Shoppers are being urged to check for two specific words on frozen prawn packaging before eating, as a simple mistake could lead to norovirus. The advice comes after experts noted that many people assume frozen prawns are already cooked simply because they appear pink.
While many raw prawns are blue-grey and turn pink during cooking, certain varieties, including Argentinian red shrimp and langoustines, can already look pink or reddish when raw. The two words shoppers need to find on the packet are “raw” and “cooked”.
Why colour is not a reliable guide
Julian Klenda, seafood expert at Maine Lobster Now, explained: “The colour of the prawn and the photograph on the bag are not reliable safety checks. Some raw varieties naturally look cooked, so the wording on the packet must make that decision for you.”
On many frozen packets, “raw” or “cooked” appears within the product description rather than in a large warning. Shoppers should look directly above or below the main product name on the front of the bag.
Klenda said: “The packet may have ‘jumbo king prawns’ printed prominently across the front, while the important description underneath says ‘raw, peeled king prawns’ in much smaller lettering. On a cooked product, it might say ‘cooked and peeled cold-water prawns’.”
How to check if prawns are raw or cooked
If the front is unclear, shoppers should turn the packet over and check the first lines near the ingredients, storage directions or cooking instructions. Phrases such as “cook before eating”, “cook from frozen” or “defrost thoroughly before cooking” mean the prawns are not ready to eat.
By comparison, cooked frozen prawns may say “ready to eat once defrosted” or provide defrosting instructions without a cooking time. The check is particularly important for frozen raw king prawns, Argentinian red shrimp, marinated prawn skewers and mixed seafood bags. Breaded or battered prawns may also contain raw shellfish despite looking like a fully prepared product.
Klenda warned: “Do not assume that peeled, marinated or coated means cooked. Those words describe how the prawns have been prepared, not whether the centre is safe to eat.”
Chilled tubs of cocktail or salad prawns are commonly sold cooked, but shoppers should still look for “cooked” or “ready to eat” and follow the use-by date and refrigeration instructions.
What to do if the packet does not say
If neither word is visible, Klenda recommends reading the complete preparation panel before opening the bag. A cooking temperature or frying, grilling, boiling or oven time indicates that further cooking is required.
He advised: “If the packet provides no clear description or preparation instructions, do not taste one to find out. Check the supermarket’s online product listing or contact the retailer or manufacturer using the details on the packaging. For loose prawns from a fish counter, ask a member of staff directly whether they are raw or cooked.”
A packet with a missing, torn or unreadable label should be returned rather than guessed at. Shoppers should also avoid using smell as proof that an unclear product is safe, as food-poisoning bacteria do not necessarily create an obvious odour.
Raw prawns that require defrosting should be thawed in a covered container in the fridge rather than left on the kitchen worktop. Raw prawns and their thawing liquid should be kept away from salads, cooked rice and other ready-to-eat foods, while hands, knives and chopping boards must be cleaned after contact.
To cook frozen prawns safely, Klenda warned: “Follow the packet exactly, because some prawns should be cooked from frozen while others need to be defrosted first. Do not leave them thawing on the kitchen counter for several hours.”
Once defrosted, shoppers should follow the packet’s time limit and use the prawns promptly. They should not assume freezing has killed every harmful microorganism.
What does the NHS say?
Eating fish or shellfish that is not fresh or that has not been stored and prepared hygienically can cause food poisoning. Shellfish such as mussels, clams and oysters that are raw or not thoroughly cooked can contain harmful viruses and bacteria that can cause food poisoning. Thorough cooking usually kills any bacteria or viruses.
Most of the shellfish we eat is cooked first, but oysters are often served raw. Raw shellfish, particularly oysters, can contain low levels of certain viruses, such as norovirus. If you're serving oysters raw, be especially careful when buying and storing them.
Shellfish can also contain toxins. Depending on the type of toxin present, the symptoms from eating contaminated shellfish may include: nausea, vomiting, diarrhoea, headaches, numbness, breathing difficulties, memory loss, disorientation, and abdominal pain. These toxins do not break down during cooking. If you're older, pregnant or have a weakened immune system, you should avoid eating raw or lightly cooked shellfish to reduce your risk of getting food poisoning. This also includes young children.
