Can rice, flour, grain, oil and condiments be eaten after their expiration date? The answer is different from what you think

Many people always think that rice, flour, grain, oil and various condiments are difficult to spoil; or some people think that the shelf life on these food packaging is the shelf life after opening. So what is the real situation? Today, let's talk about the shelf life of food.

What is the shelf life?

The word "shelf life" is often seen on food packaging labels, and usually means that the quality of the food will not change significantly within the specified period of the shelf life.

According to the definition in my country's standard GB7718-2011 "Pre-packaged Food Labeling Standard", the shelf life is the period during which the pre-packaged food maintains its quality under the storage conditions specified on the label. In other words, only pre-packaged food has a shelf life, and non-packaged food does not have one.

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We need to remind you that the shelf life is when the packaging is intact and unsealed. Once the food is unsealed, it is no longer a "pre-packaged food under specified storage conditions" and has no shelf life .

Expired ≠ Cannot be eaten

Expired = Cannot be eaten

Since it has expired once it has been opened, does that mean it cannot be stored or eaten?

Actually, it’s not.

The shelf life guarantees that the product quality is optimal within the marked time, but food that has exceeded the shelf life can still be eaten if the color, aroma and taste have not changed.

However, food that has exceeded its shelf life will have its quality changed and cannot be eaten. The "shelf life" refers to the final date on which food can be eaten, that is, the final edible date of food under normal conditions. After the shelf life, the quality of food will change and a large number of pathogenic bacteria may be produced. If consumed, it may cause food poisoning. Therefore, food that has exceeded its shelf life cannot be eaten.

Shelf life and storage period diagram丨Ruan Guangfeng

We need to remind everyone that how long food can be preserved has a lot to do with storage conditions.

Generally speaking, the higher the storage temperature, the shorter the shelf life of the same food . For example, if food can be stored for 12 months at -18°C, it does not mean that it can be stored for that long at room temperature of 25°C; if it is sealed, it can be stored for half a year, but if it is left open, it certainly cannot be stored for that long.

For example, rice can usually be stored for a long time, but if it is opened, it is easy to get damp, moldy, and infested with insects, and it will be inedible. Therefore, when storing food, you must pay attention to keeping the food in the right conditions.

How long can it be kept after opening?

Once food is unpacked, it is easily affected by the external environment and prone to spoilage, so it should be eaten as soon as possible. How long it can be kept depends on how you store it. Therefore, when storing food, pay attention to:

1

Rice, flour and other staple foods

Rice, flour, beans and other staple foods are dry and have little water content, so they are easy to store, but they are afraid of moisture and insects . Therefore, after unpacking, try to store them in fresh-keeping bags and boxes with good sealing properties, and store them in a well-ventilated, cool and dry place. Nowadays, there are fewer people at home and people cook less, so try to buy small bags of rice and eat them as soon as possible after opening .

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2

Cooking Oil

Edible oil is mainly afraid of oxidation. When storing, try to avoid sunlight and high temperature . When storing, pay attention to store it in a dark, cool and dry place . If it is opened, it should be consumed as soon as possible.

3

Soy sauce, oyster sauce

The main fear is insects and "white film", especially in summer and autumn in the south, because of the high temperature and humid air, it is easy to get insects and mold.

When storing soy sauce, please keep it away from light and heat. It is best to store it in a cool and dry place. After opening, wipe the bottle mouth and body clean and cover the bottle cap tightly to prevent flies, cockroaches and other pests from invading.

It is recommended to store oyster sauce in the refrigerator and take it out when using it. It should be consumed as soon as possible after opening. Some types of soy sauce also need to be stored in the refrigerator, so when buying soy sauce, you should pay attention to whether the product label is marked with words such as "refrigerated", and then store it according to the requirements marked on the food label.

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4

vinegar

Vinegar has a high acidity, which is not popular with bacteria, and is usually more durable. It is recommended to store it in a cool and dry place . Of course, it should be consumed as soon as possible after opening.

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5

Salt, MSG

Salt and MSG are mainly afraid of moisture, and they tend to clump when wet, but there is no safety problem. Keep them in a cool and dry place.

6

Honey

Because of its high sugar content and high osmotic pressure, it is difficult for microorganisms to grow, so honey can usually be stored for a long time. However, after the honey is opened, it will be affected by the storage environment, such as absorbing moisture from the air and getting damp, and some osmotic pressure-resistant yeast will grow inside, so the honey will gradually deteriorate.

Planning and production

Author: Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center

Review丨Zhang Yu, researcher/PhD, Chinese Center for Disease Control and Prevention, national health science expert

Planning丨He Tong

Editor: He Tong

Proofread by Xu Lailinlin

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