Final Report NUTR 453 Candace Crowley, Amanda Jones, Blake Criss December 1, 2014

Transcription

1 Final Report NUTR 453 Candace Crowley, Amanda Jones, Blake Criss December 1, 2014

2 Title The Effect of Greek Yogurt in Place of Ricotta Cheese on the Viscosity, Color, Water Activity, and Palatability in Ricotta Pancakes Abstract Many Americans today are classified as either over weight or obese, and this trend is continuing to increase. More than one third (78.6 million) of U.S. adults are obese (CDC, 2014). Obesity related conditions include heart disease, stroke, type 2 diabetes, certain cancers, and other leading causes of preventable death. Because obesity is so commonplace in today s society, this experiment was produced in order to make Americans more aware of substitutions that can reduce the amount of fat content in their diets. Evidence suggests that lowering total energy intake, along with a reduction in total fat intake can have a substantial impact on body weight and risk of chronic disease. Fat replacers are used to provide some or all of the functional properties of fat, while providing fewer calories than the fat being replaced (ADA, 2005). These replacers are used in a variety of products from baked goods to frozen desserts. In this experiment, a recipe for ricotta cheese pancakes was altered to replace the ricotta cheese with non fat and regular Greek yogurt. Three trials were run on each of the three types of pancake variables (ricotta, nonfat Greek yogurt, and regular Greek yogurt). The goal was to create a pancake with Greek yogurt that maintained the favorable characteristics of the ricotta pancake, while decreasing fat and retaining protein. The results showed that neither variation of the Greek yogurt (non fat or regular) was able to produce the desirable flavor and texture provided by the ricotta in the pancakes. Consequently, we can infer that it is quite difficult for the food industry to create recipes that achieve a good balance between flavor/desirable characteristics and nutritional qualities. Introduction As time passes, more and more Americans are struggling with obesity and weight gain. As previously stated, more than one third (78.6 million) of U.S. adults are obese (CDC, 2014). Much of this issue may stem from the fact that the most delicious and preferred foods are not always the most nutritionally adequate. With that, many consumers value eating delicious foods over the nutritious ones. This experiment attempts to provide consumers with a pancake that is not only delicious, but also nutritionally adequate. In this experiment, the ricotta cheese in pancakes is replaced with Greek yogurt in order to decrease fat intake and retain protein. The purpose of the experiment is to produce a much more nutritious pancake, while retaining the flavorful pancake taste. In a study performed by Desai, consumers were documented on their descriptive profile and sensory tests. The study showed that consumers prefer Greek yogurts with firm, dense texture, moderate sweet aromatic, milk fat and dairy sour flavors, and moderate sour taste (Desai, 2013). Also in the study, consumers were informed of the protein content in the Greek yogurt and were aware of its great nutritional value. Perhaps knowing the

