Freshness Exposed: The Truth Behind Your Supermarket’s Fresh, Frozen, and Canned Produce

When most people go to the supermarket to buy fruits or vegetables, they usually believe that the “fresh” section is the best choice. Sure, canned or frozen produce might be more convenient but fresh produce must be healthier — right?

The idea that “fresh” produce is the healthiest option is a common misconception. The reality is that most of the fruits and vegetables found in the produce section of the supermarket are really weeks or even months old and have lost huge amounts of their nutritional value. In many cases, it is healthier to buy frozen or even canned produce instead of what is being sold as “fresh.”

Here, we will explore what really goes into making the Fresh, Frozen, and Canned produce found in supermarkets so you can make the best choices when shopping.

Part 1: Fresh Produce

You’ve probably heard that it is best to “buy local” and “buy in season.” But did you ever really stop and consider how fresh produce gets to the supermarket? How it is possible to have produce like tomatoes in the middle of winter, or tropical fruits like bananas in your city where they obviously don’t grow? (Unless they were grown in an automated grow box like a Grobo.)

The Problem of Getting Fresh Produce to Cities

It wasn’t that long ago that people only ate local and seasonal because they had no other choice. They mostly lived in rural areas and raised their own food, or purchased from their neighbors. In the 19th century, there was a huge global shift towards urbanization. By 1891, 28% of the US population lived in cities. Today, that number is 81%. It isn’t just the United States either. According to the United Nations, as of 2007 half of the world population is living in cities. (Source)

The produce industry has come up with all sorts of technologies in order to get produce to these people in cities. In some ways, we should be thankful. Before all the advancements in food distribution methods, diseases like scurvy were very common because people living in cities had no access to foods with vitamin C. (This wasn’t an issue on farms though because it was common practice to preserve vitamin C-rich foods using canning, drying, etc.)

But there has also been a very dark side to all the technologies we’ve developed for produce distribution. By eating food produced thousands of miles away, and stored for months before making it to our tables, we are exposing ourselves to dangerous chemicals and GMOs, while also sacrificing taste and nutrition.

Controlled Ripening of Fresh Fruit

When fruits ripen, they go through chemical and physical changes. Their pectin changes into a water-soluble form. The unripe fruit goes from being firm and mealy to soft and juicy. The moment the fruit is ripe, it will also start to degrade. This is a natural process which allows the nutrients of the fruit to be returned to the soil.

Because ripe fruit is soft and degrades so quickly, it is very difficult to transport the fruit, especially long distances. If fruit were picked and transported when ripe, growers would have to figure out a way to get fruit from the farm to the consumer within a matter of days — something which is very difficult when food is grown and distributed on such a large scale.

Here we need to differentiate between two types of fruits:

• Climacteric Fruits: These are fruits which contain a natural chemical called ethylene which causes them to ripen even after they are picked. Examples include tomatoes and apples.
• Non-Climacteric Fruits: These are fruits which don’t contain ethylene, so do not continue to ripen after they are picked. Examples include blueberries, oranges, and bell peppers.

With non-climacteric fruits, there isn’t too much that the industry can do. The fruits have to be picked when they are ripe (or close to ripe) and cannot remain in storage for very long times. This is why you will not find fresh berries in the winter. But, with climacteric fruits, the industry has exploited their ripening abilities. They use artificial methods to delay ripening and then induce ripening before sale.

Delayed Ripening Technology

Because climacteric fruit will ripen even after picked, growers can harvest them as soon as they are mature, but before they have begun to ripen. The fruits are still hard at this point so are easier to transport. Growers can then use any of numerous artificial techniques to prevent the fruit from ripening, allowing them a larger window of time to get the produce to the supermarket. Many of these techniques are described by the International Service for the Acquisition of Agri-Biotech Applications (ISAAA):

a. Suppression of ACC synthase gene expression. Enzyme expression is hindered when an antisense (“mirror-image”) or truncated copy of the synthase gene is inserted into the plant’s genome.

b. Insertion of the ACC deaminase gene. The gene coding for the enzyme is obtained from Pseudomonas chlororaphis, a common nonpathogenic soil bacterium.

c. Insertion of the SAM hydrolase gene. The gene coding for the enzyme is obtained from E. coli T3 bacteriophage.

d. Suppression of ACC oxidase gene expression. ACC oxidase is the enzyme which catalyzes the oxidation of ACC to ethylene, the last step in the ethylene biosynthetic pathway.

These are just some of the ways that ripening is delayed in climacteric fruits. Yes, this is genetic modification. Yes, chemicals are used. Yes, it could be dangerous to our health.

Aside from the potential adverse health effects of delayed ripening technology (which haven’t been extensively studied!), there are other downsides of delaying ripening in fruit.

First off, the taste of the fruit is affected by delayed ripening. Because the fruits are picked before they are ripe, the fruit never went through its natural chemical changes — such as the acids breaking down so the fruit becomes sweet instead of bitter. Even though the industry will use “ripening technology” to turn a green tomato red, it isn’t a substitute for nature. Even the International Service for the Acquisition of Agri-Biotech Applications (ISAAA) admits that produce which is artificially ripened will have a poor taste despite appearing fully ripe.

