Is it possible to lowering Fat in salad dressing without losing taste, color or texture properties? Fiona Mc Grath, November 19 th 2007,

Transcription

1 Project on Fat substitutions: Is it possible to lowering Fat in salad dressing without losing taste, color or texture properties? Fiona Mc Grath, November 19 th 2007, Purdue University FN 453

2 Abstract Over-consumption of fat increases risk of cancer, obesity, and heart disease. These are three very serious and very prevalent problems in today s society. Drewnowski, 1997 believes a liking for fatty foods to be a universal trait. It is a natural instinct in humans to choose a meal for taste rather than nutritional value. What I wish to discover is can it be possible to make a low fat yet equally appeal alternative? An aim of this project was to change people s predetermined opinions, by showing in a blind taste test that the lowest fat salad dressing is not always easily picked out. Another aim was to prove objectively that fat can be lowered without detrimental effects to texture or color. To do this the Brookfield viscometer and the Hunter colorimeter was used. In doing this little change was found between tastes of 100% vegetable oil salad dressings and 0% vegetable oil salad dressings (100% Oat-trim used instead). Not much taste or texture changes were noticed. And the majority of the taste remained intact, almost prefer to the original. Whilst color was marginally darker. However the 50:50 mix of vegetable oil and Oat-trim had thinner texture and less flavor. It was all-over an inferior product. This proved that if done right lowered fat food is not only extreme health beneficial, but can be done without lose of flavor and texture.

3 Introduction It is a common belief that low fat salad dressings are less tasty than there fuller fat alternatives. As Zind says in Dressings Slim Down there is a perennial tug-of -war between making food taste nice and making it healthy. And he admits that salad creams were at the center of the struggle. It is definitely true to say fats add a pleasant aroma, taste and smell to our foods. However to change this way of thinking is to bring people around to a healthier lifestyle. High levels of fat intake leads to health problems, such as coronary heart disease, cancers and obesity. To lower fat intake is to lower body weight and in turn is to raise life expectancy. As reported by Sigman-Grant et al, Campaigns by hospitals and public health agencies spanning from the 1980 s to 1990 s encouraged reducing and eliminating of selected items such as salad dressings. However in today s society a more balanced approached is taken. Rather than complete elimination of unhealthy food, there is encouragement to either use sparingly or use a healthier alternative. (Sigman) More recently the food industry was urged by the Institute of Medicine to lower fat content in foods. This inspired the trend for low-fat versions of most selected foods (cheeses, table spreads, dressings, desserts and sauces. Referred to as selected foods, as they are disposable in the diet. Another factor is negative body image being more prevalent in heavier people. Schulze et al discussed this. They noted that obesity has been on the increase for the last few decades. He discovered, that shockingly over 65% of American adults are either over-weight or obese. This is mainly due to poor diet choices. Females are normally considered most susceptible to this pressure. Women on diets rely mainly on dietary fat reduction, to lose weight (Liebman, 2002). (Cengiz, 2007) Lower intake of dietary fat, saturated fatty acids and cholesterol is what world health organizations are mostly campaigning for. The recommendation for fruit or vegetable stands at five portions a day. This is to ensure adequate nutrient supply. This is still not meet by more than 50% of the population of the US. Fruits and vegetable are a naturally low-fat highly nutritional food, if these are not being consumed only lesser foods can take their place. Therefore the need encouragement to consume salad is necessary. Salad is seen as a great meal, low in fat and high in nutrients. However to make salad appetizing to the majority of the population a dressing is needed, and this is where the low calorie benefits are lost. This is why a low-fat alternative is much appreciated. Healthier changes to salad cream came in the form of altering old formulas, the most successful of these was the use of exotic fruits to add flavor. Pomegranate was seen by Zind to be most popular.

