Freezing Herbs (Biology Experiments)

Certain herbs, such as parsley, chervil and chives are preserved better by freezing than by drying. The secret is to package them so that you may keep air out and moisture in.
Things Required:
A bunch of herbs (parsley, basil, dill, sage, thyme or chives)
Thick small plastic bags, jars or freezer containers
Paper towels
Labels and felt-tipped pen
Drinking straw (optional)

Wash the herbs in cold water and remove any leaves that are rotting. Drain and pat them dry with paper towels.
Strip the leafy herbs from their stems. Package the leaves in small plastic bags leaving 1/2 inch of headroom. You can use a drinking straw to remove as much air as possible. Or making sure that no water enters the bag, you can dip it in a pot of water. This pushes the plastic against the food, forcing out all the air.

Seal the bag tightly, using freezer tape if the bags are not self-sealing. Label each one with the name of the herb and the date, and place the bags in the freezer, preferably at 0°F (-18°C).
This Is What Happens:
At that low temperature, herbs last up to a year and maintain flavour, colour and nutrients. You can add them to soups, stews, sauces, salads and other foods while they’re still frozen.
Science Behind It:
Enzymes, protein molecules that speed chemical reactions, harm foods by changing their colour, texture, taste and nutritional value. Like heating, freezing slows down active enzymes and delays the spoiling process.
You remove the air because air pockets between the food and the plastic bag collect moisture from the food, which results in frost and freezer burns. As ice crystals form, the water expands and ruptures cell membranes and walls.
Because food expands during freezing, you don’t fill the bag completely. The bag or other container will split if it’s too full for the contents to expand freely.
If the freezer temperature is higher than 0°F (-18°C), the herbs will not keep their flavour as long. Each 10°F (-12°C) above zero cuts the storage life in half.
You can substitute frozen herbs for fresh in recipes, but remember to use them while they’re still frozen. If you let them thaw, microbes and enzymes have time to wilt and darken them.

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