Benefits of soy protein on health and volume of angel food cake

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1 Jessica Borst Kaylyn Herrold FN 453-Written Report 11/23/2009 Benefits of soy protein on health and volume of angel food cake Abstract: Soy protein is a food whose use has been increasing in recent years. In addition to being a nutrient-rich food and a complete protein source, soy also offers many health benefits for chronic diseases such as cardiovascular disease and diabetes (Montgomery 2003). Soy protein can also increase the volume of egg white foams, which has important food quality properties (Wang 2009). The purpose of this study was to evaluate the use of soy proteins on the volume of angel food cakes while giving the cakes the added health benefit of soy. Two different soy proteins were used at levels of rams and rams and height, texture, color, water activity, and consumer preference were evaluated. Although there were some differences between the control and the variables, there were no significant differences except for the Hunter colorimeter a value. These findings show that the health benefits of adding soy protein to angel food cakes are attainable without negatively altering the quality of the food. This is an important finding that could lead to more work in the area in the future. Introduction: Soy protein has become increasingly popular in recent years. This protein, found in soybeans, offers many health benefits, including cardiac, pregnancy, obesity, diabetes, and cancer prevention, as well as menopausal benefits (Montgomery 2003). Soy is also the only vegetable food source that contains all of the essential amino acids (Montgomery 2003). Soy protein has also been shown to increase the volume of egg white foams (Wang 2009). This could be beneficial in foods that rely on foam volume since increased volume can lead to better texture and mouth feel. Because of the variety of health benefits that soy offers and the food quality benefits of an increased foam volume, supplementing a regular food, such as angel food cake, with soy protein can offer increased nutrition and increased sensory qualities. The concept for this project was developed after studying an article by Guang and Tong Wang. In this study, the effects of soy protein on the foaming properties of egg whites were observed. It was found that as the amount of soy protein in relation to egg white increases, the foam expansion increases (Wang 2009). Because of these results another experiment using Guang and Tong Wang s two highest soy levels as a reference was developed to try to increase angel food cake volume. In addition to using two levels of soy protein, two different types of soy protein were used to see if the type of soy protein affects volume. The two types of soy are a soy protein isolate powder and a soy protein powder. It was thought that increasing the volume of the egg white foam would most likely increase the volume of the angel food cake, making it softer, lighter, and better in texture.

2 2 In addition to improving the sensory qualities of the angel food cake, soy protein will improve the health benefits of the cake. Soy protein has been shown to improve many aspects of health. It has been shown to help reduce the risk of cardiovascular disease, such as atherosclerosis, and diabetes. Both of these diseases are epidemic in the United States and affect many people worldwide. Being able to improve the health of the population using soy would be a great accomplishment. One study showed that soy protein may play a role in reducing the risk of cardiovascular disease. The authors studied cholesterol fed rats to observe the effects of soy protein on the serum lipid profile and lipid-metabolizing enzymes. Improving these levels could help reduce the risk of diseases such as atherosclerosis. A cholesterol rich diet will increase VLDL and LDL serum cholesterol levels and increase serum triglyceride concentrations. However, when 20% soy protein was included in the rat's cholesterol diet, the VLDL, LDL, and serum triglyceride concentrations dropped. The rats with a 5% soy protein diet also had a significant decrease in serum VLDL, LDL, and triglyceride levels. The soy protein seems to have a significant effect compared to the control rats who consumed no soy protein. The control group had a significant increase in serum cholesterol levels when fed a cholesterol rich diet with no soy (Onyeneke and others 2008). Another study that demonstrates the health benefits of soy is one that observed the effects of soy protein on decreasing the urinary albumin excretion and improving the serum lipid profile of men with diabetes and nephropathy. Diabetes can lead to coronary heart disease and nephropathy. The authors of this study used a 7 month crossover design on male patients with type 2 diabetes and nephropathy. Many diabetic patients have elevated urinary albumin excretion from kidney problems. This is also indicative of cardiovascular disease risks. This study found that soy protein can significantly reduce urinary albumin excretion and LDL cholesterol while increasing HDL levels. This evidence suggests that soy protein consumption can help reduce the risk of kidney disease and cardiovascular disease in diabetic patients (Teixeira and others 2004). Evidence suggests that soy protein can increase egg white volume, reduce the risk of cardiovascular disease, and reduce the risk of kidney disease. Because of these associations, the purpose of this experiment was to add soy protein powders to egg white foams to help increase the volume and improve sensory qualities of angel food cake while also increasing the health benefits. By increasing the volume, it was thought the texture and consumer preference would increase. Factors such as color and appearance were also measured to observe whether the addition of the soy protein affects these factors, which could cause less of a preference for the modified angel food cake. The independent variable that changed was the type of soy protein and the amount of soy protein added. The types of soy protein that were used were Now Sports Soy Protein Isolate and Nature s Plus Soy Protein Powder. The amounts added were rams and rams. The dependent variables measured included volume, texture, color, water activity, and consumer preference. The methods chosen to measure these variables included measuring height with a ruler, using a texture

