Shrimp, squid and octopus

Why

Shrimp have delicate muscle proteins that set within a few minutes: as soon as the flesh turns opaque and firm it is done, and every extra minute dries it out and makes it tough (Fish: when is it done card). Squid has muscle shot through with collagen: brief, fierce heat keeps it tender, longer cooking makes the muscles contract, squeeze out juice and go rubbery, and it only softens again after long gentle stewing, when the collagen dissolves into gelatin; tougher octopus softens only with such stewing. Octopus is therefore almost always braised or simmered slowly, 45–75 minutes in ATK recipes, and according to ATK it turns out more tender when previously frozen, because ice crystals disrupt the muscle fibres. Shrimp and squid are mostly sold frozen and often with water-retaining additives such as sodium tripolyphosphate; they then release more water in the pan and brown poorly, so it pays to read the ingredients and dry them well before cooking. For safety the same applies as for fish: the US FDA gives 63 °C at the core for seafood and, for shrimp, the sign that they are firm, pearly and opaque.

How to do it

• Thaw frozen shrimp and squid in the fridge or in a sealed bag in cold water (Thawing meat and fish card) and dry them thoroughly before cooking.
• Sear shrimp in a hot pan or wok in a single layer for just a few minutes, until firm, pink and opaque; then take them out at once.
• Add shrimp to a sauce, curry or soup only at the end and let them just finish in barely bubbling liquid; return pre-seared ones only to heat through.
• Sear or fry squid briefly over high heat, just until opaque, or stew it long and gently in a sauce until it softens again; test by biting.
• Braise octopus covered over low heat, usually 45–75 minutes, until a knife slides easily into the thickest part of a tentacle and the skin at the tentacle joints tears.
• When the label lists a moisture-retaining agent besides shrimp, expect water in the pan: sear in smaller batches and let the pan get hot again in between.

If it goes wrong

Keep stewing rubbery squid or octopus in the sauce over low heat until it softens again; more brief searing only toughens it. Overcooked shrimp will not soften again; chop them finely into a sauce, salad or rice and next time take them out as soon as they turn opaque. When shrimp release water in the pan and will not brown, take them out, boil off the liquid or pour it into the sauce, and finish the shrimp in smaller batches in a hot pan.