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Lab #5:Katherine Kopfler Gluten and Bread Tessa ThrallsOctober 30, 2012IntroductionGluten is a protein complex composed of two components, glutenin and gliadin, found naturally in grains such as wheat, rye, barley and spelt. The protein complex is formed when gluten-containing flour and water are combined and manipulated. As the protein fractions are mixed, they are able to cross-connect and associate together to form sheets of gluten. The elastic nature of these gluten strands lends extensibility in the early stages of the baking period. During leavening, the elasticity of gluten matrix traps carbon dioxide that provides the structure and volume of baked goods. This gas-retaining ability expands with the increased heat during baking and allows gluten to stretch producing a light, airy interior structure and tender crumb in the final product. (1,2,3) Unlike gluten-containing wheat flour, yeast breads prepared with any grain that does not contain gliadin and glutenin will not rise, regardless of the amount of leavening agents utilized. Without the framework and elasticity of the gluten matrix, the carbon dioxide bubbles from leavening agents will not be trapped and therefore, will be lost to air causing a dense texture. In order to supply a component to trap the gas bubbles and provide the overall structure of a gluten-free dough or batter, gums such as xanthan, guar, or agar are used. (2,4)Although the gluten matrix is important, the key element contributing to the texture of all baking products is leavening, a process by which air, steam, or carbon dioxide is incorporated into batters and doughs allowing for the desired volume and texture to be achieved in the final product. In the realm of leavening agents, three primary types exist including biological, chemical, and mechanical, which are utilized in accordance with the specific ingredients being used and the preferred textural outcome. For instance, the act of sifting, beating, whipping, and/or creaming ingredients incorporates air into the batter or dough and is considered mechanical mechanism of leavening. This type of leavening is used for products such as whipped cream, angel cake or other foods requiring egg white/yolk foam. (1,2,5)Biological leaveners, such as yeast or yeast in conjunction with bacteria, are living organisms that ultimately produce carbon dioxide that is released into the dough or batter as a byproduct of the metabolism of sugar. Several strains and forms of yeast exist, yet all are single-celled organisms that produce gas through the process of fermentation where carbohydrates are converted to carbon dioxide and alcohols. The production of carbon dioxide causes dough to expand as trapped gas forms pockets or bubbles. Products requiring yeast are yeast breads such as loaf breads, pita, crescent rolls and baguettes. Certain yeast strains produce carbon dioxide in an acidic environment, which is created by the release of lactic acid by the bacterium Lactobacillus sanfrancisco. This combination of microorganisms is used in sourdough starters in order to produce large volume and a sour flavor. (2)A third mechanism of leavening is the reaction of an acidic and alkaline ingredient that generates carbon dioxide, which expands in the product during baking. This type of leavening is achieved by the chemical agents baking powder or baking soda in combination with and an acidic ingredient such as tartaric acid or soured dairy. Food products requiring chemical leavening are quick breads such as pancakes, waffles, and muffins. (2)Many baking goods require a mixture of leavening agents including the creation of steam during baking which can maintain or increase the pressure of the gas or air pockets already in existence. Regardless, the goal of leavening is the expansion of the batter or dough resulting in optimal textural properties such as crumb structure, cohesiveness, consistency, and uniform distribution of cell pockets. (1,2)Results/DiscussionTable SEQ Table \* ARABIC 1: Focaccia Bread ResultsTreatmentBaked Height (mm)ColorCrumb Structure (Pore uniformity)Crumb Structure (Pore Size)??1-white2-cream3-tan4-brown5-grey1-non-uniform2-slightly uniform3-enough uniform4-almost