Is it safe to use expired canned tomato paste?

Quick Answers

Using expired canned tomato paste can be risky. While it may still be safe if used shortly after expiration, the longer past the date the greater the risk of foodborne illness. Canned foods can spoil over time as seals fail. Spoiled tomato paste may show signs like bulging cans, discoloration, strange odors, or mold. When in doubt, it’s best to discard expired tomato paste and purchase fresh cans. Proper food handling and cooking can reduce but not eliminate risks from contaminated tomato paste.

Many home cooks have opened their pantry only to find a can of tomato paste lurking in the back past its stamped expiration date. This leaves them with a dilemma – is it still safe to use or is it destined for the trash? With the rising costs of food, there is an understandable reluctance to discard anything before its time. However, saving a few cents may not be worth the potential risks from spoiled or contaminated foods.

In this article, we will examine in detail the safety and risks of using expired canned tomato paste. Factors explored include:

  • How expiration dates are determined for canned tomato paste
  • Changes that can occur in tomato paste after expiration
  • Signs of spoiled tomato paste
  • Potential risks from bacteria and toxins in spoiled tomato paste
  • Proper handling and cooking guidelines
  • When expired tomato paste must be discarded

Equipped with this information, readers will be able to make informed choices about the safety of their expired tomato paste. The goal is to provide knowledge to allow balanced decisions between reducing food waste and protecting health.

How Expiration Dates Are Determined for Canned Tomato Paste

To understand the significance of expiration dates, it helps to know how they are established in the first place. For canned tomato paste, there are no federal regulations dictating how expiration dates must be determined. Instead, manufacturers are responsible for setting their own dates based on a few different factors:

  • Shelf life tests: Food companies perform shelf life tests to determine the expected shelf stability of their products over time. Samples are stored under standard conditions and tested periodically for changes in quality, texture, and other attributes.
  • Container integrity: The ability of the can to maintain a hermetic seal over months or years of storage is evaluated. Loss of seal integrity speeds spoilage.
  • Food safety factors: Expected times for pathogenic bacterial growth or toxin production are incorporated. More acidic products like tomato paste are less prone to bacteria.
  • Quality standards: Beyond safety, companies determine when an undesirable loss of flavor, color, texture, or nutrition occurs.

Expiration dates are set conservatively to account for variabilities between cans and during distribution. However, not all cans spoil at the same rate. Temperature fluctuations and minor handling damage can accelerate spoilage in some containers. This means properly stored cans may retain quality and safety for some time past the stamped date, while others spoil earlier.

Changes That Can Occur in Tomato Paste After Expiration

Although canned tomato paste can potentially be used for 1-2 years past its sell by date before major spoilage occurs, there are some subtle changes to expect as it ages past its prime:

  • Diminished nutrition: Levels of heat-sensitive vitamins like vitamin C and B vitamins slowly degrade over time.
  • Flavor changes: Subtle losses in fresh tomato flavor and aroma occur due to oxidation and compound degradation.
  • Color fading: The vibrant red hues slowly fade to drab brown tones.
  • Texture changes: The paste may thicken and become grainy or lose consistency.
  • Can corrosion: Acidic tomato paste can react with the metal can over time, causing minor pitting.

These types of changes mean that expired tomato paste won’t have the fresh quality of a newer can, even if it has not yet spoiled. However, slight degradation in color, texture, or nutrients does not make the tomato paste inherently unsafe to consume.

Signs of Spoiled Tomato Paste

While slightly faded color and a bit of thickening are normal, there are more obvious visual and olfactory red flags to be on the alert for when opening an expired can of tomato paste:

  • Bulging or leaking can: These are signs bacteria have produced gas and pressure has built up or seal integrity is lost.
  • Deeply discolored paste: If the red color turns a very dark brown, black, or greenish hue.
  • Mold: Fuzzy growth anywhere in the can or on the paste is a very bad sign.
  • Separated liquid: Clear orange or red fluid separated from the thicker paste.
  • Strange odors: Unpleasant aromas like sour, rotton, or alcoholic smells.

If you observe any of these warning signs upon opening, do not taste or use the tomato paste. While not a guarantee of safety, if the paste appears normal with no obvious spoilage, has no odd odors, and the can is in good condition, the risks are lower.

Potential Risks from Bacteria and Toxins

Why is spoiled, expired tomato paste so concerning? Consuming contaminated tomato paste can introduce harmful bacteria, molds, and toxins into your body and food.

Bacterial Contamination

Potential bacterial contaminants include:

  • Clostridium botulinum – Causes deadly botulism poisoning. Spores can survive canning and produce toxin over time as oxygen decreases.
  • Listeria monocytogenes – Causes listeriosis with flu-like symptoms. Can grow under refrigeration.
  • Salmonella – Causes salmonellosis food poisoning with diarrhea, fever, and cramps.
  • Escherichia coli – Certain strains cause severe bloody diarrhea.
  • Staphylococcus aureus – Produces heat-stable enterotoxins leading to violent illness.

Mold Contamination

Molds that grow in spoiled tomato paste can produce toxic chemicals called mycotoxins. Even small amounts of these toxins can cause issues like:

  • Nausea, vomiting, and diarrhea
  • Organ damage
  • Cancer risks
  • Neurological problems

Preformed Toxins

Bacteria like Staphylococcus aureus can produce toxins that are not destroyed by heating. Consuming staphylococcal enterotoxins can lead to violent vomiting and diarrhea very quickly.

Proper Handling and Cooking Guidelines

While expired tomato paste carries enhanced risks, proper handling and thorough cooking can reduce the chances of foodborne illness. Here are some recommendations if you choose to use tomato paste past its expiration date:

  • Inspect the can carefully before opening. Discard any bulging, leaking, or heavily damaged containers.
  • After opening, check the paste for any signs of spoilage like mold, odors, or separation.
  • Bring any sauce or dish containing the tomato paste to a full rolling boil for 1-2 minutes.
  • Make sure to stir as it heats to distribute heat evenly.
  • Boiling for 5 minutes can further reduce risks.
  • Steaming or microwaving tomato paste is not sufficient to kill bacteria.
  • Refrigerate any leftovers within 2 hours and use within 3-4 days.

Proper cooking methods reduce but cannot completely eliminate the hazards if tomato paste is extensively spoiled. It cannot make the product as good as new either. The boil times required would likely further degrade texture and flavor.

When Expired Tomato Paste Must Be Discarded

To avoid foodborne illness, these situations require the tomato paste be discarded and not consumed:

  • The can is bulging, leaking, heavily damaged, or rusty.
  • Any mold is visible on the paste itself.
  • An unpleasant or putrid smell is present when opened.
  • The paste is discolored or has separated liquid.
  • More than 3-4 years past the expiration date printed on the can.

If none of the above warning signs are present, using tomato paste 1-2 years past its sell by date is less risky. However, the older it is, the more vital proper handling and thorough cooking become.


Expired canned tomato paste should not automatically be discarded out of an abundance of caution. With careful inspection and proper cooking, even tomato paste a few years past its prime may be safely consumed in most cases. However, the further past its expiration date, the higher the risks of spoilage and foodborne illness become if the container seal has failed.

Consumers should weigh whether the potential savings are worth the safety tradeoffs. Tomato paste is fairly inexpensive and widely available. Err on the side of caution if cans show any visible damage or signs of spoilage upon opening. When it doubt, remember the old adage – better safe than sorry.

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