viscosity. During cooling or prolonged storage of the paste, the semi-crystalline structure partially recovers and the starch paste thickens, expelling water. This is mainly caused by the retrogradation of the amylose. This process is responsible for the hardening of bread or staling, and for the water layer on top of a starch gel (syneresis). Some cultivated plant varieties have pure amylopectin starch without amylose, known as waxy starches. The most used is waxy maize, others are glutinous rice and waxy potato starch. Waxy starches have less retrogradation, resulting in a more stable paste. High amylose starch, amylomaize, is cultivated for the use of its gel strength.

**Starches consist of Polysaccharides consisting of long chains of repeating units of glucose **

//Amylose tends to //
 * Gel! **

//Amylopectin is considered non-gelling and tends to be more // 
 * Gummy! **

Starch makes up a lot of our diet and undergoes 4 major processes: <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 16px; line-height: 23px;">**Gelatinization**: Occurs when a starch is heated in a liquid

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">**Gel Formation:** Goes through the same process of gelatinzation. As the product cools sol (a fluid starch paste) <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">or gel (a semisolid paste) form. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 16px; line-height: 23px;">This process is directly dependent on the amount of amylose present. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 16px; line-height: 23px;"> (It is important to know that adding fruit before the sol turns into a gel will weaken the gel formation of the gelatin because proteins and fats can surround the starches and prevent them from gelling. Ingredients like fruit should be added right before the sol turns into a gel.)

Retrogradation is a reaction that takes place in gelatinized starch when the amylose and amylopectin chains realign themselves, causing the liquid to gel. When native starch is heated and dissolves in water, the crystalline structure of amylose and amylopectin molecules are lost and they hydrate to form a viscous solution. If the viscous solution is cooled or left at lower temperature for long enough period, the linear molecules, amylose, and linear parts of amylopectin molecules retrograde and rearrange themselves again to a more crystalline structure. The linear chains place themselves parallel and form hydrogen bridges. In viscous solutions the viscosity increases to form a gel. At temperatures between –8 and +8 °C the aging process is enhanced drastically. Retrogradation can expel water from the polymer network. This is a process known as syneresis. A small amount of water can be seen on top of the gel. Retrogradation is directly related to the staling or aging of bread. Retrograded starch is linked to a reduction in colon cancer. Retrogradated starch is less digestible. Chemical modification of starches can reduce or enhance the retrogradation. Waxy, high amylopectin, starches have also much lesser tendency to retrogradate. Also additive as fat, glucose, sodium nitrate and emulsifier can reduce retrogradation of starch. //<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">To prevent, use the product as soon as possible! //
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">Retrogradation: **<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">As the gel cools the starch contracts and water begins to seep out
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">We call this synernesis or weeping ;( **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">Pyrodextrins are brown in color. <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;"> <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%; line-height: 24px;">**This process is partially responsible for the browning of toasted bread!** //<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 16px; line-height: 24px;">Increases sweetness of the product too :) //
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">Dextrinization ** : <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 16px; line-height: 23px;">When starch is subject to dry heat it breaks down to form pyrodextrins in a process known as dexrinization.

**<span style="color: #ff0090; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 130%;">Below is a data table to clearly see what we did in class when we worked with different kinds of starches and added them to heated water! ** <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Right: 3 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Left: 3 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Bottom: 2 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Average: 3.5 ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was very clear and glossy. ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was bubbly and gelled well. || <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Right: 4 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Left: 3.5 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Bottom: 0 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Average: 2.875 ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was clear and not as bubbly as tapioca. ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It is starting to become lumpy with some bubbles. || <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Right: 9 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Left: 4 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Bottom: 6 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Average: 6.75 ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was white and starting to crack. (retrogradation) ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was starting to crack and looked a little dry. || <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Right: 3 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Left: 4 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Bottom: 3.5 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Average: 3.375 ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It gelled, but it was a little lumpy. ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was also starting to crack, but not as badly as rice was. || <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Right: 4 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Left: 3 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Bottom: 3 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Average: 3 ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It gelled well, so the amount of sugar added was not enough to stop gelling. ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was starting to crack and looked dry on the surface. || <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Right: 7 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Left: 5 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Bottom: 4 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Average: 6.375 ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It gelled, but not as well as with sugar. ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It had a smooth surface. || <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Right: 11.5 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Left: 4 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Bottom: 12 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Average: 9.125 ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was a little lumpy. ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was very watery, because the acid weakened the thickening of the gel. || <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Right: 0 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Left: 3 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Bottom: 4 <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Average: 2.25 ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was very sticky. ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">It was very lumpy and solid, so it did not gel well. ||
 * < **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Starch ** ||< **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Hot viscosity (based on viscosity test) ** ||< **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Cold viscosity ** ||< **<span style="font-family: 'Times New Roman','serif'; font-size: 12pt;">Appearance (when cold) ** ||
 * < <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Tapioca ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Top: 6
 * < <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Arrowroot ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Top: 4
 * < <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Rice ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Top: 8
 * < <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Cornstarch ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Top: 3
 * < <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Cornstarch with sugar ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Top: 2
 * < <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Cornstarch with acid ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Top: 9.5
 * < <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Wheat Flour ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Top: 9
 * < <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Browed Flour ||< <span style="font-family: 'Times New Roman','serif'; font-size: 12pt; line-height: normal; margin: 0in 0in 0pt;">Top: 2

