Deep-frozen food is better than its reputation
Frozen food is an integral part of our diet nowadays. Since the pandemic the percentage of Americans who eat frozen food daily or every few days has increased to almost 40%. This includes ready-made meals and bakery products, but also a lot of vegetables, meat and fish.
This is not surprising, because after all, with frozen food you can quickly conjure up a meal without much effort. Vegetables and fruit do not need to be cleaned, washed or chopped. Whether fish, meat or vegetables: In any case, frozen food has a longer shelf life, is easy to portion and facilitates storage. Nevertheless, frozen food has a bad reputation among many people. According to common opinion, freshly purchased goods are basically the better choice, because freezing damages the taste and, above all, valuable ingredients such as vitamins are destroyed by freezing.
Does freezing damage the ingredients?
Food chemists and nutritionists in Hamburg, Germany investigated the latter objection a few years ago. In a complex study, they investigated how the proportion of healthy ingredients in some vegetable species changed under different storage and processing conditions.
For an optimal comparison, different types of vegetables were harvested at the same time from the same field. Then they were cleaned, washed, chopped and finally stored under different storage conditions. This means that half of the vegetables were blanched and then shock-frozen at minus 18 degrees Fahrenheit. The other half was stored in the refrigerator.
The chemists chose vitamin C as their “freshness marker”, which is considered to be extremely sensitive because, like many other vitamins, it rapidly degrades under the influence of heat, light and oxygen.
The results of the study were clear, i. e. the vitamin C content, e. g. of green beans stored in the refrigerator, decreased by around 70 percent within two weeks. Frozen green beans, on the other hand, still had around 80 percent of the original vitamin C content even after one year. Similar results were also observed for peas and carrots.
Furthermore, the scientists also investigated the content of secondary plant substances, which are also believed to have a health-promoting effect. Green beans, for example, have a high content of quercetin and kaempferol, or carrots have a high content of carotenoids and flavonoids, which protect plants from UV radiation, and in the human body the secondary plant substances are supposed to strengthen the immune system and fight against free radicals.
Again, the study showed that, when stored in the refrigerator, the secondary plant substances were degraded by up to half after only two weeks. In frozen state, a large proportion of these substances could be preserved for over four months.
Keep in mind when deep-freezing!
However, the valuable ingredients are only preserved if the food – be it fruit, vegetables, meat or fish – is shock-frozen as soon as possible. Slow freezing creates large, coarse ice crystals that destroy the cells of the frozen food, causing cell fluid to leak out. As a result, ingredients are lost and the taste and consistency suffer.
Over the years, the industry has developed a wide range of freezing processes, from cold air freezing (-40°F – particularly suitable for berries, peas) to cryogenic methods (sprayed with liquid carbon dioxide or nitrogen and temperatures from -108 to -300°F – suitable for meat, fish and bakery products) to contact freezing (-40°F metal plates – e. g. for fish fillets or cream spinach).
Due to the rapid freezing process, the metabolic processes in the cells are almost completely brought to a standstill. At the same time, only small, fine-grained ice crystals are formed which do not harm the frozen food.
Standard household freezers and freezers with shock-freeze function can reach temperatures of up to minus 22 degrees Fahrenheit. The aging process of the cells slows down, but the degradation processes do not stop completely. In other words, they run in slow motion. Therefore, frozen food should in principle not be stored for more than one year.
Keep your eyes open when shopping
While frozen fruits, vegetables, meat and fish can be regarded as healthy, ready-made frozen dishes must be viewed more critically. This is because different foods have a different freezing behavior due to their structure, and the duration of “freezing through” also differs. Therefore, in the laboratory, colorants, flavorings and preservatives as well as flavor enhancers and binders are used to prepare these ready meals in such a way that they still appeal to the consumer after thawing, although they are composed of different ingredients.
What is Metabolic Balance’s position on deep-frozen food?
Metabolic Balance also sees freezing as one of the best ways to preserve food over a longer period of time. Especially when seasonal vegetables and fruits ripen in abundance in the garden, you should make use of it. The low temperatures stop the metabolic processes in the food and thus also the growth of microorganisms. If a few points are observed when freezing, taste and nutrients are also preserved in the home kitchen. In addition, frozen products enable people, who have little time left, to prepare their meals to eat healthily despite the lack of time.
Frozen vegetables sometimes contain even more valuable ingredients than many supposedly fresh products, which in fact often have already been transported a long way.
Useful tips for freezing:
- Spread berries on a tray and freeze briefly to prevent the berries from sticking together. Store the frozen berries in bags or freezer containers in the freezer.
- Clean vegetables, wash, cut into bite-sized pieces, blanch and then chill very quickly, preferably with ice water, to preserve vitamins, then freeze immediately.
- Raw fish should be frozen no later than 24 hours after purchase. Gut fresh fish, clean and freeze briefly, then immerse briefly in cold salt water before final freezing. This gives the fish a protective layer of ice.
- Slice bread, place parchment paper between each slice, wrap and freeze.
- Basically, you can also freeze any home-cooked food or leftovers without hesitation. Pre-cooked food should be cooled down quickly, filled into airtight containers, sealed tightly and frozen quickly.
Be aware! Some cooked foods are not suitable for freezing, such as boiled potatoes, casseroles, sauces – especially if they have been prepared with cream.