Saddleback Journal of Biology - Saddleback College

Spring 2010 Biology 3B Paper
20
18
Average Number of Colonies
16
14
12
10
8
6
4
2
0
Zero percent Five percent Greater than ten percent
Sodium Chloride Concentration
Figure 1: Statically significant difference were found amongst the average number of colonies (17.7 ± 0.617 (±
S.E.M, n = 10) on the zero percent concentration compare to five percent concentration (0.9 ± 0.298 (± S.E.M, n =
10) and greater than ten percent. The growth on the five percent slice (0.9 ± 0.298 (± S.E.M, n = 10) is also
significant compare to the greater than ten percent slices (0 growth). The graph shows the average colonies on zero,
five and greater than ten percent concentration and the error bar of ± SEM, n = 10. The p value was P = 1.49x10 -68
Discussion
Initial results show there was a difference in the
average number of mold colonies when the sodium
chloride concentrations used were varied. The zero
percent group showed a high number of colonies
(17.7 ± 0.617 (± S.E.M, n = 10), the five percent
group showed some growth (0.9 ± 0.298 (± S.E.M, n
= 10) but very few compare to the zero percent
group. Elevated concentrations (ten percent or above)
showed no sign of fungi growth. The hyperosmosis
environment created by the high sodium chloride
concentration will make the fungus cell tries to adjust
the concentration inside the cell equal to the
concentration outside; eventually the cell will lose all
the water, become dehydrated and died. People use
salt as one method of food preservations based on the
phenomenon that discussed above. Salt can be used
as part of the drying process. Salt increases the
storage time of some foods such as fish and it
enhance the flavor of dried foodstuffs. The use of salt
water brine is another common method of
preservation and it has the benefit of stopping the
growth of harmful organisms. Although it is possible
to wash off excess brine or salt from salted food, this
food will taste salty and the over-consumption of salt
does carry a risk of dehydration. In the case of this
experiment, the hypothesis being tested was correct;
the high sodium chloride concentration will slow
down or stop the growth of bread mold. The result is
also very consistent with Godinho & Fox’s study
which stated the salt content will affect mold growth
(Godinho & Fox, 1981).
Literature Cited
Anonymous (2010). Hold That Mold. University of
California, Berkeley, Wellness Letter, 26(6), 8.
Cuppers, H. G., Oomes, S., & Brul, S. (1997). A
model for the combined effects of temperature and
salt concentration on growth rate of food spoilage
molds. Applied and Environmental
Microbiology, 63, 3764-3769.
Godinho, M., & Fox, P. H. (1981). Effect of NaCL
on the germination and growth of Penicillium
roqueforti. Milchwissenschaft, 36, 205-208.
Gray, W. D., 1970. What We Find When We Look at
Molds. New York: McGraw-Hill Book Company.
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Saddleback Journal of Biology
Spring 2010