Household Ingredients Compared  ›  Guides

Food safety at home: freezing, thawing, storage times and date marks — what the rules actually are

Most home food-safety questions come down to three things: how cold, how long, and whether the freezer is a kill step or a pause button. The short answers are that the fridge should be 4°C or colder and the freezer −18°C or colder, that fresh fish keeps only a day or two in the fridge but months in the freezer, and that freezing is a pause button — it stops bacteria growing, it does not kill them, and it does not make raw fish safe to eat raw. This guide gives the numbers, says where each one comes from, and says plainly where Singapore publishes no figure of its own — in those cases the figures below are the US Department of Agriculture's, labelled as such.

The two numbers that matter: fridge and freezer temperatures

The Singapore Food Agency (SFA) gives the home temperatures plainly: fridges and chillers at 4°C and below, freezers at −18°C or below. Its guidance also names the range bacteria grow fastest in — the "temperature danger zone" — as 5°C to 60°C. The US Department of Agriculture's Food Safety and Inspection Service (FSIS) draws the same zone slightly wider, at 4°C to 60°C (40°F to 140°F); the practical rule is identical either way: food should be cold or steaming hot, not in between.

SFA adds three practical points that matter in a Singapore kitchen: leave space between items so cold air can circulate, do not overstock the fridge or freezer (blocked airflow means uneven cooling and faster spoiling), and do not open the doors more often than necessary. If your fridge has no thermometer, a cheap fridge thermometer is worth having — every storage time in this guide assumes the fridge really is at 4°C or below and the freezer really is at −18°C or below.

Freezing fresh salmon: yes — and how to handle a whole salmon

Yes, it is fine to freeze fresh salmon. Freezing does not destroy nutrients, and good-quality frozen salmon is usually frozen soon after it is caught. What freezing does change is texture: ice crystals and drying at the surface (freezer burn) make thawed fish a little softer and drier than fresh, which is why the storage times below are about quality, not safety. The US Department of Agriculture is blunt about the distinction: "Food stored constantly at 0°F will always be safe. Only the quality suffers with lengthy freezer storage." In other words, a salmon fillet forgotten at the back of the freezer for a year is a quality question, not a safety one — provided the freezer held −18°C the whole time.

Salmon is a fatty fish, and fat goes rancid in the freezer faster than lean flesh does. The USDA's FoodSafety.gov cold food storage chart gives fatty fish (salmon, mackerel, tuna) 2–3 months in the freezer for best quality, against 6–8 months for lean fish such as cod. That is the window to aim for — not a deadline after which the fish is unsafe, but the point after which it starts tasting tired.

Buying a whole salmon

A whole salmon is usually the cheapest way to buy it, and the freezer is what makes it practical. The steps:

1. Buy from a licensed establishment and keep it cold on the way home. SFA advises chilling fish as soon as possible after purchase and following the storage instructions on prepacked fish. Do not buy chilled fish that is displayed at room temperature.
2. Have the fishmonger gut and clean it if you are not doing it yourself at home straight away — a whole ungutted fish spoils faster than a cleaned one.
3. Portion it before freezing, not after. Cut it into the meal-sized fillets or steaks you will actually cook at once. Thawing a whole fish to cut off one portion, then refreezing the rest, repeats the damage twice — and raw fish thawed in the fridge should not be refrozen raw a second time without cooking (see thawing below).
4. Wrap it airtight. Freezer bags with the air squeezed out, heavy-duty foil, or a vacuum sealer. Air trapped in a loose pack dries out the surface and causes freezer burn. Label each pack with what it is and the date it went in, and use the oldest first.
5. Freeze it promptly. Fresh fish keeps only 1–2 days in the fridge (USDA figure), so a whole salmon bought on Saturday should be portioned and frozen the same day, not left in the chiller until Tuesday.

Pages where this matters most: fresh salmon, frozen seafood and smoked salmon.

What freezing kills, and what it does not

This is the single most misunderstood fact about the freezer, and it matters most for raw fish.

• Freezing kills parasites. The FDA Food Code sets out three equivalent time-and-temperature processes for destroying parasites in fish intended to be eaten raw: −20°C or below for 7 days; −35°C or below until solid, then 15 hours at −35°C or below; or −35°C until solid, then −20°C or below for 24 hours. These are commercial deep-freezing processes.
• A home freezer does not meet them. A home freezer runs at about −18°C, which is warmer than the −20°C the FDA protocol requires — so freezing salmon at home for a week does not count as parasite destruction under that protocol. Commercial "sashimi-grade" fish is frozen at −35°C or colder by the supplier.
• Freezing does not kill bacteria or viruses. The USDA FSIS states it plainly: freezing to 0°F (−18°C) inactivates microbes — bacteria, yeasts and moulds — present in food, but once thawed they can become active again and multiply at about the same rate as on fresh food. Viruses such as norovirus survive freezing intact. Freezing is a pause button, not a kill step; cooking is the kill step.
• Freezing does not remove toxins. If bacteria produced toxins in the food before it went into the freezer, freezing does nothing to those toxins.

