Dr. G.K. Goyal Principal scientist Dairy Technology Division NDRI, Karnal-132001 1.0 INTRODUCTION
Packaging contains, protects, preserves and informs. It also provides two more functions namely selling and convenience. In many instances the only difference between comparative brands lies in the packaging, and only packaging influences the selling operation. As industries grow and as consumers demand more and more convenience , the need for quality packaging undoubtedly increases. Hence, there is more packaging in the world every year, rather than less. It is important that packaging must make the maximum contribution to the success of the marketing and distribution operations of which it forms a vital part.
The safe delivery of packaged food product mainly depends on the maintaining of its original quality by protecting it against external deterioration influences. This is achieved through the barrier properties of the packaging material. The required protection of the food stuff may be achieved with a single layer of polymer or necessitates the use of multi-layered films including different polymers, coatings and metal foils besides metal cans . The barrier properties mainly originate from its permeability to gases and vapours that are noxious to the quality of the product. For the majority of foods including butter and ghee, the gain of moisture leads to physical, biological and / or chemical defects. More harmful than moisture is oxygen for butter and ghee . Its fixation to the product is irreversible. It causes lipid oxidation and provokes rancidity especially when the package allows light transmittance.
2.0 BUTTER AND ITS PACKAGING
Table butter consists of milk fat ( 80% by weight), 3% common salt, 1.5% curd. It also contains about 15% trapped moisture. The natural colour of butter is due to carotene and other similar fat- soluble pigments in the fat globules of the milk. The flavour of butter is produced by the fermentation of bacteria in the cream. Although souring gives a full flavour, the use of butter cultures or starter organisms gives a better control of flavour and avoids the danger of undesirable taints.
2.1 Protection Required
Packaging must protect the butter in relation to its flavour, body and texture, appearance, moisture and colour. Also, butter readily absorbs odours. Because of the nature of emulsion, butter is especially prone to rancidity caused by the oxidation of the fats, producing a “ fishy‘’ taint. The fishy taste and smell is due to the presence of metallic contamination of the butter by traces of metals dissolved off the dairy equipments.
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2.2 Present Status
Packaging of butter is done in bulk and retail packs. The size of bulk packing ranges from 25 to 50 kg and is done in boxes, tubs or casks. Retail packing varies from 25gm to 500 gm and is generally packed in parchment paper, grease proof paper, also in thin cans and Al foils. Where flexibles are used, cardboard cartons are also commonly used in order to give added protection to the product. The glossy carton also makes the back very attractive having printing in different colours and graphics.
2.3 Flexibles for Butter
2.3.1 Vegetable Parchment Paper
Although, vegetable parchment is the most commonly used wrap, but it does not prevent oxygen and light penetration which lead to deterioration of the product . For packaging of butter sterile –plasticized grade of vegetable parchment paper should be used to suit high speed packaging machine. Vegetable parchment paper is good bearer to grease. It should not contain excessive numbers of microscopic pin holes and should not have more than 9% moisture. It is important that vegetable parchment is stored under proper humidity conditions (50-80%) at dust free, and it should be free from moulds.
2.3.2 Multipacks and Laminates
A very useful and interesting list of laminates consisting of different combinations of more than two components including Al foil, paper, PE, PVDC, PP, cellophane, polyester, wax, adhesive, lacquer, hot melt, heat sealable coating, polyamide and vegetable parchment for the packaging of milk and milk products including butter has been presented (Malansnicka,1975).The U.K. Ministry of Agriculture, Fisheries and Food has published the levels of vinyl chloride in flexible packages made from PVC for butter. In order to offer protection against light for butter, a multipack for tub shaped container made from a stackable plastics tray (e.g. polystyrene) with formed tubs (e.g. PVC), into which coated board segments can be inserted, has been developed (Brummer, 1978). However, butter can also be packaged safely in Al foil/ vegetable parchment as it would avoid the exposure of the product from air and light, and would also prevent contamination by the micro-organisms.
3.0 GHEE AND ITS PACKAGING
Ghee is clarified butter fat and occupies a very prestigious place in Indian dietary.
Though, cost-wise ghee is quite expensive, it is consumed extensively due to its characteristic flavour and aroma, unique taste and high nutritive value . The milk fat constitutes 99.5% of ghee and rest 0.5% of material present in ghee is unsaponifiable matter, which is a complex mixture of substances like sterols, vitamins etc which though present in small quantities are of considerable significance. Moisture in very small quantity (approximately 0.5% by weight) is also present in ghee as it is not possible to eliminate cent percent moisture from ghee during its preparation.
3.1 Protection Required
Since ghee contains very small quantity of moisture, danger from micro- organisms won’t be immediate. The product therefore needs protection from chemical spoilage which is
activated by oxygen, light, metals(Cu, Fe), humidity and temperature, besides spoilage from the surroundings by absorption of foreign odours etc., and also from the physical hazards.
3.2 Present Status
Majority of the dairies in public as well as private sectors are packing ghee in lacquered or unlacquered tin cans of various capacities. Some of the dairies sell loose ghee to local consumers through their sales depots or stores, where the possibility of adulteration cannot be completely ruled out. The advantages of using tin cans are manifold. They protect the product well against tampering and can be transported to far –off places without much wastage during transit. Besides the tin cans are attractive with colourful designs. But tin cans involve foreign exchange and are very expensive.
