The Effect of Various Protein Sources On the Quality of Chocolate Chip Muffins

The Effect of Various Protein Sources On the Quality of Chocolate Chip Muffins Team Members:, Dr. James Daniel, F&N453: Due Date: November 24, 2008 ABSTRACT There are individuals that may not be physically able to consume dairy, such as those with lactose intolerance or dairy allergies. These individuals have to look for milk alternatives when looking to meet the dietary guidelines of calcium, vitamin D, and other important nutrients. Although lactose cannot be tolerated, it has been shown that yogurt is more easily digested (Kolars, 1984). In this study, the effect of replacing milk with yogurt and soy-based proteins on the texture and flavor of chocolate chip muffins is examined. There were four variables being tested: a combination of milk and yogurt (control), milk only, yogurt only, and firm tofu. The results of a sensory evaluation, as well as measures of texture and water activity, indicate that the most desirable muffin consists of a combination of milk and yogurt. INTRODUCTION The consumption of protein in food products is very important for bone and muscle health, as well as many bodily processes. According to the National Dairy Council, an 8-ounce glass of milk contains about 16% of the Daily Value for protein (National Dairy Council, 2004). Calcium is also of much significance. The National Institute of Health has indicated that calcium consumption among every gender and age group does not meet the current recommended calcium intake (National Institute of Health, 2004). Meeting these recommendations can be hard to meet, as the population has been consuming diets higher in fats and sugars partly due to busy lifestyles. The supplementation of milk in muffins can be beneficial to one s health in various ways, but can also make an enjoyable food edible for those who would not be able to otherwise consume such products. Patients with lactose intolerance suffer unpleasant and painful side effects when they consume lactose. (National Institute of Health, 2006) According to KidsHealth, there are 30 million 50 million people who are lactose intolerant in the United States alone (Gavin, 2004). Though yogurt is still a dairy product, it has been observed that those who are lactose intolerant can still digest it. The New England Journal of Medicine referred to yogurt as an auto-digesting source of lactose (Kolars, 1984). In their studies they found that when yogurt was digested it released lactase that was able to digest the lactose in the intestines. The subjects absorbed the lactose from yogurt more than from other milk products and reported fewer side effects. Digestion benefits can be provided to those who may not be lactose intolerance as well. Many gastrointestinal conditions benefit from the consumption of yogurt (Adolfsson, 2004). Tofu will also work to benefit various health risks in consumers. Soy is found to be a good source of isoflavones and lignans. Research shows that these phytoestrogens may provide health

benefits to cardiovascular diseases, cancer, osteoporosis, and menopausal symptoms. Replacing milk in the muffins will hopefully provide extra benefits, but also still remain the same pleasing product. To be sure than the muffins are still palatable, a series of taste tests will be done. Muffins are usually so palatable due to their very moist, soft texture. The moisture content will be measured with a water activity machine, and texture will be tested with a texture analyzer. METHODS Overall Design The overall design of the experiment was to use the same chocolate chip muffin recipe, but substitute various protein sources for each variable. The original recipe, which can be seen in Table 1, used a combination of milk and yogurt, and the other independent variables being tested were milk only, yogurt only, and firm tofu in place of the milk and yogurt (AllRecipes.com, 2008). The experimental procedure was repeated on three separate occasions to offer data for three trials to be averaged. TABLE 1 Chocolate Chip Muffin Recipe Ingredients. Original Modified (independent variables) 115 g butter, softened 115 g butter, softened 100 g white sugar 100 g white sugar 2 eggs 2 eggs 235 ml milk 355 ml [independent variable] 120 ml plain yogurt 5 ml vanilla extract 5 ml vanilla extract 375 g self-rising flour 375 g self-rising flour 85 g semi-sweet chocolate chips 85 g semi-sweet chocolate chips Procedure Before entering the laboratory, the water activity machine was turned on to provide ample warm-up time. Since the original recipe yielded 12 muffins, calculations were done to scale down the yield to only four muffins for each variable. The oven was preheated to 350 F before preparation of the batter to ensure the proper temperature would be reached on time. The cooking equipment and utensils were then gathered and brought to the work station. All ingredients were measured using a digital scale or a glass liquid measuring cup. Four large mixing bowls were needed, and each was labeled with a variable name. The following procedure was repeated simultaneously for each variable, resulting in four different batters in each bowl. The 28.75 grams of butter had to be softened in the microwave for 15 seconds, and then a metal spoon was used to cream it together with 25 grams of sugar in a large mixing bowl. Half of an egg was then beaten in with an electronic mixer. To fulfill the scaled-down version of the original recipe (one-fourth amount), one egg was weighed on a scale and the weight was divided in half to ensure a controlled product was produced for each variable and trial. Next, 58.75 ml of milk, 30 ml of yogurt, and 1.25 ml of vanilla extract were mixed in with an electronic mixer. Since this is the control variable, each of the other 3 variables were 2