uniform5-uniform1-large2-slightly large3-medium4-slightly small5-extremely smallControl (whole wheat flour)152.524Thick cell wallsWhole Wheat Pastry Flour172.323Bread Flour16.71.51bigger pores at top2Thin wallsVital Gluten Flour83quickly fell3.5light brown1bigger pores at top4Bastyr's Gluten-free Flour Mix11224consistent pores throughout3Cup-4-Cup213132.5100g Chestnut Flour & 100g Chia Flour124dark grey5very close together and all small41Brown Rice Flour, Potato Starch, Guar Gum, Tapioca Starch2Cornstarch, brown rice flour, white rice flour, potato starch, tapioca starch, milk powder, and xanthan gumTable SEQ Table \* ARABIC 2: Focaccia Bread Sensory Score CardTreatmentCrumb CohesivenessFlavorCrumb ConsistencyPreference?1-greatest force to break2-moderate force to break3-minimal force to break4-easily breaks5-crumbles to touch1-no bitter, no sour, sweet and salty2-slighly bitter, slightly sour3-mild bitter, mild sour4-bitter5-extremely bitter and sour1-greatest chews2-high chews3-moderate chews4-low chews5-least chews1-extremely desirable2-desirable3-slightly undesirable4-moderately undesirable5-extremely undesirableControl (whole wheat flour)32Balanced, slightly sour3Dense2Whole Wheat Pastry Flour31Slightly salty, earthy31.5Bread Flour31Balanced, slightly sweet41Vital Gluten Flour1extremely tough, gummy1Slightly umami1extremely elastic, springy5Bastyr's Gluten-free Flour Mix14Crumbly3Yeasty, sour4Falls apart in mouth2.5Cup-4-Cup223Sour2Grainy3100g Chestnut Flour & 100g Chia Flour25Bitter, soapy241Brown Rice Flour, Potato Starch, Guar Gum, Tapioca Starch2Cornstarch, brown rice flour, white rice flour, potato starch, tapioca starch, milk powder, and xanthan gumThe amount of protein (gluten) in the bread affected its volume, consistency and texture. The gluten matrix formed from moisture and manipulation is able to trap CO2, which causes the matrices to stretch, and results in thinner, more tender cell walls. So, the breads with the most gluten should rise the most, be the least dense and the most tender. The bread with the highest gluten content was made with vital gluten flour. It did rise the most by far during the baking process (see Table 1), but it promptly fell resulting in a dense, gummy product. Bread flour is made from the endosperm and the aluorene layer, so it has the second most gluten. It rose slightly less than the pastry flour, but it did have larger pores and thin cell walls. The result was tender and easy to chew. The whole-wheat flour (control) rose the least out of the gluten-containing breads. This is expected because it contains the wheat bran, which is high in fiber. Fiber is able to cut some of the gluten strands resulting in less gluten and a reduced ability to trap CO2. It had small cells and the end product was dense and chewy. The gluten-free breads rose significantly less (2-5mm) than the gluten-containing breads. They each contained a different kind of gum which aided in the rising process. Gums are able to form structure and trap CO2 similar to the gluten matrix but not as well. The flour containing xantham gum (Cup 4 Cup) rose the most (see Table 1) and had the largest cell size. The other two gluten free flours: Bastyr’s blend and the chestnut/chia blend contained guar gum and chia seeds, respectively. They both rose the same amount, but Bastyr’s mix had larger pores and was much less dense of a product. It was more tender and easier to chew.ConclusionThe blend of chestnut and chia seed flour is an attractive gluten-free product because of its nutritional value and the ratio of macronutrients present. Chia seed is a soluble fiber that is beneficial for the gastrointestinal tract, may help lower cholesterol levels, and help regulate blood levels. It is also high in omega-3 fatty essential fatty acids and essential amino acids. Furthermore, many people have reported being sensitive to gums (xantham gum or guar gum), so chia seed is a beneficial substitution for them in gluten-free baking. In terms of chestnut flour, not only does it contain vitamin E, B vitamins, potassium, phosphorous, magnesium, and high quality protein, but it also has a much higher carbohydrate to fat ratio than other nut flours making it seem ideal for baking. In addition, the