3 3 analyzer, a Hunter colorimeter, a water activity system, and a Hedonic rating scale. These methods are standard and should be able to accurately evaluate the volume, texture, color, water activity, and consumer preference. Methods: In this study, ram and ram samples of each soy protein were added to a standard angel food cake recipe. A control was also prepared that contained no soy protein. The cakes were made, baked, and then evaluated by measuring height, texture, color, water activity, and consumer preference. These procedures were completed a total of three times for each variable to ensure that an accurate set of results were obtained. The procedure for this study was adapted from the Food Science Laboratory Manual by Karen Jamesen. The procedure is as follows: 10 g powdered egg whites 74 ml water 26 g cake flour 2.5 ml vanilla 82 g sugar cream of tarter 0.8 g salt 0g, or soy protein according to variable Preheat oven to C (400 F). Sift ½ of sugar with flour and salt. Set aside. Add powdered egg whites to warm water. Stir for 2 minutes, giving the powder time to absorb the water. Add soy protein according to variable. Beat egg whites until foamy. Add cream of tartar. Beat to soft peak - tips form when beater is removed and gently fold over. Add ½ of sugar and vanilla. Beat to stiff peak-points form when beater is removed. Fold in flour-sugar mixture. Pour into 6-inch unoiled angel cake pan. Bake at C (400 F) for minutes. Invert cake and allow it to cool in pan. Loosen cake from sides of pan with a spatula. Variables: Control- standard angel food cake with no addition of soy protein Variable 1- standard angel food cake with addition of Soy Protein Isolate Variable 2- standard angel food cake with addition of Soy Protein Isolate Variable 3- standard angel food cake with addition of Nature's Plus Soy Protein Powder Variable 4- standard angel food cake with addition of Nature's Plus Soy Protein Powder After the cakes cooled and were removed from the pans, the objective tests were performed. First the height of the cakes was evaluated as an indicator of volume. Cake

4 4 height was measured using a standard ruler. Measurements were taken on a flat surface from the bottom of the cake to the highest point of the risen cake. After height was recorded all other objective measurements were performed. The Hunter calorimeter was used to evaluate color of the cakes. Texture was evaluated using the texture analyzer with the cone probe. The setting for the texture analyzer was the cake setting with 10mm pass into the cake. Water activity was measured using the water activity system meter. Detailed instructions for using the Hunter calorimeter, texture analyzer, and water activity system meter were followed from The Food Chemistry Laboratory by C. Weaver and J. Daniel. Subjective testing was done through the use of a sensory panel composed of 8 classmates. This was done using a hedonic scale to evaluate appearance, texture, and flavor. Also, a simple ranking exercise was used to determine overall preference. Each sample was assigned a three digit number and the variables are not identified to the panel. All samples were cut into pieces of approximately the same size and shape. The following is an example of the sensory score card: Rate appearance, texture, and flavor on a 9-point hedonic scale with 9 = very desirable appearance, very desirable texture, and very desirable flavor and 1 = very undesirable appearance, very undesirable texture, and very undesirable flavor. Sample Appearance Texture Flavor Please rank the samples from least overall preference to most overall preference with 1 being the least preferred and 5 being the most preferred. Sample Ranking

