What Happens to Packed Food After the Expiry Date?

October 28, 2025 •

4 min read

According to the USDA, confusion over date labels contributes significantly to food waste, with many consumers throwing out perfectly good items. Knowing what happens to packed food after the expiry date is key to differentiating between a decline in quality and a genuine health risk, empowering you to make smarter choices about your groceries.

Quick Summary

Expiration dates on packaged food vary, with 'use by' indicating safety for highly perishable goods while 'best by' refers to peak quality. Proper storage and observing sensory signs are crucial for determining edibility, minimizing unnecessary waste.

Key Points

Differentiate Date Labels: 'Use by' dates signal a safety risk for perishable items, while 'best by' dates are about a product's peak quality and freshness.
Trust Your Senses (with Caution): For foods with a 'best by' date, your eyes, nose, and taste can reliably detect spoilage, but for 'use by' items, harmful bacteria may not be detectable.
Beware of Damaged Packaging: Canned goods showing signs of bulging, deep dents, or leakage can be contaminated with dangerous bacteria and should be discarded, regardless of the date.
Understand the Science of Spoilage: Food degrades over time due to microbial growth and oxidation, which are slowed by processing and proper storage, not instantly triggered by a specific date.
Practice Safe Storage: Extending food life and safety relies on proper storage, such as refrigeration for perishables and airtight containers for dry goods, not solely on the package date.
Minimize Food Waste Wisely: You can reduce waste by using the 'best by' date as a guide rather than a rule, freezing items to prolong their shelf life, and adopting a 'first in, first out' approach with your food.

Understanding Food Date Labels

Before diving into what happens to packed food after the expiry date, it's crucial to understand the different types of date labels used by manufacturers. These labels are often the primary source of confusion, and their meaning varies significantly depending on the product. With the exception of infant formula, these dates are largely unregulated and relate more to quality than safety.

'Use By' Dates: About Safety

This is the most critical date to observe, particularly on highly perishable foods like fresh meat, poultry, fish, and dairy. A 'use by' date indicates the last day the manufacturer recommends for safe consumption. After this date, there's a higher risk of harmful bacteria, like Listeria, reaching dangerous levels, even if the food looks and smells fine. For these items, the 'sniff test' is not a reliable indicator of safety.

'Best By' or 'Best Before' Dates: About Quality

This label is found on a wide range of products, including dried goods, canned foods, frozen items, and some dairy. A 'best by' date signifies the period during which the product will have the highest quality, flavor, and texture. After this date, the food is typically still safe to eat, but its quality may gradually decline. For example, crackers might lose their crunch, or spices might lose potency, but they won't necessarily make you sick.

'Sell By' Dates: For Inventory Management

This date is primarily for retailers and helps them manage stock and ensure products are sold while at peak quality. It is not a safety indicator for consumers. Products can often be safely consumed for some time after the 'sell by' date has passed.

The Science of Spoilage

Food does not magically become spoiled the moment the date on the package passes. Spoilage is a gradual process driven by various chemical and microbiological factors. The packaging and processing methods are designed to slow this process, but they cannot stop it indefinitely.

The Role of Microorganisms

Bacteria, mold, and yeast are the primary agents of spoilage. Microorganisms that cause decay can produce off-flavors, change texture, and alter the appearance of food. In perishable foods, some bacteria, such as Salmonella and E. coli, can multiply to dangerous levels, causing foodborne illnesses. Proper storage conditions, like refrigeration, slow the growth of these microbes.

The Impact of Oxidation

Exposure to oxygen can cause fats and oils to go rancid, resulting in an unpleasant odor and taste. This process, called oxidation, is why many packaged snacks have airtight packaging to preserve freshness. Over time, even with proper packaging, a small amount of oxygen can degrade the product.

