The Mutts

Abstract:
By Jamie Mooney Revised By Becca Hernandez & Araya Negash
    Is there a difference between the compositions of oranges from different US coasts? Due to the fact that Florida and California oranges inhabit different climates, we hypothesize that there will be a difference. To support this hypothesis, we performed a series of carbohydrate, photosynthetic, and enzymatic tests.
We first performed carbohydrate/sugar tests. Benedict’s test was used to determine whether the fruits contained free aldehyde or ketone groups. Both California and Florida oranges contained ketones. Barfoed’s test was similar, and showed that oranges from both coasts contain di- or polysaccharides. Lastly, we used Selivanoff’s test to find if the sugars were ketose or aldose. Our results revealed that both varieties of oranges contained di-ketose sugars. Bial’s test assessed for furanose rings, which were not present in either orange. Both Florida and California oranges contained pyranose rings.
The following tests performed, the photosynthetic tests, showed the absorption rate of light. The Absorption Spectrum test determined that the leaves of both California and Florida oranges had nearly identical absorption rates, and produced similar absorption graphs. Using Paper Chromatography, we determined that both fruits had carotene, chlorophyll a, and chlorophyll b.
The last sets of tests done were the enzyme tests.   First the pH was tested, then we tested for the presence of the enzyme PPO. Both oranges had a pH of 5 and neither contained PPO. After performing these tests, the results of these experiments do not support a noticeable difference in carbohydrates, photosynthesis and enzymes between oranges from California and Florida.

Discussion:
By Becca Hernandez Revised By Araya Negash & Jamie Mooney
        Is there a difference between sugars, enzymes, and photosynthetic activity between California oranges and Florida oranges? Our alternative hypothesis states that there will be. If two different varieties of the same fruit are tested for carbohydrate, photosynthetic, and enzymatic differences, we believe that significant differences will be found. We carried out multiple carbohydrate, photosynthetic, and enzyme tests to support this. The research we found from these tests did not support this hypothesis.
    The first tests that were performed were the carbohydrate tests. Benedict’s tests analyzed solutions for the presence of reducing sugars. It is used to determine whether or not the carbohydrate contains a free aldehyde or ketone group. The test results were identical. Neither the California orange nor the Florida orange produced any copper precipitate indicating that no reducing sugars were present in solution (Figure 1). The second carbohydrate test performed was Barfoed’s test. This test is used to determine whether the reducing sugars are monosaccharides, disaccharides, or polysaccharides. Monosaccharides can be distinguished from disaccharides and polysaccharides because only the monosaccharides can react fast enough to reduce copper ions. Again neither the California orange nor the Florida orange produced any precipitate (Figure 2). Therefore, both brands of oranges contained di and polysaccharides. The third test, Selivanoff’s test, is used to distinguish between ketose and aldose groups. Both solutions of the California and Florida oranges reacted in roughly one minute, signifying the presence di-ketose groups for both oranges (Figure 3).   Although both solutions turned red, it took the California orange slightly longer than the Florida orange to change. The last carbohydrate test performed was Bial’s test; it is used to test for the presence of a furanose ring. The solution of both the Florida orange and the California orange did not produced any precipitate, indicating that pyranose rings are present in solution (Figure 4). In overview the results of all the carbohydrate tests do not support our hypothesis that the carbohydrate makeup of California oranges and Florida oranges are different.
    Next, the photosynthesis tests were performed. The absorption tests indicated that the California oranges and the Florida oranges had a similar absorbency rate (Table 5). Further evidence of the similarities of the absorbency rates of both varieties of oranges can be seen in the resembling absorbency graphs (Figure 5). The paper chromatography test indicated that the two varieties of orange leaves contained identical pigment bands. All of the strips contained 3 bands (Figure 6). The Rf values that we calculated from these pigment bands were used to identify the pigments present (Table 6). Our results indicated the presence of carotene, chlorophyll a, and chlorophyll b (Maleszewski et al, 2003).
    The last tests to be performed were the enzyme tests. In a comparative pH test, both oranges had a pH of five (Figure 7). We expected the California orange to be more acidic, so our hypothesis was not supported. The next test performed was for the presence of PPO. We hypothesized that there would be PPO in both brands of oranges. We tested to see if PPO was present by putting catechol on both types of orange. The results were clear. Neither of the two varieties of oranges reacted with the catechol. Therefore, our results support that the flesh of both California and Florida oranges do not contain PPO. In response to this discovery we researched what other enzyme could be performing the PPO in these oranges. During our search we came across research journals referring to the effect of PPO inhibitors on plums (Siddiq 1994). We realized that there was a possibility that these oranges could contain PPO inhibitors like L-cysteine or sodium metabisulfite (Siddiq 1994). By placing orange stock solution on potato tubers and testing for the presence of PPO we determined that PPO inhibitors are present in both type of orange (Table 9).
    After completing our research we realized that many errors could have been made. Since the experiment spanned a time of seven weeks, the oranges could have been acquired at different times of the growing season, which could alter the fruit. Also, not all of the oranges were from the same tree, which could have had an effect on the fruit. We were also unaware of the harvest time of the oranges. The differences in harvest time affect the fruit, therefore it may have affected out results. Also it is possible that human error could have altered the outcome of some of our tests. There is a chance that certain test tubes were not thoroughly cleaned and leftover residue in the tubes from past experiments could have affected our results.
    In conclusion, our results did not support our hypothesis that there are differences in the composition of California and Florida oranges. For example, the carbohydrate tests showed that the sugar content of both varieties were practically identical. The absorption spectrum test showed clear similarities in the light absorption rates of both California and Florida oranges. Also the pigment chromatography tests of both varieties of oranges were very similar. The results of the enzyme test showed that neither of the oranges contained PPO, rather they contained PPO inhibitors. Also, when determining the pH, both had a pH of 5. Despite the fact that our research did not support our hypothesis our data can still be applied in the creation of genetically modified foods. The creation of genetically modified oranges will require a great deal of information about oranges and all of its varieties (Aked 2002). Possibly another research group could adapt our data to create oranges with not only a better taste, but a longer shelf life and shorter maturation period (Aked 2002)