5 5 In order to control variables other than the amount or type of soy protein added to the angel food cake, careful precautions were taken. Precise measurements of all other ingredients were used. Each stage of the beating process was carefully monitored so that each cake batter was reaching the same desired stage (i.e. soft peak and hard peak). Each cake was placed in the same size and shape pan and baked for the same amount of time. Also, cakes were cooled for the same amount of time and in the same manner (inverted). Cakes were removed from the pans at the same point during the cooling process. These precautions should have enabled an accurate evaluation of the variables in question. This entire procedure was repeated and completed a total of three times. Results: Table 1.1 Average Height (cm) of Sample Cakes and Range of Values Variable Average Standard Deviation Range Control Nature's Plus Nature's Plus Average Height (cm) Control Nature's Plus Nature's Plus Variable Figure 1.1 Average Height (cm) of Sample Cakes

6 6 Table 1.2 Average Texture Analyzer (g) of Sample Cakes and Range of Values Variable Average Standard Deviation Range Control Nature's Plus Nature's Plus Texture Analyzer (g) Control Nature's Plus Nature's Plus Variable Figure 1.2 Average Texture Analyzer (g) of Sample Cakes Table 1.3 Average Water Activity of Sample Cakes and Range of Values Variable Average Standard Deviation Range Control Nature's Plus Nature's Plus

7 Water Activity Control Nature's Plus Nature's Plus Variable Figure 1.3 Average Water Activity of Sample Cakes Table 1.4 Average Hunter Colorimeter Values of Sample Cakes and Range of Values Variable Average Standard Deviation Range Control L A B L A B L A B Nature's Plus L A B Nature's Plus L A B

8 Hunter Colorimeter Values Variable Figure 1.4 Average Hunter Colorimeter Values of Sample Cakes

9 9 Table 1.5 Average Subjective Values for Appearance, Texture, and Flavor of Sample Cakes and Range of Values Appearance Texture Flavor Mean Std Dev Range Mean Std Dev Range Mean Std Dev Range Control Nature s Plus Nature s Plus Average Hedonic Rating Appearance Texture Flavor 0 Control Nature's Plus Nature's Plus Variable Figure 1.5 Average Subjective Values for Appearance, Texture, and Flavor of Sample Cakes Based on Hedonic Scale Discussion: Addition of soy protein to angel food cakes did not result in the expected objective observations. Soy protein has been shown to increase the volume of egg white foams (Wang 2009). According to Table 1.1 and Figure 1.1, it can be seen that although the height of the sample cakes varied, there really were not any major differences among the variables. Statistical analysis revealed that the differences in averages for the heights of the sample cakes were not significant, P-value > Although it was found that as the amount of soy protein in relation to egg white increases, the foam expansion increases (Wang 2009) it appears that this same principle does not apply to the use of soy protein in increasing the overall volume of an angel food cake. Data from the texture analyzer is represented in Table 1.2 and Figure 1.2. This data again reveals no set trend in texture change in relation to the type or amount of soy protein added to the angel food cakes. Statistical analysis revealed that the differences

