Nalgene

Brassica oleracae , the Low-Carb Alternative for Solanum tuberosum based on Barfoeds, Iodine and Bradford assays.

Nalgene

By Adrienne Hopper, RajReni Kaul, Jessica Levely, and James Mashni

Cell and Molecular Biology LBS 145

Dr. Luckie

Febuary 29,2005

Dieters following the Atkins diet are directed to cut back on foods high in carbohydrates. Unfortunately for dieters many key foods are carbohydrate rich, so substitutions are suggested (Anonymous-1, 2004). One substitution we investigated was the substitution of white cauliflower for Idaho potatoes. Through various assays including Barfoed's, Iodine, and Bradford , we compared the nutrient values of potatoes and cauliflower. Along with the previous assays, we also conducted the Hill's reaction and Resistant Starch assay. All assays were replicated three times. The Hill's reaction tests the amount of photosynthesis based on electron transfer. Resistance starches act like fibers which are types of indigestible complex carbohydrates. Fiber is not a source of energy and is excreted from the body. Fiber can be thought of as a dieter's dream; it creates a sense of fullness in the stomach, therefore reducing the intake of additional food (Tsang, 2005). The Resistant Starch test concluded no significant difference between the cauliflower and potato. Using the Bradford assay we found that there was no significant difference between the protein concentrations of the potato and cauliflower. The Barfoed's test we made quantitave by running through the spectrophotometer. The results showed a higher concentration of monosaccharides in cauliflower. The iodine test concluded that only potatoes contain starch, meaning potatoes have more polysaccharides. The Hill reaction resulted in showing higher amounts of photosynthesis in the potato. These assays we conducted helped to support our hypothesis that cauliflower is a good substitute for potatoes.

A major component of the Atkins diet is to increase the level of protein intake, while reducing the amount of carbohydrates eaten(Anonymous-1,2004). The assays that we ran were used in combination to evaluate the overall benefit of eating cauliflower instead of potatoes, according to the diet. From these results, our hypothesis that cauliflower is a good substitute for potatoes with respect to the Atkins diet, is supported. The three major areas we tested were carbohydrates, protein, and photosynthesis activity.

Using the Barfoed's test, we determined if monosaccharide molecules, such as fructose and glucose, are present in potatoes and cauliflower. In past studies, the presence of fructose, sucrose, and glucose has been found in both vegetables, while cellulose was only found in potatoes (Olsen, 2004). From the past research, we expected to find monosaccharide in both vegetables (Olsen,2004). We had to run this test twice. The first time we recorded if monosaccharides were present. The second time we ran the products through the spectrometer to find absorbency, and a rough idea of the amount of precipitate, which are painted monosaccharide molecules. The higher the absorbency the higher concentration of precipitate. The absorbencies of the cauliflower and potato were analyzed with a t-test. From the t-test, we can reject the null hypothesis, that there is not a significant difference between the absorbency values of the vegetables. We can conclude that there is a higher concentration of monosaccharide sugars in cauliflower than potatoes. This does not mean we can make any conclusion about the presence of polysaccharides and disaccharides in either vegetables. Our results may not be as accurate as past research because of the sensitivity of the Barfoed's test(Cataldi et al., 1997). Past studies have shown all three types of sacchrides present in both vegetables(Cataldi et al.,1997).

The next test we ran to test carbohydrates, was the Iodine test, which tested for the presence of starch. We expected to observe positive results for both the potato and cauliflower (Miller, 2003 and Nuehaus et al., 1995) We found starch present in potatoes. This is reaffirmed by past research, and established nutritional findings. The majority of the potato's carbohydrates are complex coiled sugars, also known as starch (Miller, 2003). On the other hand, starch was not found in cauliflower using the Iodine test. Past research has extracted starch from cauliflower buds (Nuehaus et al ., 1995). The research by Nuehaus et. al may have used a more sensitive method for detecting starch, which might explain the contradiction in results.

