Jackie Eberhard Individual Project-F&N 453 November The Effect of Varying Amounts of Oat Flour on Texture and Flavor of Muffins Abstract: The purpose of this study was to test whether varying amounts of oat flour would have an affect on texture, volume, and appeal of muffins. Four batches of muffins were made, three having varying amounts of oat flour to replace some or all of the all-purpose flour. One of the batches was the control, which contained 100% all-purpose flour. Each batch was tested using a texture analyzer and a seed volume apparatus. A sensory panel was conducted to see if there was a change in moistness, crumb, and flavor. The moistness, crumb, and flavor of the various muffins had mixed results. The texture analyzer and seed volume apparatus were used for objective data with volume results being mixed, and texture measurements having similar results. The findings agreed with the original hypothesis, which stated that when oat flour is substituted for all-purpose flour, the texture, moisture content, and flavor will be different between the two muffins. Introduction: The American public is not getting a sufficient amount of fiber in their daily diet. The FDA recommends at least 25g of fiber based on a 2,000-calorie diet in order to have beneficial effects (Deis 1999). Fiber has been shown to reduce cholesterol levels in the body and reduce the risk of coronary heart disease. Soluble fiber is the fiber that performs the function of binding cholesterol and bile acids in the gut and removing it from the body (Sayar and others 2006). One of the reasons bile acid binding is beneficial is because they are the end product of cholesterol metabolism (Sayer and others 2006). One of the most common fibers that aid in lowering cholesterol is oat, which contains a substance thought to bind bile acids called β-glucan. A finding in the study by Sayar suggests that many components work synergistically to bind bile acids. However, soluble β-glucan can bind more effectively than other components (Sayar and others 2006). The substance β-glucan may have this effect because it is more viscous (Drzikova 2005). One of the goals of the food industry should be to find ways of incorporating fiber into foods the public loves to eat. This study used oat flour as a substitute of all-purpose flour in muffins. This substitution will increase the fiber content no matter how much is added. This specific study used 50%, 75% and 100% oat flour. Fiber can affect a baked good if too much is used. This study was pushing the content to observe at which point oat flour would affect the muffin s texture, appeal, and moisture content. Some considerations when adding more fiber to baked goods are flavor, particle size (grainy product), and browning (Hazen 2006). Some recommendations for substituting allpurpose flour in baked goods are: 1 ½ cup of ground rolled oats or 1 cup oat flour for 1 cup all-purpose (Oregon State 2006). Wheat flour can also be substituted for oat flour in recipes, with 1 cup wheat flour equaling ¾ cup oat flour (Oregon State 2006).
When starches are extruded in processing, many factors can affect the physical properties of the substance. Other ingredients, temperature, and pressure can end up affecting the functional and sensory properties, and can also up the viscosity (Drzikova 2005). A study conducted by Liu et al, studied the effects of processing of fiber on physical and sensory properties (Liu and others 2000). The article stated that increasing the percent of oat flour in a product may have several different results. Density can be increased, and gumminess and chewiness can be lowered (Liu and others 2000). Some observations of this study showed roughness, compact, dry surface, curving, and irregular in correlation with how much oat flour was used (Liu and others 2000). Oat flour does contain a higher amount of unsaturated fat and fiber which may be the reason for these observations. Oat flour has been shown to provide many nutritional benefits as stated above. B- vitamins are essential for many functions in the body and oat flour is an excellent source (Eborn 2001). Since oats have been known to aid in reducing cholesterol levels in the blood and aiding in digestion, it has been referred to as the cleansing grain (Eborn 2001). Vitamin E is also abundant in oats. Vitamin E can reduce staling in breads if the flour used is 25% oat flour (Eborn 2001). Going back to the effects of oat on sensory properties, oat can retain moisture and thus aid in a longer shelf life for the product (Namamillers 2006). However, the gluten content in oats is low, so this needs to be taken into consideration for baked goods. Gluten is a protein in flour that is formed