Raw fish: sashimi and yusheng

Singapore's SFA treats ready-to-eat (RTE) raw fish as a high-risk food, because it goes through no cooking step. Its guidance for consumers:

• Raw fish for raw eating is sold separately. Fish intended for raw consumption is generally sold and marketed separately from fish intended for cooking. "Fresh" or "chilled" salmon from the cooking-fish counter is not sashimi fish, and frozen salmon is not sashimi fish either — the test is whether it was sold and handled for raw consumption, not whether it was fresh or frozen.
• "Sashimi grade" has no legal definition. In the US there is no USDA or FDA certification behind the label; in Singapore the SFA framework is the ready-to-eat one. The label is a seller's claim about handling and freezing, not a grade a regulator awards. Buy from a licensed establishment you trust, and check that the pack says it is intended or suitable for raw consumption.
• Risks are real and named. Raw fish carries a higher germ count than cooked fish, and a risk of parasitic disease — SFA names herring worm disease, caused by parasites attaching to the wall of the stomach, intestine or oesophagus. SFA tests raw fish for microbial pathogens and parasites, and importers must source from suppliers with proper cold-chain management — but no check removes the risk entirely.
• Some people should not eat raw fish at all. As a general precaution, SFA says people with lower immunity — including young children, older people, and people with chronic diseases such as diabetes — should avoid consuming raw fish altogether.
• Storage matters. Ready-to-eat raw fish should go into the chiller at 0°C to 4°C soon after purchase, and you should follow the handling and storage instructions on the pack. Do not eat it past its date.
• When in doubt, cook it. SFA's own advice: cooking is an effective way to kill bacteria and parasites, so if you are unsure whether a piece of fish was meant for raw eating, cook it thoroughly.

The same applies to yusheng at Lunar New Year: the raw fish in it is ready-to-eat raw fish, with the same rules — buy it from a licensed establishment, keep it chilled at 0–4°C until serving, and do not leave it sitting out while the table fills up.

How long things keep: fridge and freezer

The table below is the USDA's FoodSafety.gov Cold Food Storage Chart — fridge at 4°C (40°F) or below, freezer at −18°C (0°F) or below. Singapore publishes no equivalent day-count chart for the home: SFA's home guidance says only to buy chilled fish or meat in quantities you can consume within the next few days. So these figures are USDA figures, labelled as such, and they are the numbers Singapore shoppers have to work with.

Read the table correctly: the fridge column is about safety — eat it within that window. The freezer column is about quality — the food stays safe indefinitely at −18°C, but after the window it gets drier, blander, or more freezer-burned. Freezer burn itself is not unsafe; it is moisture loss at the surface, and you can trim it off.

Source: USDA FoodSafety.gov Cold Food Storage Chart (2023). Fridge times assume 4°C or below; freezer times assume −18°C or below and airtight wrapping. The chart lists fatty fish at 1–3 days in the fridge in its 2023 version; the widely quoted figure for fresh fish is 1–2 days, and this guide uses that. No USDA freezer figure for cooked rice was found in the chart, so none is given here.

Two things the table hides. First, raw meat and poultry keep their quality longer than cooked versions, because cooking drives out moisture — that is why a raw roast lasts 4–12 months in the freezer and the same roast cooked lasts 2–3. Second, the freezer column is a rotation guide, not an expiry date: the USDA's position is that food kept constantly at −18°C stays safe indefinitely, and the months are when it stops tasting its best.

Safe thawing — and refreezing

The USDA FSIS recognises exactly three safe ways to thaw meat, poultry and fish. The method you choose decides whether you can refreeze it later without cooking.

• Never thaw on the counter. FSIS is explicit: perishable food should never be thawed on the counter or in hot water. The outside warms into the danger zone while the centre is still frozen, and bacteria multiply on the surface. Cooking later does not destroy the toxins some bacteria leave behind.
• Never use hot water. It warms the outer layer into the danger zone and starts cooking the surface while the interior stays solid.
• Use fridge-thawed fish and meat within 1–2 days. Ground meat, poultry and fish thawed in the fridge should be cooked within 1–2 days; whole cuts within 3–5 days.
• The two-hour rule decides the rest. Perishable food should not sit at room temperature for more than 2 hours — 1 hour if the air is above 90°F (32°C), which in Singapore is most afternoons. Food left out longer than that should be thrown out, not refrozen and not reheated.

Cross-contamination: keeping raw food away from ready-to-eat food

SFA's home guidance is short and practical:

• Keep raw meat and seafood away from other foods, because their juices can cause cross-contamination. Store raw food in tightly wrapped plastic bags or covered containers in the fridge, so juices cannot drip onto food below — raw meat goes on the bottom shelf.
• Use separate chopping boards for raw meat and fish and for ready-to-eat food such as salad, bread and cooked dishes. Wash boards, knives and hands with soap and water after handling raw meat or fish, before touching anything else.
• Do not wash raw meat. SFA says so directly: the raw juices may contain bacteria that can splatter around the kitchen. Washing does not make raw meat safer, and it spreads the bacteria further. The same applies to raw chicken — the cooking step is what makes it safe, not a rinse.
• Cook seafood thoroughly, especially when cooking for young children, people with illnesses and older people (SFA).
• Wash hands after handling raw food, before handling anything ready to eat, and after touching the bin, the phone or your face in between.

