Table of contents
What kind of prawns does Mercadona sell?
Mercadona primarily works with two types of frozen prawns, both under the Hacendado brand:
Argentinian red shrimp (Pleoticus muelleri): Caught in the Southwest Atlantic (FAO area 41), in the waters of Argentina and Uruguay. It is a wild shrimp, caught by trawlers and frozen on board. Its natural color is pinkish-orange, even when raw. Common sizes: L1 (20-30 pieces/kg), L2 (30-40 pieces/kg).
Ecuadorian shrimp (Litopenaeus vannamei): Aquaculture-farmed, raised in coastal farms in Ecuador. Also known as white shrimp or vannamei. It is the most produced shrimp in the world — Ecuador exports over 1 million tons per year. Its raw color is grayish-translucent.
Mercadona also sells frozen peeled shrimp, pre-made garlic shrimp, and cooked prawns, but the two star products are the raw frozen prawns in bags.
Origin: Argentina vs. Ecuador — two different animals
It's not just a difference in geographical origin — these are distinct species with completely different flavor profiles, textures, and nutritional values.
Argentinian Red Shrimp:
- Wild — eats whatever it finds on the seabed
- Intense, almost sweet flavor, with iodine notes
- Firm and juicy texture
- More fat and omega-3 than farmed varieties
- Natural pink color (doesn't need cooking to look "done")
- Catching season: March to June
Ecuadorian Shrimp:
- Aquaculture-farmed — fed with compound feed
- Mild, neutral flavor, less "of the sea"
- Softer, less firm texture
- Lower omega-3 content
- Grayish raw color, pink after cooking
- Available year-round (continuous production)
The difference is comparable to that between a free-range chicken and an industrially farmed one. Both are chicken, but the eating experience is quite different. The Argentinian tastes truly of the sea; the Ecuadorian is a decent but bland protein.
That said, the Ecuadorian variety has its fans: if you're making garlic shrimp with lots of garlic, chili, and good olive oil, the neutral flavor of the Ecuadorian works because it absorbs the seasonings. If you're grilling them with salt, you need the Argentinian.
Glazing: the trap no one looks at
Here's the fact that completely changes the price equation.
Glazing is the layer of ice that covers each frozen prawn. It's applied by spraying water onto the blast-frozen product — the water instantly freezes, forming a protective layer that prevents dehydration and freezer burn.
So far, so good. The problem is that glazing is included in the declared weight (unless the label states "drained net weight"). And typical glazing accounts for between 10% and 30% of the product's total weight.
Let's do the math:
| Product | Bag weight | Estimated glaze | Actual product weight | Price | REAL €/kg |
|---|---|---|---|---|---|
| Argentinian shrimp L1 | 800 g | ~15% (120 g) | ~680 g | €8.90 | €13.09/kg |
| Argentinian shrimp L2 | 800 g | ~15% (120 g) | ~680 g | €7.50 | €11.03/kg |
| Ecuadorian shrimp | 800 g | ~20% (160 g) | ~640 g | €6.50 | €10.16/kg |
| Peeled shrimp | 400 g | ~25% (100 g) | ~300 g | €5.20 | €17.33/kg |
Glazing percentages are estimates based on independent checks. Glazing varies between batches.
How to check it yourself: Weigh the frozen bag. Thaw the product in a colander over a bowl in the refrigerator for 4-6 hours. Re-weigh only the drained product. The difference is glaze water + released water. For prawns, up to 20-25% of the weight you pay for is ice.
It's not that Mercadona is cheating — legislation allows it as long as the drained net weight is stated on the label. The problem is that almost no one reads it or does the math.