from glutenin and gliadin that are wheat flour proteins. Gliadin has intra-molecular disulfide bonds that add extensibility and viscosity to baked goods (Daniel 2006). Glutenin contains intra- and intermolecular disulfide chains, and aids in the elastic property of gluten. When these two proteins are mixed with water, gluten forms, which will eventually become the structure or web that traps air. The air or gas that is trapped is what gives the baked good texture and volume (Daniel 2006). The three most common leaveners are air, steam and carbon dioxide (Daniel 2006). Overall, if oat flour is to be used for things like bread that require higher amounts of gluten, some type of gluten needs to be added along with the oat flour. Methods and Procedures: This experiment used a standard muffin recipe to determine if replacing a certain percentage of all-purpose flour with oat flour would have an affect on the muffin s texture, flavor, volume, and mouth-feel. The experiment used four variations, with one of the variations set as the control, containing 100% all-purpose flour. The recipe consisted of the following ingredients and their measures: Ingredients: 230g all-purpose flour 100g white sugar 11.4g baking powder 3g salt 177mL milk 80mL vegetable oil 1 egg (Recipe provide by AllRecipes.com)
As stated above, the recipe was repeated with four variations on the type of flour used. The first variation called for 50% all-purpose flour and 50% oat flour. The amounts used were 115g oat flour and 115g all-purpose flour. The second variation used 75% oat flour and 25% all-purpose flour, using 172.5g and 57.5g respectively. The third variation used 100% oat flour in the muffin recipe, which called for 230g oat flour. The final variation, or control, used 100% all-purpose flour. Since the original recipe called for this particular flour, this batch of muffins was used as a comparison of data for the muffins containing the various amounts of oat flour. The experiment of the four variations of muffins was repeated three times, all on different days. For the first trial with the 50/50 variation, milk was added directly to the dry ingredients. This was a mistake, since the milk, egg, and oil were to be mixed first, and then added to the dry mixture. This did not seem to affect the general appearance or texture of the muffins. The muffin batter made from the all-purpose flour, the control batch, had a thick consistency compared to the other muffin batters. The dough for the 50/50 variation was thick in consistency and tan in color. After baking, the muffin itself was golden, soft inside and outside, and pulled apart easily, but did not fall apart because of a too-soft crumb. The 75% oat flour variation had a batter that was very runny in consistency. The finished muffin was very soft and fell apart easily. This observation was also seen with the third variation of the 100% oat flour muffins. The muffins were very soft and crumbly. The finished control muffin in this trial with the 100% allpurpose flour was firm, but still had a soft texture. The third trial had similar results in the batters and finished products of the muffins for the 50/50 and 75% oat flour muffins. However, the third variation of 100% oat flour had a few mistakes. It was unclear if sugar had been added to the dry ingredients, so the sugar was added before the wet ingredients were added. It could be that this muffin had more sugar than what was suppose to be added. The muffin was observed to have a sweeter taste than the other muffins. The batter was very runny and the muffins were moist. This could be due to the competition with water and sugar for placement in the muffins. The controlled muffin batter for trial three was thick as seen in the other two trials; however, this batter seemed to be more clumpy. The equipment used for the experiment included: 1 large bowl, 1 small bowl, 1 fork, 1 spoon, 1 1/2 cup muffin pan, paper muffin cups, 1 kitchen scale, 1 small glass bowl and 1 100mL graduated cylinder. Below is the procedure for making the muffins: Procedure: 1. The oven will be preheated to 205º C (400º F). A muffin pan containing 12 holders will be lined with baking cups. 2. Use a kitchen scale to weigh out all of the dry ingredients into the small glass bowl and use a graduated cylinder to measure out the volume of the liquid ingredients. 3. In a large bowl, the flour, sugar, baking powder, and salt are to be combined using a spoon. In a separate small bowl, the milk, oil and egg will be combined with a fork and blended until smooth. Add the wet ingredients to the dry ingredients at once and mix until the dry ingredients are moistened (batter will be lumpy); approximately 45 turns of the spoon.
