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Melanin is a substance that produces a dark color
called melanosis (spots), and which affects some products for human
consumption, such as shrimp. In these organisms, melanosis is detrimental to
their appearance, affecting consumers’ preference. However, this pigment is
produced by an enzyme called phenol oxidase, and it DOES NOT affect humans who
eat organisms with melanosis (Figura b).
In shrimp, phenol oxidase has mainly a bearing on the
response system of microbial agents (as defense) in healing wounds (live shrimp
with melanization spots indicate a scar tissue in a wound and in shedding when
the shell hardens). On the other hand, it is known that hemocyanin, (a protein
present in shrimp in charge of moving oxygen and carbon dioxide, as blood),
under certain conditions, can also cause melanosis.
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Figure a. Organisms recently harvested without melanosis. |
Figure b.Organisms stored for 10 days showing melanosis. |
It is worth pointing out that the only negative
consequence of melanosis is that shrimp might show deterioration, which can
make people stop buying them and cause economical loss.
Even though there are products that can avoid
melanosis, their use is NOT recommended because they can generate allergies in
some consumers. In fact, the Economic European Community has banned any food
additive.
The use of antimelanosis products in shrimp and other
organisms is limited. Therefore, it is necessary to know this phenomenon to
find alternatives that retard or reduce melanosis.
Due to this situation, our general objective is to generate knowledge on the melanization process in Penaeus vannamei shrimp stored at 0°C.
Besides:
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Identifying the
enzyme(s) involved in the process
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Defining if
hemocyanin participates in the process
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Defining if there
are genes that promote melanization
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Identifying shrimp
families that are least prone to melanization
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Evaluating other
parameters of freshness and deterioration related to melanization in shrimp
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Fisheries Ecology 
