Lead Section~
For my assigned article, I will be editing the article titled "Doughnuts." I plan to examine the physical properties of donuts, exploring the science between cake and yeast donuts. In addition, I will explore the ingredients in donuts and how they function at the molecular level.
Week 6 Assignment: Improving the existing article of "Doughnuts"
In the existing article I plan to edit, I have identified what needs to be added regarding the molecular composition and the molecular structure of this food. Specifically:
- The ingredients that are involved in making this confectionery product and their functions (eggs~structural, flour~structural, salt~flavor, milk~structural, sugar~flavor\structural, fats & oils~structural, baking powder~aeration)
- Molecular structure of each ingredient-whether they are composed of starch, proteins, etc
- The differences between cake and yeast donuts
- The molecular struture of certain fillings
- Additives and their function for processed donuts
Week 7, 8, 9, & 10:
This is a user sandbox of Hat36. You can use it for testing or practicing edits.
This is not the sandbox where you should draft your assigned article for a dashboard.wikiedu.org course.
To find the right sandbox for your assignment, visit your Dashboard course page and follow the Sandbox Draft link for your assigned article in the My Articles section.
7~Molecular Composition of Doughnuts
Found under Week 9
Cake vs Yeast Doughnuts
Yeast doughnuts and cake doughnuts contain most of the same ingredients, however, their structural differences arise from the type of flour and leavening agent used. In cake doughnuts, cake flour is used, and the resulting doughnut is denser because cake flour has a relatively low gluten content of about 7 to 8 percent[1]. In yeast doughnuts, a flour with a higher protein content of about 9 to 12 percent is used, resulting in a doughnut that is lighter and more airy.[1] In addition, yeast doughnuts utilize yeast as a leavening agent. Specifically, “Yeast cells are thoroughly distributed throughout the dough and begin to feed on the sugar that is present… carbon dioxide gas is generated, which raises the dough, making it light and porous.”[2] Whereas this process is biological, the leavening process in cake doughnuts is chemical. In cake doughnuts, the most common leavening agent is baking powder. Baking powder is essentially “baking soda with acid added. This neutralizes the base and produces more CO2 according to the following equation: NaHCO3 + H+ → Na+ + H2O + CO2.”[3] The differences in the final structure of a cake and a yeast doughnut can be shown by Figure ...
8~Beginning of my article
9~Physical Structure of Doughnuts
The physical structure of the doughnut is created by the combination of flour, leavening agent, sugar, eggs, salt, water, shortening, milk solids, and additional components. The most important ingredients for creating the dough network are the flour and eggs. The main protein in flour is gluten, which is overall responsible for creating elastic dough because this protein acts as “coiled springs.”[4] The gluten network is composed of two separate molecules named glutenin and gliadin. Specifically, "the backbone of the gluten network likely consists of the largest glutenin molecules, or subunits, aligned and tightly linked to one another. These tightly linked glutenin subunits associate more loosely, along with gliadin, into larger gluten aggregates."[5] The gluten strands than tangle and interact with other strands and other molecules, resulting in networks that provide the elasticity of the dough. In mixing, the gluten is developed when the force of the mixer draws the gluten from the wheat endosperm, allowing the gluten matrix to trap the gas cells.[4]
Eggs function as emulsifiers, foaming agents, and tenderizers in the dough. The egg white proteins, mainly Ovulblumins, “function as structure formers. Egg solids, chiefly the egg white solids combined with the moisture in the egg, are considered structure-forming materials that help significantly to produce proper volume, grain, and texture.”[2] The egg yolk contributes proteins, fats, and emulsifiers to the dough. Emulsifying agents are essential to doughnut formation because they prevent the fat molecules from separating from the water molecules in the dough. The main emulsifier in egg yolk is called lecithin, which is a phospholipid. “The fatty acids are attracted to fats and oils (lipids) in food, while the phosphate group is attracted to water. It is this ability to attract both lipids and water that allow phospholipids such as lecithin to act as emulsifiers.”[5] The proteins from both the egg yolk and the egg whites contribute to the structure of the dough through a process called coagulation. When heat is applied to the dough, the egg proteins will begin to unfold, or denature, and then form new bonds with one another, thus creating a gel-like network that can hold water and gas.[5]