4. The cups of the pan should be filled 2/3 of the way full. Bake for 20 minutes. Cool the muffins for one minute after removing them from the oven. 5. If possible, the same oven should be used each time, in order to keep the temperature used accurate for both the control and experimental group. The time of 20 minutes should also be followed for each variation to keep the procedures consistent. Subjective evaluation: After the muffins were allowed to cool, four muffins from each variation were set aside on a plate. Each variation of muffins was identified with a three-digit number in order to keep the tasting blind. These muffins were set out for people to try as a sensory evaluation in order to give personal feedback as to the appeal of each muffin. The sensory card filled in by the panel consisted of a 5-point scale measuring for moistness, flavor, and crumble, with 5 being favorable and 1 being less favorable. The following is an example of the sensory card: Sensory Evaluation Moistness More moist Least moist 425 122 580 840 5 4 3 2 1 Flavor More flavorful Least flavor 425 122 580 840 5 4 3 2 1 Crumb Softer crumb Rough crumb 425 122
580 840 5 4 3 2 1 Objective evaluation: Four muffins from each variation were set aside in order to run objective test for volume and texture. Three muffins were wrapped with saran wrap with minimal wrap around the muffin. These three muffins were tested for volume using the Seed Volume Apparatus. A muffin is placed in the bottom chamber of the apparatus and the tall top section of the apparatus is closed and locked over the muffin. The metal slide is pushed back, letting all of the seeds in the upper part of the instrument flow over the muffin. After the seeds settle, the reading from the scale is recorded in cm3. This was repeated with two other muffins from the chosen variation at the time of testing. The average of the three muffins was recorded as the volume of the muffins for that particular variation. The second objective test was for texture using the Texture Analyzer. The probe attachment was used in order to measure the texture for the muffins. The last of the four muffins taken from a variation was cut in half and placed under the probe in order for the probe to penetrate the inside. The Texture Analyzer was set to muffin, and three quick test runs were done on the muffin half. The muffin was moved slightly each time a test was run to try different areas inside of the same muffin. The three readings were averaged and this was recorded as the texture in grams for that particular variation of the muffin recipe. Discussion The overall results found for the objective information on the muffins was varied among each trial. However, when the average of the three variation trials is compared to the average of the three control trials, more clear conclusions can be made. The texture of the muffins was determined using the Texture Analyzer. As seen in Table 2, the 100% all-purpose muffins, the control muffin, have 0.1g more force than any of the variations. This shows that the control muffin has a firmer texture on average than the oat flour variations. Whole grain baked goods usually are shown to have a more dense texture, or less air pockets (Hazen 2006). This is due to less gluten found in oats. The texture of soluble fiber, such as oat flour, is said to sometimes have a chewy or gummy texture (Hazen 2006). This could be the reason why the texture of the muffins with oat flour is softer than the all-purpose flour. The softer the texture of the muffin, the less grams of force is needed to penetrate the food. This would show a lower force needed, which is consistent with the averages found in the three trials of the oat flour variations. Figure 2 shows the small variation between the 100% all-purpose muffins and the 50/50 oat/all-purpose muffins. The volume of the muffins was determined by the Seed Volume Apparatus. As seen in Figure 1, the muffin with the most volume was shown to be the 100% oat flour variation. Since oat flour has less gluten, there is less structure that will stop the leavening process. In other words, the muffin will puff up more due to less gluten development. Table 2 shows the muffin with 100% oat flour had 2cm 3 more volume than the all-purpose muffin, so the results are fairly close.
According to the results of the Texture Analyzer and the Seed Volume Apparatus, the muffins did appear to change composition when oat flour was substituted for the allpurpose flour. This agrees with the original hypothesis that the muffins texture will change when different flours are used in the same recipe. A sensory evaluation was used in this experiment to determine the appeal of moisture of the muffins, flavor, and the softness of the crumb. A Hedonic scale from 1-5 was used, with 5 being the most satisfactory. Figure 3 shows the muffin with 100% oat flour was determined to be the moistest among the sensory panel. In order to have a moist product, the flour needs to retain more moisture. Whole grain fibers like oat flour tend to hold more moisture than all-purpose flours, which have a short fiber length (Hazen 2006). As seen in Table 3, the muffin with 100% oat flour had on average a higher moistness value (+/- 1.42), which means it is significantly different from the 75% oat flour and 100% all-purpose muffins. This also implies that the oat flour will provide different moisture content than the control muffin. Moving on to flavor, Figure 4 shows the 75% oat flour muffin had the same result of 4 on the Hedonic scale as the 100% oat flour. However, according to Table 3, the muffin made with 100% oat flour has a lower standard deviation, which means that it is closer to the average the sensory panel chose. This implies the 100% oat muffins were chosen more for flavor than the 75% oat flour muffins. The final sensory evaluation was for the crumb of the muffins. According to Figure 5, the 100% oat flour and 100% all-purpose flour muffins were chosen as having a softer crumb. As seen in Table 3, the 100% oat flour muffins have a lower standard deviation from the mean (+/-1.26). This may imply the 100% oat flour muffins were chosen for a softer crumb more times than the 100% all-purpose muffins. The conclusion from the findings go along with the original hypothesis that changing the all-purpose flour in a standard muffin recipe to a whole grain flour will affect the texture, moisture content, and flavor of the muffins. However, the data was fairly close, so more research needs to be done to determine if this is the case in all muffins substituted with whole grain flour instead of all-purpose. Other variables or ingredients need to be taken into consideration in future experiments. The only variable changed in these trials was the amount and type of flour used. Other ingredients may need to be adjusted when using a different type of flour, such as fat or water amount used. If theses changes are considered, the texture, moisture content, and flavor may not have a difference between muffins with two different types of flour.
