Are canned foods really “junk food”? That may be a little unfair… Eating them this way is healthier →

When it comes to canned food, many people think of it as "full of preservatives" because of its long shelf life and ready-to-eat characteristics, and even think that it is not as healthy as fresh ingredients. Indeed, canned food often has a long shelf life, and can even be stored for three to five years, which makes many people label it as "junk food." But is this really the case? In fact, canned food is really misunderstood .

Canned food not only preserves the nutrients in food but also prolongs the shelf life of food. In some cases, it is even more advantageous than fresh food. The "secret to freshness" does not rely on preservatives, but on unique processing technology and sealing technology.

China has been the world's largest canned food producer and exporter for many years, accounting for about a quarter of the world's total. However, there are still many misunderstandings about canned food. Today, let's uncover the truth and give canned food a fair evaluation.

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Canned food really has no "preservatives"

Because there is no need

GB 2760-2024 "National Food Safety Standard for the Use of Food Additives" officially came into effect on February 8, 2025, which clearly stipulates that preservatives shall not be used in canned foods. This policy not only marks a leap forward in my country's food industry technology, but also breaks the long-standing misunderstanding that canned foods are "preservative-dependent."

According to the National Economic Industry Classification and Code formulated by the National Bureau of Statistics, canned products are mainly divided into canned meat and poultry, canned aquatic products, canned fruits and vegetables, and other canned foods. They all have one thing in common, which is that the shelf life is very long, mostly 2 to 3 years .

Canned hairtail source: Photographed by the author

In fact, this is not surprising. After all, the original intention of canning was to extend the shelf life of food.

Nowadays, with the development of science and technology, the production and processing of canned food has become more and more modernized. The secret of being able to preserve it for a long time without adding preservatives lies in the production process.

GB 7098-2015 "National Food Safety Standard Canned Food" stipulates that canned food is a commercially sterile canned food made from fruits, vegetables, edible fungi, livestock and poultry meat, aquatic animals, etc., through processing, canning, sealing, heating and sterilization. Semi-finished products must be sterilized within 2 hours after canning and sealing. The current mainstream method is thermal sterilization. By adjusting the time and temperature, the thermal sterilization effect can achieve commercial sterility while retaining the nutritional components of the food itself to the greatest extent. It is generally divided into low-temperature sterilization and high-temperature sterilization.

Low temperature sterilization is 80~100℃, also known as normal pressure sterilization, for 10~30 minutes. It is suitable for canned fruits and some canned vegetables with high acid content (pH below 4.6). For example, canned yellow peaches, canned pineapples, canned citrus fruits, etc., which can keep the flesh intact and taste close to fresh fruits; canned pickles and canned ketchup also need low temperature sterilization.

High temperature sterilization is 105~121℃, also known as high pressure sterilization, and the time is 20~90 minutes. It is suitable for meats with low acid content (pH above 4.6) and non-acidic meats, aquatic products and most canned vegetables. For example, canned luncheon meat, canned braised pork, canned sardines, canned sweet corn, canned green beans, canned chickpeas, etc. are also sterilized at high temperature, which can soften the texture of the ingredients while retaining the complete dietary fiber.

With the development of food processing technology, new technologies such as controlled atmosphere sterilization and microwave sterilization are now available. They have short sterilization times, good effects, and are more conducive to preserving the color, flavor and nutrition of the food itself.

After such sterilization, there is no room for microorganisms to survive. After high-temperature sterilization, it needs to be cooled to below 40°C. At this time, negative pressure will be formed inside the container, and the lid will be sealed more tightly, making it difficult to open. After the whole process, no microorganisms can survive inside the can, and microorganisms outside cannot enter, so no preservatives are needed.

Canned food can also be nutritious

Scientific comparison subverts cognition

Canned food can be stored for a long time without going bad, so some people think it is not as good as fresh food and has little nutritional value. The fact may overturn many people's cognition. For the same storage period, food stored in cans may help preserve some nutrients better than fresh food stored at room temperature and reduce the loss of some nutrients.

1

Canned fruits and vegetables - better storage than room temperature

Fresh fruits and vegetables have the highest nutritional value when they are just ripe and have not been picked. Once they are picked and stored and transported for a long time, the nutrients will gradually be lost . For example, green peas will lose 51% of their vitamin C within 24 to 48 hours after being picked.

