Enzymes in fruits can cause browning and loss of vitamin C. Because fruits are
usually served raw and people like their uncooked texture, they aren't blanched
like vegetables. Instead, enzymes in frozen fruits are controlled by using
chemical compounds. The most common compound is ascorbic acid, or vitamin C.
It can be in its pure form or in commercial products such as this Fruit Fresh.
Temporary measures to control browning can be used also. Fruit can be placed in lemon juice,
a citric acid solution (this is citric acid), or packed in a sugar syrup.
However, none of these methods are as effective as using an ascorbic acid solution.
Select fruits of the highest quality and optimum maturity and freshness.
Remember that freezing does not improve the quality of the fruit. Choose fresh, firm,
ripe fruits. Freeze them before they lose freshness. If they can't be frozen,
immediately refrigerate to prevent spoilage. Sort by size, ripeness, and color.
Work in small quantities to avoid loss of quality and nutrients.
Wash and drain all fruits before removing the cores, peeling, or seeding.
So lift the fruit out of the water to keep the dirt from redepositing on the fruit,
and don't let the fruits soak in the water.
Also, don't use copper, galvanized, or iron equipment. The acid in the fruit can
react with metal and cause harmful compounds or "off" flavors.
There are several ways to pack fruits for freezing -- in a syrup pack, sugar pack,
dry pack, or unsweetened pack. Most fruits have a better flavor and texture when
packed in sugar or syrup, but it isn't necessary to use sugar for preservation.
If you're watching your sugar intake, it can be left out. In fact, artificial
sweeteners can be used as well. The way the fruit is packed is dependent on the
intended use. Fruits packed in syrup are usually best for uncooked desserts.
Those packed unsweetened or in dry sugar are best for most cooking purposes
because there is less liquid in the product. As I demonstrate specific steps
for packing fruit, I'll cover some basic information about the different types of packs.
So when using a syrup pack the proportion of sugar to water depends on
the sweetness of the fruit to be frozen. A heavy syrup is recommended for most
fruits and a lighter syrup may be appropriate for mild-flavored fruits
to prevent masking of flavors. When making all types of syrup, you'll start with
4 cups of lukewarm water, as I have here. For a light syrup you'll add 1 cup of sugar,
and stir well until the sugar is dissolved.
This is the consistency of a light syrup.
It's not much different from just the way the water looks when it rolls off the spoon.
When making a medium syrup, you'll use 2 cups of sugar for
every cup 4 cups of water. Since I already have 1 cup in my water,
I'll add another cup of sugar here,
again stirring well to make sure that the sugar is dissolved. This is a medium syrup.
And here is the consistency.
It's a little bit thicker than what we have in the light syrup. You can see -- from where
I'm standing you can see it kind of coats the spoon. So that's a medium syrup.
And, actually, when you're stirring it you can actually see that it has more body
than the light syrup. When you want to use a heavy syrup that's 3 cups of
sugar for every 4 cups of water, so I'll add 1 more cup to my medium syrup.
Again, you'll want to stir to make sure that all the sugar is dissolved.
This water now has taken on a nice heaviness, a good body.
That syrup coats the spoon even more so than the light syrup did.
So that's the heavy syrup. We'll want to chill this before packing our fruit.
I've put that in the refrigerator to chill. Because warm water was used, the syrup
will need to cool before packing the product. Warm water freezes slower and
deteriorates the product. So I'll let that cool and be back to finish the process.
Dry packs for small fruits, such as berries, give a good-quality product
without added sugar. Simply pack the fruit into the container.
We'll use a rigid container here.
And you'll want to leave 1/2 inch headspace.
Put on the lid and freeze. A tray pack can be used for any type of berry.
This is an alternative that may make the fruit easier to remove from the container.
Simply spread a single layer of berries on a cookie sheet or shallow
tray and freeze. When frozen, transfer into a container and return to the freezer.
The fruit pieces remain frozen individually and can be poured from the container.
Be sure to pack immediately after freezing to avoid freezer burn.
We'll use this heavy syrup to pack the rhubarb.
Now this rhubarb has already been cleaned and chopped. You can pack the
fruit in a container of your choice. Here I'm using a 1-pint canning and freezing jar.
For 1-pint wide-mouth jars, leave 1/2 inch of headspace,
and then add just enough of this cold syrup to cover the fruit.
This will be about 1/2 to 3/4 cup of syrup per pint. Now, to keep the fruit under the syrup
if the fruit has a tendency to float, you may place a small piece of crumpled
parchment paper on top and press the fruit down into the syrup before sealing the container.
This is an option. We don't need to use the parchment paper
with this rhubarb so I'll not use this.
