The black splotches are caused by a condition known as melanosis. Skin cells on a fish naturally change color depending on sunlight, stress, time of year, depth and water turbidity. You've probably noticed that bass can change colors while in a livewell—it's the same process. The difference is how the pigmentation is regulated.

• Blackspot or Melanosis is the harmless but unappealing surface discoloration on shrimp, crab or lobster

• The enzyme polyphenol oxidase (PPO) is present in and under the shell of shrimp and other crustaceans and acts as a catalyst in the reaction that causes blackspot 

• PPO remains active until the shrimp are frozen or cooked. The activity will resume in frozen raw shrimp upon thawing

• 10% of a harvest is generally thrown out because of blackspot. Less yield

How Blackspot Develops 

• Reaction initiated by a naturally occurring enzyme polyphenol oxidase (PPO)

• In the presence of oxygen, PPO converts monophenols (colorless) to diphenols 

• Diphenols are converted to highly colored quinones 

• Quinones react

Benefits

• Kopnol (Hexyl Resorcinol) does not only cure the symptoms, but attacks the cause of enzymatic browning 

• Sucessfully prevents blackspot from the time the shrimps are caught until they are put on your dinner plate 

• Only one treatment necessary versus repetitive treatments with sulfites to bleach away blackspot 

• Kopnol  increases yield and prevents downgrading of shrimps from class I to class II shrimps 

• Unlike meta-bisulfites, there are no health risks during handling 

• Functions as a processing aid and does not require labeling on finished product