Higher Nutrition Values of Organic Peanut Butter by Carbohydrate, Photosynthesis & Protein Analysis


Rod Arzadon

Megan Hinkley

Carrie Sorensen

Ashley Throckmorton

There are many types of peanut butter, from organic to reduced-fat. We tested organic, natural, processed, and reduced-fat peanut butters in various carbohydrate, photosynthesis, and protein tests. We hypothesized that organic peanut butter is a healthier choice because it does not have as many added sugars, is higher in protein, and contains beneficial compounds such as folate. To determine the types of carbohydrates present, we used Iodine, Barfoed’s, Benedict’s, and Selivanoff’s tests. In the Iodine test, processed and reduced-fat tested positive for presence of starch, while natural and organic did not. Benedict’s test showed that reduced-fat had reducing sugars present, while Barfoed’s test distinguished it contained monosaccharide reducing sugars. Organic, natural, and processed did not test positive for reducing sugars in Barfoed’s and Benedict’s tests. Selivanoff’s test showed presence of ketoses in all four samples. To test for pigments present in all four types, we used paper chromatography. According to our results, there were no pigments present; therefore no rate of flow constants could be calculated. We used the absorption spectrum to identify at which wavelengths light was absorbed, supporting the results of paper chromatography. The absorption was similar for all four varieties of peanut butter. The Bradford Assay was used to determine protein concentration. We found the amount of protein in our sample to be as follows: organic: 0.0072468 and 0.00422 µg/µL; natural: 0.0072548 and 0.004326667 µg/µL; processed: 0.0066644 and 0.004831733 µg/µL; 0.007106 and 0.004604 µg/µL. No significant differences were found between the four peanut butter solutions.