Canned foods are mostly made directly from fresh food ingredients. During the processing, the potassium, calcium, and magnesium content of fruits and vegetables will not decrease due to sterilization, and dietary fiber will be retained. Although heat-sensitive vitamin C and B vitamins are lost a lot, only a small part of the nutrients will be lost during transportation and storage, and further loss of vitamin C is usually no more than 15%.

The University of Illinois in the United States once conducted a relatively comprehensive comparison of the nutritional components of fresh fruits and vegetables and canned fruits and vegetables. Although the high-temperature heating in the canning process will cause some loss of vitamin C and vitamin B, the vacuum seal of the can isolates oxygen , so the nutritional loss is significantly less than the nutritional loss of fresh fruits stored at room temperature or the nutritional loss of frozen fruits and vegetables.

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In addition, canned food is rarely processed further, resulting in less nutrient loss , while fresh vegetables mostly need to be cooked before they can be eaten, which can lead to a further loss of 15% to 55% of vitamin C and 11% to 66% of vitamin B1.

The vitamin C content of canned citrus fruits we usually eat has been measured to be 10~47 mg/100 g, while the vitamin C content of fresh citrus fruits is usually 20~40 mg/100 g, so there is not much loss in comparison.

There is also the canned sweet corn that everyone loves to eat. A study found that after heating at 15°C for 25 minutes, compared with fresh sweet corn, although the vitamin C content was lost by 25%, the total antioxidant activity of sweet corn was significantly increased by 44%. Even more surprising is that the ferulic acid (an antioxidant ingredient) increased by 550%, and the total phenolic substances also increased by 54%.

Other studies have found that canned foods are usually richer in carotenoids than fresh foods , and may even increase their bioavailability. Carotenoids are an important source of vitamin A for the human body. Compared with fresh tomatoes, canned tomatoes have increased lycopene and higher beta-carotene content, which may be 50% higher than fresh tomatoes; the U.S. Department of Agriculture Nutrition Database shows that canned pumpkins also have higher beta-carotene and vitamin A than fresh pumpkins.

Canning has also been shown to increase the protein (>7%) and dietary fiber (>5%) content of several pulse varieties while also reducing the amount of lectins.

In addition, some canned fruits are added with vitamin C to extend the shelf life as an anti-oxidant. For example, the canned yellow peach in the picture below may have a higher vitamin C content than fresh yellow peaches.

2

Canned meat

Although the high-temperature sterilization process of canned meat will cause loss of heat-sensitive B vitamins in the meat, it will not have much impact on protein and n-3 series unsaturated fatty acids. The following table is a nutritional comparison between fresh tuna and canned tuna. Currently, most canned tuna on the market are yellowfin tuna and skipjack tuna.

In addition, canned fish also retains more vitamin D. There are few foods rich in vitamin D, but mackerel is a common food with a relatively rich vitamin D content, which is 16.1 micrograms/100 grams. Even canned mackerel contains 7.3 micrograms/100 grams. Eating 100 grams (about 1 palm) can meet 73% of the vitamin D requirements of an average adult.

A study in the United States showed that people who often eat canned food (≥6 cans/week) have a richer food intake than those who do not eat canned food often (≤2 cans/week), such as fruits, vegetables and protein-rich foods, and also have a higher intake of potassium, calcium, dietary fiber, etc. Therefore, in addition to fresh foods, nutritious canned foods can also improve nutrient intake and overall diet quality.

Therefore, canned food is not without nutrition, please do not misunderstand it. When it is difficult to consume enough fresh food, canned food is a good choice, which helps to improve the quality of diet and enhance nutrition.

Eating canned food like this is more reassuring

The "National Basic Edition Household Emergency Supplies Reserve Recommended List" and "Family Emergency Plan" issued by the Ministry of Emergency Management of the People's Republic of my country both recommend canned food as household emergency reserve food.

1

Look at the appearance

If you want to eat canned food in a healthy way, first of all, you should choose food produced by regular manufacturers, and familiar brands are better. In addition to looking at the shelf life, you should also look at the appearance of the can , and avoid choosing cans with fat tins, rust, loose seals and air leaks.

