Checking Shrimp Quality

No matter what species of shrimp you choose, getting good quality is the key to getting a good deal. Consider the following a mini-buyers' guide to ensure you get the best.

1. APPEARANCE: Look for shrimp of uniform color, size and condition.

Defects, Causes and Criteria:

Not properly rinsed and iced, their digestive enzyme will be oxidized, resulting in black spots. Can be deactivated by antioxidants such as ascorbic acid and sodium bisulfate.

Note: Black spots themselves are not harmful, but are an indicator of mishandling at time of harvest.

YELLOWING:

Sodium bisulfate often is used in excess, despite FDA laws, Look for unusual yellowing of the undesired of shrimp (swimmerets tail) as well as a bleached appearance.

TRANSLUCENCE:

A sure sign of sodium tripolyphosphate abuse. STP is used to reduce dehydration during cold storage and cut drip loss when thawed. It is abused (added in amounts exceeding 1-2% to add illegal weight to product, especially shrimp an scallops. If it feels glassy or overly slimy in the raw, thawed state, its probably been soaked too long. Also beware a tart, almost metallic, chemical flavor.

PITTED OR GRITTY SHELLS:

If heavy concentrations of sulfates are mixed directly with ice and applied to shrimp, rather than dissolved in water beforehand, the sulfates will pit and corrode the shells. Watch for un-dissolved sulfate residues on the shells.

EXPOSURE: Improperly iced shrimp will actually begin to cook (turn pink) on the boat, which promotes bacterial growth and decomposition. this pink discoloration most often occurs along the back, lower sides, swimmerets and tail.

PIECES: any portion of a shrimp that contains fewer than five whole tail segments, Pieces should be less than 5% of pack, except for salad shrimp (15%).

SANDVEINS:

 A black or dark vein in the tail of a shrimp that is part of its digestive tract. (Any vein less than two segments long is not a defect).

BROKEN AND DAMAGED:

Any shrimp that is crushed, mutilated, cut or missing a segment.

UNIFORMITY:

A poor uniformity ration indicates a mixing in sizes, which affects count and appearance. Divide the weight of the 10 largest shrimp by the weight of the 10 smallest shrimp in any one package. Acceptable uniformity ratios can vary depending on usage.

COLOR:

Color should be uniform within the package. Mixed colors usually indicate mixed species, some of which may be of an inferior quality or type. Uneven pink tints may indicate a decomposed product (see exposure).

2. ODOR: Shrimp should smell like fresh seaweed or seawater.

Defects, Causes and Criteria:

HYDROGEN SULFIDE: This "rotten egg" smell is a by product of bacterial decomposition.

AMMONIA: Caused by the chemical decomposition of the product.

PETROCHEMICAL:

Bilge water can leak into the shrimp hold and cause a gas or oil flavor and odor.

CHLORINE:

A chlorine washing solution often is used to mask off-raised shrimp, these feed odors are caused by algal blooms within the ponds and by run-off from adjacent agricultural land.

3. TEXTURE: Shrimp should be firm and moist.

Defects, Causes and Criteria:

FIBROUS, TOUGH AND DRY:

Caused by improper storage temperatures, repeated refreezing or extended frozen storage (beyond a year).

MUSHY:

Evidence of poor handling practices (improperly iced, beheaded and/or rinsed) of raw material. This texture is normal for some deepwater shrimp species (see Chalky).

CHALKY:

Evidence of exposure to intestinal juices for extended periods due to product packed head-on or necks improperly removed. Some deep-water species such as Taiwan pinks may exhibit this texture.

NOTE: some species will exhibit mushy or chalky textures during molting or reproductive periods.

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