Freezing fruits and vegetables at home

Freezing Fruits and Vegetables at Home Cooperative Extension Service The University of Georgia College of Family and Consumer Sciences Advantages of Freezing  Many foods can be frozen  Good natural color, flavor and nutritive value can be retained  Texture usually better than for other methods of food preservation  But this is personal preference  Foods can be frozen in less time than they can be dried or canned Advantages of Freezing  Simple procedures  Adds convenience to food preparation  Proportions can be adapted to needs unlike other methods  Kitchen remains somewhat cool and comfortable Disadvantages of Freezing Foods  Texture of some foods is undesirable because of changes due to the freezing process  Initial investment and cost of maintaining a freezer is high  Storage space is limited by how much the freezer will hold How Freezing Affects Food Enzymes in Vegetables and Fruits  To prevent color and flavor changes, as well as loss of some nutrients, enzymes should be controlled  Are slowed down but not destroyed during freezing (Enzymes are small proteins in foods that start or help with reactions, such as those that cause browning, off-flavors, mushiness, etc.) How Freezing Affects Food  Enzymes in Vegetables  Are destroyed by heat, called blanching, before packaging and freezing  Enzymes in Fruits Usually controlled by ascorbic acid (also called vitamin C) or some other additives  Fruits are usually not blanched, but can be   People like them raw and uncooked How Freezing Affects Food Rancidity  Another natural change that causes off- flavors, particularly in fatty foods  Not a common problem in fruits & veggies  Will continue to happen at freezer temperatures, but slower than at warmer temps  Best control is to keep as much air out of the package as possible How Freezing Affects Food  Textural Changes  The water in food freezes and expands  Ice crystals cause the cell walls of fruits and vegetables to rupture, making them softer when thawed  Some vegetables with very high water content not freeze well: celery, lettuce, some tomatoes How Freezing Affects Food Rate of Freezing is Very Important Freeze Foods Quickly! Best Advice for Freezing  Freeze foods quickly  Set freezer temperature at -10o F at least 24 hours ahead of freezing large quantities of fresh food  Spread packages out around the freezer, until frozen, then stack  Hold at 0oF for best quality 10 How to Blanch Vegetables  In Boiling Water Use blancher with lid or a kettle with basket and lid  Have gallon water per lb of vegetables  Place vegetables in blanching basket  Lower vegetable into vigorously boiling water Put lid on Water should hardly stop boiling or return to a boil within a minute  If water keeps boiling, begin timing immediately Otherwise, wait for water to come back to a boil  51 How to Blanch Vegetables  Steam Blanching Use kettle with tight lid and basket  1” to 2” of boiling water in bottom of pan  Vegetable should be in a single layer in basket  Start timing when covered   Takes 1-1/2 times longer than water blanching Check times, however, for each food 52 How to Blanch Vegetables  Microwave Blanching  Not widely recommended at this time  May not be effective – enzymes not inactivated completely by uneven heating  Usually does not save time  Have  to very small quantities If you have directions from a source you trust, try small quantities at first and see if you like the quality after a period of frozen storage  This is not a safety issue, as long as frozen food is always stored frozen, but improper blanching will affect quality 53 How to Blanch Vegetables  After blanching in water or steam, cool immediately in cold water  Change water frequently or use running water or iced water (1 lb ice per lb vegetable)  Cooling time should be the same as the blanching time  Drain thoroughly 54 Types of Pack for Vegetables  Dry Pack  Pack after the vegetables are blanched, cooled, and drained  Pack quickly, pushing air out of package as you work towards top 55 Types of Pack for Vegetables  Tray Pack  After draining, spread pieces in a single layer on a shallow pan  Freeze firm  After first hour, check often  Package quickly, pushing air out as you work 56 Thawing Foods for Serving  Fruits Best if served with ice crystals  Thaw:   In refrigerator - to hours per pound of fruit in syrup  At room temperature - to hours per pound  At room temperature in cool water - ½ to hour per pound  In microwave oven - follow manufacturer’s instructions 57 Thawing Foods for Serving  Dry sugar packs thaw faster than syrup packs  Unsweetened packs thaw the slowest  When used in recipes, allow for added sugar and more juice 58 Thawing Foods for Serving  Vegetables  Cook without thawing  Corn-on-the-cob should be partially thawed so cob will be hot  Leafy greens cook more evenly if partially thawed 59 Oh No! You’ve done all this work … and the freezer stops running! 