The effect of adding different amounts of Avocado on Ice Cream. Maria Holland F&N 453 Individual Project Written Report November 19, 2007

Transcription

1 The effect of adding different amounts of Avocado on Ice Cream Maria Holland F&N 453 Individual Project Written Report November 19, 2007

2 The effect of adding different amounts of Avocado on Ice Cream Abstract: Some research suggests that diets including monounsaturated fatty acids (MUFA) can have a positive effect on cholesterol, blood pressure, blood clotting and inflammation. Avocadoes provide a significant source for MUFA. The purpose of this experiment is to determine which weight (g) of added avocado will produce the best texture and palatability for the consumer. Mint flavored ice cream was used as a control. To the control, three different amounts of avocado were added at 70g, 170g, and 270g respectively. For a subjective test, a taste panel was used for each trial to rate the final product on overall appearance, texture and taste. A Texture Analyzer and Hunter Colorimeter were used as objective measures for the ice cream. Findings show that the addition of 70g avocado had the least impact on the overall appearance, texture and taste of the ice cream. The control sample with no added avocado was most accepted. The addition of 270g avocado was not accepted by the participants. In conclusion, a small addition of avocado to ice cream provides a similar texture and taste as the control ice cream, as well as additional vitamins, minerals and healthy monounsaturated fats. I. Introduction: Background According to nutrition facts of fresh Avocados, they contribute nearly 20 vitamins, minerals and beneficial plant compounds that can contribute to the nutrient content of your diet. Phytonutrients are thought to help prevent many chronic diseases. Due to their mono and polyunsaturated fat content, they are a healthy substitution for foods rich in saturated fat. One fifth of a medium avocado (1 oz) has 50 calories and 76 milligrams of beta-sitosterol, which may help maintain healthy cholesterol levels. Avocados act as a nutrient booster by enabling the body to absorb more fat-soluble nutrients, such as alpha-and beta-carotene as well as lutein, in foods that are eaten with the fruit (Unlu and others 2006). Lutein is a natural antioxidant that may help maintain eye health as we get older. These avocados were found to contain the highest content of lutein among commonly eaten fruits as well as measurable amounts of related carotenoids (Lu and others 2005). Obesity is a major health concern because it is implicated in the development of many chronic diseases. Strategies recommended for weight control have generally recommended the adoption of low-fat diet, which results in energy restriction and cardiovascular disease risk reduction (Noakes and others 2005). According to the American Heart Association, avocados can help consumers meet the dietary guidelines which are to eat a diet that is low to moderate in fat. The fats should be primarily unsaturated and low in saturated fat and cholesterol. The avocado is the only fruit that has monounsaturated fat. Also, according to the dietary guidelines, one should keep total fat intake between 20 to 35 percent of calories, with most fats coming from sources of polyunsaturated and monounsaturated fatty acids, such as fish, nuts, and vegetable oils (Dietary Guidelines). Diets rich in monounsaturated fats could serve as a means to reduce CVD risk, typically by lowering triglycerides and raising HDL cholesterol levels (Appel and others 2005).

3 Some of these health effects may be due to the antioxidant pigments present in avocado (Ashton 2006). It is important therefore to maximize the effectiveness of these compounds that are present in avocado fruit and their oil s. It has been suggested that oil may enhance pigment bio-absorption in humans and provide a method for increasing the health benefit of lipid soluble pigments (Ashton 2006). A study determined that consumption of a fruit as a lipid source with carotenoid-rich foods enhances carotenoid absorption in humans (Unlu and others 2005). Although the avocado in this experiment will not be added to a carotenoid-rich food, this is an example of research that has been done in relation to the benefit of avocados. Methods and Purpose The purpose of this experiment is to incorporate the presence of monounsaturated fats into a common food product, ice cream, to help increase consumption. In order to accomplish this purpose, independent variables were controlled and dependent variables were used to measure the outcome. Hypothesis is which weight (grams) of added avocado will produce an ice cream with the best texture and palatability? Null Hypothesis states that the different amounts of added avocado will have no effect on the texture or palatability of the ice cream. Independent variables include three different amounts of avocado added to the mint ice cream. The amounts that will be used are a control with no avocado, 70g avocado added, 170g avocado added, and 270g avocado added to the mint ice cream. Dependent variables that will be measured are texture, color and preference of the taste panel. For Objective measures, the texture analyzer is used to measure the texture and the Hunter Colorimeter is used to measure the color and appearance of the ice cream and variables. For subjective measures, a taste panel will rate the overall appearance, texture and taste of the ice cream on a scale of 1-5 (1=strongly dislike and 5=strongly like). II. Methods: Overall Design The objectives of this experiment are to create a flavor of ice cream that incorporates a nutrient-dense food instead of an energy-dense food item, to add nutritional value by adding the avocado, and to make an ice cream that is palatable and appealing to the taste panel. Three different amounts of avocado were added into three separate ice cream batches to be compared to a control mint flavored ice cream with no added avocado. Each of the ice cream samples were then tested for texture, color and taste using the Texture Analyzer, Hunter Colorimeter and sensory panel, respectively. This same design was used over a serried of three separate trials.

