The beverage industry in India is investing in expansion and technological development to improve all aspects of beverage development. This twopart article describes the innovations and technologies in the field of beverage packaging. The materials and processes used to pack beverages are also being upgraded. Beverage packaging is a complex technological branch in the food processing and packaging industry. The traditional returnable glass bottle has given way to newer plastic containers and cartons. The current trend is to improve the conventional containers, extend their share in the market, extend the shelf-life of their products, provide greater consumer convenience and ultimately produce economical packages. The changing market scenario has altered the scope of this industry exponentially.

The packaging of all types of beverages should possess the following attributes:

• It should be leak-proof.

• It should protect the contents against chemical deterioration.

• It should not pick up external flavours.

• It should be hygienic and safe.

• It should retain the carbonation in the case of carbonated beverages.

• It should be economical, easy to use and disposable.

• It should be aesthetically appealing.

The key parameters to be considered when selecting a packaging system are as follows:

• Process

• Distribution, shelf-life, legislation

• Product composition and quality when produced and at full shelf-life

• Product protection required during storage, distribution and retail sale

• Pack size, printing options, displays, etc.

• Packing system concept, automation options, ability to integrate with existing and/or future systems

• Consumer appeal and image of product and packing

Packaging materials for non-alcoholic beverages
Non-alcoholic beverages are classified into non-carbonated and carbonated drinks.



Non-carbonated drinks
These types of drinks comprise fruit beverages, coffee and tea. The packaging material used for each of these beverages is described below.

Fruit beverages
These include fruit juices, drinks and nectars. They contain fruit juice, water, sugar, dextrose, invert sugar syrup, etc. The major deterioration that occurs in fruit beverages is loss of nutrition,
physico-chemical changes and microbial growth. The main cause of fruit juice spoilage is yeast, and its growth depends on the temperature. The spoilage of raw fruit juice at room temperature results in alcoholic fermentation followed by the oxidation of alcohol and fruit acids by yeasts or moulds that grow on the surface. To avoid this, every living yeast cell must be removed or suppressed by pasteurisation, filtration and/or preservatives.

The product characteristics to be considered in relation to packaging are listed below:

• Acidity: All the fruit juices usually maintain an acidic character because they contain organic acids.

• Enzymes: Enzymes exist in all fruit juices. Sometimes they have to be destroyed, while at other times, they have to be added.

• Vitamin C (ascorbic acid): The vitamin C content of a fruit increases until just before ripening, and then decreases due to the action of the enzyme ascorbic acid oxidase. When fruits are cooked, most of the ascorbic acid is transferred from the tissue to the liquid. It may also be oxidised since oxidation occurs more easily in iron, copper or badly tinned vessels. Loss of vitamin C also occurs during storage. Storing products at low temperatures and preventing contact with air and light reduces this loss. The addition of sulphite has a preservative effect on vitamin C.

• Colour and flavour: Many fruit drinks contain certain legally permitted colourings. These are added to overcome the bleaching effect of the sulphite used as a preservative and to lend an attractive appearance.

Packaging materials used for fruit juices

• Glass containers: The use of glass bottles for the packaging of fruit beverages was widespread, although the hot-fill/hold/cool process had to be applied with care to avoid breaking the containers. Glass is still the preferred packaging medium for high-quality fruit beverages. However, more juices are now being packed aseptically in cartons. Glass bottles have improved over the years; newer bottles are lightweight. Bottles now have a surface coating to increase abrasion resistance, and wide-mouth containers fitted with easyopen caps are the norm.

• Metal containers: Tinplate cans made of low carbon mild steel of 99.75 percent purity with easy-open ends are used. These tinplate containers are either two or three-piece containers. They are lacquered internally to prevent corrosion.

• Plastic containers: Fruit juices contain organic substances, which are sensitive to bacterial contamination. Packaging of such products is carried out through hot filling in order to achieve an extended shelf life. PET (Polyethylene terephthalate) bottles are usually used for hot filling applications. Special features are added to the containers during the design and manufacturing processes. The package is heat set in order to improve the temperature resistance of the containers. PET resins with a higher Tg (glass transition) temperature and/or a faster rate of crystallisation are used. Normally hot-filled PET bottles are designed to be about 1.5 times heavier than cold-filled bottles. Reinforcing ribs and grooves are also provided along the circumference and base of the bottle. After filling and capping operations, the liquid continues to cool, which results in the formation of a vacuum. The bottle wall can deform under the influence of the vacuum. This problem is overcome by providing vacuum panels in the container side wall. Generally, lower levels of PET co-polymer are preferred and intrinsic viscosities of about 80 are acceptable. Flexible plastic packages offer economic savings over conventional glass and metal containers but they are permeable to oxygen. Therefore, it is critical to select a flexible package that minimises the permeability of oxygen. Flexible laminated pouches like metallised polyester, polyester or polyethylene are used in the hot-fill packaging method without retorting to acidic fruit juices. These are used either as flat or stand-up pouches. However, the shelf-life of the product in these pouches is limited.

