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Starch Lab ReportBy June Saxton6/18/2013IntroductionIn this paper, we will examine how time, temperature, agitation, acidity and different ingredients affect the gelatinization of cooked starch paste and how moist and dry heat effect the cooking properties of starch as well as the effect of water temperature on starch dispersion through the use of two different kitchen experiments. Experiment A-Starch PrinciplesMaterials and MethodsFor this experiment the materials used were a glass measuring cup, a wire whisk, tablespoon, a one quart pan, a muffin tin, cornstarch, flour, sugar, lemon and water. All the mixtures were mixed using 2 tablespoons of starch and one tablespoon of water except the lemon one which was mixed using 2/3 cup water and 1/3 cup + 2 tablespoons freshly squeezed lemon juice and the cornstarch and sugar one was made with 1 cup water, 1/3 cup sugar and 2 tablespoons of corn starch. The starch and liquid were mixed together and whisked to make sure there are no lumps in the pan. The pan was then placed on the stove and cooked over medium heat, stirring constantly until it boiled for one minute. Each mixture was then poured into a section of the muffin tin and filled to the top and allowed to cool. I placed the mixture in the refrigerator for about 60 minutes because my house was 80 degrees and I did not feel that the muffin cups could cool sufficiently. Since they were in a muffin tin, I was unable to unmold them. Instead, I spooned them into small bowls.ResultsTable 3.1?TABLE FOR THE EVALUATION OF STARCH GELSNumberStarchAmount of Starch (Tablespoon)Firmness (Cooled Paste)Appearance (Cooled Paste)1Flour2?Runny/saucy?Barely gelled3Cornstarch2?soft?Slightly gelled5Cornstarch, water, lemon juice2?firm?Well gelled7Flour, darkly browned2?soft?Softly gelled8Cornstarch and 1/3 cup sugar2?Medium ?Gelled a little more than just cornstarchSamples 1, 3, 5, 7 and 8Samples 3 and 8 bottomSamples 1 and 7From left to rightSample 5 topLeft to rightDiscussionCornstarch thickens a lot more than flour because it has twice the thickening power and thickens faster when reaches the boiling point. It also contains more amylose. Flour takes longer to cook and thicken (Who’s in the Kitchen, 2009). The addition of an acid to a starch paste enhances the thickening power. I would recommend that a slurry be made and then cooked. Dry heats effect on flour is to darken it. The longer it is cooked and the higher the temperature, the darker that the resulting product will be. It also thickens a little more. Adding sugar to the starch mixture helped it to thicken a little more than with just starch. Gelatinization occurs when a starch is heated in water and the structure of the starch molecules if disrupted as water is absorbed and starch granules swell. The starch thickens until peak viscosity is reached and it also increases in translucency. Gelation occurs upon cooling of the gelatinized starch paste. Starches containing a large portion of amylose form firmer gels than those that contain a lower concentration (Benton & Scheule, 2010). Experiment B-Effect of Water Temperature on Starch DispersionMaterials and MethodFor this experiment the materials used were water, flour, a glass measuring cup, a tablespoon and saucepan.Using the glass measuring cup 2 tablespoons of flour were stirred into 8 oz. of cold water. The mixture was then allowed to stand for 10 minutes. To further observe the reaction of water on starch, 1 cup of water was boiled in a 1-quart saucepan and 2 tablespoons of flour was added to the boiling water while stirring constantly.ResultsWhen cold water was first stirred in 1 cup of water, a temporary suspension was formed. After standing for 10 minutes the flour settled the bottom. When flour was added to boiling water and stirred while added, the flour granules swelled up and the gelatinization process was started, but all the starch was not incorporated and lumps formed. Mixed with water After settling-side After settling-top Boiled for one minuteDiscussionFlour settles to the bottom of the container after a few minutes because adding cold water to them only forms a temporary suspension which will settle after a few minutes (Conforti, 2008). Lumps form in a heated solution of flour and water because near the simmering point the starch granules swell suddenly and huddle together. These lumps cannot be dissolved (Sawtelle, 2009). A starch slurry is a mixture of cold water and starch stirred together until the starch dissolves (Who's in the Kitchen, 2009). This mixture is effective in preventing lumps in the starch mixture because it makes it easier to incorporate the starch into the hot mixture. A slurry made with flour requires a longer time to cook in order to thicken the mixture and this allows the flour taste to cook out. Cornstarch has twice the thickening power of flour and works immediately when a slurry of it added to hot liquids with no starchy taste (Who’s in the Kitchen, 2009).ReferencesBennion, M., & Scheule, B. (2010).?Introductory foods. (13th ed.). Upper Saddle River, NJ: Pearson Prentice Hall.Conforti, F. D. (2008).?Food selection and preparation, a laboratory manual. (2nd ed.). Blackwell Pub.Sawtelle, H. (2009, March 11).?The sauce thickens - how to avoid lumps. Retrieved from 's in the Kitchen? (2009, December).?How to make (and use) a slurry. Retrieved from ................
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