Research Project. The Effect of Ground Flaxseed on the Physical and Sensory Properties in Banana Bread. Adam Gehring Avery Warwick Pauline Lay

Transcription

1 Research Project The Effect of Ground Flaxseed on the Physical and Sensory Properties in Banana Bread Adam Gehring Avery Warwick Pauline Lay Purdue University Dr. James R. Daniel FN 453- Food Chemistry Report Submitted: November 19, 2012

2 ABSTRACT According to numerous studies, the American population fails to incorporate the recommended amounts of omega-3 fatty acids and fiber into their daily diets. Omega-3 fatty acids are considered essential fatty acids because the body cannot function without them and research shows that they play a major role in preventing a large number of serious illnesses. Insufficient amounts of fiber leads to constipation, weight gain, blood sugar fluctuations, and diet related nausea and tiredness. Flaxseed is a power food because it contains the benefits of both dietary fiber and omega-3 fatty acids and very few calories. The effects of added flaxseed to banana bread on texture, water activity, color, and overall consumer acceptance of taste, texture, and overall appeal was evaluated. Three variations of banana bread were prepared: Control (0% added flaxseed), Variation 1 (50% added flaxseed), and Variation 2 (100% added flaxseed). The control and both variations were each tested three times in three different trials. The Texture Analyzer showed that adding flaxseed caused the average compressive force to increase. According to the Water Activity System Meter, the water activity in the bread decreased as more flaxseed was added to the original recipe. The color of Variation 1 was slightly darker than the control, and Variation 2 was even darker yet. Overall the Control was most preferred by the panelists and Variation 1 was preferred over Variation 2. I. Introduction Omega-3 fatty acids and dietary fiber are both extremely important nutrients that are needed to help a healthy body function properly. The adequate intake level for dietary fiber is 14g per 1000 calories or 25 g per day for women and 38g per day for men, yet the average American is only consuming about 15g per day (Satija and Hu 2012). Consumer intake of omega-3 is also considerably low. The average American only gets 1.6g of omega-3 into their diet everyday when they should be aiming for 2.85g per day (Harper and Jacobson 2001). Deficiency for both of these nutrients is most likely due to consumers feeling as though the sources of these to nutrients have an unpleasant taste. A solution to this problem would be to incorporate enough flaxseed, which contains both omega-3 fatty acids and fiber, into banana bread to increase the 2

3 nutritional benefits of the bread without causing too much of a change to the physical and sensory properties or making the bread undesirable to consumers. In order to accurately test and be able to replicate this study, key physical properties were measured to compare the texture, water activity, and color between the control and variations in differing flaxseed amounts in the banana bread. The banana bread was prepared using a controlled method of no addition of flaxseed (0% flaxseed added). Variation 1 included the same ingredients as the control, but also an addition of 33g of ground flaxseed (50% flaxseed added). Variation 2 included an additional 66g of flaxseed (100% flaxseed added). The independent variable in this experiment is the amount of flaxseed that is added to the three bread variations. This includes the Control bread that had no added flaxseed, Variation 1 with 33g of ground flaxseed, and Variation 2 with 66g of ground flaxseed added. The dependent variables include texture, water activity, color, and overall consumer acceptance. These were tested to find the effects that the independent variable had on each dependent variable. A. Effect of Texture The Texture Analyzer with the use of the cone prone was one of three methods used in the experiment. This test was important because desirable texture plays a large role in consumer acceptance. The data from this test determined the compressive strength of the banana bread. It measured the texture and how hard the bread was in regards to the added flaxseed. B. Effect of Water Activity The Water Activity System Meter was used in this experiment to test that the amount of flaxseed had on the food s water activity. It measured water activity based on dew point of the sample (Weaver and Daniel 2012). This test is important because water activity is directly related to texture and shelf life of a food product. C. Effect of Color The Hunter Colorimeter was used to measure color deviations between the three variations of bread. The main purpose was to evaluate the effect that adding flaxseed had on the lightness or darkness of the bread. This was an important factor in the experiment because color and appearance have a large impact on consumer acceptance of new food products. 3

