Starch lab final donnesha 5 PDF

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The Mico University College Experimental Foods Lab Tittle: Starch Aim: To compare the behavior and appearance of different gelatinized starches Lab #5 Donnesha Stewart 20171923 9/03/2020 Ms. Haley

Introduction Starches are used to thicken a variety of things. Swelling in these products will produce thickness when you want to aheive viscosity. Every starch has different thickening properties and can be used in different products. The aim of this experiment is to explore the process of gelatinization. We will also be comparing the behavior and appearance of the gelatinized starches prepared in these experiment with the use of a line spread test and appearance, and the depth of the starch before and after unmoulding. According to Lexico Dictonary (nd) Starch is an odorless tasteless white substance occurring usually in plant tissue and is found mainly in cereals, rice, pasta and potatoes. It is a polysaccharide that functions as a carbohydrate store and is a very important essential of the human diet, it is also insoluble in cold water. Starches are also used in everyday life to thicken a variety of things during food production and preparation because of its gelatinization properties, Starch gelatinisation is a process of breaking down the intermolecular bonds of starch molecules in the presence of water and heat, allowing the hydrogen bonding sites (the hydroxyl hydrogen and oxygen) to engage more water. This irreversibly dissolves the starch granule in water. All starches are made up of varying proportions of amylose and amylopectin. This ratio varies not only among the different types of starch, but among the many plant varieties within a type. Waxy starches are those that have no more than 10% amylopectin. When trying to achieve the viscosity wanted in a starch paste or gels you must have gelatinization taking place. This will give you the characteristics wanted for these pastes and gels. Additionally, during the process of the lab, dextrinization of flour was also done to test its ability of gel. This was done by browning of the flor in dry heat and is chemically defined by

Science direct (2003) posits dextrinization as “ the process involving the browning of starch foods when subjected to dry heat. It is defined as the breakdown of starch into dextrins (disaccharides) and it is a non-enzymatic browning and chemical change which is easily digested as partial breakdown is complete” Every starch has different thickening properties and can be used in different products to make the characteristics wanted. Some starches when heated to high temperatures will thin and will not end up producing a gel. Each starch has different cooking times, cost and yields The line spread test and sag test will also be utilized to determine the strength of the gel and the viscosity. Upon completion of this lab, it is expected that I should have a better knowledge of starches and how to choose a starch during food preparation to ensure effectiveness in the outcome of a recipe

Procedure

Materials 16g starch 236 ml water Saucepan Cooking spoon

The starch and water was combined in a heavy saucepan, and Slowly stiredintil dissolved. The mixture was cooked over direct heat while stirring to prevent lumping. The mixture was heated to a boil unless mixture appears start to thin. If the mixture starts to thin, immediately note the temperature and stop heating. If thinning is not apparent, bring to boil. Preform a line spread test, prepare for further testing by placing each mixture in a custard cup, covering tightly, and placing in a shallow pan of ice water to cool. The mixture was measured and evaluated for sag, depth and spread.

Results Fig1: Depth for Before and After un-moulding of cooled starches and % sag test

Starches 1. 16g Corn-Starch

Depth Before Unmolding 2.4cm

2. 16 G All Purpose Flour

2.1cm

3. 16g Dextrinized A.P.F

Depth After Unmolding 2.0

Percentage Gelation Sag / % 16.5% Gel

.75

64%

Did not gel

3cm

.25 cm

91%

Did not gel

4. 8G Corn Starch

1cm

.5cm

50%

Did not gel

5. 16 G Cassava

2cm

1.1cm

45%

Did not gel

6. 16 Corn- Starch +50g Sugar

2.9cm

7. 16g Corn- Starch + 60ml Lemon Juice 8. 16g Corn- Starch + 25sugar + 30ml Lemon Juice

2.8cm 2cm

Inconclusive/Sample spoilage

Gelled

2.2cm

21%

Gelled

1cm

50%

Did not gel

Fig2: line spread test showing viscosity of samples after 2 minutes / averages

Starches 16g Corn-starch 16g All-Purpose Flour 16g Dextrinized All Purpose Flour 8g Corn starch 16g Cassava 16g corn starch + 50g sugar 16g corn starch + 60ml Lemon Juice 16g corn starch + 25g sugar +30ml Lemon Juice

Viscosity after 2 minutes

4.2 4.4 6 4 3.8 4.1 3.75 4.1

Fig:3. The effect of sugars and acid on the gelation and appearance of starches Starches samples 16g Corn starch 16g All-purpose flour 16g Dextrinized All-purpose flour 8g Corn starch 16 Cassava 16g Corn starch + 50g sugar 16g Corn starch+ 60ml Lemon Juice