• Aseptic packages: Ready-to-serve fruit beverages and fruit pulps or concentrates are packed in aseptic packages, which provide excellent protection. These aseptic packages are made by combining thermoplastic with paperboard and aluminium foil. Their multi-layered construction enables the carton to protect the contents from various factors that are responsible for spoilage. An aluminium foil layer is a strong barrier for oxygen and light. The inner plastic layer made of polyethylene makes it possible to seal the liquid. The outer paper layer provides stiffness, making it possible to produce the cartons in a brick shape, thus enabling maximum utilisation of available storage and transportation space. Excellent graphics enhance the display and shelf appeal and also provide information regarding the product. The aseptic process ensures that the product is bacteria-free before being packaged.

To provide convenient access to the contents, beverage cartons offer a variety of opening devices. A familiar opening device is the drinking straw, which is attached to the package. The pull-tab opening is another recent trend. The tab can be easily detached from a pre-punched hole without compromising the package integrity. Custom-designed caps and closures can also be
incorporated on beverage cartons for easier pouring and to enhance the brand image. Beverage cartons are now available in the new prism shape, which is comfortable to hold. This unique shape offers maximum display effectiveness and high space efficiency. These packs are shelf-stable at room temperature, and the shelf-life and nutrient composition of the fruit juice is influenced by the barrier properties of the tetrapak.

• Bag-in-box system: It consists of a collapsible bag within a rigid container, a filling machine to introduce the liquid product into the bag and a dispenser to draw the product out.

Bag: The outer container can be a box, a crate or a drum. The bag actually consists of two bags. The inner bag contains the liquid and the outer bag provides the barrier properties. Both are heat-sealed at the edges. The tubular spout fitted to the bag aids in filling and dispensing the product. As little as 3 litres or as much as 1000 litres can be packed in this package. The bag itself consists of three components:

• An inner layer

• An outer layer

• A spout

The function of the inner layer, the one in contact with the material being packed, is to provide the bag with a seal integrity. The seals should be strong enough to withstand constant mechanical and chemical pressure for at least twice the expected shelf-life of the product. Generally, the inner layer is not designed for barrier properties unless the product needs an extra barrier, which the outer layer cannot provide. Plastic films manufactured from high-performance polyethylene, with excellent sealing and puncture properties are usually used as materials for the inner layer.

The function of the outer layer is to provide the bag with a barrier commensurate with the expected shelf-life of the product. In this respect, the bag-in-box system scores over other packaging forms, because unlike other packaging materials like jars and cans, the barrier property and the cost of this packaging form can be varied. The shelf-life expectations and storage conditions play an important part in determining the barrier requirements of the outer layer. The standard outside layer is a metallised film laminate, which under standard conditions has an OTR of 1cc/m2/24 hrs.



The spout and cap assembly are made from injection-moulded plastics. The spout is provided with a flange, which is welded to the bag's inner layer during manufacture. The spout and cap have two functions: they are used to fill the product in the bag and dispense the product from the pack. Several spout types are available ranging from a simple bung-like configuration to varieties that can only be opened on the filling machine. The caps come with various tamper-evident features as well.

Rigid containers: The purpose of this container is to hold the bag during storage, transportation and use. The bag, which is made from flexible films, is incapable of being stored and transported. Hence, each bag is individually stored in a rigid outer container after filling. For packs with a capacity of less than 50 litres, corrugated fibreboard cartons are generally used as rigid containers, while plastics and metal drums are used for packs above 50 litres. For very large bags, polygonal (6–8 sides) corrugated fibreboard containers made from 7–9 ply are used, though there are other alternatives as well.

Coffee
Some of the major deterioration reactions in coffee are as follows:

• Staling due to loss the of flavour volatiles or chemical changes caused by moisture and oxygen absorption.

• The evolution of carbon dioxide, which is emitted during the roasting process.

• The ingress of moisture in instant coffee results in caking. This usually happens when the moisture content reaches 7-8 percent. The initial moisture content of instant coffee is 2-4 percent.

Hence, while developing a packaging system for coffee, the following aspects should be considered:

• Moisture or vapour ingress

• Oxygen permeability

• Carbon dioxide and volatile component egress

• Grease-resistance

The packaging materials used are tinplate containers, composite containers, glass jars and flexible plastic pouches. The flexible laminates most widely used are 12μ PET, 2μ Al Foil, 70μ LDPE and MET PET or LDPE. Aluminium-foil-lined plastic pouches are most popular, with a 59-percent contribution in terms of volume.

Tea
The unique taste and colour of tea is due to polyphenols (catechins) and amino acids (theamine). The flavour is due to the essential oils present in the fresh leaves and volatile components developed during the manufacturing process. The different types of tea include black tea fermented), Oolong tea (semi-processed) and green tea (non-fermented). Deterioration is caused by the loss of volatile components and the increase in undesirable ‘taints’ arising from the oxidation reaction with fatty acids. Deterioration in green tea results in a reduction in the ascorbic acid content, changes in colour (from bright green to olive green) and odour. The most common packaging material is a paperboard carton with a liner or an overwrap of polypropylene (PP0 or regenerated cellulosic film. Other containers are plastic jars, bottles, pouches, strips and envelopes. (To be continued)

Courtesy: ICPE-ENVIS