If you’re seeking an efficient way to maintain fresh vegetables‘ goodness year-round, freezing is the ideal solution. Freezing is a widely adopted preservation technique, especially suitable for vegetables that retain their qualities even after being frozen.
Apart from providing access to seasonal varieties at any time, freezing ensures that vegetables’ color, texture, flavor, and most of their nutritional value are preserved.
Selecting fresh vegetables
For optimal outcomes, it’s best to choose high-quality, fresh, and ripe vegetables. Freezing should occur immediately after harvesting or purchasing the vegetables, although they can be stored in the refrigerator before freezing.
Keep in mind that freezing doesn’t halt food deterioration but slows it down. This also applies to enzymatic activity responsible for unpleasant flavors, color loss, and nutrient depletion in vegetables. Consequently, it’s advisable to blanch the vegetables before freezing to deactivate the enzymes and preserve the vegetables at their best.
Blanching: the key to optimal freezing
Vegetables that are properly blanched and carefully frozen will retain a nutritional value comparable to that of fresh vegetables subjected to cooking. However, it’s essential to note that some vegetables with high acidity levels can be frozen without blanching.
When freezing vegetables, there is a risk of dehydration due to the dry air in the freezer. To prevent this, using airtight containers that seal perfectly is crucial.
Blanching involves immersing raw vegetables in boiling water for a specific duration depending on the nature and size of the vegetables. After blanching, the vegetables should be cooled and drained.
It’s vital to adhere to the blanching times as insufficient time can lead to rapid deterioration, while excessive time may overcook the vegetables and result in the loss of benefits associated with water cooking. Hence, calculating the blanching time carefully and cooling the vegetables rapidly is crucial.
Tips for efficient freezing
To properly blanch vegetables, follow these steps:
Blanching: Steps to follow
- Prepare boiling water: Bring 4 liters of water to a boil for approximately 500 g of vegetables or 8 liters for 500 g of leafy vegetables.
- Place the vegetables in the basket: Arrange the vegetables in a metal basket or on a cloth for easy and quick removal from the boiling water.
- Blanch the vegetables: Immerse the vegetables in the boiling water, cover the container, and start counting the blanching time. Ensure that the water quickly returns to a boil.
- Rapidly cool the vegetables: After the blanching time, cool the vegetables by immediately immersing them in very cold water (10°C) and let them soak for only the required cooling time. Avoid leaving them in the water unnecessarily.
- Drain and package: Drain the vegetables and place them in freezer bags, removing as much air as possible. Label the bag with the name of the vegetable, quantity, and freezing date.
Fast freezing is essential to preserve the quality of vegetables. Since vegetables contain a significant amount of water, slow freezing can lead to the formation of large crystals that damage cells, compromising texture and causing nutrient loss.
To avoid this, avoid overloading the freezer with excessive quantities of products to be frozen simultaneously. Freeze only the amount that can be frozen within 24 hours, such as 1-1.5 kg/2,2 lb if the freezer capacity is 27 liters/7,13 gal. Smaller portions freeze more rapidly, ensuring better quality.
To achieve optimal preservation, maintain a constant temperature of around -18°C/-0,4 °F in the freezer. At this temperature, vegetables can be stored for approximately a year while maintaining excellent quality.
Thawing and Jar Storage
Thawing frozen vegetables
Most frozen vegetables can be cooked directly without fully thawing. Complete thawing may result in flavor and nutrient loss. To thaw the vegetables, leave them in their sealed packaging at room temperature or in the refrigerator.
Bear in mind that thawing time will be longer if you choose the refrigerator method. Once thawed, you can cook them by immersing them in boiling water, covering the container, and bringing it back to a boil before reducing the heat. The cooking time will be shorter than with fresh vegetables, as frozen vegetables have already undergone partial cooking during blanching.
Storing vegetables in jars
Jar storage is an older method compared to freezing but still widely used. Despite the popularity of frozen foods, the consumption of canned vegetables remains high.
However, it’s important to note that the nutritional value of canned vegetables may be slightly lower or similar to that of fresh or frozen vegetables, and the loss of vitamins and minerals may be even greater if the preserving liquid is discarded (a common practice).
Canned vegetables may contain additives such as EDTA, calcium gluconate, calcium salts, and citric acid, which help preserve the color, texture, flavor, and prolong preservation. When purchasing canned vegetables, ensure never to select swollen or damaged cans, as the contents may be altered and potentially dangerous.
Carefully read the labels of canned products to know the ingredients and recommended storage methods. By following the instructions correctly, you can enjoy high-quality jarred vegetables and maintain their nutritional value over time.
Food safety vegetables
When dealing with canned vegetables, food safety is of utmost importance. It’s essential to pay attention to the quality and safety of canned goods to avoid health risks. Here are some crucial tips to bear in mind:
Check the can and discard damaged ones
Upon opening a canned item, immediately check its condition. If the content is leaking, the liquid splatters, there are signs of foam, or you detect a smell of fermentation, mold, or sulfur, it’s best to discard the can without even tasting its contents.
Unpleasant appearance or odor may indicate content deterioration and potential health risks.
Pressure cooking for homemade preserves
If you wish to prepare homemade canned vegetables, it’s important to use an appropriate sterilization technique. Low-acid vegetables can become toxic if only sterilized in a boiling water bath. The botulinum toxin, in particular, develops in low-acid environments.
To deactivate this toxin and ensure food safety, pressure cooking at a temperature of approximately 120°C/248 °F is necessary.
An autoclave or a specific pressure cooking device is indispensable for this purpose. However, tomatoes, thanks to their acidity, can be safely sterilized in boiling water, unlike other vegetables that require pressure cooking.
Additives and preserving liquid
However, it’s important to note that the loss of vitamins and minerals in canned vegetables is greater compared to fresh or frozen vegetables. Therefore, avoid discarding the preserving liquid, as it contains vitamins and minerals from the vegetables themselves.
By carefully following these precautions and using proper preparation and preservation techniques, both freezing and jar storage can be effective methods to maintain the quality and safety of vegetables.
Choosing healthy and safe foods is essential to ensure a balanced and enjoyable diet.