4 II. Methods Preparation The recipe used for making the banana bread samples was obtained from Allrecipe website with adjusted modification of removal of ¼ cup of chopped walnuts and substitution of it with ground flax seed in order to make two variables. There are 3 samples including control, variable 1 and variable 2. Below are the listed ingredients for each sample. Banana Bread Recipe (Control): 1 cup white sugar (200 grams) 1 large egg 2 cups all-purpose white flour (250 grams) ½ teaspoon table salt (2.85 grams) ½ cup vegetable oil (115 grams) 1 teaspoon baking soda (5 grams) Variable 1: Addition of 5 Tbsp ground flaxseed per mini-loaf tray (32.5 grams). Variable 2: Addition of 10 Tbsp ground flaxseed per mini-loaf tray (65 grams). Procedure To ensure accuracy, the replications were made as identical as possible and the steps were followed exactly the same. Below are the steps for making the banana breads. 1. Preheat oven to 177 C. 2. Spray loaf pans with non-stick cooking spray. 3. In large bowl, mix sugar, oil, and egg until creamy and light yellow. 4. In a small bowl, mash bananas with fork. 5. Add bananas to sugar, oil, and egg mixture. 6. Then add the flour, baking soda, and salt. 7. Stir mixture until completely smooth. 8. Measure batter in liquid measuring cup and divide the total amount into 3 equal parts. 4

5 9. Put equal amounts of batter in 3 different bowls. 10. Set aside 1 bowl as the control. 11. In the remaining 2 bowls, add differing amounts of ground flaxseed according to variables 1 and Stir until the flaxseed is evenly distributed. 13. Spoon the batter from all 3 bowls into separate mini-loaf trays. 14. Bake for 30 to 40 minutes or until toothpick poked in center comes out clean. 15. Take out of oven and let cool until desirable. After cooling, the samples were pulled out of the loaf pans and were cut into small pieces with similar sizes. Variable 1 will supply one tablespoon of ground flaxseed per slice. Variable 2 will supply two tablespoons of ground flaxseed per slice. The first variable will contain around 1.5 grams of omega-3 fatty acids per serving, and will add about 1.9 grams of fiber to the serving size of banana bread (Bassett and others 2009). The recommended intake of omega-3 fatty acids is 2.85 g/day, therefore a single slice of banana bread would fulfill 52% of that recommendation (Harper and Jacobson 2001). The recommended amount of fiber a woman should eat is about 25 g/day, and for a man it is around 38 g/day (Satija and Hu 2012). Variable 1 would only contribute about 2 grams of fiber, however variable 2 would contribute 4 grams per serving because twice the amount is added. With 4 grams of fiber per serving, that equals 16% of the recommended intake for women and 10% for men at 25 and 38 g/day, respectively. Variable 2 would contain about 3 grams of omega-3 fatty acids, and this amount would be 105% of the recommended intake of 2.85 g/day. The same procedure was made 2 times more as replication to increase precision and accuracy of the results. Each control and variable was presented as 3-digit code number. Sample 752 as the control, sample 450 as variable 1 and sample 241 as variable 2. Objective analysis To compare the water activity content of the 3 samples, water activity system was used. The water activity was measured 3 times for each sample in one trial. Also, to ensure accuracy, the same part of banana bread was measured in every trial. Besides water activity content, the texture of the banana bread samples were also measured using stable micro systems texture analyzer with cone probe to see the effect of 5

6 addition of ground flax seed on texture of banana bread. As done with water activity system, the sample of one trial was measured 3 times. Consistent setting was chosen for every measurement. The hardness of each sample was recorded in grams. The last objective method was using Hunter Colorimeter to compare the difference in color for each variation. The measurement was also done 3 times for each sample in one trial. The number for L, A and B measurements was recorded. Subjective analysis Organoleptic properties such as texture, flavor, and overall experience were also observed using 9-point hedonic scale, descriptive analysis and rank order sensory tests. The samples were presented using the same 3-digit code for every trial and the panelists were not informed about what was tested to reduce bias. The panelists were the students that were in the Stone Hall room 229 during testing. The texture of the 3 samples was compared and the panelists were asked to describe the hardness of each sample. The panelists were also asked to rank the sample from the most desired taste to the least desired taste. And last, the panelists were asked to score the overall experience of each banana bread with 9-point hedonic scale. Below is the scorecard used for the subjective analysis. Subjective Analysis: For our sensory analysis we used the hedonic scale and ranking system to test the taste, texture, and overall appeal of the three samples of banana bread. 1) Describe the texture of the three samples Sample 752: Sample 450: Sample 241: 6