Leftovers

The USDA FSIS leftovers rules fit on one hand:

• Into the fridge within 2 hours of cooking — 1 hour if the room is above 90°F (32°C). Cool food quickly: spread rice in a shallow container, divide a big pot of soup into smaller containers, and do not leave the pot on the stove to cool all evening. The two-hour clock runs from when the food leaves the heat, not from when you finish eating.
• Eat refrigerated leftovers within 3–4 days. That covers cooked meat and poultry, soups and stews, rice and pasta, and cooked vegetables.
• Reheat to 165°F (74°C) right through, measured with a food thermometer in the thickest part. Bring soups, sauces and gravies to a rolling boil. In the microwave, cover the food, stir halfway, and let it stand so the heat spreads — cold spots are where bacteria survive. "Steaming hot throughout" is the test if you have no thermometer.
• Reheat only once. The UK Food Standards Agency advises reheating leftovers only once, and never reheating rice more than once; the USDA FSIS does not set a number, but requires 165°F every time and use within 3–4 days. Either way, the practical rule is the same: reheat only the portion you plan to eat, and throw away what is left of a reheated portion rather than cooling and reheating it again. Each cooling and reheating cycle gives bacteria another pass through the danger zone.
• Reheating does not rescue food that sat out too long. Food that spent more than 2 hours at room temperature should be discarded, not reheated — some bacterial toxins survive heat.
• Cooked rice deserves a special mention. It can carry Bacillus cereus spores, which survive cooking and grow if the rice sits warm. Cool rice fast, refrigerate within 2 hours, and reheat until steaming hot — and only once.

Use-by vs best-before: what the dates mean in Singapore

This is where Singapore differs from most other countries, and the difference catches people out.

The Singapore twist: under the current Food Regulations, all four wordings — use by, best before, expiry date, sell by — count as the expiry date for selling. Once the date has passed, a shop in Singapore may not sell the food at all, whichever wording is on the pack. That is a selling rule, not a safety rule: it does not mean a tin of biscuits becomes unsafe the day after its best-before date. The Ministry of Sustainability and the Environment told Parliament in February 2024 that both dates indicate the expiry date because quality may have deteriorated, and SFA has been studying whether only safety-related date marks should count as "outdated" under the new Food Safety and Security Act 2025. Until that changes, the practical reading for your own kitchen is: treat use-by as a hard safety deadline, and treat best-before as a quality promise — check a past-best-before food by sight, smell and storage before deciding, and never eat past-use-by chilled food on the grounds that it "looks fine".

Practical checks

A routine that covers most of this guide, in the order you actually do things:

1. At the shop: buy chilled fish and meat last, keep them cold on the way home, and do not buy chilled or frozen food displayed at room temperature. Check the date mark — use-by for chilled perishables, best-before for dry and frozen goods.
2. At home: fridge at 4°C or below, freezer at −18°C or below. Raw meat and fish in sealed bags or covered containers on the bottom shelf. Fresh fish into the pan or the freezer the same day.
3. Freezing: portion first, wrap airtight, label with the date, oldest first. Salmon within 2–3 months for best quality; lean fish 6–8 months; mince 3–4 months.
4. Thawing: fridge overnight if you can plan ahead, cold water with the water changed every 30 minutes if you cannot, microwave only if you cook immediately after. Never the counter, never hot water.
5. Cooking: fish to 145°F (63°C) or until opaque and flaking; leftovers reheated to 165°F (74°C) and steaming hot right through, once only.
6. Leftovers: into the fridge within 2 hours, eaten within 3–4 days, reheated once. Anything that sat out more than 2 hours goes in the bin, not back in the fridge.
7. Raw fish: only fish sold for raw consumption, kept at 0–4°C, eaten promptly — and if you are unsure, cook it.

Pages where these checks are most useful: fresh salmon, frozen seafood, smoked salmon, fresh chicken, sandwich bread, rice, frozen ready meals and eggs, plus the sugar and salt guide and the daily recommended nutrients guide.

What this page is not

• Not medical advice. These are population food-safety rules from SFA, the USDA and the FDA. If you are cooking for someone with a weakened immune system, a chronic illness, or a condition where food safety is managed medically, the extra steps for them come from their doctor or dietitian, not from this guide.
• Not a ranking of foods or brands, and not a score. Nothing here is ranked against anything else; the storage times are a timetable, not a verdict.
• Not a complete food-safety manual. It covers the home questions that come up most — freezing, thawing, storage times, cross-contamination, leftovers and date marks. Commercial food handling, canning, fermentation and food business rules are not covered here.
• Not Singapore figures where Singapore publishes none. The storage times and thawing figures are the USDA's, labelled as such, because SFA publishes temperatures and principles for the home but no day-count storage chart. Where the two agencies draw a line differently — the danger zone, the number of reheats — both are stated rather than one picked silently.
• No specific prices are quoted anywhere on this page, because prices vary by shop and week.