Packaging Materials

Butter is a high fat product and contains about 80% fat, 15-16% moisture, 2-3% salt and 1.5% curd. The natural flavour of butter is unique but it is prone to oxidative deterioration. Therefore, a packaging material must protect the flavour of butter against spoilage. In presence of sunlight and metallic contamination, it develops flavour defect like rancidity. Also, butter absorbs the taste and odour of other articles in the surroundings and develops defects. Therefore, preferred to use only such material in contact with butter, which has a low metallic content and provides adequate protection to flavour. In addition, it should also provide protection to its body & texture and colour & appearance against any deterioration. Microbial,enzymatic and chemical reactions also affect the quality of butter leading to its limited shelf life. Thus, it is obvious that the prevention or delay of certain reactionsand the maintenance of the physical  properties are necessary to store butter in a good condition for longer period. This can only be achieved by using an appropriate material for packaging of butter. Packaging material must be non-toxic, non-greasy,non-sticky and amenable to packaging systems. In addition, it should offer:

•  Protection against external environments like light, humidity, gases and odours,etc.
•  Protection against loss or gain of water vapour and moisture;
•  Protection against contamination with yeast, mould and bacteria;
•  Protection against mechanical damage (sufficient strength);
•  Resistance to corrosion and de-lamination;
•  Ease and safety of transport;
•  Convenience to retailers and consumers;
•  Convenience to identify the product;
•  Appeal to the consumers.

Materials which offer these advantages include wood, parchment paper, flexible films and laminates, aluminium-foil, wax coated paper and paper-boards, tin plated cans, etc. are available for packaging of butter.

i. Water vapour, gas and light transmitting materials- Vegetable parchment is the common packaging material in this group, which is most commonly used for butter. It is impermeable to water and fat but it does not provide protection against water vapour, light, and oxygen. Vegetable parchment paper used should not have more than 9% moisture and excessive numbers of microscopic pinholes. The paper should be stored in a dust free place where the humidity ranges between 50-80% and above the ground on shelves. The place should be free from mould. For better results, sterile plasticized grade of vegetable parchment paper is used and is also suitable for use in high-speed packaging machines.

ii. Water vapour tight, but light transmitting material (film) - Examples of these materials are cellophane coated with wax or polyethylene. Tubs or cups made of poly-vinyl-chloride, polyethylene and polystyrene/poly-vinyledene-chloride laminate come under this group.

iii. Water vapour, gas and light tight material (foil) - Typical example of this group is Aluminium-foil laminated with parchment or imitation parchment and provided with protective coating of lacquer on the outer surface of the foil.In order to avoid de-lamination, two component lacquer laminated or polyethylene coated material instead of wax laminated material has been developed and used.

iv. Large Packages- In earlier days, butter was packaged in wooden barrels or boxes in 50 kg lots. With a view to better handling, easier storage, more efficient use of storage space and for reasons of economy, fibre-board boxes have been introduced which can generally hold 25 kg of butter. Before the box is filled it is lined with parchment or other suitable materials. Boxes may be filled directly from the churn using a butter pump or from the discharge line of a continuous butter-maker. It is, of course, also possible for the boxes to be filled manually from a butter trolley but it is more hygienic to use butter pump. The following factors should be considered while selecting material for butter boxes:

•  Thickness and type of fibre-board,
•  Water repellant properties,
•  Basic weight of the material in g/sq. m.,
•  Moisture absorption in a specified period at a predetermined relative humidity and temperature,
•  The use of paper coating,
•  Bursting strength,
•  Compression strength,
•  Design of the insert, top and bottom sheets.

Nowadays a large number of flexible packaging materials like films, foils and laminates, which meet the requirements are available. These films and laminates have the components such as Al. foil, polyethylene, cellophane, poly-vinylidene cellophane, polyester, polyamide, vegetable parchment, wax, adhesive, lacquer and hot melting and heat seal-able coating. Also, in order to offer protection against light multi-pack tub shaped containers, made from stackable plastic (polystyrene) trays with formed tubs (PVC) into which coated board segments can be inserted,are also available. Butter can also be packaged safely in Al. foil/parchment paper laminate. Such laminates are impermeable to air, gases, light and moisture. It also has sufficient mechanical strength and provides protection against microbial contamination. It is non-toxic, opaque and can make airtight containers. The packaging material consisting of aluminium and parchment or grease-proof material is usually produced from a thin aluminium foil (0.009 mm thick) which is treatedon the surface with lacquer to afford protection against corrosion. The aluminium foil is laminated to parchment or 40/42 g greaseproof paper or other suitable materials. It is very important to avoid de-lamination of the material.There is only limited market for butter packed in cups produced from Poly-vinyledene chloride or cardboard boxes with insert of parchment.