A System Built for Supermarkets, Not for You
Here's a fact that might surprise you: there is no standardised legal definition of what date labels on food packaging mean. Food manufacturers can print almost any date they want, formatted however they like, with whatever label text they choose.
The result is a chaotic system in which various labels appear on packaging, and most consumers assume they all mean roughly the same thing. They don't.
What Each Label Actually Means
- Best Before / Best By: A quality date set by the manufacturer. Food is almost always safe to eat after this date; it may just be slightly less fresh.
- Use By: This is the one to take seriously. It applies to products that have genuine safety implications if consumed past their date, like raw meat or fish.
- Sell By: This label is aimed at retailers, not consumers. It tells the shop when to rotate stock off the shelves. Food is typically good for several days after this date.
The Science of Food Spoilage
Spoilage happens through two primary mechanisms: microbial growth (bacteria, mould, yeast) and oxidation (exposure to air and light). Microbial growth is slowed dramatically by cold temperatures and prevented entirely by freezing. This is why freezing food essentially pauses its clock.
Oxidation tends to affect flavour and colour long before it becomes a safety issue. Beef that has turned slightly grey is oxidised but not necessarily spoiled.
The Sensory Test: Trust Your Nose and Eyes
The most reliable food safety tool you own is your senses. Before throwing something away based on a date, actually examine it:
- Does it smell off? Sour, rancid, or putrid smells are reliable indicators of genuine spoilage.
- Does it look unusual? Visible mould or unusual sliminess are major warning signs.
- Has it separated? Some separation is normal (oil and water) and can be mixed back.
For most foods, if it passes the sensory test, it's safe to eat regardless of what the package says.
Specific Shelf Life Guidelines
- Eggs: Fresh eggs sink and lie flat; eggs that float should be discarded.
- Hard cheeses: Mould on the outside of a hard cheese can be cut off with a one-inch margin.
- Canned goods: Properly stored, canned goods are safe to eat for years beyond their best-by date.
- Cooked leftovers: Most cooked foods are safe for 3-4 days in the refrigerator. If in doubt, freeze immediately.
The Real Cost of Over-Caution
Date label confusion is a primary driver of household food waste. Consumers throw away food that is perfectly safe simply because they saw a date had passed. Building a smarter habit is simple: apply the sensory test and stop letting package dates make decisions for you.
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