10 10 in averages for the texture of the sample cakes was not significant, P-value > Referring to Table 1.2 and Figure 1.2 again, it can be noted that the standard deviations for this data are relatively large with the lowest standard deviation being 7.30 and the highest This reveals that there was a lot of variation in the texture measurements that were gathered for these cakes, which reveals why no significant differences may have been revealed. These results also show that although adding soy protein to the angel food cakes may not have had a positive effect on texture, the addition did not have a negative effect either. Table 1.3 and Figure 1.3 reveal that just like texture and height, there seems to be no trend in relationship to the type or amount of soy protein compared to the water activity of the sample cakes. Yet again statistical analysis revealed that differences in averages for the water activity of the sample cakes was not significant, P-value > The standard deviations for water activity were very small. Therefore, it can be concluded that addition of soy protein to angel food cake has no effect on the water activity of the cake. Hunter Colorimeter values (l, a, and b) were measured for each sample cake. The averages and standard deviations are presented in Table 1.4 and Figure 1.4. Once again statistical analysis revealed that the differences in averages for l, a, and b were not significant, P-value > There was one exception to this: comparing the a value for the Now Foods sample and the Nature s Plus sample. This resulted in a P-Value <0.05 and is considered very significant statistically. This reveals that the largest difference in color was observed between different soy proteins of different levels. Overall, objective results for this study revealed that adding different amounts of different types of soy protein did not really affect the angel food cake. The control was not significantly different in height, texture, color, or water activity than any of the other samples. This would suggest that adding soy protein may not increase volume of the angel food cake, but that adding soy protein could increase the health benefits of angel food cake without affecting its quality. Subjective data collected from the sensory panel is represented in Table 1.5 and Figure 1.5. Statistically differences in both flavor and texture ratings across all three trials were not significant, P-value > Statistical analysis did reveal that some of the differences in appearance ratings were significant, P-value <0.05. The control was preferred significantly more in appearance to the sample cake containing Now Foods Soy Protein; however, there was no significant difference between the control and any other variables. The Nature s Plus and variables were both significantly preferred over the Now Foods. This may have been due to the fact that the Now Foods Sports Soy Protein Isolate actually contained more protein compared to the Nature s Plus Soy Protein powder, suggesting that added protein led to a decreased preference for appearance. The control contained no added protein, but was not significantly preferred over all of the variables. For this reason it is hard to

11 11 come to a single conclusion about the affect of added soy protein on appearance of angel food cakes except for the fact the Now Foods 3.2g variable was least preferred. The end results of this study seem to conclude that adding soy protein neither affects the volume or other sensory qualities of angel food cake. This means that although volume was not increased as was thought, adding soy protein could add health benefits to angel food cake without affecting a consumer s preference for it. Further studies in this area are needed. Suggestions for future work include adding more soy protein to the sample cakes. This might reveal more significant results and would increase the health benefits. Levels of soy protein used in this experiment may be low to consider tremendous health benefits, but research must be started somewhere. It is also suggested that the future studies focus on one type of soy protein with varying levels of soy protein instead of trying to compare types or brands of soy proteins. In retrospect, it is also noted that angel food cakes are a very delicate food to work with and that there are many factors that may affect results other than the type or amount of soy protein added. No matter what precautions are taken to ensure that all cakes are made in the same fashion, beating times and stages may still vary with human error. References: Jamesen K Angel food cake. Food Science Laboratory Manual. Upper Saddle River: Prentice Hall. p.185. Montgomery K Soy Protein. Journal of Perinatal Education 12(3): Onyeneke EC, Oluba OM, Adeyemi O, Aboluwoye CC, Eriyamremu GE, Ojeaburu SI, Adebisi KE, Adeyemi O Effect of soy protein on serum lipid profile and some lipid-metabolizing enzymes in cholesterol fed rats. Journal of Alternative Medicine 5(2):8-8. Teixeira SR, Tappenden KA, Carson L, Jones R Isolated soy protein consumption reduces urinary albumin excretion and improves the serum lipid profile in men with type 2 diabetes mellitus and nephropathy 1,2. Journal of Nutrition 134(8): Wang G, Wang T Improving Foaming Properties of Yolk-Contaminated Egg Albumen by Basic Soy Protein. Journal of Food Science. Retrieved Sept. 28, 2009, from Weaver CM, Daniel JR The Food Chemistry Laboratory. 2 nd ed. Boca Raton: CRC Press.