prepared using 88.75 ml of either milk only, yogurt only, or tofu only. Finally, 93.75 grams of flour was blended in with an electric mixer and 21.25 grams of semisweet chocolate chips were folded in using a metal spoon. To make certain the muffin variables would not get mixed up, a different color of muffin paper cup was used for each and recorded on a sheet of paper. The paper cups were then placed into a metal 12-compartment muffin tray and filled with batter to three-fourths full. A second metal 12-compartment muffin tray was used for the remaining 4 muffins. There was also enough extra batter to make 1-2 additional muffins for each variable, so this batter was also scooped into paper muffin cups and baked to be used for testing. The muffins were taken out of the oven with baking mittens after 15 minutes of baking and tested for doneness with a toothpick. It was determined that the muffins were not yet completely cooked, so they were placed into the oven for 5 minutes longer and checked again. After 20 minutes the muffins were fully cooked and the trays were removed from the oven with baking mittens and placed on top of the oven to cool. During this time the oven was turned off, and the dishes were washed, dried, and put away. The ingredients were also taken back to the store room. Subjective and Objective Analysis Once the muffins had time to cool, they were removed from their paper cups and cut into bite-sized pieces to be sampled for the sensory analysis. One muffin from each variable was saved to be used for the objective testing. The cut up pieces were put onto a paper plate, labeled with a 3-digit number, and set out on a table with sensory evaluation score cards to be tested by other classmates. An example of the sensory score card used can be seen in Table 2. The participants of the sensory analysis were unaware of which variation was being sampled to provide randomization. The cards were collected afterwards and dated for each trial. While the students were tasting the muffin samples and filling out the sensory score cards, samples were taken to another laboratory for objective testing. The guide to the use of equipment in this experiment can be found in the Food Chemistry Laboratory Manual, C. Weaver and J. Daniel, 2003, pages 107-132. The amount of moisture is indicated by water activity, which was measured using a Water Activity System Meter (Aqua Lab CX-2, Decagon Devices, Inc). Each muffin sample was prepared in plastic sample dishes to no more than half way full. The sample cup was then inserted into the sample drawer and the measurement was recorded once complete. This process was repeated for each variable. The texture was measured using a Texture Analyzer (Stable Micro Systems Ltd). A puncture probe was attached and adjusted to the proper height. The parameters that were used can be seen in Table 3. Once the samples were prepared to be of uniform size and shape, each variable was tested separately and the measurements were analyzed and recorded (Weaver, 2003). 3

TABLE 2 Sensory Evaluation Score Card. Paired Preference Test Which sample (537 or 961) do you prefer? Which sample (961 or 742) do you prefer? Which sample (408 or 537) do you prefer? Which sample (742 or 408) do you prefer? Please indicate how much you like or dislike the sample by checking the appropriate box. Sample 742 Sample 408 Neither like Extremely Sample 961 Neither like Sample 537 Neither like Neither like Appearance Please comment on appearance of each sample. Include color and distribution of chocolate chips. Sample742: Sample 408: Sample 961: Sample 537: TABLE 3 Texture Analyzer Parameters. Pretest Speed 2.0 mm/sec Test Speed 5.0 mm/sec PostTest Speed 5.0 mm/sec Rupture Test Dist 1.0 mm/sec Distance 20 mm Force 2000 g Time 5 seconds Count 5 4

