Cheese Technology

Module 14. Packaging, storage and distribution of cheese

Lesson 29
PACKAGING OF CHEESE

29.1 Introduction

Packaging refers to putting a commodity into a protective wrapper or container for shipment or storage. Any material to be used for packaging natural cheeses must:

a) afford general protection

b) prevent moisture loss

c) improve appearance

d) protect against micro-organisms and

e) prevent oxygen transmission

Packaging of cheese is mainly done to protect the cheese at the time of storage and transportation. Traditionally, cloth was used with wood to give support and protection, but the invention of polymers or plastics has revolutionized cheese packaging. Cheese manufacturing is now-a-days highly mechanized and at the same time, many developments are taking place in the area of cheese packaging also.

Cheese is packaged mainly in two forms:

a) Packaging cheese for storage and ripening (bulk packaging)

b) Packaging for consumers (retail packaging)

29.2 Bulk Packaging of Cheese

For bulk packaging of cheese, it is either paraffined or vacuum packed in flexible film. For waxing, the cheese can be lifted by means of suction and half immersed in wax and then other half can be immersed. For vacuum packaging, there are now available vacuum packaging machines, gas flushing machines, over wrapping machines and vacuum skin packaging machines. Paraffining is now completely replaced by film packaging as it causes considerable loss of cheese while removing paraffin. Many cheap and easy-to-apply films are now available.

29.3 Modern Packaging Materials and Forms

a) Materials—the basic ones are paper (usually coated or lined), parchment, foil (usually aluminum), polythene, propylene, treated cellulose and cellulose acetate (e.g. cellophane), polystyrene, polyester, polyamide (nylon), rubber hydrochloride (e.g. cryovac) and Saran (a mixed polymer). Laminates are now more common.

b) Forms - wrappers, cartons, bags, tubes, tubs, jars, cans, etc.

29.3.1 Film packaging

This has become synonymous with ‘rindless cheese’. In the latter, green cheeses of uniform size and shape are ripened in bags made of plastic films. The wrapped cheese may be placed in a wooden box or jig to preserve its shape. If the cheese is made and ripened in the conventional way, it may be cut into retail portions and wrapped by such method as the cryovac.

Desirable properties of films for packaging

a) The film must be strong so that it does not tear or change its property when rubbed against a sharp point.

b) It should be easily applied and sealed.

c) It must be impervious to water vapor and oxygen.

d) When the film is in contact with cheese, it should not change its inherent properties.

e) The material must be chemically inert and non-toxic for humans.

Plastic film packaging of cheese is applicable to varieties except such extreme types as cottage (which has very high moisture content) and as Parmesan (which is very low in moisture). There are many advantages and few disadvantages of film packaging which are summarized as follows:

29.3.1.1 Merits

i) It affords a considerable saving in labor.

ii) It protects the cheese from attacks by molds, insects, rodents and fault-inducing microorganisms.

iii) It is easily applied and the method can be readily mechanized.

iv) There is practically no loss of moisture and of weight in the cured cheese (In traditional ripening the loss may be 3 to 7%, even up to 12 %)

v) The method permits and is suitable for packaging small quantities, which make handling and retail trade easier.

vi) The method is most easily used for rectangular blocks.

vii) It is cheap and convenient.

viii) Humidity control is unnecessary during ripening and storage.

ix) More cheese can be stored in a given volume.

x) Turning is unnecessary during ripening.

xi) It permits ‘rindless curing’ so that whole of the cheese can be eaten. (When rind is formed as in traditional method, the loss can be as high as 10%).

29.3.1.2 Demerits

i) Not all technical problems in film packaging have been solved. (For example, failure to obtain a perfect seal and to remove all air may result in mould growth).

ii) The moisture content of the cheese at packaging must be less than for traditional packaging and must be carefully standardized. Failure to do so may lead to the growth of taint-producing organisms.

iii) The ripening process in some cheeses (such as Camembert) may be affected.

iv) The film does not always give the same mechanical protection to cheese as traditional methods.

v) The most careful attention to detail is necessary in film packaging.

29.4 Retail Packaging of Cheese

Retail packaging is an important aspect which affects not only the shelf life of cheese but also its marketability. Cheese is available in the form of slices, cubes, tubs, paper board cartons with foil overwraps, etc. These are available in different retail sizes like 100 g, 200 g etc. With the developments taking place in packaging technology, cheese packaging is also revolutionized. Active packaging and modified atmosphere packaging is being used for retail cheese packaging.

29.5 Developments in Packaging of Different Types of Cheese

29.5.1 Soft cheese

Special packaging requirements

The packaging material requirements for soft cheeses differ considerably depending on whether the cheese concerned is a soft cheese with a mold formation (surface mold, Camembert), blue-veined cheese (Roquefort), or a so-called smeared cheese (Munster). Different bacteria and mold flora require packaging material to have specific properties.

