Title: The effect of the addition of cocoa powder on color, palatability, and texture of Rice

Transcription

1 Garret Brooks, Chris Manganais, and Michelle Meadors Title: The effect of the addition of cocoa powder on color, palatability, and texture of Rice Krispy treats. Abstract: In today s society people are constantly seeking out various food products that are enjoyable and beneficial to their health and well-being. One of the more popular foods that exhibit both of the aforementioned characteristics is chocolate. Chocolate consumption has also been shown to reduce the risk of cancer. The phenolic compounds found in chocolate exhibit antioxidant effects, which reduce the damaging effects of free radicals in the body. Due to the popularity of chocolate as well as its known health benefits, 70% cocoa has been added to a conventional recipe for chocolate Rice Krispie Treats. The dependent variables associated with the experiment will include analysis of texture using a texture analyzer, color using a hunter colorimeter, the force associated with breaking through the product using a shear press, and a hedonic scale based on taste preference. The Hunter Colorimeter revealed that the more cocoa powder added, the lower the L value is which correlates to a darker color. The shear press did not really decipher any particular attribute as to the cocoa changing the shear force. The survey provided results which indicated that the greater the amount of cocoa added, the greater the hedonic preference. Introduction: Chocolate has been popular throughout the world for years, even dating back to the Incas and Mayans. According to Rimbach, Cocoa is a rich source of dietary polyphenols. In vitro

2 as well as cell culture data indicate that cocoa polyphenols may exhibit antioxidant and antiinflammatory, as well as anti-atherogenic activity (Rimbach 2009). There has been further studies seen that these claims have held true. According to a study conducted by Flammer coronary vasomotion was assessed after 40g of dark chocolate and the respective test and control groups consumed regular chocolate. The results concluded that dark chocolate helps coronary vasodilatation and vascular function. It also decreases platelet adhesion. These effects were seen 2 hours after consumption. These beneficial effects were in conjunctions with a reduction of serum oxidative stress (Flammer 2007). Based on the information found on previously conducted research it was determined that this experiment being preformed would test 40g of dark chocolate. It will be added in the form of cocoa powder by adding 21.5g of 70% cocoa powder. According to Klimczak, The process of creating the tumor begins and develops when the balance between the production of reactive oxygen species (ROS) and their deactivation by the "antioxidant protective barrier of the organism" is disturbed (Klimczack 2010). Therefore, intake of chocolate increases the amount of antioxidants in the body, leveling out the balance between reactive oxygen species and antioxidants. There is a logical relationship between the dependent and independent variables in this study, as adding cocoa powder to the mixture will alter the composition. A change in color is likely as cocoa is a darker substance, most likely yielding a darker product. Changes in texture due to addition of the powder will most likely not be present. Also, a change in force needed to break through the product will likely be noticed as the addition of the powder will alter chemical composition as well as interactions within the product, either increasing or decreasing force needed to break through the product. These

3 methods have been chosen, as they seem to be the most relevant objective and subjective measurements that will be affected or altered by the addition of the cocoa powder to the product. These are some of the standard procedures when testing a new product. Hence the purpose of the project is to see if we can detect any changes in the product as the cocoa powder was added in various levels, as well as determining whether or not the altered product is more favorable than the original product it is being compared to. The addition of 70% cocoa powder to Rice Krispy treats will increase antioxidant intake without altering flavor. The independent variable is the amount of cocoa powder added to the Rice Krispy treat mix and the amounts that are going to be added are 16g and 21.5g cocoa powder. The dependent variables that are going to be measured are color, force to break through the treat, the preference of a taste panel, and texture. The purpose of this experiment is to produce a Rice Krispy treat with the addition of cocoa powder to improve health benefits by increasing antioxidant intake without affecting the taste of the product. Methods: The recipe is going to be used from the website cooks.com. One mix will be made at a time and each Rice Krispy Treat mix will make a 9X13 pan of treats to make 24 bars (2X2 servings). It is as listed below. Control First melt 57.48g butter in large saucepan over low heat. Add 284.7g marshmallows to the mixture and stir until all ingredients are completely melted

4 Add g of Rice Krispies to the mixture and stir until the cereal is well coated with the mixture then remove from heat. Lastly using buttered spatula or waxed paper the mixture will be pressed evenly into buttered 13 x 9 x 2-inch pan and allowed to cool Variable 352 First melt 57.48g butter in large saucepan over low heat. Add 284.7g marshmallows to the mixture and stir until all ingredients are completely melted Add 16g Cocoa Powder (70%) to the mixture Add g of Rice Krispies to the mixture and stir until the cereal is well coated with the mixture then remove from heat. Lastly using buttered spatula or waxed paper the mixture will be pressed evenly into buttered 13 x 9 x 2-inch pan and allowed to cool Variable 453 First melt 57.48g butter in large saucepan over low heat. Add 284.7g marshmallows to the mixture and stir until all ingredients are completely melted Add 21.5g Cocoa Powder (70%) to the mixture Add g of Rice Krispies to the mixture and stir until the cereal is well coated with the mixture then remove from heat. Lastly using buttered spatula or waxed paper the mixture will be pressed evenly into buttered 13 x 9 x 2-inch pan and allowed to cool