DISCUSSION When reviewing the results, it is possible to create a muffin that keeps a desirable flavor while replacing the protein source. The muffins that used yogurt or tofu in place of milk can be an alternative for those who are lactose-intolerant. The original recipe is still the most desirable for taste, but the yogurt and tofu still show to be palatable. A study done at University of Illinois to test soy protein in baked goods showed that the use of soy decreases sweetness. (Brewer, 1992). The sweetness of the muffin was important for an enjoyable taste. Each variation proved to be moister than the control. Moisture is an important factor that should not be jeopardized when making muffins. A moist product is more desirable in muffins. It may be expected that the all milk variable would produced the moistest product, but of the altered recipes it showed the least amount of water activity. According to an experiment done on fat substitution in home baking, the use of non-fat yogurt will produce a product that is moister (Schantz, 1995). This showed true for our results with a water activity average that was.062 greater than that of the original recipe. In an experiment that used soy proteins in baked products for clinical studies, it showed that soy products retain high amounts of water (Klein, 1995). This would create a moister product because less steam would be let off and more water would be held in. This held true for the results with tofu having the highest water activity,.09 greater than the control. Overall, using an alternate protein to eliminate the problem of lactose-intolerance in chocolate chip muffins can be effective in the moisture quality aspects. Changing the protein source in a muffin can also change the texture of the finished product. The texture is also important for consumer satisfaction. With higher water activity, it would be expected there would be a softer, more tender product. This was not the case in the results of the experiment. The control was the most tender product at an average of 236.2 gram force. Milk was next with 268.1, followed by yogurt at 346.6. The yogurt may have had a firmer texture due to lesser amount of liquids in the recipe. The tofu had the largest force at 390.7 grams. This could be because of the more solid texture of the tofu. It can also be due the water absorbing properties of the tofu. The tofu absorbed a great amount of water and therefore there was a smaller amount of water to be let off in steam. Steam acts as a leavening agent in baked goods. The small amount of leavening created a more compact product. The tofu muffin hardly raised at all from their starts sizes. The product was therefore more dense and created a less tender, harder textured product. These results proved to be consist with an experiment done with soy proteins on baked products. The results from the experiment done at the University of Illinois had products with denseness increasing and baked volumes and crown peaks decreasing with soy (Brewer, 1992). This overall appearance could have contributed the taste testers taste rating. Seeing a product that looks different than what is normally expected could unconsciously cause a person to think it does not taste as good. This could have also contributed to the lower rating of taste on the tofu muffins. The experiment results could have been affected by human error or equipment error. When carrying out multiple trials it is always possible to have variations in measuring out ingredients. This could have been a possibility in Trial 2, due to the very different numbers for water activity 5

and texture. Trial 2 could have also been altered by the possibility of opening the oven while the muffins were baking, the conditions of the laboratory, or rack position. The amount of chocolate chips in each muffin could have greatly affected results as well. Greater amounts of chocolate chips will lead to a sweeter, more desirable taste. They would also affect water activity. The chocolate chips could also be near the top of the muffin where the Texture Analyzer penetrated the muffin, altering the results. The Texture Analyzer could have contributed to error as well. Due to the high amount of use during the many experiments being conducted, the machine was not working one day. The trial could have been conducted near the time the machine was not properly functioning. If this experiment were to be carried out again, a few things may want to be considered. Be sure that laboratory conditions are always consistent and oven racks are the same. It may be possible to add chocolate chips to the muffins once the batter has been poured into the pan. This will ensure that each muffin has the same amount of chips and therefore will have the same sweetness. The substitution of proteins in chocolate chip muffins can provide more acceptable products for lactose-intolerant people. The different proteins will affect the muffins texture, water activity, and taste. More research may be needed on this substitution to determine further acceptability of the product for lactose-intolerant. RESULTS TABLE 4 Effects of Various Protein Sources on Water Activity of Chocolate Chip Muffins Variable Trial 1 Trial 2 Trial 3 Average St Dev Control 0.687 0.311 0.834 0.611 0.270 Milk 0.739 0.338 0.867 0.648 0.276 Yogurt 0.714 0.483 0.821 0.673 0.173 Tofu 0.870 0.411 0.823 0.701 0.253 TABLE 5 Effects of Various Protein Sources on Texture of Chocolate Chip Muffins Variable Trial 1 Trial 2 Trial 3 Average St Dev Control 229.3 213.8 265.5 236.2 26.53 Milk 326.0 188.1 290.3 268.1 71.57 Yogurt 436.8 291.4 311.7 346.6 78.74 Tofu 472.1 295.9 404.1 390.7 88.86 6

