Is the packaged corn on the market "zombie corn"? You must know these facts about corn

I don’t know if you have noticed that supermarkets are now full of all kinds of vacuum-packed corn, frozen corn, and sweet corn kernels that you can eat directly after tearing open the package.

Vacuum-packed corn. Photo credit: Photo by the author

These processed corns make our lives more convenient, but many people also worry about the following issues while eating them:

When I eat this kind of corn, I always feel that the taste is not that good, it is not quite right;

How long is the shelf life of this corn? Is it extremely stale?

Is there anything added to this corn before it is vacuum sealed?

…

Some time ago, a video claiming to be about "zombie corn" went viral. In the video, a blogger seemed to be furious as he revealed that "zombie corn" was all about technology and hard work, and that it not only had a small sweet drink, but also existed as "zombie corn" that had been frozen for many years. Although there was no source or evidence for this video, the horrifying claim about "zombie corn" still spread quickly and caused panic among many people.

Image source: Internet shooting

So, is this processed corn "zombie corn"? Can we eat it for a long time? Is it much worse than fresh corn? Let's talk about it in detail today.

Too long to read version:

“Zombie corn” is a completely fabricated and horrifying statement created by marketing accounts.

Both vacuum corn and frozen corn are processed by high temperature sterilization and rapid freezing, which not only prolongs the shelf life but also retains most of the nutrients. Although the taste of processed corn will change slightly, it is still good overall.

It is recommended that you eat more fresh corn in the summer when it is ripe to enjoy its best taste and nutrition; in other seasons, you can choose processed corn, which is convenient and can satisfy your cravings. When purchasing, pay attention to whether the packaging is complete, whether the standards are implemented, whether the label is compliant, and whether the date is fresh.

In short, the combination of science and technology and agriculture gives us more choices. Whether it is fresh corn or processed corn, each has its own advantages, and everyone can choose according to their own needs. In order to attract attention, many marketing accounts often smear normal science and technology, and then sell products by pulling them down. Everyone must keep their eyes open and not be led astray.

Preserving fresh corn is a difficult task!

Corn is divided into grain corn (mainly threshed after fully mature and used for grain processing, feed, industry, etc.) and fresh corn according to its use. What we are discussing here is fresh corn.

Corn matures in summer, from July to September in the north and from June to August in the south. Corn likes warmth and is heat-resistant. It is sown in the south from late March to early April each year, and in the north a month later. It can be harvested after 80-120 days. Some late-maturing varieties need 150 days to mature in a lower temperature environment.

Therefore, fresh corn is generally available in large quantities from July to September each year. Corn can also be bought in other seasons. Most of them are corn grown in Yunnan, Hainan and other regions to fill the market. At this time, corn is relatively expensive.

The weather is often hotter during the season when corn is on the market in large quantities. Although the price is very cheap, it is difficult to keep fresh corn fresh: it usually starts to turn yellow and wilt after 1-2 days at room temperature; even if it is placed in the refrigerator, it can only last for 3-5 days. If it is kept for too long, the kernels will lose water and the taste will become bland, and it will taste like chewing sawdust. If you want to preserve it for a long time, or eat corn in other seasons, you have to take a more scientific approach.

In recent years, corn has become popular as a healthy and fat-reducing food, and many people eat it as part of their main meals. However, because fresh corn has a limited shelf life and off-season supply is "stretched", "processed corn" is increasingly available on the market.

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Processed corn has a long shelf life

Mainly due to the upgrade of processing methods

When it comes to "processed corn", canned corn was more common in the past, but now there is a more suitable processing method for corn - vacuum packaging.

Vacuum-packed corn has high requirements for corn maturity, because only the right maturity will have a better taste, higher sugar content and aroma. Too old or too tender will affect the taste of the final product.

The vacuum-packed corn process is complicated and time-sensitive. After picking, the filaments must be removed quickly, and the ears that are moldy, missing grains, water grains, have flower grains, or are not mature enough must be removed. The ears are then trimmed into a uniform length (usually 12 to 20 cm) and graded by length.

