The Effects of Emulsifiers and Stabilizers in Hollandaise Sauce November 20, 2006 Cory Block F&N 453: Food Chemistry Abstract: Emulsifiers and stabilizers are common additives in food processing. These additives can be used in many different products. In particular, these substances are used in salad dressings and different sauces. Stabilizers and emulsifiers can change the palatability, viscosity, and color of a product. Hollandaise sauce already has an emulsifying agent lecithin. The additives used were xanthan gum and carrageenan. The xanthan gum additive caused the greatest increase in viscosity followed by the carrageenan and finally the control. Taste and palatability were negatively affected by the addition of these stabilizers. Overall the addition of supplementary emulsifiers and stabilizers is not beneficial to the final product. Introduction: An emulsion is defined as a colloidal dispersion of one liquid in another. They form the basis of a huge range of food products and are generally stabilized by either protein and/or emulsifiers (Wilde 2004). Emulsions have three parts which make up the entire product. There can be two types of emulsions; oil in water or water in oil. In oil in water emulsion, the dispersed phase (oil droplets), continuous phase (water), and the third phase is an emulsifier. An emulsifier has two functional areas; one hydrophobic end with an affinity for oil and a hydrophilic end with an affinity for water (Charley 1998). These properties allow the emulsifier to decrease surface tension between the two phases. Different types of emulsifiers are required depending on the hydrophilic/hydrophobic balance. Those emulsifiers with a low HLB will be used in water in oil and those with a high HLB will be used in an oil in water emulsion. The temperature at which the mixing occurs can also affect the product. Synergistic interaction occurs at a mixing temperature of 25 to 80 C, but a stronger synergistic interaction was observed at mixing temperature 80 C (Khouryieh). Emulsifiers can be both natural and synthetic. Naturally occurring emulsifiers can be found in milk, eggs, meat, and plant proteins. Hollandaise sauce is an emulsion of butter and lemon juice using egg yolks as the emulsifier. The emulsifying agent in egg yolks is lecithin. Lecithin is a phospholipid which is chemically known as phosphatidyl choline (Charley 1998). The egg yolks ability to emulsify is associated with its stabilizing ability due to the protein content within the egg yolk as well. Hollandaise sauce has the tendency to separate after a particular amount of time. The addition of supplemental stabilizers could prevent this from happening and improve the overall product. The three different hollandaise sauces will be tested objectively for viscosity using the Brookfield viscometer and color using the Hunter Colorimeter. The hollandaise sauces will also be subjected to an evaluation panel for color, palatability, and taste. The overall purpose of the project is to investigate the independent variables effects carrageenan and xanthan gum will have on hollandaise sauce.
Methods: The procedure for each trial requires the following ingredients and supplies: 2 Egg Yolks (33g) Speck of Cayenne Lemon Juice (15ml) Butter or Margarine divided into 3 parts (113g) Xanthan gum or Carrageenan (.035g) 1. Preparation Place egg yolks in top of double boiler. Add lemon juice, 1/3 butter or margarine, and emulsifier. Cook over hot, not boiling, water stirring constantly until thickening begins. Add second portion of butter or margarine. Allow mixture to thicken again. Then add third portion of butter or margarine and seasonings. Serve as soon as thickened. After product is finished it will be tested using the methods in subsequent sections. 2. Objective Testing The three sauces will be tested using the Brookfield viscometer. To test viscosity in this fashion a sample of the sauce is placed in a glass beaker. The sauce was tested immediately after the third thickening. The spindle which was used was number five and was attached to the lower shaft. The spindle number was set on the display screen to match the spindle being used. The spindle was then inserted into the test material until the fluid level is at the immersion groove on the spindle s shaft. The Hunter Colorimeter was utilized to evaluate the color. Calibration of this machine is set using the white and black standardizing templates. The sample is placed over the eye which then calculates the L, a, and b values displaying them on the computer screen. 3. Subjective Testing A small amount of each sample is poured into a custard cup for the taste panel. The taste panel is presented the three custard cups with randomized numbering on the cups. The sauces are tested with crackers to make the process easier and more appealing. The survey panel is given a card to fill out.
Color: Rank the following samples in terms of color from most appealing (1) to least appealing (3). Sample 234 Sample 987 Sample 461 Palatability/Mouthfeel: Rank the following samples from most appealing (1) to least appealing (3). Sample 987 Sample 461 Sample 234 Taste: Rank the following in accordance of best taste (1) to worst taste (3). Sample 461 Sample 234 Sample 987 Figure 1: Taste Panel Evaluation: The format follows that of a rank order test.
Results: The three different sauces were tested for viscosity and color. The results are as follows: 1800 1600 1400 1200 1000 cp(centipoise) 800 600 400 200 0 Control Xanthan Gum Carrageenan Figure 2: Average Viscosity of 3 Hollandaise Variables. The values determined by the Brookfield Viscometer are measured in centipoise (cp). The sauce with the highest viscosity at a value of 1710cP was Xanthan gum. Carrageenan had the same effect with a value of 1576cP followed by the control at 1030cP. Table 1: Average Hunter Notation Color Values. L a b Control 74.54 0.25 24.51 Xanthan Gum 78.23 1.11 26.98 Carrageenan 72.02 2.22 27.49 The data shows that emulsifiers have negatively altered the color of the product. The values given by the Hunter Colorimeter supports this idea. The L-value correlates with lightness of the sample, the a-value with the red-greenness, and the b-value with the yellow-bluish of the color. This is also reinforced by the subjective testing of the evaluation panel.