Potential Health Risks of Consuming Expired Foods

While many items past their 'best by' date are harmless, consuming food that has truly spoiled, especially perishable items, can lead to foodborne illnesses. Symptoms can range from mild discomfort to severe, life-threatening conditions. Vulnerable populations, such as children, the elderly, and those with weakened immune systems, are at a higher risk.

Common signs of spoilage include:

Visible mold: On bread, cheese, or fruits, mold is a clear sign of spoilage, and for soft foods, it's best to discard the entire item.
Off-odors: A sour, rotten, or unpleasant smell indicates bacterial action.
Changes in texture: Foods becoming slimy, mushy, or unusually hard signal deterioration.
Altered color: Discoloration can be a result of oxidation or microbial growth.
Damaged packaging: For canned goods, bulging, severe dents, or leakage can indicate the presence of harmful bacteria like Clostridium botulinum, which causes botulism, a rare but dangerous illness.

Practical Steps to Avoid Food Waste Safely

To strike a balance between food safety and minimizing waste, follow these practical steps:

Follow the use by rule strictly: Never consume highly perishable items after this date, regardless of appearance or smell.
Use your senses for best by items: For shelf-stable products past their 'best by' date, use sight, smell, and taste to judge edibility.
Store food correctly: Following manufacturer's instructions, like refrigerating after opening, can significantly extend a product's life.
Practice 'First In, First Out': Use older products first to prevent them from sitting too long.
Use the freezer: Freezing perishable items like meat, poultry, or vegetables before the 'use by' date can extend their life for months.

Comparison of Date Labels


Feature	'Best By' Date	'Use By' Date
Primary Concern	Product Quality	Food Safety
Associated Foods	Shelf-stable items like crackers, canned goods, frozen vegetables	Perishable items like meat, fish, salads, dairy
Post-Date Safety	Generally safe to eat if no signs of spoilage	Never eat after the date has passed
Indicator for spoilage	Quality deterioration (staleness, less potent flavor)	Potential for harmful bacteria growth, even without sensory cues
Effect of proper storage	Extends peak quality but doesn't guarantee indefinite safety	Critical for validity, but still a hard safety cutoff

Conclusion

Navigating the world of food expiration dates requires more than just glancing at a label. It's about understanding the distinction between quality and safety indicators, and using common sense combined with sensory checks. While 'use by' dates are hard safety cutoffs for perishable goods, 'best by' dates are flexible guidelines for quality. By learning the science of spoilage and adopting smart storage practices, you can significantly reduce food waste without compromising your health. When in doubt, however, it is always safest to throw it out. For further guidance on food storage, refer to the USDA's food safety resources, including the FoodKeeper App available via their website.

Frequently Asked Questions

It depends on the date type. 'Use by' dates indicate safety, and it is risky to consume food past this date. For 'best by' dates, which indicate quality, food is often safe to eat for a period after the date if stored properly.

A 'Best by' date refers to the manufacturer's estimate of peak quality and flavor, not safety. A 'Use by' date, however, relates to food safety, and the food should not be consumed after this date.

For foods with a 'best by' date, using your senses is often a reliable way to check for spoilage. For foods with a 'use by' date, the sniff test is unreliable, as dangerous bacteria may be present without any smell or visible changes.

For foods past their 'best by' date, the nutritional content, taste, and texture can gradually decline. The food may still be safe, but you may not receive the full nutritional value listed on the label.

Yes, if stored correctly and the can is undamaged, many low-acid canned goods can be safe to eat for years past the 'best by' date. However, discard any cans that are bulging, leaking, or have severe dents.

The biggest risk is foodborne illness caused by harmful bacteria like Salmonella, E. coli, or Listeria, which can grow to dangerous levels in spoiled perishable food and lead to serious health complications.

Freezing halts the growth of bacteria, so you can freeze perishable foods before their 'use by' date to extend their life. The quality, however, may be affected after thawing.

Unlike 'best by' dates, which are about quality, 'use by' dates are for items that spoil quickly and could become an immediate danger to human health due to microbial growth, even if the food appears normal.