The reason that we use that parchment paper is that fruit that's exposed to
air deteriorates faster, so the parchment paper will keep the fruit under the syrup.
Now for containers with wide-mouth openings like I have here, we use
1/2 inch headspace for pint containers and 1-inch headspace for quart containers.
For containers with narrow top openings, leave 3/4 inch headspace
for pints and 1 and 1/2 inch headspace for quarts.
This rhubarb is sealed and ready to freeze.
I'm using strawberries to demonstrate using a sugar pack for freezing fruit.
These strawberries have been cleaned and the stems removed.
Slice the strawberries and place them in a container of your choice.
Then you'll want to sprinkle sugar over the fruit -- just enough to make the fruit white.
Now, for hard fruits such as apples, you may need to stir these gently
for the sugar to dissolve. However, for soft, sliced fruits, such as peaches,
these strawberries, figs, plums, and cherries, you'll just allow them to set for 15 minutes.
I've prepared some strawberries ahead of time to demonstrate
how the sliced fruit makes its own juice. You'll notice the nice
syrup that we have here, and, in fact, you may be able to see some of the sugar
that has yet to dissolve and is sitting on top of the strawberries, and that's OK.
So after your fruit has set and made its own juice, you can transfer it
to a container of your choice. However this is a freezer container so using 1/2
inch of recommended headspace. I'm ready to seal and freeze.
In an unsweetened pack, the fruit is packed in water or unsweetened juice.
Products preserved in unsweetened packs usually don't have the plump texture
and the good color of those packed in sugar.
Sugar substitutes work well in unsweetened packs.
They produce a sweet flavor, but they don't furnish the beneficial effects of sugar,
such as color protection and thickness of syrup. Labels on these commercial
products give the equivalents to a standard amount of sugar, so use these
directions to determine the amount of artificial sweetener to be added to your product.
Another consideration in preparing fruits for freezing is preventing discoloration.
Some fruits, such as peaches, apples, pears, and bananas, darken quickly
when exposed to air and during freezing. They may also lose flavor when thawed.
There are several ways to prevent darkening of fruit and flavor loss.
Ascorbic acid, or vitamin C, is effective in preventing discoloration in most fruits.
Ascorbic acid in powdered form is available at grocery stores and some
drug stores. Ascorbic acid tablets may be used but are more difficult to dissolve.
They must be finely crushed before adding to water. Fillers in the tablets
may also make the water cloudy, but it's not harmful. 1/2 teaspoon of
powdered ascorbic acid is equal to 1,500 milligrams. So when using ascorbic acid
in a syrup or liquid pack, you'll add 1/2 teaspoon of powdered or crushed ascorbic
acid to 2 cups of cold syrup shortly before using. This is the heavy
syrup we prepared earlier for the rhubarb pack. I'll sprinkle 1/2 teaspoon
into 2 cups, and then just stir this gently -- you don't want to stir in any air.
Let it dissolve and then refrigerate the syrup until you are ready to use it.
In sugar or dry packs, you'll dissolve 1/2 teaspoon of ascorbic acid
in 3 tablespoons of cold water. I have 3 tablespoons of cold water here.
I'll add to that the 1/2 teaspoon of ascorbic acid,
and, again, mixing that until all of the powder is dissolved.
And then once it's dissolved, you'll sprinkle the mixture over the fruit
just before adding the sugar. I've prepared some apple slices
to demonstrate how the ascorbic acid does, in fact, keep these types of fruits
from darkening. These have the ascorbic acid and these are just sliced apples
that have been sitting out at room temperature.
You'll notice that the ascorbic acid does give you a much nicer product.
In addition to the ascorbic acid, there are commercial products, and these are
designed to prevent discoloration and can be used in freezing. You'll want to
always follow manufacturer's instructions when working with any of these types of mixtures.
Here are the strawberries and the rhubarb that were prepared earlier.
Before freezing, make sure you label the bags or containers using a waterproof marker.
List the name of the product, the amount of the product, whether it's in
cups, ounces, or pounds, and the date it was processed. Place these packages in
the freezer. Arrange them loosely or in a single layer so they freeze quickly.
Home-frozen products have a storage time of 8 to 12 months when properly packaged
and stored at zero degrees Fahrenheit. After this time, the food should still be
safe, yet the quality may be affected. Freezing is a safe method to preserve
any food. It is one of the easiest, most convenient, and least time-consuming
methods of food preservation. Remember that if no home canning recommendations
exist for a particular product, freezing is always a safe option. Follow the
directions in this module to enjoy high-quality, nutritious foods at any time of the year.