7 2) Rank samples 752, 450, and 241 in descending order based on the desirability of taste. Most Desirable: Least Desirable: 3) Hedonic Test: Rate sample 752 by checking the box you agree most with [ ] Like extremely [ ] Like very much [ ] Like moderately [ ] Like slightly [ ] Neither like nor dislike [ ] Dislike slightly [ ] Dislike Moderately [ ] Dislike very much [ ] Dislike extremely Rate sample 450 by checking the box you agree most with [ ] Like extremely [ ] Like very much [ ] Like moderately [ ] Like slightly [ ] Neither like nor dislike [ ] Dislike slightly [ ] Dislike Moderately [ ] Dislike very much [ ] Dislike extremely 7

8 Rate sample 241 by checking the box you agree most with [ ] Like extremely [ ] Like very much [ ] Like moderately [ ] Like slightly [ ] Neither like nor dislike [ ] Dislike slightly [ ] Dislike Moderately [ ] Dislike very much [ ] Dislike extremely 8

9 III. Results Table 1.1, below, depicts the water activity mean and standard deviation values acquired from the Water Activity System. According to the table, the mean ranges from the highest value of to the lowest value of 0.788, and this could have powerful implications on the shelf life of the various products, which will be discussed later in the report. It should be noted that there was no significant difference between the three trials. Table 1.1 Water Activity (a w ) Trial Control: No flaxseed added ± Variable 1: 5 Tbsp flaxseed added ± Variable 2: 10 Tbsp flaxseed added ± Mean a w ± standard deviation. No significant difference was observed. a w Figure 1.1, located below, shows a visual representation of table 1.1. Water Activity (aw) Control: No flaxseed added Variable 1: 5 Tbsp flaxseed added Type of Banana Bread Variable 2: 10 Tbsp flaxseed added Figure 1.1 Water Activity System readings for the three trials of banana bread. The control displayed the highest mean a w while variable 2 showed the lowest mean a w. 9

10 Table 2.1 and Figure 2.1, below, show the mean Texture Analyzer readings and the standard deviations for the three tested samples. The control and variable 1 were not statistically different from one another, but the control and variable 2 were statistically different. Variable 1 and variable 2 were statistically different from one another as well. It appeared that as more flaxseed was added to each variable, the higher the Texture Analyzer readings became. Also, higher values could be due to the texture analyzer probe being in close proximity to the crust during the testing process. Table 2.1 Texture Analyzer Measurements Trial Force (grams) Control: No added flaxseed 33.2 a ± 14.7 Variable 1: 5 Tbsp flaxseed added 36.4 a ± 7.8 Variable 2: 10 Tbsp flaxseed added 91.0 b ± 28.9 Mean texture analyzer readings ± standard deviation. a-b Data bearing different superscripts are statistically significant (p < 0.05). 140 Texture Analyzer Force (grams) a a b 0 Control: No added flaxseed Variable 1: 5 Tbsp flaxseed added Variable 2: 10 Tbsp flaxseed added Type of Banana Bread Figure 2.1 Texture analyzer readings (grams) of the three different variations of banana bread. a-b Data bearing different superscripts are statistically significant (p < 0.05). 10