Ripening Technologies

Consumers obviously don’t want to buy green tomatoes, peaches, plums, etc. So, once the fruits reach the distribution center, chemicals are used to quickly ripen the fruits. The fruits will appear fresh and ripe, even though they were picked weeks (or months!) before.

There are several different chemicals which can be used to ripen climacteric fruits after they’ve been picked. One of the most common is calcium carbide, which is a material used in welding. It contains arsenic, phosphorous, and produces an acetylene gas which may affect the neurological system. It is known to cause health affects like headaches, dizziness, sleepiness, mood disturbances, memory loss, and seizures. Yet somehow the produce industry thinks it is a good idea to spray it all over our fruits! (Source)

In an article published at Academia.edu, one researcher had this to say of artificial ripening with calcium carbide (CaC):

“Although fruits developed good peel color with CaC, the intensity of color developed commensurate with increase in the concentration of CaC used; but fruits were less in flavor volatiles and had shorter shelf-life. Actu-ally CaC only changes the skin color, whereas the fruit remains raw inside. More raw/immature the fruit, higher CaC is required to ripen it. This makes the fruit taste-less, unhealthy and slightly toxic. It also breaks down the organic composition of vitamins and other micronutrients.”

The Storage of “Fresh” Produce

It isn’t just climacteric fruits that you have to worry about. All the so-called fresh produce in the supermarket could have actually been sitting around in storage for weeks — or even over a year — before it is sold.

According to recommendations published by the Food and Agricultural Organization (FAO), here is how long produce can be stored before reaching the supermarket:

• Apples: 1–6 months
• Cabbage: 5–6 months
• Lettuce: 2–3 weeks
• Tomatoes: 2–3 weeks
• Potatoes: 2–12 months
• Carrots: 1–9 months
• Garlic: 6–7 months
• Pumpkins: 2–5 months
• Cucumber: 28 days
• Pomegranate: 2–3 months

Keep in mind that these are just recommendations. Studies of supermarket produce have found that they may actually be much older than this — such as one study which found supermarket apples are over a year old! (Source)

How is it possible to store an apple over a year without it going bad?

In addition to the delayed-ripening technologies used for climacteric fruits, here are some of the tricks that the industry uses to make produce last longer and look fresh, even when it was picked long ago:

• Chilling: Produce is chilled immediately after harvest so it will deteriorate more slowly.
• Controlled Atmosphere: The produce is put into storage areas where the oxygen levels are lowered and carbon dioxide levels are increased to slow down deterioration.
• Fungicides: Produce will be sprayed with fungicides to prevent mold from growing on them. Methyl bromide is commonly used.
• Sanitizers: Sanitizers are sprayed on the produce to prevent bacterial and pest infestations. Chlorine and sulfur dioxide are most commonly used.
• Sprout Suppression: With produce like potatoes, garlic, and onions, sprouts and root formation is prevented by spraying chemicals like Maleic Hydrazide and (3-chloroisopropyl-Nphenylcarbamate.

(Source 1, Source 2)

Yes, there are health effects associated with the chemicals used to preserve produce. Unfortunately, we have yet to see any large-scale studies about how exactly these chemicals are affecting our health. Right now, the industry simply deems it “safe” to have the chemicals in low doses.

Aside from the chemicals, there are other concerns about storing food for long times — particularly for nutrition.

Produce Storage and Nutrient Loss

Many of the nutrients found in produce are not stable, meaning that they will break down over time or when exposed to certain conditions. This is particularly true of antioxidants, the molecules which are important for immunity and help prevent cancer.

According to this study, antioxidant activity in apples drops after 3 months of cold storage. By the time an apple has been stored for almost a year, it will have nearly no antioxidants remaining! Another study found that English spinach will lose 47% of its folate and 46% of its carotene after 8 days of cold storage.

Part 2: Canned Produce

I personally am not a big fan of canned produce because the packaging is wasteful, and because canned produce which has been sitting in water can have a mushy texture. But, when it comes to health, canned produce may be better than fresh in some cases.

The Canning Process

When fruits or vegetables are harvested for canning, they are picked at their peak ripeness. They are then taken to the canning factory. To reduce spoilage, most canning factories are located just a few miles from the farm. Depending on the produce, the fruits or vegetables may be treated differently before canning. For example, fruits are often pitted and peeled before canning. Most vegetables are usually blanched before canning. (Source)

The produce is put into cans, sealed, and subjected to heat under steam pressure. The heat kills any organisms which might cause food spoilage. Because the cans are sealed, the food can keep for years because there is no oxygen or organisms which would normally cause the food to spoil.

Taste of Canned Produce

The heat treatment of canned foods, as well as the water they are packaged in, can affect the taste and the texture of canned foods. To mask this, manufacturers often add copious amounts of salt. The salt also helps prevent spoilage, though the canning process alone is enough to do this so the excess salt isn’t really needed. Many fruits are also canned in a sugary syrup, which makes them even sweet and adds unnecessary calories.

