Oil Replacement with Fruit Puree in Waffles Allison Shaffer John Oswalt Mary Duff NUTR 453 November 18, 2013
ABSTRACT The purpose of this experiment is to determine the relationship of physical attributes of waffles through different tests with the type of fat and fat replacer used. The recipe chosen used vegetable oil as a fat and the variables chosen to test were fruit purees: applesauce and bananas at equivalent measurements. The waffles were all made with the same waffle iron, to ensure there were no cooking differences. These waffles were then analyzed through the Texture Analyzer and Hunter Calorimeter to determine the differences in texture and browning within the different variables. Also, panelists were selected to rate the physical attributes; appearance, texture, flavor, and overall liking using a hedonic 9 point scale. There was little difference found between the color ratings of the variables and the control, both objectively and subjectively, and the flavor of the variable products, despite minor fruity undertones was found to be acceptable to consumers. The texture was lacking due to the unaccounted for high water activities of the fruit purees in comparison to the oil they were replacing and, thus the variable products were quite soft and required far less penetration force from the Texture Analyzer than the control did. INTRODUCTION Food is a necessity for the sustainment of life. Whether it be sunlight for plants, or the plants for herbivores, it is a need of each living creature to find an adequate food source. The problem is, not every food source is what the living creature may need. Even though a human may have enough calories to sustain their lives, they may not have the right type of foods to continue the highest caliber of nutrients to attain the best status of health that they can achieve. Research has found that nearly eighty to 99% of Americans have an intake that is low in one of the four main food groups (Nicklas, 2013). It was also found that nutrient dense types of fruit
have become under-consumed. Some of the barriers associated with the fruit group is the lack of availability, accessibility, seasonality, and difficulty in eating fruits that are not appetizing. The Academy of Nutrition and Dietetics suggest that some ways to help incorporate fruits into the diet is to incorporate them into foods or use them as snacks (Academy of Nutrition and Dietetics, 2012). To help address this problem of inadequate ingestion of fruits, it was hypothesized that there would be a use of various fruit purees to replace oils in baked goods. Waffles were chosen because it is often looked over as a food that can be nutritionally enhanced. One study looked into the use of different fruit purees in cakes (Camire, 1997). The study found that the use of different fruit purees helped to increase the fruit intake, reduce calories, and increase the nutrient density of the baked goods. METHODS The purpose of this experiment was to evaluate the effect of using a fruit puree as a fat replacement in waffles while maintaining the characteristics of the control, waffle with fat. These different characteristics include texture, volume, color and palatability. Two variables were used in the experiment: banana puree and applesauce, and a control, waffle with oil. Recipe: All-purpose flour - 250 grams Baking Powder - 14 grams Eggs 2 (separated) Salt - 1.175 grams 2% Milk - 414.75 ml or 420 grams White Sugar - 12 grams Vanilla Extract - 5 grams Control: Vegetable oil 200 grams Variables: Applesauce 200 grams Banana Puree 200 grams Procedure: Weigh out and combined the flour, baking powder, and salt in a mixing bowl. In a separate mixing bowl add the 2 egg yolks, milk, and oil/fruit puree. Gently whisk together until homogenous. Then slowly add the dry ingredients, 1/3 at a time. Stir until mixture is moist; mixture will contain lumps. Finally, pour the waffle batter onto heated waffle iron. Heat until waffle is cooked through. Yields 8 waffles approximately 10.2 cm
In order to minimize as many extraneous variables as possible, it is important to measure all ingredients in the measurements provided above and follow cooking instructions. Also, it is critical to make sure that the environmental factors such as room temperature are constant. Most importantly, the ingredients for each trial must be the same brand types to help eliminate differences between products. After the product is made, it needs to be tested objectively using the Texture Analyzer and the Hunter Calorimeter. All of these attributes for the waffles made with fruit puree should compare with that of the control waffle made with oil. It is also important to collect subjective data from taste panelist to find out how the general public accepts the product. This may be one of the most important tests because if the product is not accepted then the health benefits will not matter. Subjective data is acquired with a Hedonic Scale Test. A hedonic scale uses a rating system on a 9 point scale. 1 being dislike extremely and 9 being like extremely. Participants in this experiment used the following scale and table: Variable Number Appearance Texture Flavor Overall Liking 253 729 581