Table 5: The purpose of the absorption test is to measure the absorbency of the chloroplasts that are present in the leaves of both California and Florida oranges.

   Absorbance
Wavelength     Cal Cal Cal    Fl Fl     Fl
(nm)     Orange   Orange    Average    Orange    Orange    Average
400         1.380    1.460    1.4200       1.228    1.236       1.2320
415    1.280    1.260    1.2700       1.234    1.247    1.2405
430    1.200    1.230    1.2150    1.254    1.250    1.2520
445   1.030    1.010    1.0200    1.118    1.130    1.1240
460   0.867   0.873    0.8700      0.925    1.030    0.9775
475   0.817    0.820    0.8185    0.887    0.932    0.9095
490    0.749    0.763    0.7560    0.805    0.845    0.8250
505    0.628   0.640    0.6340    0.638    0.640    0.6390
520   0.526    0.529    0.5275    0.507    0.510    0.5085
535    0.462    0.460    0.4610    0.446    0.450    0.4480
550    0.420    0.419    0.4195    0.410    0.413    0.4115
565    0.410    0.407    0.4085    0.390    0.393    0.3915
   580   0.399    0.403    0.4010 0.387    0.386    0.3865
   595   0.394    0.399    0.3965    0.382    0.380    0.3810
   610    0.393 0.395    0.3940 0.379    0.380    0.3795
   625    0.392 0.390    0.3910    0.385    0.387    0.3860
   640    0.387   0.388    0.3875    0.393    0.389    0.3910
   655    0.428   0.430    0.4290 0.457    0.460    0.4585
   670    0.553   0.560    0.5565    0.637    0.639    0.6380
   685   0.529   0.534    0.5315    0.590    0.588     0.5890
   700       0.339   0.330    0.3345    0.317       0.314       0.3155

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