Locust Bean Gum as Fat Replacer in Broccoli and Cheddar Soup Jacqueline Vahle and Samantha Steed FN 453 11/22/2009
ABSTRACT The role of locust bean gum (Cesagum) in operating as a fat replacer was investigated in broccoli and cheddar soup. In experiment one, the soup contained 9.49 grams (g) of Cesagum cold water dispersed in 118.3 milliliters (ml) of water, while the second experiment used 2.37 g of Cesagum cold water dispersed in 118.3 ml of water. In both experiments, viscosity was increased due to the water holding capabilities of the Cesagum. L values decreased in both soups with the Cesagum, chroma increased in the soup with 9.49 g yet decreased in the soup with 2.37 g, and hue on average increased in both soups with the Cesagum. The soup containing cream was preferred to both soups containing Cesagum in appearance, texture, and flavor. Due to the objective and subjective conclusions, evidence indicates the broccoli and cheddar soup with the Cesagum does not have the same texture and palatability as the broccoli and cheddar soup without the Cesagum. INTRODUCTION It is recognized that flavor, texture, and nutritional aspects of many foods are dependent on the presence of lipids (Hui 2007). Lipids contribute around 37 percent (%) of the average American s daily caloric intake. While they are important for maintaining good health, over consumption of lipids can have adverse effects (Hui 2007). The Dietary Guidelines describe a healthy diet as one that is low in saturated fats, trans fats, cholesterol, salt, and added sugars. Excess intake of calories from fat and carbohydrate leads to obesity with an increased incidence of diabetes and high blood pressure (Hui 2007). The challenge to lower the fat content in foods, yet retain flavor and texture, is the foundation aim of this study. In past studies, many fat substitutes used in foods have been chemically synthesized from conventional fats and oils to retain the functional characteristics and reduce the caloric contribution. Few studies have examined fat substitutions in a soup using a natural seed gum such as locust bean. Locust bean gum is a polysaccharide derived from the carob tree. It is extracted from the carob seed, which is found within the fruit of the tree. The white, semitransparent endosperm of the seed is the desired gum (Whistler 1973). It has been used since ancient times for its thickening properties, but industrial utilization of locust bean gum began early in the 20 th century. There are four main grades of locust bean gum: top high grade, normal high grade, industrial grade, and technical grade. Cesagum, made by Tate & Lyle, groups a range of these different grades together. Probably the functions of greatest concern when altering the lipid profile of a food product are those that affect the flavor and texture quality (Hui 2007). Functional properties of locust bean gum derivatives are stabilizing, swelling power, and great ability to absorb water (Whistler 1973). The derivatives are not affected by lactic acid, making it ideal to be used in milk based soup such as Broccoli and Cheddar. When a soluble polysaccharide is placed in water, the abundant water molecules quickly penetrate amorphous regions and do not hydrate beyond the intermediate gel stage (Whistler 1973). In order to fully evaluate the significance of change in texture due to the substitution, the Brookfield Viscometer provides objective data showing consistent values comparing the soup with the cream and the soup with the Cesagum. The Hunter Colorimeter report changes in appearance due to color between the Cesagum soup and the cream soup. Changes in flavor are reported through randomized subjective testing by semi trained panelists. The aim for this study is to retain the same texture, appearance, and flavor in the broccoli and cheddar soup with fat replacer Cesagum.