Appearance Very firm Less firm/ less translucent Runny/Dark Brown Runny Translucent Soft/ More translucent Less firm than cornstarch only

16g Corn starch + 25g Sugar + 30ml Lemon Juice

Runny

Discussion

The line spread test was used to measure the flow distance of the thickened fluid, in centimeters, across a flat surface, The average of the samples after unmoulding yield varying results based of the type of starch, the Dextinized flour had the highest average in termes of spread as its average was almost 2 cm higher than the other test samples, the possible reasons for this is because dextrinsed starches lose most of their thickening power. Reference world (nd posits that dextrinization is a chemical change in the starch molecule caused by the break down of sugar chains within the molecule. The sugars which are transformed into shorter chains and separated from the parent molecule and are called dextrins and are know to reduce viscosity. When starches are dextrinzed the thickening power is reduced and becomes more soluble. The corn starch control test, all purpose flour, corn starch plus sugar and corn starch plus sugar and lemon juice also had averages that showed the samples were very close in viscosity. All of these starches can be categorized as native starches , improved native starches, or modified starches as they are derived from plants and are without chemical modifications. Bennion and Scheule(2010). The native starches such as cornstarch, cassava , would behave differently in the samples due to the various composition and ratios of amylose to amelopectin fractions. And would be more likely to produce gels that are more viscous. The cassava flour which is a native starch contains 15 to 24% of amylose which is slightly less than the amount of amylose in the other starches, so it wouls produce a gel that is less viscous than the other starches and the greater the amount of amylose the stronger the gel that will be formed. Test sample 7 with the addition of acid had a average viscosity that was lower than all other etst samples which was due

to the hydrolysis process, the hydrolysis of starch is done by the mixing of starch with water and addition of an acid to produce a random breaking of linkages points along the molecular chain. Known as acid thinned starch. Bennion and Scheele (2010) postulates that the acid will help to produce a paste with low viscosity after heating, which is now glucose. The acid was the catalyst that caused the reaction to take place. The samples were also evaluated for depth and percentage of sag. The sag test was done using the formulae of 100 x moulded height – unmoulded height Moulded height The test samples that were made with the corn starch all showed gelation properties which is evident in cooked and cooled starches.and the process continues throughtout the entire cooling process. Starches such as cornstarch that has alrge amount of amylose form better gels way more than would be formed from cassava starch, as was evident from the testing. According to Science buddies (2012) “Cornstarch is made up of many molecules of glucose, specifically amylopectin and amylase. When starch is heated with water, the starch granules swell and burst, causing them to break down and release the glucose molecules into the water. When the heated solution of cornstarch and water cools down, the amylase molecules can bind each other again to create a molecular mesh. The more amylase molecules there are, the firmer, or more viscous, the mesh will be”. These properties of cornstarch resulted in the sample made form cornstartch to produce better gels. The sample made with half the concentration of cornstarch to the 237 ml of water had a 50% sag agter unmoulding as the increase in water as there are less cornstarch molecules available for the water to soak up, which will result is a less viscous sample and will have more sag agfter unmoulding.

Research gate 2013) postulates that with the addion of an acid to a starch formulation does not automatically lead to hydrolysis. For acid hydrolysis to take place both pH and high temperature are needed, as it has been found that no hydrolysis can take place without sufficient temperature alternation. The sample that was conducted with the addiotion of an acid and sugar produced a 50% sag and did not gel after completion of the test. Beleia, Miller, & Hoseney, (2006). Posits that when sugar is dissolved in water, the sugar displaces part of the water. “Therefore, the moisture content of a starch granule in a sugar solution is always less than 30%; and the gelatinization temperature is increased. When sugar is dissolved in water, the water activity is decreased. This decreased water activity was shown to increase the onset melting point of crystallized dextrins. Thus, the well known effect of sugar increasing the onset temperature of starch gelatinization appears to be a result of the displacement of the water inside the starch granule and the lower water activity. Causing the solution to not gel and have a high sag %. Previous studies have indicated that sugar will cause a delay in gelatinization of starch. The more sugar that is added, the more of a delay in gelatinization will occur. A delay in gelatinization will result in a lower viscosity. sugar competes with the starch for the water. And causes it to not sweel to its full potential. Some of the solutions that were testsed did not gel. Bennion and schedule posited that there are several factors that may affect the gelation properties of starches, and these includes “ temperature of heating, tiem of cooking, intensity of agitation, acidity or ph of mixture or the addition of other undesirable ingredients”. Since most of these factors were carefully controlled during the testing process, it can be assumed that the agitation or stirring may have been a factor affecting the gelling of some samples, as if the agitation is too intence or is continued too long, it accelerates the rupturing of

