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Thursday, September 8, 2011

Freeze Summer Produce

Freezing is one of the easiest and quickest ways to preserve food for later use.  With fresh fruits and vegetables being harvested daily, now is the time to preserve those precious gems of summer for use later during the frosty days of winter.
Whether fruits or vegetables are going to be frozen, some kind of pre-treatment may be necessary to stop enzyme action.  In the case of fruits, enzymes cause browning or discoloration and the loss of vitamin C.  The most common way to stop the enzyme action in fruits is the use of ascorbic acid (vitamin C).  Ascorbic acid may be used in the pure form or in a commercial mixture, such as Fruit-Fresh by Ball®. Be sure to follow the manufacturer’s instructions when using either form.
With vegetables it is necessary to provide a heat treatment or blanching to prevent the loss of flavor and texture destruction.  Blanching is the technique where vegetables are exposed to boiling water or steam for a short period of time and then plunged into ice water to stop the cooking action.  If the ice water step is not used the vegetable will continue to cook causing a loss of flavor, color, and texture as well as nutrients.  Blanching also helps destroy the microorganisms living on the surface of the vegetable.
There are two ways to blanch:  water or steam. Steam blanching takes 1.5 times longer to process than water blanching, but is ideal for broccoli, pumpkin, sweet potatoes, and winter squash. To steam blanch use a pot with a tight fitting lid and basket that holds the food at least three inches above the water. For water blanching use a kettle with a tight fitting lid large enough to hold one gallon of water or a blancher and a basket to hold the vegetables.
Some pointers for freezing fruits and vegetables include: 
§  Select fruits and vegetables that are at their peak of maturity and freshness.
§  Work with small quantities to prevent loss of quality and nutrients.
§  Work under sanitary conditions. 
§  Wash small lots of product at a time with several changes of cold water. Do not soak tender fruits or they will become water logged.
§  If the products cannot be frozen immediately, refrigerate them. 
§  If preparing fruits do not use copper, galvanized, or iron equipment because the acid of the fruit will combine with the metals creating harmful compounds or off-flavors.
§  Be sure the freezer is at 0oF or lower.
§  Do not overload the freezer. A good rule of thumb is to only freeze 2 to 3 pounds of food per cubic foot of freezer space in a 24 hour period.  If the freezer is overloaded, the freezing rate is slowed down allowing for a lesser quality product.
If you need a good food preservation book I have copies of So Easy to Preserve at the MSU Extension office for sale.  Reference:  So Easy to Preserve, by Cooperative Extension/The University of Georgia.