Water Activity 1.200 1.000 0.800 a w 0.600 0.400 0.200 0.000 control milk yogurt tofu Variable Figure 1 Average measurements of water activity for various protein sources in chocolate chip muffins. 600 Texture Analyzer 500 Force (g) 400 300 200 100 0 control milk yogurt tofu Variable Figure 2 Effect of various protein sources on average penetration force of chocolate chip muffins. 7

Control Preference like 33% neither like 17% like 50% Figure 3 Sensory analysis of average preference for control variable of chocolate chip muffins. like 10% Milk Preference dislike 10% like 50% neither like 30% Figure 4 Sensory analysis of average preference for milk variable of chocolate chip muffins. 8

Yogurt Preference like 17% like 33% dislike 50% Figure 5 Sensory analysis of average preference for yogurt variable of chocolate chip muffins. Tofu Preference like 33% neither like 50% like 17% Figure 6 Sensory analysis of average preference for tofu variable of chocolate chip muffins 9

REFERENCES Adolfsson, Oskar, Simin Nikbin, and Robert M. Russell. 2004. Yogurt and Gut Function. American Journal of Clinical Nutrition; 80: 245-56. AllRecipes.com. 2008. Chocolate Chip Muffins II. Retrieved Sept 25, 2008. < http://allrecipes.com/recipe/chocolate-chip-muffins-ii/detail.aspx>. Brewer, S., Potter, S., Sprouls, G., & Reinhard, M. (2007). Effect of Soy Protein Isolate and Soy Fiber on Color, Physical, and Sensory Characteristics of Baked Products. Journal of Food Quality, 15(4), 245-262. Retrieved November 20, 2008. <http://www.interscience.wiley.com/ journal/119327211/abstract?cretry=1&sretry=0/>. Gavin, Mary L. 2004. Lactose Intolerance. The Nemours Foundation. Retrieved Sept 25, 2008. < http://kidshealth.org/kid/health_problems/allergiesimmune/lactose.html>. Klein, B., Perry, A., & Adair, N. (1995). Incorporating Soy Proteins in Baked Products for Use in Clinical Studies. Potential Public Health Impact of Soy Protein, 1, 666S-674S. Retrieved November 20, 2008. <jn.nutrition.org/cgi/reprint/125/3_suppl/666s.pdf>. Kolars, J. C., M. D. Levitt, M. Aouji, and D. A. Savaiano. 1984. Yogurt: An Autodigesting Source of Lactose. New England Journal of Medicine. Vol. 310, No. 1. National Dairy Council. 2004. Milk s Unique Nutrient Package. <http://www.nationaldairycouncil.org/nationaldairycouncil/ Nutrition/Products/ MilksNutrientPackage.htm>. National Institute of Health. 2004. Dietary Supplement Fact Sheet: Calcium. Office of Dietary Supplements. < http://ods.od.nih.gov/factsheets/calcium.asp>. National Institute of Health. 2006. Lactose Intolerance. Retrieved Sept 25, 2008. < http://digestive.niddk.nih.gov/ddiseases/pubs/lactoseintolerance/>. Schantz, R., & Mcnulty, J. (1995). Fat Substitution in Home Baking. Cooperative Extension Service, B-990, 1-2. Retrieved November 20, 2008. <ces.uwyo.edu/pubs/wy990.pdf>. Tunick, Michael H. 1987. Calcium in Dairy Products. Journal of Dairy Science. Vol. 70, No. 11. Weaver, Connie M. and James R. Daniel. 2003. The Food Chemistry Laboratory: A Manual for Experimental Foods, Dietetics, and Food Scientists, 2 nd Ed. West Lafayette, IN: CRC Press. Pages 107-132. 10