ratio of macronutrients is similar to one diabetic exchange of carbohydrate suggesting this may be a good product of diabetics. (6,7)However, the result of the chestnut/chia blend focaccia bread made in class was less than desirable. It did not experience substantial rise resulting in a dense, chewy product; also, the flavor was unpleasant. One problem with the chestnut/chia bread flavor was the extreme bitterness. Most gluten-free recipes do not call for quite as much chia seed flour. Its use as a gum in gluten-free baking means that only a small amount of it is needed. Also, in order to act as a gum and create more of a rise, the chia seed needs to be soaked in boiling water before being added. (6)In 2010, Demirkesen et al., studied different ratios of chestnut and rice flours with various gum blends and emulsifiers. It was determined that gluten-free breads containing a chestnut/white rice flour ratio at 30/70 with a blend of xanthan/guar gums and an additional emulsifier (DATEM) resulted in higher quality ratings in term of volume, hardness, color and sensory values. After further researching the emulsifier, it appears it is commonly derived from GM soybean oil and therefore, is not suggested; although considering an alternative could prove beneficial. White rice flour is high in carbohydrates and low in fat, protein, and fiber. It contains moderate levels of manganese and trace amounts of B vitamins, omega-6 fatty acids, phosphorus, and potassium. Comparatively, chia seeds contain moderately high amounts of protein, fiber, omega-3 and omega-6 fatty acids, calcium, manganese, phosphorus, potassium, and B vitamins. (7,8,9,10)Rather than necessarily substituting the rice flour for chia flour, a recommendation that may improve the bread is adding a small amount of tapioca flour to the chestnut/chia blend. The tapioca flour has a high starch percentage that enhances the texture of gluten-free baked goods. Also, the addition of tapioca flour would reduce the fiber percentage provided by chestnut and chia seed. Although the fiber content of chestnut flour can provide emulsifying, stabilizing, and thickening properties, it has the potential for drawbacks such as low specific volume, firm texture, dark color and bitter taste when it is used in excess. Fiber in high amounts has the potential to cut gluten strands and create a dense texture, which could then be reduced by the addition of naturally low-fiber tapioca starch. (7,8)A suggested provision to the gluten-free chia/chestnut recipe includes increasing the amount of chestnut flour to 170g, adding 25g of tapioca starch, and one tablespoon of chia seed flour, and no guar gum. The one-tablespoon chia seed flour should be mixed with 2 tablespoons (30mL) boiling water and added it to the recipe with the wet ingredients. The water content should be reduced by 30mL. Ideally the resulting baked product will have greater volume, lighter texture, improved crumb consistency and a balanced flavor profile. ReferencesMcWilliams M. Dimensions of Baking. In: Foods Experimental Perspectives. 7th ed. Upper Saddle River, New Jersey: Pearson Prentice Hall; 2012:391-421.Piccinin D. Food Science Lab 5: Gluten and Bread. Kenmore, WA: Bastyr University; Fall Quarter 2012.Corriher S. Cookwise. New York, NY: HarperCollins; 1997.Gluten-Free Baking. Colorado State University Extension. HYPERLINK " /foodnut/09376.html" /foodnut/09376.html. Accessed October 28, 2012. Leavening agent. Wikipedia. . Accessed October 28, 2012.Chia seeds and flaxseeds. Gluten-free girl and the chef. . Accessed October 28, 2012.Demirkesen I, Mert B, Sumnu G, Sahin S. Utilization of chestnut flour in gluten-free bread formulations. Journal of Food Engineering. 2010;101:329–336. Sacchetti G, Pinnavaia G, Guidolin E, Dalla-Rosa M. Effects of extrusion temperature and feed composition on the functional, physical and sensory properties of chestnut and rice flour-based snack-like products. Food Research International. 2004;37:527- 534.White rice flour nutrition facts. Self Nutrition Data. facts/cereal-grains-and-pasta/5726/2. Accessed October 28, 2012.Chia seed nutrition facts. Self Nutrition Data. . Accessed October 28, 2012. ................
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