11 Table 3.1 and Figure 3.1, located below, shows the Hunter Colorimeter readings and the standard deviations for the three samples of banana bread. The control was determined to be statistically significant to both of the other two variables at the L, a, b readings except the a reading in variable two. Variables 1 and 2 were not considered statistically significant except for the a reading for variable 2 once again. The L reading showed the largest value change from the control to variables one and two. The control had an average of and for variables 1 and 2 the means were and 29.34, respectively. Table 3.1 Hunter Colorimeter Results Hunter Colorimeter Trial L a b Control: No added flaxseed a ± a ± a ± 2.84 Variable 1: 5 Tbsp flaxseed added b ± b ± b ± 0.16 Variable 2: 10 Tbsp flaxseed added b ± ab ± b ± 0.41 Mean Hunter Colorimeter reading ± standard deviation. a-b Data bearing different superscripts in the same column are statistically significant (p < 0.05) a b b a a b ab b b L a b Figure 3.1 Hunter Colorimeter readings (L, a, b). a-b Data bearing different superscripts are statistically significant Hunter Colorimeter Reading (p < 0.05). Control: No added flaxseed Variable 1: 5 Tbsp flaxseed added Variable 2: 10 Tbsp flaxseed added 11

12 Table 4.1 and Figure 4.1, shown below, display the subjective consumer preference ranking according to the most desirable sample through least desirable sample. Only three options were available to rate the samples because there were three samples. The participants chose the control to be the most desirable product with 73% of the votes going toward it. The least desirable sample was variable 2 with 73% of the votes as well. The second most preferred sample was variable two, receiving 55% of the medium ranking results. It is noteworthy that not a single participant voted variable 2 as their favorite, or most desirable, sample. Table 4.1 Rank Distribution in Terms of Desirable Taste Panelist Distribution (%) Trial Most Medium Least Control: No flaxseed added 73% 18% 9% Variable 1: 5 Tbsp flaxseed added 27% 55% 18% Variable 2: 10 Tbsp flaxseed added 0% 27% 73% Most Medium Least 100% 90% 80% 27% 27% 70% 60% 73% 50% 40% 30% 73% 55% 20% 10% 0% Control: No flaxseed added 18% Variable 1: 5 Tbsp flaxseed added 18% 9% Variable 2: 10 Tbsp flaxseed added Figure 4.1 Panelist distributions on the ranking of most desirable, moderate desirability, and least desirable. 12

13 Another subjective test was performed and this was the 9-Point Hedonic scale. Table 4.2 and Figure 4.2, portrayed below, display the results of the subjective data obtained. The control had a mean ranking of 7.4 ± 0.7, which is between 7 like moderately and 8 like very much. The small standard deviation means that most of the ratings were very close to the average. Variable 2 received a mean ranking of 6.6 ± 1.6, which is between 6 like slightly and 7 like moderately. It should be mentioned that variable 2 had the highest rating overall with one participant rating it at 9 which is like extremely. Also, the standard deviation for variable 2 was the highest at 1.6 and this meant that certain participants really enjoyed this sample while others did not enjoy it nearly as much. Variable 3 received a mean of 5.2 ± 1.3, which is between 5 neither like nor dislike and 6 like slightly. It also had a fairly high standard deviation at 1.3, but the overall score was much lower than the other two. In fact, variable 3 was considered to be statistically different from the control and variable 1. The control and variable 1 were not statistically different in terms of the 9-Point Hedonic scale. This could potentially mean that the incorporation of flaxseed to banana bread is liked as well as the control sample of banana bread. Table 4.2 Overall Taste Results for the Three Trials Trial 9-Point Hedonic Scale Score Control: No flaxseed added 7.4 a ± 0.7 Variable 1: 5 Tbsp flaxseed added 6.6 a ± 1.6 Variable 2: 10 Tbsp flaxseed added 5.2 b ± 1.3 Mean value ± standard deviation. a-b Data differences are statistically significant (p < 0.05). 13

14 9.0 Average Score on a 9-Point Hedonic Scale a Control: No flaxseed added a Variable 1: 5 Tbsp flaxseed added b Variable 2: 10 Tbsp flaxseed added Figure Point Hedonic scale results for overall taste ratings. a-b Data differences are statistically significant (p < 0.05). IV. Discussion Based on the results of both objective and subjective analysis methods, the effect of addition of ground flaxseed on water activity, texture, color and overall taste was observed. Water Activity It is shown from table 1.1 and figure 1.1 that there is no significant difference between the control and all the variables. However, there is a general trend that shows the decreasing water activity content with increasing flaxseed addition. Water activity is important as one of the aspect that will affect the product s shelf life. Although most bacteria won t grow in water activity less than 0.9, but chemical reactions, enzymes activity and molds growth could still occur in the banana breads, even with the addition of flaxseed as they have the water activity that ranges from 0.78 ± to ±