the starch granules, decreasing the viscosity and in order to minimize this the stirring must be minimized. The amount of sugar that is added must also ne controlled as addition of too much sugar raises the temperature at with starches gelatinize and reduces the thickness of the paste.as it the sample test that was done with the cassava did not gel and had a 45% sag after unmoulding, particularly due to the size of the granules, Hegenbart, S (2006) posited that granule size ca be a a minor contributing factor in how rapidly a starch gelatinizes and its gelatinization temperature, both have amylose contents in the same range, but cassava starch granules are much larger and, as a result, swell more easily. "The larger the granule, the less molecular bonding we have so they swell faster," "But they also break down faster, they tend to build larger but more delicate structures that will break down easily. Some starches may be more firm than others partially do to the constitients of the starch, the added ingredints and proceses it undergoes, it also deoends highly on the amount of amylose and amelopectin that it contains According to Manisha S. 2016) Amylose molecules typically make up approximately one-quarter of starch. Amylose is a long linear chain composed of thousands of glucose units with attachment of the carbon 1 and carbon 4 of glucose units, and therefore contains glycosidic linkages that forms a three-dimensional network when molecules associate upon cooling, and is responsible for the gelation of cooked, cooled starch pastes Bennion and schedule (2010) posited that The branches make amylopectin less soluble in water than amylose. Starches with a high percentage of amylopectin will thicken a mixture but do not form a gel. The greater the amylopectin, the more viscous the starch paste and the greater the amount of amylose the stronger the gel. A starch that is high in amylose will make a gel that is more firm,

Conclusion The data from this lab indicates that sugar causes a delay in the gelatinization process. It also indicates that acid causes a cornstarch mixture to reach a maximum viscosity faster than with sugar or just cornstarch. Overall, when a mixture contains both sugar and acid, the mixture will have the hardest time forming a gel, as opposed to a mixture with just acid or just sugar. It can be concluded that most forms of starch are thickening agents. The choices of starch used in the lab we are slightly different in nature as some were “ native, improved native and some were modified starches.” Bennion and Scheule (2010) These thickening agents can be used in soups, sauces, salad dressings and desserts. The process of gelatinization must happen to make the correct viscosity of starch pastes to receive the desired characteristics of a starch gel. All starches will give different thickening properties producing starch pastes and starch gels. To make sure you are using the correct starch for a recipe you must first learn the different characteristics of each starch. The size of the granules of the starch must also be considered as Small granule starch has been shown to be good for a smooth mouthfeel, which is a good property for evaluating food for sensory appeal. This knowledge is important to persons who are engaged in food Production and Preparation Depending on the consistency and properties of starch that is needed in a recipe. As choosing the correct starch will significantly impact the finished product. It is also important to note how the ingredients can react with each other as acidic ingredients such as lemon juice or vinegar can

inhibit the thickening properties of cornstarch and flour preventing gelatinization. Choosing the correct starch may be the deciding factor to the final desired outcome of a product.

Reference

Starch. (n.d.). In Lexico.com dictionary. Retrieved from /https://www.lexico.com/en/definition/starch

Reference world.com nd https://www.reference.com/world-view/dextrinisation8d0dfbc1059118ed Benion and schuele 2010

Science buddies (2012) https://www.scientificamerican.com/article/bring-science-home-gooeygels/

Olsson, Erik & Menzel, Carolin & Johansson, Caisa & Andersson, Roger & Koch, Kristine & Järnström, Lars. (2013). The effect of pH on hydrolysis, cross-linking and barrier properties of starch barriers containing citric acid. Carbohydrate Polymers. 98. 1505-13. 10.1016/j.carbpol.2013.07.040.

Beleia, A. & Miller, Rebecca & Hoseney, Russell. (2006). Starch Gelatinization in Sugar Solutions. Starch ‐ Stärke. 48. 259 - 262. 10.1002/star.19960480705.

Scott Hegenbarthttps://www.naturalproductsinsider.com/foods/understanding-starchfunctionality 2006) Manisha s 2006) http://www.biotechnologynotes.com/food-biotechnology/foodchemistry/classification-of-food-starches-food-chemistry-biotechnology/14098...