29.5.2 Fresh Cheese

Special packaging requirements

29.5.2.1 Protection against light

Metals are impervious to light. With regard to fresh cheese packaging this concerns first and foremost aluminium, whether in the form of lids to seal plastic containers or as deep-drawn containers. A high degree of imperviousness to light can be achieved through the addition of carbon black or brown pigments (total transmission approaching 0%). As black cheese packaging would not be acceptable to the consumer, such light-preventing layers are usually produced as the inner sheet of multilayer films by co-extrusion. This has not been done in dairy industry because of cost. The outstanding barrier property of aluminium is also found with vacuum metalized plastic films (e.g. polyethylene terephthalate polyester (PETP), oriented polypropylene (OPP), cellophane or paper).

29.5.2.2 Protection against the effects of oxygen

In order to avoid the diffusion of oxygen, especially in packed fresh cheese with a long shelf-life, the most impervious packaging material possible must be selected. This is achieved using Al (foil or strips), metalized plastics or by means of O₂–resistant layers in plastic combinations such as polyvinylidene chloride (PVDC), ethylene vinyl alcohol (EVAL) or polyvinyl alcohol (PVAL).

When selecting mono or multilayer combinations (bags or thermoformed containers) it should be borne in mind that the data concerning gas permeability always refers to flat (unfolded) material, measured at +23^oC. When a pack is formed, the permeability may change significantly due to capillarity in the sealed seam, thinning of the material at the base of deep-drawn containers or fractures caused by bending in bags.

29.5.2.3 Protection against loss of moisture

The absorption of moisture is not of any significance for packaged fresh cheese. On the other hand, however, fresh cheese with a long shelf-life must be protected against loss of moisture. In addition to the specific properties of water vapor permeability of the various packaging materials, the way they are processed into finished packs is also important.

29.5.2.4 Protection against contamination

Quite apart from contamination through leaks in the packs or lids, the packaging material itself may be contaminated to a greater or lesser extent. Paper which is used as wrappers may be affected as a raw material or during production by bacteria and/or mould conidia.

Due to high temperatures involved in processing, plastics are considered virtually bacteria-free. However, the possibility of contamination from the environment cannot be ruled out during further converting into film and containers.

29.5.3 Hard cheese

29.5.3.1 Emmental cheese

A pressed, ‘block’-shaped Emmental Cheese (84 kg) is wrapped in cling film and stacked on a specially designed pallet, which can be mechanically turned during the ripening/storage period. The smaller ‘block’-shaped Emmental could be packaged mechanically in a Cryovac-BKIL bag. This type of packaging material is a laminate of different layers of plastics.

29.5.3.2 Cheddar and related cheese varieties

Different systems have been employed for the packaging of Cheddar Cheese and other British varieties. These may include the following:

a) Pukkafilm

This type of packaging material consists of a waxed cellulose laminate. First, the cheese block is wrapped with the laminate; secondly, it is over-wrapped with waxed cellulose; and thirdly the cheese is placed in a chamber for sealing by the application of heat and pressure.

b) Unibloc system

The pressed cheese is wrapped with a plastic film, e.g. Saran and over-wrapped with a layer of paper prior to packaging within six wooden slats. The cheese is compressed within the slats by a specially designed machine, and the pressure is maintained by placing four metal straps around cheese. In some instances, the wrapped cheese is placed within a thin cardboard box before final packaging. This box serves as a dispatch unit when the cheese leaves the factory, and the wooded slats are retained on the premises.

c) Storpac

The packaged cheese, e.g. in a vacuum pouch or heat-shrink bag is wrapped in a thin cardboard box (optimal) and is placed in a wooded box with a loose cover. The latter piece is held onto the box using a plastic band for strapping. On dispatch the strap is removed from these boxes which are retained in the factory.

d) Heat-shrink bags

An example of such a bag is the Cryovac-BB4L bag, which consists of three main layers: polyolefine, a PVDC barrier layer against oxygen and moisture and a cross-linked polyolefine. Gas production in Cheddar cheese during the maturation period is considered a serious problem, and a quick remedy is to package the cheese in carbon dioxide permeable material, e.g. Cryovac-BKIL bag.

e) Vacuum pouch

Different types of plastic film laminates can be used to package Cheddar cheese, and such pouches should provide a barrier against oxygen ingress and moisture loss. One such example is the Diolon pouch which consists of 20 μm nylon (polyamide) and 60 μm polyethylene.

29.5.3.3 Gouda, Edam and related cheeses

After brining stage, the cheese is plasticized twice to prevent mould growth during the ripening period, and this process is repeated several times if the cheese is to be stored for long periods. Prior to dispatch, the cheese is washed, dried and coated with paraffin wax and over-wrapped with a red cellophane film (the latter packaging material is optional). The mechanical handling of cheese in the store and the waxing equipment are of great concern.

An alternative approach for the packaging of the ‘loaf’, block or ‘round’ Dutch cheeses is to wrap the product in a heat-shrink bag, which is then either sealed by heat with a metal clip.

However, recent reports indicate that the protective packaging of foods is not available in a single packaging material if the desired shelf-life has to be achieved. Various packaging materials are used in combination to give the desired shelf-life of cheese. Plastic combinations, Al-foil/paper laminates, cellophane/paper combinations, etc. are in use these days. Modified Atmosphere Packaging has contributed greatly great to increase the packaging speed and thus reduce the cost. Still cheaper combination packages and modern methods are in demand mainly as consumer packages with all the desirable properties.