Diets can be found all over the headlines in newspapers and as feature stories on the news. The newest fascination with dieting has come with one object in mind: lowering carbohydrate intake. There have been many studies done to support the idea that peanuts, as well as many other types of nuts, are indeed a healthy food choice having fewer added sugars. Organic and natural peanut butter have fewer additives than other peanut butters and therefore are thought to be healthier. Nuts are low in saturated fatty acids and high in monounsaturated and polyunsaturated fatty acids (Kris-Etherton, et al. 1999b). These types of fat are easier to digest. This is ideal for diets such as The Zone and Atkins. Also peanuts are found to have an average of 7.48 g of available carbohydrates in a 100 g edible portion, and peanut butter is found to have 21 g of carbohydrates in a 100 g edible portion (Souci, et al, 2000). This helps to provide a healthy and tasty snack for those watching their carbohydrate intake. To our knowledge and as defined by the USFDA, organic and natural peanut butters will fit better in a balanced diet than Peter Pan or Reduced-fat Peter Pan peanut butter.
We hypothesized that organic peanut butter is a healthier choice than natural, processed, and reduced-fat when shopping for peanut butter because it does not have as many added sugars, is higher in protein, and contains beneficial compounds such as folate.
We used several tests to determine the carbohydrates in our four varieties of peanut butter: Selivanoff’s test distinguished between mono/disaccharide ketoses and aldoses; Barfoed’s test distinguished between monosaccharides and poly/disaccharides; Benedict’s test showed whether or not reducing sugars were present; and the Iodine test established whether starch was found in our four varieties. The results of the carbohydrate tests provided many answers. In Selivanoff’s test color turned red fastest if the substance present was a monosaccharide ketose. Organic, natural, processed, and reduced-fat peanut butter all turned red in less than one minute, which meant that there may be ketoses present (Krha, et al. 2004). Barfoed’s test was used to determine whether monosaccharide reducing sugars were present. Monosaccharides reduced the copper and changed the color due to a formation of an orange/red precipitate (Krha, et al. 2004). In this test organic, natural, and processed peanut butter formed no precipitate while reduced-fat peanut butter had an orange/red precipitate. The formation of precipitate indicated the presence of monosaccharide reducing sugars in reduced-fat. The Iodine test was used to see if starch was present. When starch was present, the addition of Iodine-potassium-iodide caused the substance tested to change to a blue/black color (Krha, et al. 2004). In the Iodine test, organic and natural peanut butters showed no color change, while processed and reduced-fat both turned a darker brown/blue color, indicating a presence of starch. Benedict’s test was used to test for the presence of reducing sugars. If a sugar solution is a reducing sugar, an orange/red precipitate will form (Krha, et al. 2004). Organic, processed, and natural peanut butters did not have precipitates form while reduced-fat had an orange/red precipitate signifying a reducing sugar.
In Selivanoff’s and the Iodine tests absorbencies were also measured at 500 nm. We used 500 nm because the peanut butter solution was darker and we thought it would be more beneficial to use a darker wavelength. A higher absorbency in processed peanut butter indicated a stronger presence of ketoses relative to the other three types of peanut butter after running Selivanoff’s test (Table 3). Natural peanut butter treated with Iodine-potassium-iodide had a higher absorbency when compared to the other peanut butters, thus showing a higher relative concentration of starch (Table 3). Masses of precipitates were measured for Barfoed’s and Benedict’s test. Reduced-fat peanut butter had a larger massed precipitate when compared to the other three types of peanut butter (Table 4). This could be expected as it was the only peanut butter solution to form an orange/red precipitate after addition of Benedict’s reagent. Barfoed’s test indicated a strong presence of reducing monosaccharides in processed peanut butter (Table 4).
We used paper chromatography to discover the different types of pigments present in our four types of peanut butter. We hypothesized that organic peanut butter would be the healthier choice and therefore would have more beneficial pigments present compared to the processed, natural, and reduced-fat. The different pigments that were tested for and found were compared to the Rf values in spinach leaves. The prediction is that the pigments in all four peanut butter types will differ very slightly, if it all. The part of the peanut used in making peanut butter does not function in photosynthetic activity, so all four peanut butter brands should test the same on all levels. Because it is not active in photosynthesis, pigments will not come from photosynthetic activity. We are expecting to see levels of carotene in the organic peanut butter and no chlorophyll. These levels should be higher in the organic peanut butter when compared to the other types because there are not as many additives. We were unable to find any pigments present in any of the peanut butter solutions (Table 5). Using a different solvent may help identify pigments present.
We also used the absorption spectrum to determine relative absorbencies at wavelengths from 400-700. We used this test to further support the results from paper chromatography. This test showed the region where the different pigments absorbed light best. We predicted that the pigments present will absorb similarly at the same wavelengths. The results of this test showed peaks at similar wavelengths for the four types of peanut butter (Figure 8). The minor peaks could represent pigments that did not separate during paper chromatography or added food coloring in peanut butters. We did not think there would be any photosynthetic activity occurring; therefore the colors absorbed should be similar in all types of peanut butter.
The Bradford Assay tests for the amount of protein present in the sample. The amount of protein in each sample was significant because we hypothesized that organic peanut butter would have a higher amount of protein due to lack of processing and favorable growing conditions. A higher protein concentration is considered healthier. Creating a standard protein assay curve by measuring varying concentrations of bovine serum albumin and finding the absorbency of each sample with the Bradford reagent will allow us to compare the amount of proteins present in each of our samples. We predict the organic peanut butter will have more proteins because it is less processed and does not contain additives that are present in the mass produced peanut butter. We found all four peanut butter solutions to have similar amounts of protein (Table 7). It would be expected that the protein concentration would be higher in natural and organic because they do not undergo processing which may destroy proteins.
Through our many tests and trials, our results did not support our hypothesis, showing no difference between the four types of peanut butter. This was shown by the results of the carbohydrate, photosynthesis, and protein tests. Possible sources of error in this lab could include mishandling of peanut butter solution, and incorrect measurements. Due to the extended time period of the experiment, breakdown of the organic peanut butter caused by a lack of preservatives and a non air tight seal on the container is also a possible source of error. Human error is another possible source of inaccuracy. The scope of our experiment was very narrow. While we only performed tests in the areas of carbohydrates, photosynthesis, and protein, further studies in more specific areas such as vitamins, minerals, and oils could be conducted. These tests could show further differences that we were not able to demonstrate.

Figure 1. Preparation of Peanut Butter Solution. Each of the four varieties of peanut butter was massed using a scale. The peanut butter was placed in a mortar that had already been zeroed on the scale (A). We used a pestle to mash the peanut butter, adding 50 mL of distilled water to the mortar to begin the mixing process (B). After being mixed, the contents of the mortar were poured into a blender, and after the addition of 100 mL of distilled water were blended for 30 seconds (C). The resulting solutions were poured into 250 mL beakers for storage (D).