4 Su also confirmed that consuming salad, raw vegetables and salad dressing leads to a higher nutrient content that average of folic acid, α and β carotene, vitamin C and E and lycopene. (Su, 2006) High fruits and vegetables intake is linked with lower cases of cancer, less premenopausal loss of bone density and prevention of the metabolic syndrome. This has been proven by epidemiologic studies (Su) Chemical processes Oat-trim is the original name for Z-Trim. It can be made from such products as the hull of oats, peas, rice soybeans or the bran of corn or wheat. It is a form of soluble dietary fiber with zero calories. Because it is based on fiber rather than fat, not only does it lower calorific value it also helps to remove waste foods from the body. As documented by Cengiz, health organizations are encouraging increased intake of complex carbohydrates, and lower intake of fats as a way of lowering risk of cardiovascular heart disease. It is a common belief that low fat salad dressings are less tasty than there fuller fat alternatives. It is definitely true to say as fats heighten our pleasure in eating. As Drewnowski noted, fats add a pleasurable aroma and taste to our foods. They affect taste and texture. Therefore these are two of the three properties I have chosen to examine in my project. The third being color. The effects on texture were measured both subjectively and objectively. To test subjectively a blind taste test was done. Panelists were given a 6-point scale on which to rate mouth feel, creaminess and thickness. A Brookfield viscometer was used as an objective method. The question asked with regards to taste was Which is your favorite? There also was a scale on which to rate creaminess and tartness. Method The design of this project was to make three types of salad dressing. The variable was the fat concentration. One salad dressing was made using the original recipe of 57.5g of vegetable oil, and was referred to as the 100% oil salad dressing. Next the salad dressing was made using half oil and half Oat-trim solution, and 50% oil salad dressing was be used to describe it. The Third had all the oil replaced by Oat-trim, and was being called a 0% oil salad dressing. This was then tested using objective methods the Hunter colorimeter to measure color and the Brookfield viscometer to measure viscosity. A Blind taste test was done as a subjective method. Oat-trim comes in powder form and must be mixed at the ratio 1 part Oat-trim to 3 parts water. Recipes For one batch of 100% oil salad dressing:

5 28.5 grams sugar substitute (splenda) 2.3g dry mustard 57.5g vegetable oil 2.3g salt 57.5g cornstarch 230gs cold water Gives roughly 345 grams of salad cream For one batch of 50% oil salad dressing: 28.5 grams sugar substitute (splenda) 2.3g dry mustard 7.2g Oat-Trim mixed with 21.5ml water 28.7g vegetable oil 2.3g salt 57.5g cornstarch 230mls cold water Gives roughly 345 grams of salad cream For one batch of 0% oil salad dressing: 28.5 grams sugar substitute (splenda) 2.3g dry mustard 14.5g Oat-trim mixed with 43ml water 2.3g salt 57.5g cornstarch 230gs cold water Gives roughly 345 grams of salad cream The taste test was done in which all samples were given a three digit code so as to eliminate ranking due to expectation. And samples were presented in a random order. Every attempt was made to present each sample in visual uniformity. One size of sample cup was used, and each was filled to the same level. A breadstick was used as a carrier for the salad dressings. Acceptance range for paired preference test were predetermined at For question 1 range is between 3-5 For question 2 range is between 2-5 For question 3 range is between 3-4 For question 4 range is between 3-5 For question 5 range is between 1-3 However after test were done these ranges seemed irrelevant to the study.

6 Sample taste test form: Triangle test Taste each sample and choose the odd one out. Put a tick in the appropriate box Which of is your favorite? Paired preference Taste each sample and rank on the scale below Rate sample creaminess on a scale of 1 to 6. 1 being not at all creamy 6 being extremely creamy Rate sample Thickness on a scale of 1 to 6. 1 being very thin, 6 being extremely thick Rate sample color on a scale of 1 to 6. 1 being white, 3 being beige, 6 being brown Rate sample mouth feels on a scale of 1 to 6. 1 being gritty 6 being smooth Rate sample tartness on a scale of 1 to 6. 1 being not tart 6 being incredible tart