Table 2: Subjective Evaluation Panel Results: Xanthan Gum Control Carrageenan Color 10 24 6 Palatability 3 30 7 Taste 8 20 12 30 25 20 Times Preferred 15 10 5 0 Xanthan Gum Control Carrageenan Figure 3: Times Preferred by Color of each Variation. The results exhibit the fact that the emulsifiers/stabilizers change the color of the product. Xanthan gum and carrageenan both negatively affected the color as determined by the survey panel with only 10 and 6 times preferred respectively with the control receiving 24 votes. 35 30 25 Times Preferred 20 15 10 5 0 Xanthan Gum Control Carrageenan Figure 4: Palatability/Mouthfeel Rating of Three Variables. Xanthan gum and carrageenan both worked well in increasing viscosity however this negatively affected the palatability of the product. It is evident that the control (30) was favored highly over the other two variables followed by carrageenan (7) and finally xanthan gum (3).
25 20 Times Preferred 15 10 5 0 Xanthan Gum Control Carrageenan Figure 5: Taste Results for Different Variations. Disregarding the texture of the products, the results show only a slight favor towards the control in taste at 20 votes. Following the control is carrageenan and xanthan gum receiving 12 and 8 votes respectively. Discussion: 1. Preface The hypothesis of the experiment was shown to be partially true. The addition of the stabilizers did in fact affect the color which correlates with the hypothesis. The palatability which was hypothesized to be unaffected by the stabilizer was shown to be false. The stability of the product was unable to be determined in this experiment; this will be discussed in the sources of error section. The results were fairly accurate and precise within all three trials. The proposed method for trial 1 was found to be a success and was repeated for trials 2 and 3. 2. Viscosity/Palatability From the results section it was concluded that the two variables containing stabilizers were more viscous. That is to say the sauces with the additional stabilizers have a greater degree of internal friction. Viscosity is defined as the ratio of shear stress to rate of change of strain (Christen 2000). The shear stress is the force applied over a particular area creating a shearing strain which is correlated with movement. The idea behind the viscometer is fairly simple. It is based on the principle that the thicker the fluid the more power it will need to overcome the shear strain or the drag of the rotating spindle (Charley 1998). Xanthan gum and carrageenan are both very effective stabilizers. Xanthan gum is a bacterial gum originating from Xanthomonas campestris. It is soluble in both hot and cold water and can produce a high viscosity at low concentration. Likewise Carrageenan has a thickening ability at very low concentrations. Commonly
used in milk and cheese products this stabilizer is able to associate with proteins increasing stability of the dispersion (Christen 2000). This may account for its relatively high viscosity allowing the carrageenan to bond with the proteins found in the eggs used in the recipe. Palatability and viscosity are intertwined. Gums/stabilizers/emulsifiers are integral ingredients in fluid foods used for controlling viscosity and mouthfeel (Yaseen). As viscosity increases the mouthfeel or palatability of the product also increases. This correlates with the results given in the previous section showing that xanthan gum had the greatest effect on viscosity and therefore also palatability. 3. Color/Taste The color of the two variations differed from that of the control. Both the Hunter Colorimeter and the survey panel back this idea up. It was not the intention of this project to analyze the difference of the colors but to illustrate that the additives have an effect on color. Xanthan gum caused a similar color change to that of carrageenan. The taste of the products were not altered significantly from the stabilizers. Disregarding the mouthfeel/palatability aspect the survey panel showed that the control was favored for taste but the results were not extremely one-sided. 4. Sources of Error One of the original objectives for this project was to examine the effect that the different stabilizers would have on the Hollandaise sauce. This was unable to be explored for a number of reasons. The sauces never separated to an extent which was able to be manually examined by the eye. Not even the control separated enough to distinguish this lack of stability. The over coagulation of the proteins in the egg while preparing the sauces could have contributed to this effect and the high viscosities. Also the time between the last thickening of the sauce and when the viscosity was measured could have varied. This would cause the sauce to increase in viscosity with cooling. With regards to the colorimetric analysis a few sources of error are possible. The calibration of the colorimeter could have been skewed to from the origin. Also the addition of the cayenne pepper can account for the difference in a-values corresponding to increased redness of the product. As with all subjective testing the results are only as accurate and precise as the panel is trained. The sauces may have been different temperatures for each panel member creating different palatability and taste. 5. Take Home Message The addition of stabilizers to Hollandaise sauce is unnecessary. The benefits of stability to the sauce are far outweighed by the disadvantages. Although taste was unaffected, color, viscosity, and palatability of the product are damaged to the extent which makes the product undesirable as determined by the survey panel. In future experiments a student my want to reevaluate how to determine stability other than visually watching for separation. Also omitting the cayenne pepper will allow for more accurate results in the colorimetric analysis.
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