freezing is a preservation method fast, effective and easy to implement in which the food industry has found a good way to preserve the qualities of the vegetable since it is collected until it reaches the homes of consumers. But are fresh vegetables and frozen vegetables equally healthy? Do they have the same nutritional quality?
Freezing and preserving nutrients
In general, it can be said that the freshly picked vegetables in the garden is healthier and provides more nutrients than frozen vegetables. What happens is that some nutrients begin to degrade from the moment they are harvested and, as vegetables are often transported over long distances, the length of time that elapses until they reach the consumer can mean that Significant amounts of some nutrients are lost.
Frozen vegetables are subjected to a drop in temperature until its main component, water, becomes solid. This decrease in temperature makes it possible to preserve its microbiological quality, preventing microorganisms from reproducing, while the chemical reactions that deteriorate the food are stopped or slowed down and causing it to lose nutrients. For example, the oxidative reactions that cause, among others, the loss of ascorbic acid (vitamin C) become very slow.
In other words, freezing vegetables extends their shelf life and preserves their nutritional properties. In addition, in many cases the organoleptic properties (taste, color and smell) are not altered either, all without using any type of chemical additive. These characteristics make freezing a very good preservation method. To ensure that the greatest possible amount of nutrients are preserved, freezing must be done quickly after harvesting, with the method of choice being frozen.
Vegetables to be frozen are often subjected to scalding. Blanching consists of immersing the vegetables in boiling water for a short period of time. The goal is to improve conservation by inactivate some enzymes that contribute to the deterioration of the vegetable. During blanching, small amounts of some thermolabile vitamins, such as vitamin C or some B vitamins, can be lost, despite this, frozen vegetables can maintain a high nutritional value for a long period of time.
If frozen vegetables are compared with fresh vegetables, on many occasions frozen vegetables provide more nutrients than fresh, depending on the time elapsed since collection. For example, it is easy for frozen spinach to provide more nutrients than fresh spinach since it loses 100% of its vitamin C content in four days.1 and 50% folate in eight daystwo. Both frozen and fresh, it preserves the content of vitamin A (carotenoids) well until the average moment of consumption1.
The same happens with animal foods, from the moment of slaughter a deterioration begins that can be slowed down by freezing. These considerations do not mean that all frozen food is healthy. For example, could not be applied to frozen processed frozen foods, whose nutrient content will be determined more by the ingredients, processing and additives used than by the fact of being frozen or not. Nor does it mean that you have to opt for frozen vegetables to the detriment of fresh vegetables, but rather that you have to take into account that fresh vegetables should be consumed in a short time and that frozen vegetables are a healthy option that allows you to have vegetables at any time. , both in season and out of season and at a good price.
Preserve the properties of frozen vegetables
Some factors can cause freezing to lose its nutrient-preserving effect. Some of the most important are:
- Cold chain: frozen vegetables must be kept constantly in a certain temperature range. In other words, the cold chain must not be broken. If the vegetable thaws, it is better to consume it soon so that it does not lose its properties. Do not refreeze.
- Preferential consumption date: Freezing slows deterioration but does not stop all reactions completely. Therefore, it is not an eternal conservation method. The preferred consumption date depends on the freezing temperature. Below 18ºC, frozen vegetables can be consumed for up to 12 months.
- Cook without defrosting: to guarantee the maximum supply of nutrients, it is recommended to cook frozen vegetables directly from the freezer. If it is going to be cooked, better with little water, preferably steamed.