When washing, use running water to remove the silk and dirt, and avoid soaking for a long time. After the corn is cleaned and looks good, it is time to pre-cook it. Pre-cooking generally uses high temperature (85-95°C) blanching to passivate the enzyme activity in the corn, prevent the loss of nutrients, sterilize and fix the color at the same time. It usually takes 10-12 minutes to blanch.

The blanched corn is then cooled to room temperature, packed in vacuum bags and sealed. Finally, the vacuum-packed corn is placed in a sterilizer for high-temperature sterilization, usually using water immersion sterilization at 121°C for 20 to 30 minutes. This step is to fully kill the bacteria in the bag. After sterilization, cool it down, wipe off the water on the surface of the package, and then check for leaks.

The whole process does not require the addition of any chemicals, but it can be stored for a long time. This is mainly because the air is extracted, high-temperature sterilization is performed, and the product is sealed, so bacteria cannot survive. Therefore, it can be stored for a long time without adding preservatives (of course, it must be produced by a regular manufacturer).

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In addition to vacuum corn, there is another common processed corn - frozen corn. Its processing method is slightly different from that of vacuum corn. In the early stage, it is also shelled and cleaned after picking, and then frozen after pre-cooking. It usually needs to be stored in an environment of -18℃.

Quick-frozen corn, like quick-frozen dumplings, is a quick-frozen food, and generally comes in two types: quick-frozen corn kernels and quick-frozen glutinous corn. However, compared to vacuum-frozen corn, frozen corn loses water during the long freezing process, affecting the taste, so it is usually best not to freeze it for too long to avoid a bad taste.

Quick-frozen glutinous corn (not vacuumed, needs to be stored and transported at low temperatures), Image source: Photo by the author

Processed corn is really nutritious!

So as to select qualified products

Processed corn is not as crisp and sweet as fresh corn, but it can better retain most of the nutrients in corn. Except for some water-soluble vitamins (such as vitamin C) and antioxidants, which will be slightly reduced, protein, carbohydrates, dietary fiber, minerals, etc. can be well retained. In addition, vacuum packaging effectively inhibits oxidation reactions and can better retain fat-soluble vitamins (such as vitamin A, E and carotene).

Of course, many people will worry whether the sealed corn has been stored for a long time or whether there is rotten corn inside. Here are a few ways to teach you how to choose qualified products.

1. Look at the packaging: Choose products from regular manufacturers. The packaging should be complete, without damage or leaks, especially for vacuum corn. If the bag is bulging, it means it is leaking.

2. Look at the label: check the production date and expiration date. The fresher the better.

3. Look at the appearance: The color of frozen corn kernels should be bright, not yellow or black; for vacuum corn, check whether the kernels are full and whether there is any obvious discoloration or shriveling.

4. Smell it: If it smells strange or sour, don’t buy it!

Another important point is to check the food safety certification. The formal product packaging will have a complete SC code (food production license number). Some will also have certification marks such as green food and organic food. These marks indicate that the product has passed strict quality inspections and is safer to eat.

Tips: You can often see purple, black, and colorful corns on the market. They are not only beautiful, but also have higher nutritional value. You can try them.

"Colored Glaze" corn (planted and photographed by the author)

The color of corn is reflected by the differences in the quantity and quality of pigments in the pericarp, endosperm and endosperm. Through hybridization and breeding, corn varieties with different colors can aggregate different color traits to cultivate colorful corn. The rich colors of corn are the result of the combined effects of pigments such as anthocyanins and carotenoids.

Planning and production

Author: Zhang Cong, a graduate student in agronomy and seed industry, majoring in vegetables

Review丨Yang Laisheng, Researcher at Lanzhou Academy of Agricultural Sciences, Ruan Guangfeng, Deputy Director of Kexin Food and Health Information Exchange Center

Planning丨Fu Sijia

Editors: Fu Sijia, Lin Lin

Proofread by Xu Lai