The texture analyzer evaluates the texture of the control and both variables, banana puree and applesauce. The texture analyzer uses force and measures in grams to indicate the texture of the product. In this experiment, a cone probe was used and the machine was put on the waffle setting in order to obtain the penetration force value for each sample. A higher penetration force value means the product is more firm and a lower number means that it is less firm. A lower value may be because the product contains too much water. Texture plays an important role in the overall liking of a product so it is critical to make sure the textures are similar. The hunter calorimeter assesses the color of the control and both variables, banana puree and applesauce. The hunter calorimeter determines color through the typical L (lightness), a (red to green), b (yellow to blue) indicators. It is important to program the hunter colorimeter by following the directions in The Food Chemistry Laboratory (Weaver and Daniel, 2003). Appearance of food is one of the first judgments a person makes about what they are going to eat. If the product doesn t look like the standard, it may be more difficult to have consumers even try the waffle let alone be subjective about other aspects of the sample that they are rating. DISCUSSION Each batter containing either the oil or the oil replacer was capable of producing a wafflelike product; however, there were differences between the texture, color, and flavor of each. These differences were determined through the hedonic ratings of taste testers and were confirmed with values obtained from the Hunter Calorimeter and the Texture analyzer. In regards to the Hunter Calorimeter, there were differences between each of the types of waffles. As shown in Table 2 and Figure 2, the average scores for each waffle are as follows; Apple had a L value of 50.89, an a value of 6.77, and a b value of 27.16, banana had a L value of 52.33, an a value of 8.12, and a b value of 27.78, and the regular waffles had a L value of 49.9,
an a value of 8.72, and a b value of 30.54. This shows that each waffle type was close to the other, but there were slight consistent differences between the coloration of each type of waffle. In terms of the hedonic ratings scored by those who sampled the product, both apple sauce and banana puree offered comparably colored products. The regular waffle had an average color rating of 6.17 and the apple sauce and the banana waffles had average ratings of 5.58 and 5.6 respectively as shown in Table 3. This similarity in color was confirmed with the Hunter calorimeter in which the standard deviations between the average L values, a values, and b values were 6.68, 2.62, and 2.93 respectively. The low variability in sample color is potentially due to the low variability in oil and oil replacer color. The vegetable oil, applesauce, and banana puree all have an observed light yellowish-tan color and thus, when used in place of one another in baked goods, should and did not affect the overall color of the product significantly due to their actual color. Another potential factor in the color differences between each variable could be due to Maillard browning. Maillard browning is affected by what type of sugar is used in the reaction and different fruits contain different types of fruits. All types of fruits contain glucose; however, they vary in their fructose and sucrose levels (Rivard, 2007). Apples tend to be higher in fructose and lower in sucrose while bananas are the exact opposite in nature (Sisson, 2013). Furthermore, bananas contain more sugar than apples with an average of 28 grams per 1 cup of puree and 18 grams in 1 cup of unsweetened applesauce ( Food Nutrients, 2013). Maillard browning requires a reducing sugar to proceed and, since both glucose and fructose are both reducing sugars and sucrose is not, the waffles containing applesauce should have a higher degree of Maillard browning (Davies and Labuza). That being said, fructose browns much slower when in the presence of albumin like from the eggs in the recipe we used and, thus, the amount of time that
the batter was in the waffle maker could have made an effect in the color difference between products (Davies and Labuza). Despite the fact that the waffles made with the banana puree had a different flavor from the regular waffles, the flavor was actually preferred in comparison to that of the waffles made with the apple sauce. According to Table 3, the banana waffles had an average hedonic rating of 6.33 for flavor in comparison to the regular waffles which had a rating of 6.92 while the apple sauce had a rating of 5.83. This is potentially due to the fact that banana puree contains about 10 more grams of sugar in a cup for cup comparison with apple sauce ( Food Nutrients, 2013). Studies such as the one entitled Sugars: hedonic aspects, neuroregulation, and energy balance in the American Journal of Clinical Nutrition have found that ingesting sugars cause a greater increase in dopamine release which is a neurotransmitter involved in pleasurable feelings (Levine et al., 2003). This increased release of dopamine in relation to the amount of sugar ingested could play an effect in why subjects preferred the waffles containing the banana puree over the waffles containing the applesauce. In regards to the texture analyzer, Table 1 and Figure 1 depict that the waffles containing applesauce had an average value around 26.27 grams of penetration force, which was the lowest compared to the waffles with banana added which had an average of 29.51 and the regular waffles which had an average of 41.12. There was a distinct difference between the texture and appearance of the waffles which was shown through both the texture analysis and the hedonic ratings. The banana waffles had a lower penetration force than that of the waffles prepared with oil but not as low as the applesauce waffles. The water activity may have accounted for these differences because banana puree and applesauce have an average water activity of 0.97 and 0.98 respectively (Chauvin et al., 2006)
