Dairy Ingredients for Food Processing

Principles of Cheese Technology 259

gas fl ush. The Hayssen RT horizontal system

employs the form - fi ll - seal method, using a

single web of a lamination containing poly-

ester and nylon with polyethylene as the heat

sealant (Brody, 2008 ). Cheese in sliced or

block form is delivered to the machine, which

conveys it to the continuous fl ow wrapper,

forming a long tube around the contents.

Inert gas fl ows in to displace the air and a

long back seam is accomplished. Transverse

seams are formed between individual cheese

units.

Another system (Multivac) involves the

use of a twin web horizontal thermoform - fi ll -

vacuum - gas fl ush system. The gas barrier

base consists of thermoformable fi lm com-

prised of nylon coated with polyvinylidene

chloride (PVDC). This base fi lm is heated

and thermoformed in line, creating cavities

into which cheese chunks and slices are

deposited. Simultaneously, a top web of fl ex-

ible material is placed on the opening and

sealed partially onto the base of the web

fl anges. The top closure material is made of

polyester coated with PVDC and the sealant

is comprised of polyethylene. Next, the

cavity is evacuated and if desired, gas fl ushed.

The packaging material assumes a collapsed

appearance, is given a fi nal seal, and indi-

vidual packages are separated apart from

each other.

Soft Cheese Packaging

Soft cheeses are normally pumped into ther-

moformed polystyrene or injection - molded

polypropylene cups or tubs. The container is

then closed with a combination of aluminum

foil heat sealed to the fl ange or friction fi t

thermoform, with or without a tamper -

resistant ring around the rim (Brody, 2008 ).

In certain soft cheeses, the product is pumped

into molds and then cut to be overwrapped.

Alternatively, the soft cheese is pumped hot

into aluminum foil overwraps. Hot packag-

ing tends to reduce the microbial load.

Another technique for packaging soft cheese

acid. Accordingly, packages start out loose
but become skintight a few days after pack-
aging. The materials generally provide good
moisture and gas barrier properties to give
excellent shelf life to cheese. The available
roll - stock form - fi ll - seal machinery is fast,
versatile, and capable of accommodating a
variety of cheese shapes and sizes. One gas
fl ush packaging machine uses roll - stock
materials that are formed into bags around
the cheese, evacuated, gas fl ushed, and heat
sealed.
The thermoformed cavity method uses
reel - fed deep draw materials converted into
pouches that are fi lled with cheese, evacu-
ated, and heat sealed with an additional layer
of plastic fi lm that acts as a lid. Shrink fi lm
is not generally used. Machines using deep
draw forming fi lms are fast and effi cient.
They give a shelf life comparable to that of
gas - fl ush system. A drawback is that the
package exhibits overwrap confi guration,
which poses diffi culty in cartoning and
storage. Punctures and leaks result in total
package failure due to lack of vacuum.
Another method entails secondary sealing
after evacuation of air and shrinking of the
fi lm. In this procedure, cheese portions are
bagged in shrinkable fi lm, evacuated by the
deep draw method, heat sealed, and then
passed through a heat chamber. The resulting
package is free from ears and excess materi-
als and has an excellent seal because of the
double protection afforded by heat sealing
and shrinkage. Localized punctures do not
cause total package failure.

Hard Cheese Packaging

In hard cheese packaging, process cheese is
generally packaged hot into tubs, with wraps
open within the molds, and allowed to solid-
ify. Individually wrapped slices are also
made by pumping thin sheets that solidify by
cooling.
Ripened hard cheeses are sliced, cubed, or
grated and packaged under vacuum or inert