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">When describing the "viscosity" of each starch product we determined this by using a viscous test. This was a sheet of paper that had numerous <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">rings on it (see picture below) <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 16px; line-height: 23px;">and we counted the number of rings each side (top, bottom, left and right) of the tablespoon of starch had when <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 16px; line-height: 23px;">dropped into the middle circle. The results showed us if the starch used determined a more gelling outcome or a substance that was more fluid.
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">This was our browned flour and it must have contained a higher percentage of amylopectin **
 * <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">because it was very gummy and sticky! **

<span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">Most starches are in a <span style="color: #ff0090; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">25% amylose <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;"> and <span style="color: #ff0090; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">75% amylopection <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;"> ratio. This ratio varies depending on the starch: for example, potato has <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">a ratio of 21:79 (amylose/amylopectin), while tapioca has a ratio of 17:83 and wheat and corn both have a ratio of 28:72. The more <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">amylose in the starch, the more gelling ability. This is because amylose is better at forming bonds with each other while amylopectin <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">can not bond as well because of its branches in its molecular structure. Wheat, cornstarch, tapioca, arrowroot and rice all gelled very <span style="font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 120%;">well, while the rest of the starches did not. This was caused by the amount of amylose and amylopection in specific starches.

media type="youtube" key="Ko8uBBiTbzk" height="390" width="480" This is the gelatinization of wheat starch. It gels well because the granules are able to take in water in.

media type="youtube" key="FRIdt-YhJvs" height="390" width="480" This is the gelatinization of potato starch. It does not gel as well because the granules could not store water as well, which is why some of the granules were starting to break apart.

[|kscereallab youtube channel] (The videos were from this youtube channel. There are other examples of gelatinization of other starches on his page.) <span style="color: #000000; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://www.ljcreate.com/products/element.asp?id=166&curr=1&prod=659 (Polysaccharide diagram) <span style="color: #000000; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Information from class handouts <span style="color: #000000; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">Brown, Amy. 2011. //Understanding Food: Principles & Preparation.//Forth Edition. Chapter 18, page 394-395 <span style="color: #000000; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://www.google.com/imgres?imgurl=http://pinoyfoodblog.com/wp-content/uploads/2008/08/leche-flan.jpg&imgrefurl=http://pinoyfoodblog.com/recipes/leche-flan-recipe/&usg=__1Scxz0KOeqKgtpVFMoTlRB_DipM=&h=377&w=500&sz=34&hl=en&start=0&zoom=1&tbnid=4Z9Aw9ndnoHnAM:&tbnh=138&tbnw=183&ei=IyR4TcPXHIzEsAPvlvW6BA&prev=/images%3Fq%3Dsyneresis%26hl%3Den%26biw%3D1314%26bih%3D780%26tbs%3Disch:1&itbs=1&iact=hc&vpx=866&vpy=136&dur=312&hovh=170&hovw=225&tx=72&ty=84&oei=IyR4TcPXHIzEsAPvlvW6BA&page=1&ndsp=24&ved=1t:429,r:4,s:0 <span style="color: #000000; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://en.wikipedia.org/wiki/Starch <span style="color: #000000; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">http://slog.thestranger.com/2008/11/am_i_toast (Toast picture) <span style="color: #000000; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">[] (wheat video) <span style="color: #000000; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 110%;">[] (potato video)
 * <span style="color: #ff0090; font-family: 'Palatino Linotype','Book Antiqua',Palatino,serif; font-size: 140%;">References: **