4 Variables Classification of Random Sample Codes which apply to all three trials Sample 413 (control) Mint Ice Cream Mixture Only Sample 514 Mint Ice Cream Mixture + 70 g Avocado Sample 128 Mint Ice Cream Mixture g Avocado Sample 226 Mint Ice Cream Mixture g Avocado Recipe The recipe used was accessed from allrecipes.com on August 28, The recipe listed is what is considered the control ice cream mixture. From this basic recipe, the three amounts of avocado will be added (70g, 170g, and 270g respectively). 240 ml Milk 240 ml Heavy Cream g Sugar 3 g Salt 3 ml Vanilla Extract 3 ml Peppermint Extract 1 ml Green Food Coloring Procedure Mixing of the ingredients took place in the Food Science kitchen lab. Sanitized equipment and utensils were used and all sanitary measures were taken. To begin the experiment all of the equipment needed was set up prior to making the ice cream and also at room temperature. The milk and cream was kept in the refrigerator to keep from cooling. The method of mixing the ice cream as well as control variables are as follows: Begin by weighing out all of the ingredients prior to mixing them. The sugar, salt, vanilla and peppermint extract and food coloring can be measured out first as they are stable at room temperature for a length of time. The milk and cream need to be weighed out and then covered and placed back into the refrigerator to keep from getting to warm. For the three variables, avocadoes are cut, peeled and weighed last as they are susceptible to browning when in open air. The avocados (for variables), milk, cream and sugar will be added to a blender and pureed. The mixture will be transferred to a mixing bowl that is room temperature and the remaining ingredients will be whisked to combine in. Place the mixture in the refrigerator and chill until it reaches 40 degrees F or below.

5 Process the mixture in an ice cream maker and follow the manufacturer s directions. Processing should take approximately minutes. This is the same procedure used to make the control (without avocado) and the three variables with 70g, 170g, and 270g avocado respectively. The following procedure for Objective measures took place for each of the three trials to be as accurate and precise as possible: Once the ice cream mixture is finished for the control and three variables, a small sample of each was taken to the laboratory for two tests to be completed: Texture Analyzer and Hunter Colorimeter. The Texture Analyzer was used to measure the force required to penetrate the ice cream. A Cone Probe was attached to the machine and was lowered down to the sample. For this test, the analyzer was set on the ice cream setting. A quick test run was selected and a graph depicted the force required to penetrate the ice cream. Results are recorded in the laboratory notebook. The Hunter Colorimeter was used to determine the color of the samples using L, a, b values. The samples were placed in a clean, clear petri dish and placed over the glass of the machine. The machine measured the color of the ice cream and the results were recorded in the laboratory notebook. A sensory evaluation was completed with a taste panel. The sensory evaluation score sheets are attached in the appendix. For the taste panel, the ice cream will be kept in the freezer until it is time to taste to keep from melting. The following procedure took place for Subjective measure: After the samples were measured in the lab, they were spooned into 1 oz. plastic cups and labeled with their appropriate sample number. The samples were tasted and scored by random participants. Scorecards were tallied and completed after enough (at least 10) participants tasted the ice cream. Trial 1 contained 10 participants, trial 2 contained 13 participants and trial 3 contained 10 participants. All participants were different for each trial. No participants participated in more than one trial. Replications, Randomization and Sampling Three trials were used for the experiment. After the first trial the variables seemed to work fine for the objective and subjective tests, therefore no adjustments were made in the recipe or procedure for trial 2. After trial 2, I decided to add in 40g of chocolate chips to all of the sample batches to see the effect there would be on overall appearance and taste. The sample code numbers were selected at random and remained the same throughout the sampling procedure. Participants were different for all three trials therefore the sample codes did not need to be randomized again.