Complete comparison table
| Feature | Argentinian (Mercadona) | Ecuadorian (Mercadona) | Red shrimp from Huelva (market) |
|---|---|---|---|
| Species | Pleoticus muelleri | Litopenaeus vannamei | Aristeus antennatus |
| Origin | South Atlantic (wild) | Ecuador (aquaculture) | Mediterranean (wild) |
| Real price/kg | ~€13/kg | ~€10/kg | €35-80/kg |
| Flavor (1-10) | 7 | 5 | 10 |
| Texture | Firm | Soft | Buttery |
| Omega-3 | High | Medium | Very high |
| Best use | Grill, paella | Garlic shrimp, rice dishes | Grill, raw, sashimi |
| Additives | Possible metabisulfite | Possible metabisulfite | None (if fresh) |
About sulfites: Most frozen prawns contain sodium metabisulfite (E223) to prevent melanosis (blackening of the heads). It is legal, generally safe, but can cause reactions in asthmatic individuals or those sensitive to sulfites. If you see that prawn heads are impeccably pink after days in the freezer, they contain sulfites.
How to properly thaw prawns
The way you thaw them makes the difference between juicy prawns and watery ones:
Optimal method — Refrigerator (12-24 h): Place the prawns in a colander over a bowl inside the refrigerator. The glazing water and the water released by the prawn will drip and separate. Never leave the prawns submerged in their own thawing water — they reabsorb the liquid and become tasteless.
Quick method — Cold water (30-45 min): If you're in a hurry, place the sealed bag under a gentle stream of cold water. NOT hot water — the surface will cook while the inside remains frozen. After thawing, drain and pat dry with paper towels.
NEVER: Microwave. It creates hot spots where the prawn partially cooks and frozen areas. The resulting texture is disastrous.
Professional tip: For grilled prawns, don't thaw them completely. Take them out of the refrigerator 10 minutes before cooking. They should be cold but not frozen. The cold temperature protects the interior while the grill sears the exterior. Result: golden exterior, barely cooked and juicy interior.
Alternatives to Mercadona prawns
If you're looking to upgrade without breaking the bank:
Local markets: Fresh market prawns (when truly fresh, not thawed and presented on a tray) are on another level. Look for prawns from Sanlúcar, Vinaròs, or Huelva. Price: €20-40/kg depending on season and size.
Specialized online fishmongers: They ship seafood with a cold chain and full traceability. The seafood arrives with its catch date, fishing gear, and area. It's more expensive than Mercadona but you know exactly what you're buying.
Canned seafood: A good can of natural cockles, pickled mussels, or razor clams can give you a premium seafood experience at a reasonable cost per serving. And you don't need to thaw anything.
If you're looking for quality seafood without complications, explore our selection of gourmet canned seafood — from Carril cockles to pickled mussels. Product caught in season, preserved at its optimal point, without glazing or surprises.
Keep exploring
Mussel properties · Frozen fish at Mercadona · Canned mussels · Canned cockles
Frequently asked questions
Are Mercadona's prawns good?
Mercadona's Argentinian prawns are a good product: wild, intense flavor, and competitive price (~€13/kg real). The Ecuadorian ones are cheaper but have a blander flavor. For daily use, the Argentinian ones are a smart buy.
How much glazing do Mercadona's prawns have?
Between 15% and 25% of the total weight is ice (glazing). In an 800g bag, you can have 120-200g of frozen water. The drained net weight is shown on the label in small print.
Are Argentinian or Ecuadorian prawns better?
The Argentinian is superior in flavor and texture — it's wild and eats from the seabed. The Ecuadorian is farmed, softer and more neutral. The price difference (€2-3/kg) doesn't justify choosing the Ecuadorian unless you're going to cook it with strong sauces.
Do Mercadona's prawns contain sulfites?
Most do — they contain sodium metabisulfite (E223) as an anti-melanosis preservative. It is legal and generally safe, but asthmatic individuals or those sensitive to sulfites should avoid them. Always check the label.
Can I grill prawns from Mercadona?
Yes, especially the Argentinian ones. Thaw well, pat dry with paper towels, grill on a very hot pan with a touch of oil, 2 min per side with coarse salt. The result is honest. It won't be a red shrimp from Huelva, but it's a decent dinner.
How many prawns do I need per person?
As an appetizer: 200-250g per person (gross weight with shell). As a main course: 400-500g per person. Subtract 30-40% for shell and head to calculate the actual edible meat. With glazing, you need more gross weight than you think.