7 Rate sample creaminess on a scale of 1 to 6. 1 being not at all creamy 6 being extremely creamy Rate sample Thickness on a scale of 1 to 6. 1 being very thin, 6 being extremely thick Rate sample color on a scale of 1 to 6. 1 being white, 3 being beige, 6 being brown Rate sample mouth feels on a scale of 1 to 6. 1 being gritty 6 being smooth Rate sample tartness on a scale of 1 to 6. 1 being not tart 6 being incredible tart Rate sample creaminess on a scale of 1 to 6. 1 being not at all creamy 6 being extremely creamy Rate sample Thickness on a scale of 1 to 6. 1 being very thin, 6 being extremely thick Rate sample color on a scale of 1 to 6. 1 being white, 3 being beige, 6 being brown Rate sample mouth feels on a scale of 1 to 6. 1 being gritty 6 being smooth Rate sample tartness on a scale of 1 to 6. 1 being not tart 6 being incredible tart.

8 Objective methods Include a texture test using the Brookfield viscometer and a colorimeter test using Hunter colorimeter. Two replications were done at each trial for 100%, 50% and 0% oil content for the Hunter colorimeter and three replications were done for Brookfield viscometer. Random representative samples of each batch were selected for testing. Using Brookfield viscometer Spindle seven was attached to the viscometer, then lower into sample until the line is fully covered. The viscometer was set to 6, 12, 30 and 60 rpms in order to measure resistance. The spindle was allowed to rotate for 20 seconds then values were read off the display screen, and noted. This was repeated three times to ensure reading was accurate. Using a Hunter colorimeter Computer was turned on and the program was Hunter colorimeter was opened. The lens was standardized using a black and a white tile. A Petri dish of sample salad was placed on the measuring port. The read average button was selected, and each sample was given a unique id. The scales were used to record data as Yxy scales and L, a, b scales. The instrument was then shut off. In the end L, a, b scales were chosen to be more appropriate This method was repeated twice at each trial for 100%, 50% and 0% oil salad dressings. Discussion Hypothesis: Low fat salad dressing= x Regular salad dressing=y Null hypothesis states that lowering the fat concentration affects the viscosity and color of the product. The alternative hypothesis is that lowering fat has little to no effects on the viscosity or color. HǾ : Hx Hy H Ǻ : Hx Hy

9 I would like to set the significance level at Meaning that there is only a 5% risk of being wrong. Control variable is percentage of fat. Dependant variable is the viscosity and degree of color. Having used 28 panelists for the blind test 19 correct responses are needed to prove with a 5% chance of being wrong that there is a significant difference between the salad dressings. When asked to choose the odd one out Only 6 out of 28 noticed a difference. 22 believe that it was possible that a low fat alternative was the same as its full-fat counterpart. As show in table 1.1. This means we can reject HǾ: Hx Hy with a 5% risk of being wrong. And we can accept the alternative hypothesis HǺ: Hx = Hy is true Table 1.2 shows that 13 panelists choose full fat salad dressing as their favorite and 15 choose variations of lowered fat salad dressing as their favorite. Showing in general that the lowered fat was preferred. Strangely 0% fat was preferred to 50% fat. One assumption that could be made from this is that Oat-trim and vegetable oil do not mix well together. Texture Creaminess As shown by table 2.1, 50% oil has lowest creaminess at a value of 4.2. This show as loses of texture and flavor and shows negative traits of a salad dressing. Whereas 0% oil and 100% oil have exact same average creaminess at 5.1 out of 6. This is an excellent example of lowering fat yet maintaining taste. It seems whilst oat-trim is an excellent replacement for vegetable oil, a mix of 50:50 oil to Oattrim is not a good mix. The combined textural properties are worse than there are individually. Graph 2.15 shows a relatively large spread of results. Thickness 100% peaks at 6, whilst 50% and 0% peak at 5. On average 100% and 0% are equal in their values at 5.1. The expected correlation between thickness and fat content would be that the 50% oil sample would be in the middle of the two. Several reasons may have caused this perhaps human error. Heating time of Oat-trim may not have been equal for all three products causing varying thickness. Perhaps the emulsify was not strong enough to bind oil and Oat-trim together. Causing a fall in its viscosity. Due to the fact that three trials were done and an average was taken I will accept the results to be true. This proves that lowering fat value affects the thickness, but it is largely dependent on the composition of the fat substitute. The all Oat-trim salad dressing, showed the highest viscosity readings. This leads one to believe that fat substitutions don t necessarily mean higher or lower