While a canned peach or canned carrot might not be as tasty as fresh ones, they are still good options — especially for cooked dishes where texture isn’t as important, like a peach cobbler or carrot stew.

Nutrition of Canned Produce

Because canned produce is subjected to very high temperatures, some of the nutritional value is lost. Vitamin C is particularly susceptible to heat and will be destroyed in the canning process. The water in the cans can also cause vitamin C and B vitamins to be lost because they are water-soluble. However, minerals and fat-soluble vitamins generally remain very stable during the canning process. In fact, some studies have found increases in fat-soluble nutrients such as carotene. This is probably due to the fact that other solids are lost in the water, increasing concentration of carotene. (Source — PDF)

Even with the nutritional loss due to canning, canned produce can be just as nutritious — or even more nutritious — than “fresh” produce because it is picked at peak ripeness and isn’t stored for long periods of time before canning. Once the produce is canned, the nutrient levels remain virtually the same within the can, even after 1 to 2 years of sitting on the shelf!

However, there are other concerns with canned produce. Upwards of 75% of canned foods are in cans which are lined with bisphenol A (BPA). BPA mimics estrogen in the body and is linked to hormone disruption and cancer. The Breast Cancer Fund recommends avoiding foods canned with BPA. The excess sugar and salt found in many canned foods also make them unhealthy choices. (Source 1, 2, 3, 4, 5, 6)

Part 3: Frozen Produce

It would seem like frozen produce would require a lot of processing to make. However, compared to the complex procedures used to keep “fresh” produce from spoiling, frozen produce is actually made very simply. This simplicity is what often makes frozen produce the most nutritious option.

The Freezing Process

As with canned produce, frozen produce is harvested at peak ripeness. The manufacturing plant is usually located right on the farm so the fresh-picked produce arrives almost immediately. Once at the plant, the produce is spray washed. The produce may be inspected before or after the freezing process.

Many frozen foods are blanched before they are frozen, especially vegetables like peas and spinach. During the blanching process, some of the water-soluble vitamins (vitamin C and B vitamins) may be lost.

There are numerous different methods for freezing produce. It might be taken through a “blast tunnel” where ultra-cold air freezes them. Or they might be put on a conveyor belt with metal plates that have been cooled from below by chilled ammonia. Usually the produce is frozen before packaging, but some produce may be packaged first and then frozen. In any of these cases, the produce is frozen very rapidly. (Source)

Taste of Frozen Produce

Most produce contains significant amounts of water inside of it. When you freeze water, it expands and forms ice crystals. These ice crystals can puncture cell walls, which is why frozen produce has a different texture than fresh produce. For example, a defrosted strawberry will be completely mushy. Colder temperatures produce smaller ice crystals, which is one reason why manufacturers try to freeze produce as quickly as possible. (Source)

The texture of food is very important to our perception of taste. (Source) Some produce which contains a lot of water simply isn’t going to taste as good as the fresh version. For example, frozen green beans pale in comparison to fresh green beans. However, produce which doesn’t contain a lot of water (such as peas or corn) generally still taste great even after being frozen. Frozen produce is also great in dishes where the texture of individual ingredients isn’t as important, such as soups or smoothies.

Nutrition of Frozen Produce

Since many types of produce are blanched before being frozen, they will lose significant amounts of water-soluble vitamins (vitamin C and B vitamins). One report says that 10% of thiamin (B1), 25% of vitamin C, and even more folate are lost in the blanching process due before freezing (though losses vary depending on the type of produce). Other vitamins and minerals are generally not highly affected by blanching. (Source 1, 2)

As for the actual freezing process, it does not noticeably affect nutrition. Even “delicate” nutrients like antioxidants — which are highly susceptible to oxidation and break down quickly in fresh produce — are not affected by freezing. So, frozen produce will have nearly as much nutrition as it did the day it was frozen.

Here are some findings from a study which compared frozen and fresh produce:

• Frozen broccoli had higher levels of vitamin C, lutein, and 4x more beta-carotene than fresh broccoli, but fresh broccoli had more polyphenol antioxidants.
• Frozen carrots had 3x more lutein, 2x more beta-carotene, and higher levels of vitamin C and polyphenols.
• Frozen blueberries had higher levels of vitamin C, polyphenols, and anthocyanin antioxidants.

(Source)

The Bottom Line

Still confused about which is the healthiest, tastiest produce to buy? Follow these guidelines:

• Always choose seasonal, local fresh produce when available and affordable (such as peaches in the summer, apples in the fall, and cabbage in the winter). Get to know your local farmer or consider joining a food co-op which specializes in local produce.
• When seasonal, local fresh produce is not available, then choose frozen versions.
• If frozen versions are not available, then choose canned produce which was canned without BPA. Watch out for excess sodium and added sugars!
• For fresh produce which isn’t available locally and doesn’t taste great frozen or canned (such as bananas), try to choose organic since these will not be GMO and are less likely to have been processed with harmful ripening chemicals.