3 nutritional value of certain food products, including Greek yogurt, would make consumers more prone to purchasing products with more protein and less fat. According to the USDA, the fat content of ricotta cheese and Greek yogurt is 32 g and 0.7 g per one cup respectively (USDA, 2014). This comparison demonstrates the remarkable improvements the replacement has on nutritional value. Many consumers enjoy the taste of Greek yogurt, so with the addition of its savory flavor to the pancakes, it is predicted that the sensory panel will enjoy the new pancake. Choosing Greek yogurt was due in part to the popularity of this product with consumers today. The Greek yogurt recipe has an advantage over the ricotta cheese one due to preserved protein content and decreased overall fat content. Also, with the retained protein content, the Greek yogurt pancakes will help preserve satiety and perceived fullness from the panel. In the study, The Effects of Increased Dietary Protein Yogurt Snack in the Afternoon on Appetite Control and Eating Initiation in Healthy Women, experimenters tested hunger and fullness when participants ate Greek yogurt. They found that eating initiation, perceived hunger, fullness, and habitual dinnertime accounted for 30% of the variability of time to dinner request (Ortinau, 2013), and that eating Greek yogurt is a healthier snack to help control appetite due to the higher protein content. Additionally, Greek yogurt was chosen over potential other replacements because it is white in color just like ricotta, so it would not significantly alter the color of the finished product. It was decided that all of the ricotta cheese (rather than only half) would be replaced by the Greek yogurt (non fat or regular) in the different variables in order to create the most nutritionally desirable product. The biggest question overall is if Greek yogurt will produce a less desirable viscosity, water activity, color, and palatability in ricotta pancakes than ricotta cheese itself? The hypothesis is that Greek yogurt used in place of the ricotta in ricotta cheese pancakes will not have an effect on the viscosity, water activity, color, and palatability. The independent variable is the Greek yogurt that is going to be used as well as ricotta cheese. The three variables will be, non fat Greek yogurt, regular Greek yogurt, and ricotta cheese. The dependent variables that are going to be measured include viscosity, water activity, color, and the preference of a taste panel. The objectives of this experiment are to create a savory pancake that uses Greek yogurt in place of ricotta cheese, and to add nutritional value by using a product of less fat content while retaining high protein. Methods The recipe we are going to use is from The Kitchn website with the title of "Recipe: Fluffy Ricotta Pancakes." We decided on this recipe because not only is it simple enough for our limited amount of time, but it also does not contain fruit (blueberries) which might affect the textural properties of the product.

4 Procedure: Recipe from web site: 250 g Ricotta cheese 115 g Flour 2 g baking powder 22 g sugar 0.5 g salt 90 ml milk 116 g eggs (2 eggs), separated into yolks and whites 2 g vanilla Butter, for the pan (we will use canola oil spray instead) Half of the recipe will be made for each of the variables (ricotta cheese, non fat Greek yogurt, and regular Greek yogurt), which will yield a total of 1.5 times the original recipe. To allot for extras, our market order is 3 times the amounts found in the original recipe. Listed below is our recipe for the different variables. Altered recipe for our variables: 125 g Ricotta cheese, non fat Greek yogurt, or regular yogurt (variable of interest) 57.5 g flour 1 g baking powder 11 g sugar 0.25 g salt 45 ml milk 58 g egg (1 egg), separated into yolks and whites 1 g vanilla

5 Canola oil spray Whisk together flour, baking powder, sugar, and salt in a small bowl. Combine ricotta/non fat Greek yogurt/regular Greek yogurt, milk, egg yolks, and vanilla in a separate, larger mixing bowl. Add the dry ingredients to the ricotta and milk mixture, stirring gently until just combined. Beat the egg whites with a handheld electric mixer until stiff. Stir a small scoop of the egg whites into the pancake batter to lighten the batter, and then fold in the remaining whites with a spatula. Heat a griddle over medium high heat. Spray the pan with canola oil, just enough to coat the surface. Use a 1/3 cup measure to pour batter onto the hot griddle. Cook the pancakes for about 3 or 4 minutes, until the undersides are golden and you see a few bubbles popping through the pancakes. Flip the pancakes and cook another 2 to 3 minutes, until golden. Repeat with the remaining pancakes (Recipe: Fluffy Ricotta Pancakes). After the product is made, the remainder of the batter will be measured in a Brookfield viscometer at rpms 6, 12, 30, and 60 as well as the water activity system to measure the water activity. Measurements of the cooked pancakes will include the hunter calorimeter to measure color and the sensory panel for palatability. The sensory panel will be based on a most flavorful to least flavorful scale. Ordering the three variables in order from most flavorful to least flavorful will show us how the consumers liked the variables in order from greatest to least. Then the variables will be ranked individually on a line scale from flat, not thick to fluffy, and very thick. This will help show us how the panel perceives the characteristics of the various variables. Replications and Sampling: To ensure the data is consistent, three trials of each test will be performed. This will allow comparing and contrasting of the three variables in each of the objective tests in this experiment. Subjective tests will also be performed to determine the palatability of the product. Random numbers will be assigned to each sample so that panelists will not have any bias when tasting the final products.