10 viscosity but they are altered one way or the other. Therefore I will accept the null hypotasis after all. Mouthfeel In table 2.4 results show that the 50% oil sample is perceived to be the grittiest, whereas 100% oil is thought to be the smoothest. With 0% lying in the middle.once again 50% has the least appropriate texture. Viscosity 100% oil salad dressing shows a steep decline in viscosity as spindle speed rises. This evens off at roughly 15 rotations per minute (rpm). This curve shows it to be a pseudoplastic. Meaning it has a Non-Newtonian flow. 50% oil s.d. has a low viscosity when compared to the 100% fat version. Its highest peak is roughly half of the original. It has a similar slope pattern though. Sloping steeply until 15 rpms then evening out. 0% oil has the highest peak of all, similar slope pattern. All three are pseudoplastics. No direct correlation between fat content and viscosity was proven here. Possibly another variable affect the results. Possibly heating time of Oat-trim was varied, causing variable thickness between samples. Therefore we can neither confirm nor deny null hypothesis These results mirrors that of the taste panel showing them to have keen senses, be accurate and well trained. Color Colorimeter Two samples were done for each trial. Therefore 6 coordinates were obtained for each point and the average was taken. The Hunter notation consists of 3 parameters. L stands for lightness, at 100 the sample is white and at 0 it is black. To denote red to green a is used. A minus symbol means it is more green than red and a positive means more red than green is present. Yellow to blue is shown on the b axis. A b means color is verging to blue and +b indicts more yellow is present than blue. With an L of % oil s.d. is the lightest color. With 50% slightly higher than 0%, but with both in the 60 s. The a value is roughly the same for all, at around -0.5, showing it s just slightly on the green side. All b values are approximately the same, lying around the mark. Showing that salad dressing has a light yellow tint. The only really difference in color observed is that 100% oil s.d is whiter than the other too.

11 These results match up well with the taste panels answers, which show they were quite accurate in their responses. Null hypothesis states that lowering the fat concentration affects the viscosity and color of the product. The alternative hypothesis is that lowering fat has little to no effects on the viscosity or color. HǾ: Hx Hy H Ǻ: Hx Hy Low fat salad dressing= x Regular salad dressing=y Since there was a perceivable difference in the color when fat was lowered, we can accept the null hypothesis with a chance of being wrong. When color is the variable HǾ: Hx Hy Taste Tartness 100% is show here to be the least tart. With 0% having a relatively even spread with a subtle peak at 4. 50% rises from continuously from 1 to 6 except for a drop at 5. The results here are widely spread meaning the panelists are somewhat undependable yet as a whole 50% was seen to have high concentration of tartness than the others. This is a negative trait associated with poorer quality salad creams. Results Triangle test Taste each sample and choose the odd one out. Table 1.1 result for forced triangle test All different Which of is your favorite? Table 1.2 results for preference test

12 Results for ranking tests Creaminess Table 2.1 average score of salad dressings creaminess. Question 1. acceptance range is between 3 6 Salad dressing type 100% oil 50% oil 0% oil Average score % oil is the least creamy. 0% and 100% have exact same average creaminess. Creaminess is both a texture and a taste, so when the two are combined very little difference is perceivable. Showing fat is not the principal determinate of taste/texture. Graph2.15 Distribution of scores for Creaminess in altered fat, salad creams.

13 Thickness Table 2.2 average score of salad dressings thickness Question 2. range is between Salad dressing 100% oil 50% oil 0% oil All are out of desired range But 50% oil is nearest to the ideal. Average score of thickness Graph 2.25 Distribution of scores for Thickness in altered fat, salad creams

14 Color Table 2.3 average score of salad dressings color Question 3. range is between 1 3 Salad dressing type Average score 100% oil % oil 2.4 0% oil 2.5 All answers in range. Therefore appearance has not been severely altered by lowering fat content. But that 100% oil is lightest Graph2.35 Distribution of scores for Color in altered fat, salad creams

15 Mouth feel Table 2.4 average score of salad dressings mouthfeel. Question 4. range is between 3 5 Salad dressing type Average score 100% oil % oil 3.8 0% oil % oil is overly gritty, therefore low fat samples considered to have superior texture in this context Graph 2.45 Distribution of scores for mouthfeel in altered fat, salad creams.