6 For the sampling procedures, the participants only knew it was a mint flavored ice cream. They remained unaware of the variables in the ice cream. Green food coloring was added to all variations to help make all the samples look the same. Also mint flavoring was added to help ensure all the samples would have a similar taste and smell to them. These steps helped to insure there was not bias to the added avocado in the ice cream. Questions were not answered and the participants did not talk amongst themselves to ensure as much bias was eliminated as possible. III. Discussion: Sensory Panel Table 1 list the sample codes used throughout the experiment. The random codes were presented in trial 1 and remained unchanged throughout the remainder of the experiment. For the subjective measures of the ice cream, a taste panel of semi-trained participants rated the samples on a scale of 1-5 (1= strongly dislike and 5= strongly like). The participants rated the appearance, texture, taste and overall rating of each sample. Tables 2, 3 and 4 contain the average ranked score for trials 1, 2 and 3 respectively. Table 5 contains the average results from all three trials as well as the Standard Deviation (SD) of the overall ranking. Figure 1 displays the final results of the sensory panel using the average scores from Table 5. According to Table 5 and Figure 1, the most preferred sample was the control, sample 413. Although the control was the most preferred of the samples, Figure 1 show s that there was not much of a difference between the control and the other variables. The control received a score of 3.4 ±.54, and sample 226 which contained 270 g added avocado, received a score of 2 ±.16. This is only a 1.4 difference on a 5 point scale. Findings from the sensory panel suggest that the appearance of the sample before tasting it may be misleading. Looking at Tables 2, 3 and 4, there is a pattern of a high appearance rating with a decline in texture and taste scores. This may suggest that the control received the highest rating based on the appearance and the participants may have expected the best flavor out of the sample based on the appearance. This may have created a bias on the final results of the taste panel. Sources of error may be in the final result of the color of the final product. In future experiments of this, it may be of best interest to make sure all of the samples are the same color before testing with a taste panel. This will eliminate any bias there would be. Initially green food coloring was added to all variations, but the amount of coloring was the same for each variation. Possibly the amount of coloring needs to change with the different amounts of added avocado to the ice cream to further ensure no bias when sampling. Consumer acceptance of ice cream depends largely on its textural quality and flavor. However, any temperature fluctuation or abuse between manufacture and consumption can cause detrimental effects on ice cream quality (Alvarez and others 2005). In regards to texture of the samples, Figure 1 displays that sample 128 (containing 170 g avocado) was preferred most by the sensory panel. This suggests that if this experiment was created again and measures were taken to make sure each sample was the exact color to eliminate bias, 170 g of added avocado may be preferred over the control. According to Table 5 there was only a.5 difference on a 5 point scale for preference of texture. This suggests that the added avocado had a small effect on the ice cream in regards to texture. These results may suggest that, to make this product accepted by the

