The time when food is nutritious is the moment of harvest. Fresh fruits and vegetables begin to decay as soon as they are dug out of the ground or plucked from trees, which are their source of nutrients and energy. Vegetables that need to be cooked fresh can lose their nutritional value if left too long.
To keep the cells active, vegetables or fruits, once picked, begin to break down their own nutrients. Some nutrients are particularly vulnerable. Vitamin C, for example, helps the body absorb iron, lower cholesterol levels and fight free radicals, but is also particularly sensitive to oxygen and light.
Stored at room temperature, carrots lose 27 percent of their vitamin C, but that’s still better than other vegetables.
Refrigeration can slow the rate of nutrient loss, but it can vary from produce to produce. Spinach stored at room temperature of 20℃ for 7 days, the loss of vitamin C is 100%. If put in freezer, will lose 75%. But after a week at room temperature, carrots lose only 100 percent of their vitamin C.
But other vegetables can lose much less vitamin C if they are kept frozen. That includes spinach, which loses only 30 percent of its vitamin C when frozen. This is because freezing halts the process of food oxidation, which is one of the reasons vegetables and fruits turn brown when they are picked.
Using quick-freezing techniques invented by the food industry, peas can be frozen quickly after being picked.
Large-scale quick freezing is a relatively new and innovative technology in the food industry. Take frozen peas. Peas can now be picked, transported, cleaned, blanched and frozen in as little as two hours. In the 1970s, the process took days to complete.
Compare that with fresh vegetables. When most fresh vegetables are picked, they are sent to packaging plants for packaging, grading, then to retail stores and finally to consumers’ baskets. In 99 percent of cases, the process takes longer than picking, processing and freezing peas.
Speed is crucial in the frozen food industry. Once the produce is picked, it’s a race between nutrition and time. Over the past few decades, technological innovations have shortened the processing of frozen peas. The quick-freezing technique USES a metal slot with two openings at each end and a grill-like bottom, with several high-speed fans at the bottom, to blow cool air into the peas, creating an “air cushion” that levitates them in the air. The peas are then stored in cold storage and packaged. Most vegetables use a similar quick-freezing process.
But one thing needs to be stated here. Leave food in high heat for a few minutes before freezing produce. This step is to inactivate enzymes that damage the texture and color of the food when it is frozen and stored. But it can also destroy the nutritional value of the food.
Extra salt and sugar are added to the cans. “, but this loss of nutrients pales in comparison to the amount of heat used in the processing of canned food. In the production of canned food, the higher the degree of heating, the greater the loss of nutrients. But as with fresh food, the rate at which different nutrients are lost varies from produce to produce.
Contains ingredients mainly for water soluble substances (such as vitamin C and B vitamins) and main food retention of nutrients to fat-soluble substances (such as vitamin A and E) the food is different, as long as the storage time is short, vitamin C content of fresh food is the highest, because the vitamin is sensitive to heat, it is easy to damage. Canned foods rich in vitamin E and A (such as canned carrots and canned tomatoes) perform better in heat treatments, but canned foods may contain unwanted ingredients.
While there’s no need to worry about frozen or canned foods, frozen foods are better because they’re packed with extra salt and sugar. However, canning can improve the safety of foods, especially those that are prone to pathogens.
Sterilization is an advantage of canned foods. This causes a greater loss of nutrients, but once food is canned, it can be stored steadily for many years. Bactericidal treatment will kill all the microorganisms, which can fully ensure its safety.
Fresh fruits and vegetables
Frozen or canned foods can also be used to make a balanced meal, but this is no substitute for the importance of fresh fruits and vegetables. One of the biggest problems during home quarantine is how to retain the nutritional value of fruits and vegetables as much as possible while shopping only once a week.
If we could eat a salad a day and fry a few dishes with frozen or canned food, we wouldn’t have to worry about nutrition. On the contrary, it’s a great way to diversify your diet.
Some experts also recommend buying local and organic produce to ensure the nutritional value of fresh produce as much as possible. Several studies have found that organic crops contain higher levels of phenols, a beneficial compound found in red wine and tea, than conventionally grown crops.
There hasn’t been enough research so we don’t know why this happens, but it could be because organic crops are produced without pesticides. To survive, organic crops produce more phenols, which increase their resistance to insects and disease. But just like buying fresh produce, buying local and organic products isn’t for everyone, especially these days.
Experts also point out that as long as the intake of nutrients is generally adequate, there is no need to limit their sources. Most importantly, be sure to eat plenty of fruits and vegetables, whether it’s frozen, canned or fresh. Fresh, frozen, canned or dried fruits and vegetables can be counted as a daily requirement. Eat all kinds of fruits and vegetables, because there are nutrients in all kinds of fruits and vegetables, and most importantly, never avoid eating them.