METHODS This experiment was carried out using three variations (control that uses heavy cream, 9.49 g Cesagum for heavy cream, and 2.37 g Cesagum for heavy cream). Each variation was replicated three times and tested for color, texture, flavor, appearance, and overall product preference. In executing the needed measurements, a Hunter Colorimeter, a Brookfield Viscometer, a Hedonic Rating System, and a Ranking Test was used for the appropriate aspects. For trial one (the control), 42.6 g of butter was melted over medium high heat in a medium pot. Then, 230 g of onions, 2.4 g of salt, 1.2 g of white pepper, and one pinch of nutmeg, was added to the melted butter and cooked and stirred for three minutes. 2.4 g of minced garlic and 2.4 g of chopped thyme leaves were added to the pot and cooked and stirred for twenty seconds. Next, 42.6 g of all purpose flour was added and cooked and stirred for two minutes, until it was well blended. Then, 709.8 milliliters (ml) of chicken stock was added slowly and whisked constantly, until it was brought to a boil. Heat was then reduced and the mixture simmered for five minutes, until it was thickened. Approximately 455.5 g of packaged frozen broccoli was pureed on grind option (medium high) in a blender for thirty seconds. It was then added to the mixture and cooked at a simmer for ten minutes. Then, 118.3 ml of heavy cream was added while the soup continued to cook at a bare simmer. The remaining 28.4 g of butter was added next, and stirred until blended. Finally, 287.4 g of shredded cheddar cheese was added, while the soup cooked over low heat, being stirred until cheese had melted. The pot containing the mixture was removed from the heat, and allowed to cool until it reached exactly 80 degrees Celsius for both subjective and objective testing. The recipe, as previously outlined, was replicated three times using the same ingredients and procedure. Then, two additional trials were conducted by replacing the heavy cream with differing amounts of Cesagum. Both of these trials were also replicated three times. Trial two replaced the heavy cream with 9.49 g of Cesagum, dispersed in 118.3 ml of cold tap water. Trial three used 2.37 g of Cesagum, dispersed in 118.3 ml of cold tap water. Trial three contained one discrepancy in that the chicken stock used was 100 milligrams less in total than that of the previous trials, due to limited product supply. All trials and replications were tested for color and appearance (using the Hunter Colorimeter and ten semi trained panelists, respectively), texture (using the Brookfield Viscometer and ten semi trained panelists), flavor (using ten semi trained panelists), and overall product preference (using a seven point Hedonic scale). A 90 ml sample, placed into a 100 ml beaker, was taken from each sample (trial one (control), trial two, and trial three and their replicates) to be tested using objective equipment: Hunter Colorimeter and Brookfield Viscometer. Trial one (control), trial two, and trial three, were each given a random three digit number to eliminate bias during the subjective testing: 765, 260, 317 respectively. Each sample was measured for color using the common L, a, and b Hunter parameters (Weaver 2003). Overall appearance was tested subjectively by having ten semi trained panelists rank 30 ml samples, in comparison to one another, from one to three (one being the best and three being the worst). Texture was analyzed with a number 5 spindle using the Brookfield Viscometer at various rpm s: 6, 12, 30, 60, and 100. Texture was also measured using those same ten semi trained panelists to rank the 30 ml samples, in comparison to one another, on that same scale of one to three. Flavor of the 30 ml samples were measured subjectively, in comparison to one another, by the same ten semi trained on a scale of one to three. Overall product preference was measured hedonically of the 30 ml sample by those ten semi trained panelists, in which the samples were rated by marking the appropriate box (ranging from dislike extremely to like extremely ). Subjective flavor, appearance, texture, and product preference measurements can be found on the sensory scorecard page attached.
RESULTS: FIGURE 1: Hunter Colorimeter measuring L Value /lightness (white to black) FIGURE 2: Hunter Colorimeter measuring a Value/ Hue (red to green)
FIGURE 3: Hunter Colorimeter measuring b Value/ Chromaticity (yellow to blue) FIGURE 4: Average Viscosities using Spindle Number 5 in the Brookfield Viscometer at 6, 12, 30, 60, 100 rpm
Table 1: Hedonic Overall Product Preference on a 7 point scale as determined by 10 semi trained panelists Trial 1 Trial 2 Trial 3 Average Control 5.8 5.6 7.2 6.0 9.49 grams 2.7 2.2 2.0 2.3 2.37 grams 5.0 5.5 5.6 5.4 Table 2: Ranking Test dependent on flavor as determined by 10 semi trained panelists (1 being the best, 3 being the worst) Trial 1 Trial 2 Trial 3 Average Control 1 1 1 1 9.49 grams 3 3 3 3 2.37 grams 2 2 2 2 Table 3: Ranking Test dependent on appearance as determined by 10 semitrained panelists (1 being the best, 3 being the worst) Trial 1 Trial 2 Trial 3 Average Control 1 1 2 1.3 9.49 grams 3 2 3 2.6 2.37 grams 2 3 1 2 Table 4: Ranking Test dependent on texture as determined by 10 semi trained panelists (1 being the best, 3 being the worst) Trial 1 Trial 2 Trial 3 Average Control 1 2 1 1.3 9.49 grams 3 3 3 3 2.37 grams 1 1 2 1.3
