Analysis of Increased Nutrition in Organic vs. Commercially Produced Apple Using Absorbency
by
Group: Potato
Samantha Gardner, Kate Jackson, Lyle Melkerson, Victoria Walter
LBS 145
Abstract
Everyday, parents must make decisions about what foods to feed their children. In deciding what type of apple to feed your child, the conflict between organically and commercially grown apples arises. We predicted that organic red delicious apples are a better source of energy and easier to digest than commercially produced apples. By performing Barfoed’s test and massing the precipitate, we found that the organic apples contained a slightly higher concentration of monosaccharides. Although this difference is not significant (flesh: p=0.468, skin: p=0.295), further testing would be useful to determine if the monosaccharide concentrations differ significantly. The iodine test, used to test for starch, provided negative results for all solutions. The absorbance spectrum of the organically grown apples was slightly lower than the absorbance spectrum of the commercially grown apples, suggesting that the organically grown apples contain less pigment. Paper chromatography did not show any pigments in the apple skin, but we believe that this test was not sensitive enough for our solution. Using absorbency, we found that PPO activity is slowed by a change in pH. Adding calcium carbonate to a neutral solution made the solution basic. Although there is no difference in the effect of pH on PPO in the organic apple compared to the commercial apple, if time allowed it would be useful to see how exposure to carbonate, an ingredient in fruit tree sprays, effects the enzymatic activity in commercial apples. Our results were inconclusive as to whether organic apples have significant benefits over commercial apples.
Figures
Figure
8. Average Absorbance of
Organically and Commercially Grown Apple Flesh vs. pH This
is a graph of the average of our results of three trials involved with PPO
absorbance. This graph gives the
absorbency at pH levels of 5-8.5 increasing on 0.5 intervals.
Discussion
Apples are a
nutritious snack commonly given to children by their mothers. Today, a
popular issue is whether organic or commercially grown foods are more
nutritious. But, which really provides the most benefits? We
predicted that the organically grown apples would be the best choice for a
mother to give her child because we thought they would contain more
monosaccharides and have higher enzymatic activity.
To find out
if organically grown apples are a healthier choice, we focused on the presence
of sugars, pigments, and enzymatic activity. In Barfoed’s test, a red
precipitate formed in both the organic and commercial solutions, signaling the
presence of monosaccharides (table 1, figure 1, 2, 3). From there,
we incubated the precipitates until they were dry and found their masses (table
1, figure 1). In our initial investigation, our results were inconclusive
because it appeared that the precipitates contained traces of skin or dirt from
the apples. We performed three additional trials of Barfoed’s test,
filtering the solutions through cheesecloth twice instead of just once.
The average mass for the organic flesh precipitate was 0.007 grams and 0.0087
grams for the average mass of the organic skin precipitate. The average
mass for the commercial flesh precipitate was 0.0066 grams and the average mass
for the skin precipitate was 0.0063 grams. This suggests that there is a
slightly higher level of monosaccharides in organically grown apples, however, when we performed a t-test we obtained
p-values of 0.295 for the skin and 0.468 for the flesh. This means that
there is a high probability that we obtained these results by chance
alone. It is possible that the amount of Barfoed’s solution that we added
to the apple enzyme extract may not have been sufficient enough to react with
all of the sugar and form a precipitate. Another explanation for our
results is that with such a small sample size it is difficult to obtain results
with a high level of significance. Further investigation would be
beneficial to see if organic apples do in fact contain a significantly higher
concentration of monosaccharides. Monosaccharides are simple sugars which
are broken down more easily by the enzymes in the body, making them easier to
digest. Since the organic apples may contain a higher concentration of
monosaccharides, they might be easier to digest making them a better choice for
a mother to give her child.
In our iodine test, used to signal the
presence of polysaccharides, starch, all of the solutions tested negative
(table 2, figure 4). We know that apples contain starches, or
polysaccharides, so all of the tests should have been positive (Byers,
1993). Since our positive control, starch, tested positive we know that
there was nothing wrong with the iodine solution we were using.
Therefore, there were other factors that created negative results. The
apples that we were using contained an insignificant concentration of starch
which may not have been detected by the iodine test (Nutrition Facts,
2002). The other possibility is that the polysaccharides may have been
broken down or filtered during the processing of our solutions causing the
negative results that we received.
