Michigan State University Extension
Preserving Food Safely - 01600506
10/13/97

### CONTAINERS FOR FREEZING

     Proper  packaging for freezing is important to  keep  food

    from
    drying out and to preserve  food value,  flavor,  color

    and
     pleasing texture.

     All  containers should be easy to seal and  waterproof  so

    they
    will not leak.  Packaging materials must be durable and

    must
     not  become so brittle at low temperatures  that  they

    crack.

     To  retain  highest  quality  in  frozen  food,  packaging

    materials
      should  be  moisture-vapor-proof    to   prevent

    evaporation.
     Many of the packaging materials on the  market

    for
     frozen  food  are  not  moisture-vapor-proof,  but  are

    sufficiently
    moisture-vapor-resistant to retain satisfactory

    quality
     of  fruits and vegetables during  storage.   Glass,

    and
      rigid  plastic are examples  of   moisture-vapor-proof

    packaging
    materials.   Most bags,  wrapping  materials,  and

    waxed
     cartons  made especially for freezing  are  moisture-

    vapor-resistant.
       Unsuitable containers include   ordinary

    waxed
     paper,  and  paper  cartons  from cottage cheese, ice

    cream,
    and milk.

     Rigid   containers.    Rigid containers  made  of   glass,

    plastic,
     tin,  or  heavily waxed cardboard are suitable for

    all
     packs,  and especially good for liquid  packs.    Glass

    canning
     jars  may  be used for  freezing  most  fruits  and

    vegetables
     except those packed in water.

     Nonrigid  containers.  Bags and sheets of  moisture-vapor-

    resistant
         cellophane,     heavy     aluminum      foil,

    polyethylene,
     or  laminated  papers are suitable  for  dry-

    packed
    vegetables  and  fruits.   Bags also can be used  for

    liquid
    packs.

     Bags  and sheets are used with or without outer  cardboard

    cartons
      to  protect  against  tearing.   Bags  without   a

    protective
    carton are difficult to stack.  The sheets may be

    used
      for  wrapping  such  foods  as   corn-on-the-cob   or

    asparagus.
     Some of the sheets may be heat-sealed to make  a

    bag
     of the size you need.  Sheets that are heat-sealing  on

    both
    sides may be used as outer wraps for folding paperboard

    cartons.

     Size

     Select a  size  that  will hold  only enough of a fruit or

    vegetable
    for one meal for your household.

     Shape

     Rigid  containers that are flat on  both  top  and  bottom

    stack
    well in a  freezer.  Round  containers and  those with

    flared
     sides  or  raised  bottoms  waste   freezer   space.

    Nonrigid
    containers that bulge also waste freezer space.

     Food  can  be removed easily, before it  is  thawed,  from

    containers
     with sides that are straight from bottom to  top

    or
     that flare out.  However, food must be partially  thawed

    before
     it  can  be removed from  containers  with  openings

    narrower
    than the body of the container.

     Bags,  sheets   and  folding paperboard  cartons  take  up

    little
     room when not in use.  Rigid containers with  flared

    sides
    will stack one inside the other and save space in your

    cupboard
     when  not in use.  Those with  straight  sides  or

    narrow
    top openings cannot be nested.

     Sealing

     Care  in  sealing  is  as  important as  using  the  right

    container.
     Rigid containers usually  are  sealed  either by

    pressing
     on  or  screwing   on   the   lid.    Some   rigid

    cardboard
     cartons need to  have  freezer tape  or   special

    wax
     applied  after sealing  to  make   them  airtight   and

    leakproof.
       Glass   jars  must  be  sealed   with   a  lid

    containing
     composition  rubber or with a lid and  a  rubber

    ring.

     Most bags used for packaging can be heat-sealed or  sealed

    by
    twisting and folding back the top of the bag and securing

    with
     a  string, a good quality rubber or plastic  band,  or

    other
     sealing device available on the market.

     Reuse

     Glass   and  rigid  plastic   containers  can  be   reused

    indefinitely.
     It is difficult to reuse aluminum foil boxes,

    because
     edges  of lids and containers are  folded  over  in

    sealing.

     Reuse of rigid cardboard cartons, unless plastic-lined, is

    not
     generally  advisable  because  cleaning  is  difficult.

    Folding
    paperboard cartons used to protect an inner bag  can

    be
    reused.

     Cost

     When you  compare  prices  of the containers  available in

    your
    locality, consider whether they   will  be reusable  or

    not.
     If containers are reusable, a higher  initial cost may

    be
    a savings in the long run.

     Care of packaging materials

     Protect packaging materials from  dust  and insects.  Keep

    bags
     and  rolls  of  wrapping  materials  that  may  become

    brittle,
    such as cellophane, in a place that is cool and not

    too
    dry.

     Freezing accessories

     Check  on  other  items  that  help make packaging easier.

    Some
     containers are easier to  fill if you use a  stand and

    funnel.
     Special sealing irons available  on  the market for

    heat-sealing
     bags,  wrappers,  and  some  types  of   paper

    cartons.
     With some sealing  irons,  a  small  wooden  block

    or
     box   makes sealing of  bags  easier  and quicker.

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