7 general population, measures need to be taken to work on the appearance and taste of the product but texture will not be a concern. In regards to taste, Figure 1 displays a pattern of a decrease in the acceptance of taste as the amount of added avocado increases. This concludes that a small amount of added avocado may be accepted to the majority of people, but more tests will need to be done to determine that maximum amount of added avocado that would be accepted. For trial 3, Table 4 shows that the added chocolate chips had no effect on the overall ranking of the ice cream. The results of trial 3 compared to trials 1 and 2 actually decreased with the addition of the chocolate chips. Suggestions could be made that the participants expected the samples to taste like Mint Chocolate Chip Ice cream, therefore setting their expectations higher based on appearance and once they tasted the ice cream something was different possibly resulting in lower sample scores. In conclusion the sensory panel provided evidence that a small amount of added avocado to ice cream may be accepted by the general population. This test made it apparent that appearance is a big determining factor on the overall preference of a sample. The bright green color of the control was most preferred while the texture of the added avocado was most preferred. Addition of chocolate chips had no effect on the overall liking of the samples. Texture The texture of the ice cream samples was measured by the Texture Analyzer after the final product was frozen. Table 6 displays the results of the Texture Analyzer for trials 1, 2 and 3. Table 7 displays the average results of the three trials as well as the SD of the results. Figure 2 displays the comparison of the results from the texture analyzer. The tables explain the force needed to penetrate the ice cream with the different variations of added avocado for each trial. According to Table 7 and Figure 2, the penetration force was greatest for sample 514 which contains 70 g of added avocado with an average force of 18.4 g. The least force of penetration was needed for the control sample 413 at 13.5 g. Due to the fact that the control had no added avocado, it may be the softest of the samples. This concluded that with the addition of avocado to ice cream, the texture gets harder to penetrate. One could conclude that the sample with the highest amount of added avocado would have the greatest force of penetration, although this is not the result of the experiment. Sources of error could have occurred in the ice cream making process. Possibly the ice cream was not in the ice cream making machine for long enough which resulted in the ice cream not forming enough crystals. Ice crystal size plays a major role in influencing the texture of ice cream (Patel and others 2006). For this experiment, texture is a critical point in determining the palatability of the final product. Along with texture, temperature is another source of error in this experiment. Temperature fluctuations accentuate the shrinkage defect (small crystal sizes) by allowing the supporting structure of ice to melt and refreeze, causing pressure on air cells resulting in a change (Patel and others 2006). The ice cream needs to remain at a freezing temperature and should not undergo temperature fluctuations. Possibly while the samples were out for sampling purposes on the Texture Analyzer, crystal fluctuations occurred.

8 Overall, the control sample 413 has the softest texture while the samples with added avocado have a harder texture. Sample 514 resulted in the hardest texture of all averaged samples and trials. Color The Hunter Colorimeter was used to determine the L, a, b values for all of the variables of ice cream as a direst measure of appearance and color. L values determine levels of black (0) to white (100). A values determine red to green colors (+ = red, - = green). B values determine yellow to blue colors (+ = yellow, - = blue). Table 8 displays the L, a, b values from all three trials. Table 9 displays the averages results from the three trials. As shown in Figure 3, as the amount of avocado increased, the L value decreased. This shift symbolizes a darker green color with the added avocado. Figure 3 also displays that as with added amounts of avocado, the b values increase. Also, the a values are all negative. This symbolizes that the colors are a shade of green which is a positive test for the mint green ice cream. Various external factors such as social and physical surroundings, including the presence of other people and sound, temperature, smell, color, time, and distraction affect food intake and food choice. Food variables such as the temperature, smell, and color of the food also influence food intake and choice differently (Stroebele and others 2004). In terms of appearance, color has a great influence on the overall appearance of a food product. As determined by the sensory panel, the appearance of the control sample 413 was preferred most by the participants. A lighter green color contributes to an overall more acceptable appearance for the ice cream. As the ice cream got darker green in color, is was less preferred by the participants. Summary of Overall Results Overall, the most preferred ice cream was the control. The control scored the highest on appearance, taste and overall score. The only area it was not the most preferred was the texture where sample 128 with 170 g of added avocado was preferred most. The texture of the control sample was the softest. This verifies why the control s texture was least accepted. A conclusion can be made that a light green ice cream, with a harder texture and a slight taste of avocado would be most accepted by the general population. Suggestions of Future Work Future work needs to be done on enhancing the color of the ice cream with added avocado. Because a small amount of added avocado is accepted, then the color needs to be enhanced so that for example, sample 514 with 70 g avocado would be most accepted. In future replications of the study, an area of interest could be using avocado as a fat replacer within the ice cream product. In this experiment it was just an added ingredient with varying amounts, but there is research being done with using avocado as a fatreplacer.

9 IV. Results: Table 1: Classification of Random Sample Codes which apply to all three trials Sample 413 (control) Mint Ice Cream Mixture Only Sample 514 Mint Ice Cream Mixture + 70 g Avocado Sample 128 Mint Ice Cream Mixture g Avocado Sample 226 Mint Ice Cream Mixture g Avocado Subjective Test: Sensory/Taste Panel Table 2: Trial 1 Data Averages for all Samples including Appearance, Texture, Taste and Overall Rating Sample 413 Sample 514 Sample 128 Sample 226 Appearance Texture Taste Overall Rating Table 3: Trial 2 Data Averages for all Samples including Appearance, Texture, Taste and Overall Rating Sample 413 Sample 514 Sample 128 Sample 226 Appearance Texture Taste Overall Rating Table 4: Trial 3 Data Averages for all Samples including Appearance, Texture, Taste and Overall Rating Sample 413 Sample 514 Sample 128 Sample 226 Appearance Texture Taste Overall Rating Table 5: Average Results from sensory panel for trials 1, 2 and 3 Averages Sample 413 Sample 514 Sample 128 Sample 226 Appearance Texture Taste Overall Rating 3.4 ± ± ±.75 2 ±.16