Results Table 1:The Average Volume of Three Trials of Muffins with Varying Amounts of Oat Flour Compared to the Control as Measured by the Seed Volume Apparatus (cm 3 ) Muffins Average Volume (cm3) Trial 1 Trial 2 Trial 3 50% oat flour, 50% all-purpose flour 1098 1060 1122 1112 75% oat flour, 25% all-purpose flour 1099 1063 1118 1117 100% oat flour 1110 1093 1115 1123 100% all-purpose flour (Control) 1108 1080 1122 1122 Table 2: The Average Texture of Three Trials of Muffins with Varying Amounts of Oat Flour Compared to the Control as Measured by the Texture Analyzer Muffins Average Force (g) Trial 1 Trial 2 Trial 3 50% oat flour, 50% all-purpose flour 20.0 25.6 16.1 18.4 75% oat flour, 25% all-purpose flour 16.6 10.7 20.0 19.1 100% oat flour 15.8 12.3 15.2 19.9 100% all-purpose flour (Control) 20.1 20.6 18.9 20.9 Seed volume (cm 3 ) 1110 1108 1106 1104 1102 1100 1098 1096 1094 1092 50% Oat 50% AP Average 75% Oat 25% AP 100% Oat 100% AP Oat Flour Percentages vs. All-Purpose Flour (AP) Figure 1: Volume of Muffins with Varying Amounts of Oat Flour for Three Trials as Measured by the Seed Volume Apparatus
25.0 Average 20.0 15.0 Force (g) 10.0 5.0 0.0 50% Oat 50% AP 75% Oat 25% AP 100% Oat 100% AP Oat Flour Percentages vs. All-Purpose Flour (AP) Figure 2: Texture of Muffins with Varying Amounts of Oat Flour for Three Trials as Measured by the Texture Analyzer Table 3: Sensory Evaluation Average and Standard Deviation of Three Trials of Muffins with Varying Amounts of Oat Flour as Tested for Moistness, Flavor and Crumb 50% Oat Flour 75% Oat Flour 100% Oat Flour 100% AP Average Moistness 3 3 4 3 St. Dev. Moistness 1.08 1.39 1.42 1.38 Average Flavor 3 4 4 3 St.Dev. Flavor 1.22 1.27 0.93 0.93 Average Crumb 3 3 4 4 St. Dev. Crumb 1.11 1.26 1.26 1.33
5 4.5 4 Hedonic Scale from 1-5 3.5 3 2.5 2 1.5 1 50% oat flour 75% oat flour 100% oat flour 100% AP Oat Flour Percent in Muffin Batch Figure 3: Sensory Evaluation Averages for Moistness of Muffins with Varying Amounts of Oat Flour 5 4.5 4 Hedonic Scale of 1-5 3.5 3 2.5 2 1.5 1 50% oat flour 75% oat flour 100% oat flour 100% AP Oat Flour Percent in Muffin Batch Figure 4: Sensory Evaluation Average for Flavor of Muffins with Varying Amounts of Oat Flour
4.5 4 3.5 Hedonic Scale from 1-5 3 2.5 2 1.5 1 0.5 0 50% oat flour 75% oat flour 100% oat flour 100% AP Oat Flour Percent in Muffin Batch Figure 5: Sensory Evaluation Averages for Crumb of Muffins with Varying Amounts of Oat Flour References: Daniel JR. 2006. F&N 453 Lecture Notes Deis RC. 1999. Dietary Fiber: A Healthy Discussion. <http://www.foodproductdesign.com/> Oct. 2006 Drzikova B, Dongowski G, Gebhardt E. 2005. Dietary fibre-rich oat-based products affect serum lipids, microbiota, formation of short-chain fatty acids and steroids in rats. British Journal of Nutrition 94:1012-1025 Eborn, D. 2001. Oats <http://waltonfood.com/self/oats.html> Oct. 2006 Hazen C. 2006. New Fiber Options for Baked Goods. <http://foodproductdesign.com/> Oct 2006 Liu Y, Hsieh F, Heymann H, Huff HE. 2000. Effect of Process Conditions on the Physical and Sensory Properties of Extruded Oat-Corn Puff. Journal of Food Science 65(7):1253-1259 2006. Oat foods: A Smart Choice. <www.namamillers.org> Nov. 2006 2006. Flour Substitute. <http://food.oregonstate.edu/g/subflour.html> Nov. 2006 Sayar S, Jannink JL, White PJ. 2006. In Vitro Bile Acid Binding Activity within Flour Fractions from Oat Lines with Typical and High β-glucan Amounts. J. Agric. Food Chem. 54:5142-5148