while the water activity of vegetable oil varies based on the oil s age, temperature, and chemical additive composition but the desirable value for the optimum texture of fresh baked goods is approximately 0.85 ( Moisture in Oil, 2006). A higher moisture content in baked goods dilutes the gluten proteins which restricts their interaction therefore minimizing the desired gluten development in baked goods (Wang et al, 2004). This simply means that baked products with higher water activities are products that have undesirable tenderness, therefore these difference in water activities between the additives could have played a factor in the textural differences between the waffles. Not only is temperature a factor in the nature of oil in baked goods, it is also a factor in the nature of banana puree in the same context. A higher temperature has been shown to increase the juice of a banana (Guerrero 1997). Therefore, the temperature of the puree could have affected the outcome of the product in the same way that the temperature of the oil could have. It is undocumented as to whether a juice increase would cause the banana puree to act more like oil in terms of properties in baked goods, however from what has been established by previously cited research, it seems unlikely that the puree would take on oil-like properties despite being heated. Furthermore, a study done by G. D. Saravacos determined that as temperatures increase, the viscosity of purees such as applesauce decreases at higher temperatures (2006). A higher viscosity would appear detrimental to gluten formation, but there is no specific research in regards to temperature of oil replacements and how it may or may not change their properties in baked goods. However, it would be an interesting avenue of research to determine if this is a factor. To obtain less varied results between the different variables in terms of texture in future experiments, one could replace only half of the oil in the waffle recipe with the various fruit purees versus the entire amount as was done in this experiment. In a study that used a half
applesauce replacement with half fat (butter) proved to be an acceptable replacement for consumers (Hayek & Ibrahim 2013). This would maintain some of the health benefits, like reducing calories and saturated fat while increasing fruit as well as nutrient intake, obtained by replacing the oil but would preserve the desirable textural qualities of the waffle. Furthermore, in future experiments, it would be helpful to utilize a low calorie fat or fat product in order to grease the waffle iron. This would ensure that the color obtained in the product is due to the differing ingredients between variables and not due to burning because of batter getting stuck. In conclusion, it was found that both types of variations had fairly similar color values obtained from the Hunter Colorimeter and ratings on the hedonic scale for their products as the control, thus confirming that the participating taste tester s ratings were be unsullied by a sample with a distracting appearance. The fruit purees were able to mimic the appearance of control, but were unable to match the flavor. Despite the fact that there were difference in flavors between the variables and the fruity aspect of the purees were not lost on the consumers, the consumers incidentally enjoyed the twist of a fruity waffle and, thus, scores were subjectively equivalent to that of the control. The one area in which the fruit purees failed to match or offer an equally pleasing alternative, like they did with flavor, was in the texture of the waffle. The texture was far from what was expected of a waffle and was significantly less crisp than the control. It was determined through the previous analysis that this was most likely caused by the higher water content of the fruit purees and the lack of accounting for that extra water in other areas of the recipe. In order to obtain products that could plausibly be the control, one would have to replace only a portion of the oil with fruit puree, rather than the entire amount as was done in this experiment.
RESULTS TABLE 1 Texture Analyzer Averages for each variable. Variable Trial 1 Test 1 Test 2 Test 3 Average Standard Deviation Apple 22.7 24.5 22.3 23.1 1.171893055 Banana 21.7 22.3 22.3 22.1 0.346410162 Control 43.2 40.9 39.9 41.3 1.692138686 Variable Trial 2 Test 1 Test 2 Test 3 Average Standard Deviation Apple 24.6 22.9 21.9 23.1 1.365039682 Banana 28.7 26.5 28.31 38.5 1.173896645 Control 39.3 37.9 38.19 27.8 0.738940683 Variable Trial 3 Test 1 Test 2 Test 3 Average Standard Deviation Apple 34.2 32.8 30.8 32.6 1.708800749 Banana 51.4 37.5 27 43.57 12.2394172 Control 38.2 39.8 52.7 38.63 7.950052411 Overall Averages Average of All Trials Average Standard Deviation Apple Banana Control 26.26666667 34.72333333 35.91 1.415244495 4.586574668 3.46037726 Figure 1 The average penetration force for waffles made with each type of oil replacer.
TABLE 2 Hunter Colorimeter Averages for each variable. Variable Average L Average a Average b Apple 50.89 6.77 27.16333333 Banana 52.33 8.116666667 27.76 Control 49.89333333 8.726666667 33.07666667 Standard Deviation 1.225036659 1.001178935 3.255520098 Figure 2 The average distribution of lightness (L), red to green (a), and yellow to blue (b) values of the variables in each trial. TABLE 3 Average Hedonic scores for the flavor, color, and texture of each variable. Variable Average Flavor Average Texture Average Color Apple 5.83 5.33 5.58 Banana 6.33 4.33 5.67 Control 6.92 7.08 6.17
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