16 Tartness Table 2.5 average score of salad dressings Tartness. Question 5. range is between 1 3 Salad dressing type Average score 100% oil % oil % oil 4.25 All samples are overly tart, low fat variety has more desirable taste in this respect Graph2.55 Distribution of scores for Tartness in altered fat, salad creams.

17 Viscosity Table 3.1 Brookfield Viscometer results for 100% oil salad dressing (s.d) rpm trial 1 trial 2 trial 3 Average *all trial result is in centipoises Graph 3.2 Graph of average Brookfield Viscometer results for 100% oil salad dressing (s.d)

18 Table 3.3 Brookfield Viscometer results for 50% oil salad dressing (s.d) rpm trial 1 trial 2 trial 3 Average *all trial result is in centipoises Graph 3.4 graphs of average Brookfield Viscometer results for 50% oil salad dressing (s.d)

19 Table 3.5 Brookfield Viscometer results for 0% oil salad dressing (s.d) trial 1 trial 2 trial 3 Average *all trial result is in centipoises Graph 3.6 Graph of average Brookfield Viscometer results for 0% oil salad dressing (s.d)

20 Colorimeter Table 4.1 Hunter Notation of 100% oil content Parameter L a b Results Average Graph 4.2 Hunter notation showing color values of 100% oil salad dressing

21 Hunter notation for 100% oil in S.D Values Series =L 2=a 3=b Table 4.3 Hunter Notation of 50% oil content Parameter L a b Results average Graph 4.4 hunter notation showing color values of 50% oil salad dressing

22 Hunter notation for 50% oil S.D Values Series = L 2=a 3=b Table 4.5 Hunter Notation of 0% oil content Parameter L a b Results average Graph 4.6 hunter notation showing color values of 0% oil salad dressing

23 Hunter notation for 0% oil in S.D Values 30 Series = L 2= a 3=b Conclusion For taste we a accept the null hypothesis for 50% oil salad dressing, as it was noticed to be grittier, and tarter than original. For taste we a rejected the null hypothesis for 0% oil salad dressing as I fell one vote short of being top favorite and it also received identical scores for creaminess, For texture we accepted the null hypothesis for 50% oil salad dressing as it was much thinner. For texture we reject the null hypothesis for 0% oil salad dressing, as texture qualities were identical to original in creaminess and thickness. Viscosity readings were very close For color we accepted the null hypothesis for both lower fat substitutes as they all had similar a and b values but L was different. Showing both deviations were darker than the original recipe.

24 Therefore results show it is possible to lower fat whilst maintaining taste; however lowed fat causes salad dressing to be a darker color. References Tom Zind Dressings Slim Down. Prepared Foods 176(3) , Mattias B Schultze et al Dietary Patterns and Changes in Body Weight in Women Joseph Su PhD, MPH and Lenore Arab PhD, MS Salad and Raw Vegetable Consumption and Nutritional Status in Adult US Population. Journal of the American Dietetic Association 106(9) Madeleine Sigman-Grant, Rex Warland, Gloria Hsieh Selected lower-fat foods positively impact nutrient quality in diets of free-living Americans. Journal of the American Dietetic Association 103(5) M. Liebman, B. A. Cameron, D. K. Carson, D. M. Brown and S. S. Meyer Dietary fat reduction behaviors in college students: relationship to dieting status, gender and key psychosocial variables. Department of Family and Consumer Sciences, University of Wyoming 36(1) Emel Cengiz and Nalan Gokoglu Effects of fat reduction and fat replacer addition on some quality characteristics of frankfurter-type sausages. International Journal of Food Science & Technology 42(3): Adam Drewnowski PhD Why do we Like Fat? Journal of the American Dietetic Association. 97(7) S58-S6