60 Freezer Emergencies  If know power will be off, set freezer controls on -10oF to -20oF immediately  Do NOT open the door  Foods stay frozen longer if freezer is full, well-insulated and in cool area Full freezer - keeps to days  Half-full freezer - 24 hours  61 Freezer Emergencies  If power interruption will be longer than to days:  Use dry ice:  50 lbs - keeps full 20 cubic foot freezer below freezing for to days  50 lbs - keeps half-full freezer for to days 62 Freezer Emergencies  Place dry ice on boards or heavy cardboard on top of food  Do not touch dry ice to skin  Do not open freezer  Room should be ventilated 63 Refreezing Thawed Foods  Texture will not be as good  General Rule:  Refreeze if freezer temperature is still 40oF or below OR if ice crystals are still present in the food 64 Disclaimer and Credits  Disclaimer:  Trade and brand names are used only for information The Cooperative Extension Service, University of Georgia College of Agricultural & Environmental Sciences and College of Family & Consumer Sciences, and the U.S Department of Agriculture not guarantee nor warrant published standards on any product mentioned; neither does the use of a trade or brand name imply approval of any product to the exclusion of others which may also be suitable  Document Use:    Permission is granted to reproduce these materials in whole or in part for educational purposes only (not for profit beyond the cost of reproduction) provided the author and the University of Georgia receive acknowledgment and this notice is included: Reprinted (or Adapted) with permission of the University of Georgia Andress, E.L 2003 Freezing fruits and vegetables at home (slides) Athens, GA: The University of Georgia, Cooperative Extension Service This material is based upon work supported by the Cooperative State Research, Education, and Extension Service, U.S Department of Agriculture, under Agreement No 00-51110-9762 65 [...]... Preparation Work under sanitary conditions  Follow recommended procedures  22 Packaging Materials Good Qualities  Moisture-vapor resistant  Prevents transfer of moisture and air in and out of the package  Durable and leak-proof  Does not become brittle and crack at low temperatures  Resistant to oil, grease or water  Protects foods from absorption of “off” flavors or odors  Easy to seal and. .. disconnecting  Door locks  Drains for defrosting 20 Location and Placement of Freezer  Place in convenient, cool, dry, well- ventilated area  Do not place by stove, range, water heater or in the sun  Do not push flush against wall Leave space for air circulation and cleaning  Be sure freezer is level 21 General Freezing Instructions  Selection of Food  Freezing does not improve quality  Choose highest... frozen foods inventory up to date 10 Check thermometer periodically 31 Freezing Fruits  Frozen in many forms – Whole, sliced, crushed, juiced  Best quality –  Optimum maturity and freshness  Immature or overripe both produce lower quality when frozen  Wash and work with small amounts at a time to preserve best quality  32 Preventing Fruit Darkening During Preparation (Peeling, slicing, etc.)... sealing area will freeze, expand, and loosen seal 28 Labels  Name of product  Added ingredients 9/15/02 Ground Beef 1 pound  Form of food - halves, whole, ground, etc  Packaging date  Number of servings or amount 29 Freezing Guidelines 1 Freeze foods at 0oF or lower  24 hours in advance of freezing large quantities of food, set freezer at -10oF or lower 2 Freeze foods immediately after prep 3 Do not... more floor space  More economical to buy and to operate than upright  Loses less cold air when opened 18 Types of Freezers  Refrigerator - Freezer Combination 2 to 6 cubic feet of freezer space  Freezer may be above, below or beside refrigerated area  Be sure temperature in freezer can be maintained at 0 degrees F or less  19 Types of Freezers  Other features to consider  Self defrosting or manual... Advice for Freezing What happens when the freezer is above 0oF ? 11 Best Advice for Freezing What happens when the freezer is above 0oF ?  Shelf life (storage time) for best quality is shorter 12 Vegetable Storage For same final quality: Temperature 0o F 5o F 10o F 15o F 20o F 25o F 30o F Length of Storage 1 year 6 months 3 months 6 weeks 3 weeks 10 days 5 days 13 How Freezing Affects Food  Fluctuating... before freezing  Ice water bath after blanching  Pack in serving size quantities  Usually up to 1 quart  Especially when whole package must be thawed to get out what is needed 26 Packing Foods to be Frozen  Pack foods tightly –  Avoid trapped air (oxygen)  Not to waste space  However, most foods need headspace or room for some expansion at the top, except     uneven vegetables like broccoli and. .. Temperatures  Ice in food thaws a little and then re-freezes  Ice crystals get bigger each time  Mushiness because large ice crystal growth damages cells more and more  Moisture pulled from product  Other quality losses speeded up due to higher temperatures  Moisture Loss  Freezer burn – tough and dry, but safe 14 Freezer Selection  Consider  Size  Shape  Efficiency  Defrosting features... well 34 Preventing Discoloration During Freezing  Ascorbic Acid  Use  amount specified for each fruit In syrup or liquid packs - add powdered ascorbic acid to the covering liquid  Usually ½ tsp (1500 mg) per quart of syrup 35 Preventing Discoloration During Freezing  Ascorbic Acid (con’t)  In sugar or dry packs, dissolve the powdered ascorbic acid in 3 T in cold water and sprinkle over fruit ... label 23 Types of Packaging Materials  Rigid Containers  Plastic freezer containers  Wide-mouth canning /freezing jars  Good for liquids or soft, juicy, or liquid-packed foods  May be reusable  Hold their shape and can be stored upright 24 Types of Packaging Materials  Non-Rigid Containers  Bags  Wrappings – plastic (such as polyethylene), heavy-duty aluminum foil, laminated paper  Good for firm, ... lettuce, some tomatoes How Freezing Affects Food Rate of Freezing is Very Important Freeze Foods Quickly! Best Advice for Freezing  Freeze foods quickly  Set freezer temperature at -10o F at least... water in food freezes and expands  Ice crystals cause the cell walls of fruits and vegetables to rupture, making them softer when thawed  Some vegetables with very high water content not freeze... People like them raw and uncooked How Freezing Affects Food Rancidity  Another natural change that causes off- flavors, particularly in fatty foods  Not a common problem in fruits & veggies 