Shortening is responsible for providing tenderness and aerating the dough. In terms of its molecular structure, “a typical shortening that appears solid [at room temperature] contains 15-20% solids and, hence, 80-85% liquid oil…this small amount of solids can be made to hold all of the liquid in a matrix of very small, stable, needlelike crystals (beta-prime crystals).”[2] This crystalline structure is considered highly stable due to how tightly its molecules are packed. The sugar used in baking is essentially sucrose, and besides imparting sweetness in the doughnut, sugar also functions in the color and tenderness of the final product. Sucrose is a simple carbohydrate whose structure is made up of a glucose molecule bound to a fructose molecule.[5] Milk is utilized in the making of doughnuts, but in large scale bakeries, one form of milk used is nonfat dry milk solids. These solids are obtained by removing most of the water from skim milk with heat, and this heat additionally denatures the whey proteins and increases the absorption properties of the remaining proteins.[5] The ability of the casein and whey proteins to absorb excess water is essential to prolonging the doughnut's freshness. The major whey protein in the nonfat milk solids is known as beta-lactoglobulin, and a crucial feature of its structure is that there exists a single sulfhydryl group that is protected by the alpha helix, and when heating of the milk solids occurs, these groups participate in disulfide exchanges with other molecules. This interchange prevents the renaturation of the whey proteins.[6] If the crosslinking of the sulfide groups does not occur, the whey proteins can rebond and weaken the gluten network.
Water is a necessary ingredient in the production of doughnuts because it activates the other ingredients, allowing them to perform their functions in building the doughnut's structure. For example, sugar and salt crystals must be dissolved in order for them to act in the dough, whereas larger molecules, such as the starches or proteins, must be hydrated in order for them to absorb moisture.[5] Another important consideration of water is its degree of hardness, which measures the amount of impurities in the water source. Pure water consists of two parts hydrogen and one part oxygen, but water used in baking often is not pure. Baker’s salt (NaCl) is usually used as an ingredient due to its high purity, whereas the salts in water are derived from varying minerals. As an ingredient, “salt is added to enhance the flavour of cakes and breads and to ‘toughen up’ the soft mixture of fat and sugar.”[3] If relatively soft water is being used, more salt should be added in order to strengthen the gluten network of the dough, but if not enough salt is added during the baking process, the flavor of the bread will not be appealing to consumers.
10~Math Equation
An important property of the dough that effects the final product is the dough's rheology. This property measures the ability of the dough to flow. It can be represented by the power law equation: τ=k.D^n where τ is the tangentic stress, k is the viscosity coefficient, D is the shear rate, and n is the flow index.[7] Many factors affect dough rheology including the type of ingredients, the amount of the ingredients, or the force applied during mixing. Dough is usually described as a viscoelastic material, meaning that its rheology depends on both the viscosity and the elasticity. The viscosity coefficient and the flow index are unique to the type of dough being analyzed, while the tangentic stress and the shear rate are measurements obtained depending on the type force being applied to the dough.
11~Reviewing peer articles
Told to disregard this assignment
12 to 14~
Existing article on doughnuts revised!
Final Weeks~Finishing updating the Doughnuts Article
- ^ a b Masibay, Kimberly Y. "Taking Control of Gluten." Fine Cooking. N.p., 2016. Web. 30 Nov. 2016.
- ^ a b c Lawson, Harry. Food Oils and Fats. New York: Chapman & Hall, 1995. Print.
- ^ a b Czernohorsky, J. H., and R. Hooker. “The Chemistry of Baking.” New Zealand Institute for Crop and Food Research, n.d. PDF File. 6 Nov. 2016. http://nzic.org.nz/ChemProcesses/food/6D.pdf
- ^ a b Pyler, E. J. Baking Science and Technology. Chicago: Siebel, 1952. Print.
- ^ a b c d e f Figoni, Paula. How Baking Works. 2nd ed. Hoboken: John Wiley & Sons, 2008. Print.
- ^ Phillips, G. O., and P. A. Williams. Handbook of Food Proteins. Cambridge: Woodhead, 2011. Print.
- ^ MIRSAEEDGHAZI, HOSSEIN (2008). "Rheometric Measurement of Dough Rheological Characteristics and Factors Affecting It". INTERNATIONAL JOURNAL OF AGRICULTURE & BIOLOGY. 10 – via Faculty of Biosystem Engineering, College of Agriculture, University of Tehran, Karaj, Iran.