6 Sensory Evaluation Taste every sample in front of you and record on this sheet. Rank in order the samples you find to be the most flavorful to the least flavorful (219, 456, 890) Most Flavorful Least Flavorful 3. On the scale below, please mark in between the line that best describes each pancake. 219 Flat, not thick Fluffy, very thick 456 Flat, not thick Fluffy, very thick 890 Flat, not thick Fluffy, very thick Discussion Data from the water activity system showed that the samples of the ricotta cheese batter and the non fat Greek yogurt had nearly the same average water activity. The regular Greek yogurt batter showed a slight difference in average water activity, but was still very close. All of the data was significant. The data is recorded and shown in a graph in Table 1 and Figure 1. This test resulted in a success of the initial goal of creating a pancake with Greek yogurt (regular or non fat) in place of ricotta cheese, while maintaining the same or similar water activity to the original ricotta Cheese batter recipe. All of the recipes have relatively high water activities and are fairly close to pure water, which has a water activity of 1.

7 The results collected from the Brookfield Viscometer are recorded in Tables 2 4, and the averages are shown in graph form in Figure 2. Unlike the water activity results, the viscosity results did not correlate as well with our predictions. Figure 2, displays how much higher the viscosity of the original ricotta batter was than the two Greek yogurt variations. Viscosity of the Non fat Greek Yogurt shows a very low viscosity compared to the other samples. The lower viscosity of the batter likely resulted in greater flatness and lower fluffiness of the cooked product, which is generally undesirable. The lower viscosity in the Greek yogurt samples can be attributed to the higher water content in Greek yogurt as compared to ricotta cheese. This was not a successful test since the two Greek yogurt samples resulted in lower viscosity and our objective was to create a product that had no difference from the original recipe.

8 Data collected from the Hunter Calorimeter can be found in Tables 5 7, and the averages can be viewed more easily in Figure 3. From the results, one can see that there is little to no difference in the color of the products. This was a successful test since the Greek yogurt variables resulted in a product that was nearly the same as the original ricotta cheese product. Part of this could be attributed to the fact that the Greek yogurt and the ricotta cheese are both white in color. It also demonstrates that Greek yogurt and ricotta cheese have similar properties that affect browning in the same ways. It should be noted that all of the products received the same amount of cooking time and doneness was measured by the time specified in the directions (4 minutes one side, 3 minutes on the other side), so no additional cooking was done on the products to make any additional color change. There could be possible sources of error in the color of the products as the heat of the pan was colder at the beginning of the cooking and throughout the process was heated for longer, so it was hotter when the later products were cooked. Overall, the test seemed to be a success. Taste preference data was collected from a sensory panel and is shown in Table 8 and Figure 4. The Figure 4 graph shows that most students preferred the ricotta cheese product and found the non fat Greek yogurt product to be mediocre. According to the USDA, ricotta cheese must have a lactic or acetic acid taste (USDA, 1981), perhaps it is this taste that is lacking in the Greek yogurt and reacts with the pancake recipe to product a desirable flavor. Additionally, they thought the regular Greek yogurt product was the least flavorful. This test did not correlate with our predictions, as we expected our products to taste the same or better than the original recipe. The tests show that the non fat Greek yogurt product was generally thought of as good and some students even thought of it as the most flavorful. The normal Greek yogurt product received only one vote as the most flavorful and was generally thought of as the least flavorful. This is a strange result as we thought that the normal Greek yogurt product would taste better than the non fat Greek yogurt product; however, it is a positive result for the overall objective of our experiment to make a product with lower amounts of fat while still keeping the protein content.

