Have you ever wondered about how food is tested to determine the best before date? Or how long can you keep that unopened box of crackers in the pantry? Food spoilage is a common problem facing both consumers and manufacturers. While some foods (like lunch meats) have a relatively short shelf life, others (such as canned goods) can last for years.
How do scientists figure out how long food will stay fresh?
There are several methods used to test food for shelf life. One common method is the accelerated shelf life test (ASLT). This type of test subjects foods to higher than normal temperatures and humidity levels in order to simulate storage conditions that would cause the food to spoil quickly. The ASLT can be used to determine the approximate shelf life of a food product under ideal storage conditions.
Another method used to test food shelf life is the active packaging method. This method uses packaging materials that are designed to absorb or release gases that can cause food spoilage.
The active packaging method can be used to extend the shelf life of a food product by keeping the oxygen levels inside the package at a safe level. An example would be that small packet of oxygen-absorbing material you find in fresh packaged meats, like chicken breasts.
Another method used is the oxygen uptake rate test (OURT). This test measures the amount of oxygen that is taken up by a food product over time. The OURT can be used to determine the shelf life of a food product under storage conditions that are not ideal.
Oxygen is one of the main agents that causes food spoilage. When oxygen is present, it can cause bacteria to grow and multiply. The OURT is used to determine how much oxygen a food product can take up before it starts to spoil.
The OURT is conducted by placing a food sample in an airtight container. The container is then placed in a chamber that is filled with nitrogen. The chamber is sealed and the oxygen level is monitored over time.
The last method we will discuss is the challenge test. The challenge test is used to specifically test for food-borne pathogens that can cause food spoilage. In this type of test, scientists inoculate a food product with known strains of bacteria and then incubate the food at specific temperatures.
The challenge test is important because it allows manufacturers to determine if a food product is safe to consume after a certain amount of time. For example, many canned goods are safe to eat years after they have been manufactured, but challenge tests are conducted to make sure that the canning process has been effective in killing all of the bacteria that could cause food poisoning.
All of these methods have their own advantages and disadvantages. The ASLT is the most common method used to test food for shelf life. However, the ASLT can only be used to determine the approximate shelf life of a food product because it does not take into account the oxygen uptake rate.
The active packaging method is a more accurate way to test food for shelf life because it uses packaging materials that are designed to absorb or release oxygen.
The OURT is the most accurate way to test food for shelf life because it takes into account the oxygen uptake rate. However, this method is not commonly used because it is also expensive.
How do you know how long your food will last?
The answer depends on the food product and the storage conditions. If you are unsure about how long a food product will last, it is best to err on the side of caution and consume the food product before the expiration date.
How long do lunch meats last in the fridge?
Lunch meats, also known as cold cuts or deli meats are a staple for many families because they are pre-cooked, ready-to-eat meats making them ideal for sandwiches or a quick tapas style dinner. But how do you know how long your lunch meat will last? And how can you tell if it has gone bad?
Lunch meats are typically preserved through a process of curing with nitrites, smoking, or adding salt. Another less common but effective way to preserve is HPP (High-pressure processing) which uses extreme pressure instead of heat to pasteurize.
HPP is a healthier alternative to nitrites for killing bacteria, because it does not form nitrosamines, a known carcinogen. HPP decreases the risk of food poisoning from bacteria like Listeria, E. coli, or Salmonella because it kills these bacteria without affecting the quality of the meat or requiring nitrites to extend shelf life.
Depending on the best before date on the package, lunch meats can last weeks if they are unopened and stored properly in the fridge. It is important to check this date. After opening, aim to consume meat within 3-5 days regardless of the best before date. If you don’t think you’ll use the meat before the expiry, it can be frozen in its original package or sealed in a freezer bag. Frozen lunch meat will maintain its quality for 1-2 months.
Regardless of expiry dates on food, you can generally tell if something has gone off by using your senses. If it changes colour or texture, feels slimy or smells bad, don’t eat it!
When in doubt, throw it out.