Of late some dairies have started packaging of ghee in simple containers e.g. PE bags, multi-layer films, glass bottles, cartons etc. In Nepal, ghee is commonly packed and sold in earthen pots. But these methods of packaging have their own disadvantages like problem of leakage with PE bags, breakage and high transportation costs in case of glass bottles etc.
3.3 Criteria of Selection
With a view to develop suitable flexible packages for ghee, it is essential to know the nature and composition of the product, its desired shelf life under specific conditions of storage in terms of light, temperature and humidity, the types and causes of deterioration, which the product may undergo during handling and storage, consumers requirements in terms of capacity, availability of flexible packaging materials and their functional properties.
3.4 Functional properties vis-à-vis Flexibles for Ghee 3.4.1 Water Vapour Barrier Films
The agency of moisture or enzyme lipase is essential to effect hydrolytic rancidity in ghee. During the manufacture, ghee is subjected to such high heat treatment(110-120 0C) that enzyme lipase is eliminated . In the process, the product gets contaminated from the lipase producing organisms and they in turn produce the enzyme, which becomes active in the presence of moisture to liberate compounds responsible for hydrolytic rancidity. Here the proper packaging material with excellent water vapour barrier properties can play a vital role in delaying this defect. HDPE, PP, Al foil, multi-layer films etc. if suitably laminated could result in packages which would be comparable to tin cans and get practically nil value for water vapour transmission rate.
3.4.2 Oxygen Transmission Barrier Films
Since ghee contains approximately 99.5 % milk fat, it is very susceptible to oxidative rancidity . Here the oxygen in contact with ghee initiates the chemical reactions with ghee which ultimately result in the production of compounds gaining very strong off-flavours such as tainty, nutty, melon-like, grassy, tallowy, oily, fishy etc. The undesirable odours of aldehydes and ketones of several types can be felt even at very low concentration. The chemistry of oxidation of fat suggests that when the fatty radicals of the unsaturated fats take up oxygen, a foul odour is produced. When the product is packed in a container the air
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available at the top provides the oxygen . Besides a small amount of air is always present in dissolved condition. Therefore care should be taken to fill ghee up to the top of the container.
Further, proper packaging material can also delay the autoxidation of ghee, i.e. if the package has a very low or negligible oxygen transmission rate (OTR), the diffusion of air/oxygen from the atmosphere into ghee can be prevented, the defect can be deferred for a long time.
These days many indigenously available flexible materials which have very low values for OTR, e.g. Polyester, Nylon-6, PVC, Saran,Al foils, and numerous laminates of certain flexible films are available.
The auto oxidation of ghee is also initiated or accelerated by certain metals in traces such as iron and copper which are always present in enough quantities in unlacquered or even in not- properly – lacquered tin cans, If the suitable flexible packages are used , the danger from such metals can also be minimized significantly.
3.4.3 Light Transmission Barrier Films
Light itself cannot cause rancidity in ghee, but can very effectively catalyze many other promoters of rancidity, both hydrolytic and oxidative. Ghee exposed to oxygen in ordinary temperatures illuminated places starts autoxidation without any induction period; the rate of autoxidation is directly proportional to the intensity of illumination. Hence, it is very essential to select the packaging materials for ghee which can effectively prevent the entry of light into the product. This can be achieved by using packaging materials having reflecting pigments, denser films like aluminum foils etc . Heavy overprinting of the packaged films can also prevent the entry of light into the product.
3.4.4 Aroma and grease Barrier Films
Its is well known that ghee is regarded by users mainly due to its characteristic pleasing flavour. Hence, it is of utmost importance that the original ‘ghee flavour’ be protected or maintained at any cost. Ghee being almost pure milk fat, it is very susceptible for picking up foreign odour from packaging materials and their components or atmosphere.
Loss of aroma can be prevented by selecting proper packaging materials which should be
‘flavour proof’ and completely devoid of any inherent odour.
Also, if the package does not have good grease resistance, the fat would seep through the package and would soon get completely spoiled. It is therefore very much essential that the packaging material for ghee should have good grease resistance properties. Following packaging films provide excellent resistance to oils and fats, namely lacquered cellophane, polymer coated cellophane, cellulose acetate, polyester, Nylon-6, PVC, Saran etc ., besides numerous laminates.
3.5 Other Important Properties of Flexibles for Ghee
The presence of well defined hard grains in coarsely packed condition is considerable in ghee. The packed ghee during transportation is bound to be subjected to hard exercise. In view of that the package should have sufficient strength to withstand the hazards of transportation as there is every possibility of ghee losing its original textural properties. It can be prevented by selecting packaging material having sufficient tensile strength, elongation, tear resistance and burst strength, besides overall mechanical strength.
4.0 CONCLUSION
Apart from functional and mechanical properties of flexibles for packaging of butter and ghee, it is essential that they have good heat sealing property and are non- toxic. For transporting ghee packed in flexible containers to far off places, packages be placed using some cushioning material to absorb the shock out of rough handling. Recent developments suggests that in addition to tin cans, many flexibles like polyester, Nylon, Co- extruded multi-layer films and laminates are in use for the packaging of ghee.
5.0 REFERENCES
Brunner, F. (1978) Multipacks for food and other goods. German Federal Republic Patent Application, 2 647 238.
Malannsnicka, W.(1975) Survey of laminate packaging of main groups of foods. Przemysl Spozywczy, 29, 475.
Potts, M.W, Baker, S.L., Hanssen, M. and Hughes, M.M.(1990) Relative taste performance of plastics in food packaging, J. Plastic Film and Sheeting, 6, 31