DISCUSSION Tables 2 and 3 and 4 showed flavor, appearance, and texture results, respectively. Our 765 sample (control) was the best in flavor and appearance. Milk fat affects the overall flavor of the product as it is an important determinant of the textural creaminess. A fat replacer should match the texture, mouthfeel, and functionality of milk fat in a food product (Ohmes and others 1998). Sample 260 (9.49 grams) was the worst in flavor, appearance, and texture. Sample 317 (2.37 grams) was neither the best nor worst in flavor and appearance. There was no difference among the panelists for texture between sample 765 and sample 317. Table 1 depicts overall product preference. Samples were measured on a 7 point Hedonic scale. Sample 765 was preferred over samples 260 and 317. Sample 765 averaged a rating of 6.0 referring to panelists preference of like moderately. Sample 317 averaged a rating of 5.4 referring to panelists preference of like slightly. Sample 260 had the least overall preference by the panelists with an average rating of 2.3 representing dislike moderately. Figures 1, 2, and 3 illustrate results from the Hunter Colorimeter and objectively evaluate the appearance of the 3 samples through a direct measure of color using numerical values to correlate to the lightness, red to green color, and yellow to blue color (Weaver 2003). The L value of a product with a more positive number indicates lightness (using a white to black scale). The a value of a product with a more positive number indicates a measure of red hue (using a red to green scale). The b value of a product with a more positive number indicates a measure of yellow hue (using a yellow to blue scale). Figure 1 results show sample 765 being the lightest and sample 317 being the darkest. This indicates that the cream in sample 765 was responsible for the lightness of the soup. The soup sample with the most Cesagum, sample 260 was the next lightest due to the Cesagum powder being white. Figure 2 results show sample 765 having neither the highest nor the lowest red to green hue. Sample 260 had the highest red to green hue and sample 317 had the lowest red to green hue. Figure 3 results show average sample results of yellow to blue hue. Sample 765 had the least and sample 317 had the most. Sample 260 had neither the highest nor lowest yellow to blue hue. Figure 4 illustrates the viscosities among the 3 samples using a Brookefield Viscometer, spindle number 5. Sample 260 displayed the highest viscosity. This would be due to the Cesagum having swelling power and great ability to absorb water. Due to the locust bean gum being a linear polysaccharide, the space occupied sweeps out greater volumes than branched molecules. Consequently, high viscosities are produced even in small concentrations (Whistler 1973). According to Aziznia and others, locust bean gum can be used in yogurt to stabilize and increase viscosity as well. Sample 765 had neither the highest nor the lowest viscosity. It contained less Cesagum than sample 260 yet its viscosity was higher than the control sample which had no Cesagum. Sample 317 had the lowest viscosity. Methods conducted could be changed on account of concentrations of the Cesagum. Sample 260 (9.49 g of Cesagum) failed to provide the product with desirable flavor, texture, and appearance, when appropriately tested subjectively and objectively. This is due to the erroneous gum to water concentration that was used in experimentation. In thickening soups, Cesagum and other locust bean gums, should contain a gum concentration between 0.2 to 0.6 %. Additionally, the gum should be subjected to hot water dispersion, not cold water dispersion, as was used in this experiment. Dispersions heated to 95 degrees Celsius and then cooled have a much higher viscosity than dispersions made in cold water. This procedure will obtain a greater efficiency as a thickener in the soup. Sample 317 (2.37 g of Cesagum) presented better flavor, texture, and appearance due to the more proportional amount of Cesagum to water used.
Future tests can be derived from this experiment. The physical properties of Cesagum (locust bean gum) have significant similarity to guaran gum (Whister 1973). These can be interchanged in food products to either confirm or deny their physical and chemical resemblance. Another proposition for future work involving locust bean gum would be incorporating its use into other foods as a stabilizer in products such as sauces, salad dressings, and cheese spreads. Opportunities for other work would be to test the effects of locust bean gums versus starch fat replacers in a food product Objective and subjective conclusions show the broccoli and cheddar soup with the Cesagum does not have the same texture and palatability as the broccoli and cheddar soup without the Cesagum. The soup with the Cesagum would have been more effective at matching the flavor, texture, and appearance as the broccoli and cheddar soup without the Cesagum had the gum concentration been between 0.2% 0.6% and hot water dispersed. Locust bean gum can be an effective fat replacer used in milk based soups if appropriate measures are followed to emulate the function of fat in milk based soup. REFERENCES Aziznia S, Khosrowshahi A, Madadlou A. 2008.Whey protein concentrate and gum tragacanth as fat replacers in nonfat yogurt: chemical, physical, and micro structural properties.journal of Dairy Science. 91:2545 2552. Dietary Guidelines. Mypyramid.gov. United States Department of Agriculture. September 10, 2009. 21 November 2009 Recipes and Cooking. Food Network.com.Television Food Network GP. 2009. 25 September 2009. Hui, Y.H. 2007. Food chemistry: principles and applications. California. Science Technology System. pp 4 18, 5 14, 17 12. Ohmes R L, Marshall R T, Heymann H. 1998. Sensory and physical properties of ice creams containing milk fat or fat replacers. Journal of Dairy Science. 81(5):1222 1228. Whistler, Roy L. 1973. Industrial Gums 2 nd ed. New York and London. Academic Press pp 323 338. Weaver C, Daniel J. 2003. The food chemistry laboratory a manual for experimental foods, dietetics, and food scientists 2 nd ed. Boca Raton, Florida: CRC Press. 137 p.