15 Texture Based on the results that are shown in table 2.1 and figure 2.1, it is shown that variable 2 has the hardest texture among all samples. There is no significant difference between the control and variable 1 although it is expected to see a significant increase of hardness in variable 1. This may be due to the error in measuring. The crust part of the control was measured that resulted in high number of force. However, there is significant difference between variable 1 and variable 2. Thus, it can be concluded that flaxseed addition causes the more rigid, dense and tougher texture in banana bread. This is also supported with the study on flaxseed addition that shows an increase in water holding capacity as more flaxseed added (Sun, J. and others, 2011). The increase in water holding capacity changes the network structure to a compact, causing the hard texture that eventually causing more force needed to compress the banana bread. However, the change in texture between the control and variable 1 could be detected by some of the panelists as the common words that describe variable 1 include slightly harder, firm and dense. There are also some panelists that chose variable 1 as their favorite, and therefore, it is possible to produce banana bread with 5 Tbsp of flaxseed addition in order to fulfill the omega-3 and fiber needs of the consumer while still well received. Color Results showed that there is a significant difference in light between the control and the variables. Although there is no significant difference among the variables themselves, but it can be concluded that flaxseed addition causes darker appearance in the banana breads. The same trend occurred to the b value where the control was most yellow while the other 2 variables were not significantly different. However, there is no significant difference can be concluded accurately in red to green color as there is no general trend that could be observed from the a value. Although it is shown in figure 3.1 that there is significant difference between the control and variable 1, but there is no significant difference to variable 2. Variable 1 was significantly greener and less red compared to the control, however variable 2 was not significantly different to variable 1, or to the control. It is shown though that variable 2 was generally redder and less green compared to variable 1, but 15

16 greener and less red compared to the control. Therefore, no accurate conclusion could be obtained. The change in color with addition of flaxseed is expected as the flaxseed itself has dark color and the color was dissolved during mixing in the batter. Correlation to subjective analysis The results of ranking test showed that the control had the most desirable texture. With common words such as moist, soft, fluffy and light describing the control, it can also be concluded that soft texture is desirable. It is consistent with the objective analysis that showed the control had the least hardness texture whereas variable 2 had the hardest texture and received the least favorable sample. The panelists also believe that the control had the best overall experience. However, based on the results shown in figure 4.2, there is no significant difference in overall experience between the control and variable 1 (addition of 5 Tbsp of flaxseed). Therefore, addition of flaxseed could be done to be enjoyed by consumers while fulfilling the omega-3 and fiber needs. This could possibly be a great way to increase the consumption of omega-3 and fiber that is still lacking here in US. There are still many things that can be worked on to flaxseed addition as fiber and omega-3 source as there are still many food products that can use flaxseed as additional ingredients. V. References Bassett CMC, Rodriguez-Lyva D, Pierce GN Experimental and clinical research findings on the cardiovascular benefits of consuming flaxseed. Applied Physiology, Nutrition & Metabolism. 34: Harper CR, Jacobso TA The fats of life: The role of omega-3 fatty acids in the prevention of coronary heart disease. American medical association [serial online]. 161: Available from ( Posted Oct 8, Satija A, Hu B Cardiovascular benefits of dietary fiber. Curr Atheroscler Rep [serial online]. Available from ( Posted Aug 8,

17 Sun, J, Li, X, Xu, X, Zhou, G Influence of various levels of flaxseed gum addition on the water-holding capacities of heat-induced porcine myofibrillar protein. Journal of Food Science, 76: C472-C478. Weaver, Connie and Daniel, James. The Food Chemistry Laboratory- a Manual for Experimental Foods, Dietetics, and Food Scientists. CRC Press (2 nd edition; pgs ) 17