10 Figure 1: Average Sensory Panel Results from trials 1, 2 and 3 as ranked by the participants Objective Test: Texture Analyzer Table 6: Texture Analyzer Penetration Force for trials 1, 2 and 3 Trial 1 Sample Texture Analyzer Force (g) 413 Control Trial 2 Sample 413 Control Trial 3 Sample 413 Control

11 Table 7: Average Penetration Force for Trials 1,2 and 3 measured by the TA (g) TA Force (g) Standard Deviation 413 Control ± ± ± ± 4.1 Figure 2: Average Penetration Forge of Variables from trials 1,2 and 3

12 Objective Test: Hunter Colorimeter Table 8: Hunter Colorimeter Results for Trials 1,2 and 3 Hunter Colorimeter Trial 1 Sample L A B Trial 2 Sample Trial 3 Sample Table 9: Average L, a, b values measured by the Hunter Colorimeter for trials 1, 2 and 3 Averages Sample L A B Figure 3: Hunter Colorimeter L, a, b average values from trials 1, 2 and 3

13 V. References: American Heart Association Website. Heart disease statistics. < Alvarez, V.B., Wolters, C.L., Vodovotz Y., Ji, T Physical properties of ice cream containing milk protein concentrates. J Dairy Sci. 88: Appel, L.J., Sacks F.M., Carey, V.J., Obarzanek, E.B Effects of protein, monounsaturated fat, and carbohydrate intake on blood pressure and serum lipids. JAMA. 294: Ashton, OB Pigments in avocado tissue and oil. J Agric Food Chem. 54: Dietary Guidelines for Americans Website Chapter 6 Fats. < Healthy Living Website. Fresh California Avocados. < Lu, Q.Y., Arteaga, J.R., Zhang, Q Inhibition of prostate cancer cell growth by an avocado extract: role of lipid-soluble bioactive substances. J Nutritional Biochem. 16(1): Noakes, M., Keogh, J.B Effect of an energy restricted, high protein, low-fat diet relative to a high carbohydrate, low fat diet on weight loss. Am J Clin Nutr. 81: Patel, M.R., Baer, R.J., Acharya, M.R Increasing the protein content of ice cream. J Dairy Sci. 89: Stroebele, N., De Castro, J.M Effect of ambience on food intake and food choice. J Nutr. 20(9): Unlu, N.Z., Bohn, T., Clinton, S.K., Schwartz, S.J Carotenoid absorption from salad and salsa by humans is enhanced by the addition of avocado or avocado oil. J Nutr. 135:

14 Appendix 1. Sensory Evaluation Scorecard 2. Trial 1, 2 and 3 Carbon Copies from Laboratory Notebook

15 Sensory Evaluation Scorecard Rate on a scale of 1-5 (1=strongly dislike and 5= strongly like) the overall Appearance, Texture and Taste for each sample: Sample 514: Based on overall Appearance, how would you rate sample 514: Based on Texture, how would you rate sample 514: Based on Taste (Flavor), how would you rate sample 514: Sample 226: Based on overall Appearance, how would you rate sample 226: Based on Texture, how would you rate sample 226: Based on Taste (Flavor), how would you rate sample 226: Sample 413: Based on overall Appearance, how would you rate sample 413: Based on Texture, how would you rate sample 413: Based on Taste (Flavor), how would you rate sample 413: Sample 128: Based on overall Appearance (color), how would you rate sample 128: Based on Texture, how would you rate sample 128: Based on Taste (flavor), how would you rate sample 128: Do you enjoy Frozen Desserts (circle one)? YES NO What is your age range (circle one)? and up What is your favorite flavor of ice cream? Rank the samples you preferred in order from 1-4 (1=liked the most and 4=liked the least)