The last test we ran for carbohydrates was an assay measuring the concentration of resistance starch. Resistance starch is healthier for the body because it acts like fiber, meaning it is not broken down until it enters the large intestine (Tsang, 2005). This is important because foods high in fiber are filling, as well as, providing digestive benefits. Resistance starch can be broken down into two categories: insoluble fiber and fermentable fiber (Anonymous-5, 2000). Fiber is also beneficial because it encourages the growth of beneficial bacteria such as bifidobacteria, and inhibits the growth of harmful bacteria, such as, Escherichia coli(Anonymous-5, 2000). Resistance starch also is beneficial because it aids in the removal toxins from the colon(Anonymous-5, 2000). When looking for a healthy substitute, high fibers are a good choice (Tsang, 2005). On the molecular level resistance starch can be in the form of amylose and amylopectin (Anonymous-5, 2000). This means they can be branched and straight chains. Since resistance starch acts like fiber, it is measured as a fiber. Potatoes have less fiber than cauliflower, so we expect to find less resistance starch in potatoes when compared to cauliflower (Anonymous-2, 2004).

The test results are contradictory to past research. Our p-value allows us to accept our null hypothesis. The results may be skewed due to inaccurate stock solutions that required specific pH levels. We did not have access to a machine that could read the pH as accurate as needed, instead we used pH paper. Also, due to the restricted times of open lab the incubation periods were not as accurate as the methods indicated. The last possible error could be due to a mechanical malfunction. During the longest incubation time of 16 hours, the shaking water bath stopped shaking.

Protein was also another important factor taken into account to assess the quality of both vegetables. Accepted nutritional values for protein levels are .03grams/gram of potatoes, compared to .013grams/ gram of cauliflower (Anonymous-2, 2004). Dietary protein is beneficial because it provides amino acids for the body to use as a building block for any new cell growth (Freeman, 2002). We ran the Bradford test twice, due to error. Factors that may have caused error are experimental timing, and dirty glassware. Once our standard curve was found, we used the line of best fit to find the protein concentration of cauliflowers and potatoes using absorbency. Our p-value from the t-test allowed us to accept our null hypothesis, that there was no significant difference in protein levels of the potato and cauliflower. This is important because a good Atkins' diet needs to be high in protein, with this substitution nutritional value with respect to protein is not lost (Anonymous-1, 2004).

The last assay we used to test appropriateness of the substitution of potatoes with cauliflower was the action spectrum assay. This assay measures the amount of active chlorophyll, which can be used to approximate the energy in the plant. Our results showed that the potato leaf chloroplasts were more active, meaning there is more NADP available in the plant. NADP is important because it will be used with ATP, to make transportable energy, glucose (Freeman, 2002). Which is then used to build and sustain the plant. We expected to observe a higher level of photosynthesis in potatoes. We compared the average differences of potatoes and cauliflower with a t-test. The p-value allows us to reject our null hypothesis of no difference. Since Idaho potatoes absorb more energy, there should be more energy stored in the potato. This logic is supported by accepted nutritional values; potatoes contain .93cal/gram, while cauliflower has .22cal/gram(Anonymous-2,2004). Therefore cauliflower is a good substitute because it has fewer calories.

From the assays we conducted, our hypothesis is supported. Cauliflower does make a good substitute for potatoes. They both have the same amount of protein, so substitution does not have any draw backs with respect to protein. The test results from the resistance starch assay showed no difference, so the substitution would not make any difference. From the Iodine test, our results showed only potatoes have starch. The potato has polysaccharides present in the form of starch, while the cauliflower has more monosaccharide. Polysaccharides are a better source of energy when following a traditional diet because it requires energy to break the bonds of polysaccharides, while monosaccharides do not (Freeman, 2002). On the other hand, when following the Atkins diet starchy foods, like potatoes, are the first to be cut from the average meal(Anonymous-1,2004). While high in starch, potatoes according to The Idaho Potato Commission have higher amounts of potassium and vitamin C (Anonymous-6, 2005). The presence of more vitamins and essential nutrients in cauliflower would make it a better substitute along with a higher concentration of resistance starch, but following Atkins guidelines; the other factors make it a good alternative for potatoes.

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Nuehaus, H, et al. 1995. Starch Degradation in Intact Amyoplasts Isolated from Cauliflower Floral Buds ( Brassicaoleracael L ). Planta 195: 496-504