The science of freezing foods and its methods
Freezing is a simple and efficient method to preserve vegetables and fruits at home. You can make frozen vegetables and fruits that are of the best quality and highest nutritional value if you do it correctly.
Our guidelines are based on:
Physical and chemical reactions that occur in the freezing process.
The effects of freezing on the tissues of vegetables and fruits.
Food microbiology.
Chemical changes during freezing
Fresh vegetables and fruits once harvested are subject to chemical changes which can lead to degradation and spoilage of the food. This is the reason these items should be frozen as quickly after harvest as is possible and when they are at the peak of maturing.
Fresh produce is a source of chemicals known as enzymes that cause the disappearance of color, loss of nutrients, changes in flavor, and changes in the color of frozen vegetables and fruits. The enzymes have to be reactivated to stop these reactions from occurring.
Blanch vegetables to remove enzymes
Enzymes found in vegetables are deactivated through the process of blanching.
Blanching refers to the exposure of the vegetables to steam or boiling water for a brief time.
Then the veggies must be quickly cooled in ice water, to stop them from burning.
In the majority of instances, blanching is vital to make high-quality frozen vegetables.
Blanching can also help eliminate microorganisms that reside on the surface of vegetables. It also can make certain vegetables, like spinach and broccoli less bulky.
Include ascorbic acid in the fruit to inhibit enzymes
The main issue associated with enzymes found in fruits is the browning and loss of vitamin C.
Since fruits are typically consumed raw, they aren't blanched as vegetables are.
The enzymes found in frozen fruit are controlled with chemical compounds that block degrading chemical reactions.
The most frequently used chemical to control pests is called ascorbic acid (vitamin C). Ascorbic acid is used in its pure form, or in commercial blends with sugars.
The fruit is soaked in vinegar-based solutions dilute in pH or covering the fruit with lemon juice and sugar does not stop browning as efficiently as treatment with ascorbic acid.
Limit the amount of air in freezing temperatures.
Exposure to air can cause frozen food items to develop rancid, oxidative flavors. Store frozen food in airtight containers or wrappers that don't allow air to enter the food. Also, take the most air possible from the bag or container in order to minimize how much air is that comes into contact with the food item.
The texture changes during the process of freezing
Water is more than 90% of the total weight of the majority of vegetables and fruits. Other chemicals and water are held in the solid cell walls, which give an appearance and structure to the fruits or vegetables. When you freeze your fruits and vegetables you're actually freezing water inside the plant cells.
When water is frozen it expands, and the crystals of ice cause cell walls to split. Therefore, the texture of thawed products is much less spongy than it would be if it were fresh. This is especially the case for foods that are usually consumed raw. For instance, when frozen tomatoes are frozen and then removed from the freezer, it turns into mush and liquid.
Celery and salads aren't typically frozen due to this. We suggest you serve frozen foods prior to them being completely been thawed. The fruit that is partially thawed is more delicious because the impact of freezing on the tissue is less obvious.
The changes in texture that result from freezing aren't as evident when food items are prepared prior to eat, as cooking softens the cell wall. The changes are less apparent in high-starch vegetables like peas, corn, and lima beans.
Make sure to freeze food as quickly as is possible
Avoid the mushy appearance of fruits and vegetables by freezing them as soon as is possible.
In the case of rapid freezing, there is a significant amount of tiny ice crystals are created. Small ice crystals cause less cell wall breakage as compared to slow freezing that producing only a handful of large crystals of ice.
Certain manuals for your home freezer suggest setting your temperature of the freezer to the coldest setting a few hours prior to putting food items into the freezer.
Examine your freezer's manual to determine what is where the coldest shelves are within the freezer. It is recommended to place frozen items on the shelves.
Do not overfill the freezer.
Each manual for the freezer provides guidelines on the maximum number of cubic yards of frozen food that is able to be stored in one go. It is typically about 2 to 3 pounds of vegetable to each cubic foot of freezer space 24 hours. If you overfill your freezer with unfrozen items will cause a lengthy slow freezing time and low-quality product.
Changes in temperature due to fluctuating temperatures
Temperature fluctuations in the freezer may cause water vapor to build upon the containers' surface. This is often seen in frozen food items that have been handled improperly.
Refrigerate frozen vegetables and fruits at 0 ° F or less
To ensure the highest quality To ensure that your frozen produce and other vegetables are of the highest quality, they should be kept at temperatures of 0 F or less. A freezer thermometer will aid in determining the true temperatures of the freezer. If your freezer comes with various temperature settings, like between 1 and 9. Check the manual to determine which settings are suitable for various uses.
Storing frozen food in temperatures that are higher than zero F will reduce the shelf life of frozen food items. Do not try to conserve energy at home by increasing the temperature of your frozen stored food over zero F.
Freezer burn
The loss of moisture or the evaporation of ice crystals from the surface of a product causes freeze burn, which is characterized by grainy brown spots that appear where tissues are dry and hard.
These areas can often produce unpleasant tastes.
Specially designed packaging to freeze food items will help prevent the risk of burning in the freezer.
The effects of microbes in the freezer
It doesn't kill microorganisms that might be present in fruits and vegetables.
While blanching can kill some microorganisms, many die in the storage in freezers, enough remain to spoil the product once it has thawed.
Take care to examine any frozen products that were accidentally defrosted due to the freezer's alarm or the door of the freezer not being shut.
The nutritional value of frozen food items is high.
When done properly is able to retain the most nutrients than traditional methods for the preservation of food. To ensure that the nutritional value is maintained in frozen vegetables and fruits it is crucial to follow the directions for the preparation of the veggies, to keep the frozen food at a temperature of 0°F, and use it within the specified storage periods.
Food freezing Answers to questions
Q; What are the advantages and dangers of vacuum-packaging food items for storage?
A: Vacuum packing machines or vacuum sealers can remove air and extend the time for storage of dried, refrigerated, and frozen food items. Vacuum packaging isn't an alternative to processed food items at home or for freezer or refrigerator storage. Vacuum packaging eliminates all air in a container. In this oxygen-free atmosphere, the spoilage bacteria can't increase in size very fast and this helps preserve the freshness of the food item.
Certain harmful bacteria, such as Clostridium botulinum which can cause deadly botulism poisoning only flourish in oxygen-free conditions and, without competition from the spoilage bacteria can grow even more quickly. Contrary to spoilage bacteria and pathogens that cause disease don't alter the appearance or color of food items.
Food items are vacuum-packed and stored in the freezer or refrigerator. Be sure not to cross-contaminate food during the vacuum packing process. Clean hands and cleaned and disinfected equipment and work surfaces are vital. Food that is frozen inside the freezer is essential.
Q: How do I prevent freezer burn?
A: Drying takes place at the top of a frozen item that was not properly wrapped. The food is safe to consume but the quality of the food isn't great. To avoid freezer burn eliminates all air and seal the bag airtight.
Q: How much food is able to be frozen at a time?
A; The best way to freeze is to only store the quantity that can be frozen in 24 hours. This is typically 3 to 4 pounds for each cubic foot that is freezer room. To ensure the highest quality, make sure that the freezer temperature is set at less than 10 ° F at a minimum of 24 hours prior to freezing large quantities of fresh food. After the food is frozen, keep the temperature of minus F at or below. Make use of an appliance thermometer to verify temperatures in your freezer.
Q: Can food spoil if stored longer than the recommended storage time?
A: No. This is a quality issue versus an issue with food safety. The recommended storage time ensures the highest quality. Food that has been stored longer is suitable for consumption, however, there could be variations in flavor as well as texture and color. To ensure the highest quality, you should use frozen vegetables and fruits within 8 to 12 months.
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