2

Choose low-fat, low-sodium, low-sugar

At the same time, you should also look at the sodium, fat and sugar content in the nutrition label, and choose a relatively low-fat, low-sodium and low-sugar one . For example, for canned tuna, try to choose water-immersed tuna instead of oil-immersed tuna. However, among the oil-immersed canned tuna, olive oil can be considered, which can help us supplement oleic acid, which is good for cardiovascular health.

According to the requirements of the General Rules for Nutrition Labeling of Prepackaged Foods:

Low salt: sodium content ≤ 120 mg/100 g (solid) or 100 ml (liquid)

Low sugar: Carbohydrate (sugar) ≤ 5g/100g (solid) or 100ml (liquid)

Low fat: fat content ≤3g/100g (or 1.5g/100ml)

3

Drink less soup

Some canned foods are high in salt, sugar, and fat . If you like them, eat them occasionally to satisfy your cravings, but don't eat them often . When eating canned fruit, drink less soup to reduce sugar intake and avoid large fluctuations in blood sugar.

4

Consume as soon as possible after opening

Once canned food is opened, it no longer has the advantage of being sealed and isolated from bacteria, and will easily spoil like ordinary food. It is best to eat it as soon as possible to avoid secondary storage.

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Canned food is not without nutrition, and generally does not contain preservatives. In today's fast-paced life, it is a good helper to help us save time and balance nutrition. High-quality canned food with low salt, low fat and low sugar is still a very good food!

References

[1] Li Zhongyi, Jiang Lixia. Research on the development of canned food[J]. Meat Industry, 2015(5):12-15

[2] Yu Xinhua. History, current situation and development strategies of canned food [J]. Food and Fermentation Industries, 2001, 27(2): 58-61

[3] Rickman, JC, Barrett, DM, & Bruhn, CM (2007). Nutritional comparison of fresh, frozen and canned fruits and vegetables. Part 1. Vitamins C and B and phenolic compounds. 944(December 2006), 930–944.

[4] Xu Wenhui, Zhou Jinyun, Cai Jing, Zhang Jun. Analysis of sensory quality and nutritional composition of domestic canned citrus products[J]. Journal of Food Safety and Quality, 2019, 10(7): 1969-1975

[5] Yang Yuexin. Chinese Food Composition Table 6th Edition Volume 1[M]. Peking University Medical Press, 2018

[6] Dewanto, V., Wu, X., & Liu, RH (2002). Processed sweet corn has higher antioxidant activity. Journal of Agricultural and Food Chemistry, 50(17), 4959–4964.

[7] Rickman, JC, Bruhn, CM & Barrett, DM (2007). Nutritional comparison of fresh, frozen, and canned fruits and vegetables II. Vitamin A and carotenoids, vitamin E, minerals and fiber. J. Sci. Food Agric., 87: 1185-1196.

[8]https://fdc.nal.usda.gov/food-details/168448/nutrients

[9]https://fdc.nal.usda.gov/food-details/168450/nutrients

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[13]https://fdc.nal.usda.gov/food-details/171986/nutrients

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[16]https://fdc.nal.usda.gov/food-details/175121/nutrients

[17]Comerford KB (2015). Frequent Canned Food Use is Positively Associated with Nutrient-Dense Food Group Consumption and Higher Nutrient Intakes in US Children and Adults. Nutrients, 7(7), 5586–5600. https://doi.org/10.3390/nu7075240

[18]https://www.mem.gov.cn/kp/shaq/202011/t20201129_372149.shtml

[19]https://www.mem.gov.cn/kp/shaq/201904/t20190401_365926.shtml

[20]https://www.researchgate.net/publication/357528768_Impact_of_the_Covering_Vegetable_Oil_on_the_Sensory_Profile_of_Canned_Tuna_of_Katsuwonus_pelamis_Species_and_Tuna's_Taste_Evaluation_Using_an_Electronic_Tongue

Planning and production

Author: Xue Qingxin, registered nutritionist

Reviewer: Zhang Na, Associate Researcher, Doctoral Supervisor, Peking University School of Public Health

Planning丨Wang Mengru

Editor: Wang Mengru

Proofread by Xu Lailinlin