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New solution for shrimp black spot disease

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Nov 3, 2021
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Black spot disease, also known as Melanosis (Black Spot) is black spots of pigment under the shell of shrimp. If this disease is detected early, it can be completely cured. Currently, there are two main methods to treat black spot disease in shrimp.


The dark spots that appear on the shrimp body are not spoiled shrimp but are caused by a naturally produced enzyme. While shrimp infected with black spot disease are completely edible, consumers refuse this type of shrimp.

The shrimp industry mainly uses one of two treatments to control black spot disease (melanosis): Sodium metabisulfite and 4-Hexylresorcinal powder. The latter is a new, and in some ways better, treatment, although sodium metabisulfite powder is more widely used and cheaper, it carries some risks for those performing the treatment. shrimp as well as for some shrimp consumers.

1. Treatment of black spot disease with Sodium metabisulfite

Sulfites are a common preservative used in wine and in bacon, to keep the attractive pink color from turning brown. In the past, it was also used in salad dressings in restaurants, especially when salads became popular, until the Food and Drug Administration (FDA). banned the use of this substance on fresh fruits and vegetables in 1986. This was in response to a petition by a consumer group, the Center for Science in the Public Interest, who wanted a ban on the substance. broader scope, due to 13 chemical-related deaths up to that point.

Sulfites are safe for most people. But some people, mainly asthmatics, have allergic reactions. These people must avoid foods that are treated with sulfites, including alcohol, dried fruit, some preserved meat products, and shrimp.

The European Union, Canada, South Africa, Australia and China have all approved 4-hexylresorcinal as a processing aid. In the US, the US has a "generally recognized as safe (GRAS)" status by the FDA. However, Japan, one of the world's largest shrimp consuming markets, has not yet approved the use of this substance. Because some consumers may be sensitive to sulfides, the FDA has established a regulatory limit of 100 ppm for sulfite residues in shrimp.

Shrimp treatment method:

The 1.25 percent (w/v) solution used in the treatment of shrimp is not hazardous, but it should be mixed in an open area with strong winds to prevent eye and throat irritation.

Soak shrimp baskets for about 1 to 3 minutes with 1.25% Sodium metabisulfite solution (by dissolving 3.1 pounds of sodium metabisulfite in 30 gallons of water (1,406 kilograms for 37,854 liters). about 500 pounds of shrimp.
However, if the soaking water becomes cloudy and bubbling, the water needs to be changed or the shrimp will carry a high amount of bacteria during the dip and this will reduce the quality of the shrimp.

– A cylindrical glass tube or plastic tank and shrimp basket are also used in standard plastic.

2. Treat black spot shrimp with 4-hexylresorcinal

In addition to allergy issues and warning labels, 4-hexylresorcinal has several other advantages, as well as a few disadvantages. Sodium metabisulfite can irritate the eyes and nose of workers when handling shrimp and can produce sulfur dioxide gas when in contact with water, which can be fatal to workers in confined spaces of the vessel.

Handling method:

4-Hexylresorcinol (EverFresh®). This chemical is used as a dip solution: 95 liters (25 gallons) 50-ppm solution of 4-hexylresorcinol with fresh water. Shrimp are dipped for 2 minutes, then drained and stored on ice or in ice water.

However, unlike sodium metabisulfite, 4-exylresorcinol is not effective when added directly to ice. Most effective when used at room temperature. This product is also ineffective in chlorinated water (sometimes used to eliminate pathogenic bacteria) or in concentrated brine used in some cryogenic systems.

* Note when using black spot treatment:

– Mix the solution in a well-ventilated place

– Use labor protection when handling (because these substances cause irritation to eyes and nose)

- Never overdose

Source: Collector
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