9 The sensory evaluations regarding the thickness of the products were recorded in Table 9, and the results are shown in Figure 5. The figure shows that most students picked the original ricotta cheese product as the thickest, and the normal Greek yogurt pancake as the flattest. Once again, these results did not correlate with our predictions. We expected the yogurt products to be the same or better in terms of thickness, yet the original ricotta recipe turned out to be the thickest product. The results seemed a little off as the non fat Greek yogurt product had a lower viscosity than the normal Greek yogurt, as shown in Table 3, and thus we would expect it to be less thick and more flat. However, results shown in Table 9 show that it was generally thought to be medium thick, and the normal Greek yogurt product was the flattest of the 3 products. One source of error for this could have been if the pancake was smashed down further with the spatula during the cooking process. This smashing could have caused the normal Greek yogurt pancake to appear thinner than the non fat Greek yogurt pancake. Additionally, differences could have been caused by variations in amount of fat. According to the USDA, nonfat Greek yogurt must contain 0.5% or less fat (USDA, 2001). Because there is less fat, other ingredients must be added in order to create the same properties found in regular Greek yogurt. These added ingredients are what could have potentially produced a slightly thicker pancake. In conclusion, we can say that the Greek yogurt pancakes were not as successful as the original ricotta cheese pancakes. Overall, the panel preferred the original recipe. Although the Greek yogurt pancakes were a healthier alternative, they did not provide the desirable flavor and texture/thickness properties provided by the ricotta cheese. Consequently, the panel preferred the ricotta pancakes. According to a paper on the position of the ADA on fat replacers, fat helps to absorb many flavor compounds, which helps to make foods high in fat more flavorful and desirable in general (ADA, 2005). Additionally, fat affects the viscosity, body, and melting point of food products (ADA, 2005). Consequently, we can see that the reason the panel preferred the ricotta cheese pancakes is their fat content. The fat found in ricotta cheese undeniably gives the pancakes the flavor, viscosity, and body that is desired by consumers. The Greek yogurt fails to provide the fat that offers these characteristics. Interesting enough though, the non fat Greek yogurt pancakes were more successful than the regular Greek yogurt pancakes. This tells us that the non fat Greek yogurt and the ricotta cheese are likely more similar to each other in the way they react in the pancake recipe than the regular Greek yogurt. The fact that the less healthy ricotta cheese produced a more flavorful and desirable pancake than the Greek yogurt variations demonstrates a key point and issue in the American society today. That is, it is very difficult for the food industry to please consumers both nutritionally and flavor wise. That is, consumers tend to prefer the characteristics associated with less healthy food products. This study suggests that further work will still need to be performed in order to create the perfect pancake. Perhaps more tests could be performed using only 50% non fat Greek yogurt and 50% ricotta cheese. This may produce a better compromise between nutrition and flavor. One of the biggest goals of the food industry is to produce products that are not only affordable, but are also nutritious and delicious. This is an area that is

10 currently being experimented with and hopefully in the future we will be able to come up with even more healthy alternatives. Results Table 1: Water Activity Results for all Variables Water Activity (aw) Ricotta Cheese Non Fat Greek Yogurt Greek Yogurt Trial Trial Trial Average Std. Dev Comparison of Water Activity Averages For All Variables Water Activity (aw) Ricotta Cheese Non Fat Greek Yogurt Greek Yogurt Types of Variables Figure 1: Averages of Water Activity (aw) results for all three variables. Standard deviation of error is shown. All values were statistically significant, p<0.05.