In the
chloroplast absorption spectrum test, we observed a decreased absorption
spectrum in the organically produced apples (figure 5, tables 3-6). The
highest absorbance in the commercially produced apples occurred at a wavelength
of 415 nm, while the highest absorbance in the organically produced apples was
seen at a wavelength of 400 nm. The lowest absorbance in the commercially
produced apples was at 700 nm and the lowest absorbance in the organically
produced apples was at 700 nm. This suggests that there are fewer
pigments in the organically produced apples than in the commercial apples. This
was not expected because there are no pesticides or fungicides used on
organically produced apples that could inhibit the photosynthetic process.
Cherry trees exposed to copper ammonium carbonate, a fungicide used on fruit
trees, produced cherries that had less red pigment (Silsby,
1974). We expected to see a similar effect in the commercial apples that
are treated with the same types of fungicides. Since our results were not
as we expected it is a logical explanation that cherry trees and apple trees
are not as similar as we originally thought. It is also interesting to
note that the solutions had their lowest absorbencies at 700 nm, since this is
the wavelength of light used by photosystem
one. This suggests that the apples do not perform photosynthesis, which
would make sense since we are working with the fruit of the apple instead of
the leaves.
When we
processed our solution for the absorbance spectrum, our red apple skin solution
turned green. This led us to believe that the apples may contain
chlorophyll, masked by the red pigment in the skin. We decided to use
paper chromatography to see if the apples contained chlorophyll a or
chlorophyll b. The paper chromatography strips showed no pigments in the
apple skin. It is possible that the apple skin does not contain
chlorophyll. Paper chromatography is not as sensitive as the chloroplast
absorption test, which may also be why no pigments were observed (Grace,
2002). It was not possible for us to obtain a solution that was
concentrated highly enough to observe pigments with the naked eye.
We
tested for the presence of PPO in both the organically and commercially
produced apples by exposing them to catechol (figure 7). Catechol is a
colorless substrate that is oxidized by PPO causing a color change (Maleszewski, 2003). The fact that both apples turned
brown suggests that both apples contain PPO.
In our enzyme test,
we found that the solutions with a pH ranging from 7 to 8 had higher absorbance
spectrums (figure 8, 9, 10, table 7). The solutions with a pH value of
five had lower absorbance spectrums because they contained fewer products from
enzymatic activity. This evidence supports our hypothesis that enzymatic
activity is slowed by high or low pH values. There was little to no
difference between the absorbance spectrums of the commercial and organic
apples, meaning that pH affects the enzymes in both apples the same way.
Copper ammonium carbonate, a fungicide used on fruit trees, contains carbonate
(Omundson, 2002). To test the effect that
carbonate has on pH, we added calcium carbonate to distilled water and tested
the pH with litmus paper. Our test showed that carbonate changes water
with a neutral pH to a basic pH (figure 11, table 8). We were unable to
definitively determine the pH of the basic solution because the carbonate
solution was dissolving the color of the litmus paper. Since most enzymes
work best in a near neutral pH, the enzymatic activity of PPO should be slowed
by a change in pH, which can be caused by carbonate. Commercial apples
are treated with fungicides containing carbonate, which leads us to believe
that enzymatic activity is slower in commercially produced apples when compared
to organically produced apples. If time permitted, further testing could
be done to prove this. If a mother were to give her child an apple that
was commercially produced, it could possibly slow the PPO activity.
Barriers that protect against microbial and viral infections are formed by the
polymerization of quinones, produced by PPO, into
insoluble polymers (
Organically
grown food has become a growing trend boasting that it is more pure and
nutritionally superior to commercially grown produce. When caring for the
nutritional needs of a child these claims are appealing, but are they accurate?
We were unable to conclude whether there is a significant advantage to giving a
child an apple that is organically grown versus one grown commercially.
Although our results were not significant, the organic apples contained a
slightly higher level of monosaccharides. We believe that further testing
would be useful in determining if organic apples contain more monosaccharides
making them easier to digest. Commercial apples are treated with
fungicides containing carbonate, which we have shown to lower pH.
Therefore, organic apples should have an increased enzymatic activity due to
their relatively neutral pH of their environment, although further testing is
necessary to prove this. Our experimental data is inconclusive as to
whether organic apples would be the better choice for a mother to give her
child before he goes out to play. However, our sources suggest that
further testing with sufficient laboratory equipment may show that organic
apples have many beneficial qualities compared to commercially produced apples