5 For objective testing the texture analyzer measurements were not conducted, because the machine was not functioning. The hunter colorimeter each sample was placed in a petri dish that was placed into the colorimeter and was used on the normal manufacturing setting and was zeroed before determining the color of the samples. Lastly, the shear press was also set to zero before measuring breaking strength. For subjective testing each sample was assigned a random number corresponding with the scorecards, so that subjects would give an unbiased answer. An example of a scorecard that was distributed is provided below. Sensory Evaluation: Scorecard Rank on a 9-point hedonic scale 9= like extremely, 8=like very much, 7=like moderately, 6=like slightly, 5=neither like nor dislike, 4=dislike slightly, 3=dislike moderately, 2=dislike very much, and 1=dislike strongly Variable A. 101 Flavor B. 352 C. 453 Discussion: Overall, the experiment went well. The colors of the Rice Krispies with cocoa powder added were darker than the Rice Krispies without cocoa powder. This was shown by the values received from the hunter colorimeter in Table 1. As seen in Figure 1, the data shows that the L value gets lower as more cocoa powder is added. Because the L value represents lightness it

6 makes sense to have the mixture with the most chocolate added forming the darkest treat in color resulting in the lowest lightness value. The addition of cocoa powder provided no significant difference in pounds of force needed to cut through the Rice Krispies treats. Looking at Table 2, it is seen that the treat with 16g of cocoa added actually took less force to cut through it than the control with no addition of cocoa power. The treat with the addition of 21.5 grams of cocoa powder took the most force to cut through. The texture analyzer would not penetrate the product properly to give an accurate reading to determine how the addition of cocoa powder to the treats affected the texture. The only data given that could contribute to the effect on texture was the sensory data on the taste of the product. This could be done if using the assumption that a bad texture would result in a bad tasting product giving a lower score on taste. The sensory data showed that there was about a 1-point difference in taste preference between the variable with 16g of cocoa powder versus the variable with 21.5g of cocoa powder. The conclusion is that this is due to a stronger chocolate taste in the variable with more cocoa powder. The subjects would prefer no cocoa, but if there were cocoa present they would prefer more rather than less. This can be seen with Table 3 shown below. Several sources of potential error were discovered in the experiment. First of all, the results showed that the addition of 16g of cocoa powder required an average of 5 pounds less of force to cut through than the control and the addition of 21.5g of cocoa powder. The error can be attributed to various elements of human error. To begin the three different batches

7 were made by three different individuals. This could attribute to some source of error due to the technique of mixing, weighing out the Rice Krispie cereal used for the treats, temperature reached when melting the marshmallows, and transferring the product to a pan. Another error that could attribute to this difference in results could be errors in operation of the shear press. The force to cut through the treat was measured for all 3 trials of the Rice Krispies with 16g of cocoa powder first instead of doing each 3 samples for each trial and then repeating for every trial. This could have attributed to an inaccurate reading of force. It can be seen that human error could have played a huge role in altering our data. Whether it was by making each trail or operating the machinery to test each trial human error could be present. Because this is a known contributor to the alteration of experimental data there are guidelines that have been presented to minimize human error. Michael Mahoney presents these guidelines in his book, Sensory Evaluation of Food, which can help reduce operator error (Michael Mahoney, 1986). Using these guideline would help minimize the error present and lead to more conclusive data. Due to the many complications from the texture analyzer further research is needed to determine if the addition of cocoa powder does affect the texture. Using a knife type attachment on the machine may give a better reading than the probe that was used in this experiment. Also research may be needed to determine the chemical alteration of marshmallows with the addition of cocoa powder. While making the different trials it was discovered that the marshmallows texture, color, and strength changed with the addition of cocoa powder.

8 Results: Figure 1: Results of Hunter Colorimeter Figure 1 represents the L, a, and b values associated with each of the three products tested on the Hunter Colorimeter. The data above shows that as more Cocoa was added the lower the L values became. This is because L value is associated with Lightness in color of the product. This is why the product with the most cocoa powder has the lowest values for L. Table 1: L a b Values from Hunter Colorimeter Hunter Colorimeter Control 16g Cocoa Powder 21.5 g Cocoa Powder L a b L a b L a b Average L Standard Deviation: +/ a Standard Deviation: +/ b Standard Deviation: +/

9 Figure 2: Results of shear press for trials 1-3 Figure 2 graphically represents data obtained from the shear press for trials 1-3 on all the products assessed in this experiment. It is visible that the product with less Cocoa powder needed less force to shear through. While the product with more cocoa powder needed more force to be sheared through. In comparison to the control the product with the most cocoa powder was the most similar in terms of force needed to shear through it. Table 2: Values of Force associated with trials 1-3 on shear press Shear Press Control 16g Cocoa Powder 21.5 g Cocoa Powder Average 7.5a 2.667b 7.667a Standard Deviation: +/-2.84

10 Figure 3: Average values for trials 1-3 obtained on the shear press. Figure 3 shows the results from the average values from the shear press. This graphic representation shows that when compared to the control, the force associated with the product containing 21.5g of cocoa powder was almost, if not the same. When observing the force associated with the product containing 16g of cocoa powder, the results show that the force needed to shear the product was much less than the control. Table 3: Subjective preference average values based on a 9 point hedonic scale. Sample Preference Description Control 16g Like Very Much Like Slightly 21.5g Like Moderately

11 References: Rice Kispy Treat Recipe. Cooking Recipies and More Available at Flammer A, Hermann F, Sudano I, Spieker L, Hermann M, Cooper K, Serafini M, Lüscher T, Ruschitzka F, Noll G & Corti R Dark chocolate improves coronary vasomotion and reduces platelet reactivity. Circulation 116(21): Klimczak A, Kubiak K, Cybulska M, Kula A, Dziki & Malinowska K [Etiology of colorectal cancer and antioxidant barrier of the organism]. Pol Merkur Lekarski 28(165): Mahoney Michael O. Sensory Evaluation of Food. Marcel Dekker Inc. pp Rimbach G, Melchin M, Moehring J & Wagner A Polyphenols from cocoa and vascular health-a critical review. Int J Mol Sci 10(10):