11 Table 2: Viscosity of Ricotta Cheese Pancakes at Various rpms using the Brookfield Viscometer Viscosity Ricotta Cheese 6 rpm 12 rpm 30 rpm 60 rpm Trial Trial Trial Average Std. Dev Table 3: Viscosity of Non Greek Yogurt Pancakes at Various rpms using the Brookfield Viscometer Viscosity Non Fat Greek Yogurt 6 rpm 12 rpm 30 rpm 60 rpm Trial Trial Trial Average Std. Dev Table 4: Viscosity of Greek Yogurt Pancakes at Various rpms using the Brookfield Viscometer Viscosity Greek Yogurt 6 rpm 12 rpm 30 rpm 60 rpm Trial Trial Trial Average Std. Dev

12 Viscosity of Various RPMs vs Each Variable Viscosity Ricotta Cheese Non Fat Greek Yogurt Greek Yogurt 0 6 rpm 12 rpm 30 rpm 60 rpm Rpm of Each Variable Figure 2: Averages of Viscosity results for all three variables from four different rpms using the Brookfield Viscometer. Standard deviation of error is shown. All values were not statistically significant, p>0.05. Table 5: Hunter Calorimeter Results of Ricotta Cheese Pancakes Hunter Calorimeter Ricotta Cheese L a b Trial Trial Trial Average Std. Dev Table 6: Hunter Calorimeter Results of Non Fat Greek Yogurt Pancakes Hunter Calorimeter Non Fat Greek Yogurt L a b Trial Trial Trial Average Std. Dev

13 Table 7: Hunter Calorimeter of Greek Yogurt Pancakes Hunter Calorimeter Greek Yogurt L a b Trial Trial Trial Average Std. Dev Hunter Calorimeter Hunter Calorimeter Averages vs. All Variables L a b L, a, b Results of all Variables Ricotta Cheese Non Fat Greek Yogurt Greek Yogurt Figure 3: Averages of Hunter Calorimeter results for all three variables. Standard deviation of error is shown. All values were not statistically significant, p>0.05. Table 8: Sensory Taste Values for all Variables 1 (most flavorful) 2 3 (least flavorful) 219 Ricotta Cheese 456 Non Fat Greek Yogurt 890 Traditional Greek Yogurt 1 2 9

14 10 Subjective Values for Taste Based on Student Preferences Students (most flavorful) 2 3 (least flavorful) Sensory Evaluation (Taste) 219 Ricotta Cheese 456 Non Fat Greek Yogurt 890 Traditional Greek Yogurt Figure 4: Sensory comparison of trials indicating that 219 (ricotta cheese) was the most flavorful and 890 (Greek yogurt) was least flavorful. Table 9: Sensory Sight Values for all Variables (Thick vs. Flat) 1 (Fluffy, very thick) 2 (medium thickness) 3 (Flat, not thick) 219 Ricotta Cheese 456 Non Fat Greek Yogurt 890 Traditional Greek Yogurt 0 4 8

15 Subjective Values of Thickness based on Student Preference Students Ricotta Cheese 456 Non Fat Greek Yogurt 890 Traditional Greek Yogurt Sensory Evaluation (Thickness) Figure 5: Sensory comparisons indicating that 219 (ricotta cheese) was the most thick and fluffy and 890 (Greek Yogurt) was the least thick and most thin. References Adult Obesity Facts. Centers for Disease Control and Prevention Web site. Available at: Published September 9, Accessed November 30, Desai NT, Shepard L, Drake MA. Sensory Properties and Drivers of liking for Greek Yogurts. J Dairy Sci Dec; 96 (12): Ortinau LC, Culp JM, Hoertel HA, Douglas SM, Leidy HJ. The Effects of Increased Dietary Protein Yogurt Snack in the Afternoon on Appetite Control and Eating Initiation in Healthy Women. Nutr J Jun 6; 12(1): 71. Position of the American Dietetic Association: Fat Replacers. J Am Diet Assoc Feb; 105(2): Recipe: Fluffy Ricotta Pancakes. The Kitchn Web site. Available at: fluffy ricotta pancakes Published June 17, Accessed November 30, USDA Specifications for Ricotta Cheese. United States Department of Agriculture Web site. Available at: Published January 15, Accessed November 30, 2014.

16 USDA Specifications for Yogurt, Nonfat Yogurt and Lowfat Yogurt. United States Department of Agriculture Web site. Available at: Published January 19, Accessed November 30, Appendix

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