By P. V. Narayanan
The advent of Aseptic Packaging has enabled the adoption of modern technology replacing traditional canning techniques such as retort and hot filling canning and use of preservatives and refrigeration. A major advantage is room temperature shelf stability and achieved through filling a sterilised package with a sterile product under a controlled hygienic atmosphere. By and large aseptic packaging is used for liquid products like milk and juices. The process essentially involves sterilisation of the liquid food externally outside the package by ultra-high temperature. The process rapidly heats and cools the product before filling. The process also ensures a minimum amount of thermal stress on the product ensuring safety. Three major factors come into play viz the material, the product and the filling/packing atmosphere. The material is pre-treated or sterilised so also the product pre-sterilised. Both enter into pack forming cum product filling and completion of the filled and closed pack in an environment of total hygiene. It is these process parameters that provide a high shelf life even without refrigeration or preservative.
The aseptic packaging media is a combined structure generally known as a laminate consisting of high-quality food grade paperboard, aluminium foil and polyethylene. Each of this substrate contributes their known specific property-functional, thereby enabling to achieve a unique benefit of the aseptic packaging. Paper board offers substance, dead fold, and stiffness beside print acceptance- a resultant brick shape (rectangular). Polyethylene is the innermost layer in contact with the product and is the sealant medium providing a leak-proof pack. Aluminium foil is the barrier against oxygen (gases), moisture and light. A protective coating or polyliner is provided on the exterior surface that enables the pack dry and /or adds to resistance to enviro exposure. The essential barrier is provided by the foil. The aseptic system is relatively expensive but considering convenience, savings in refrigeration, no preservative, etc. the add-on benefits only justify the added cost.
An extended technology was also attempted in the form of Aseptic pouch packaging to make the system more affordable to the consumer. The material combination was polymer substrates with aluminium foil but has not taken off considering cost affordability and value proposition effective.
The aseptic pack being portable, lightweight and not fragile provides a high degree of convenience. It is food safe as the aseptic process and the pack together ensure that the product inside is free from harmful microbes and environmental contaminants. The sterility created enables the pack to provide longer shelf life without refrigeration. Based on the shelf life needed the laminate structure could be altered. The resultant advantage to the consumer is savings in energy cost and being easily portable allows use as a required product. Quality is more assured as the aseptic process employs lower heat with better retention of nutrients as near as to the original texture, taste and colour. The other significant feature is a low package to product ratio-more efficient enviro needs. Compared to glass and metal or plastic basic aseptic material is transported and stored flat or rolls resulting in considerable storage space and freight advantage. It is estimated that a semi-trailer truck can transport 15 million empty packs as against 1.5 million glass bottles. The rectangular shaped packs are space-efficient and being lighter-weight truck space utilisation is better.
Being multilayer laminate, recycling of the throw away used packs had been a challenge. The composition generally is 74% paper, 24% polymeric film and 6% aluminium. However, technology now developed enables recycling and the paper component recovered as pulp converted into a board and is reused for cartons.
The foregoing primarily addressed the aseptic consumer packs with their USPs of relatively lower cost, lighter weight, reduced shelf/storage space and energy benefits. The aseptic system also enables the products to be filled at an ambient atmosphere and the products packed include fruit juices, nectars, tomato paste besides milk. The aseptic system, however, is not confined to the consumer pack but also adaptable for the bulk system as well. Pulps and concentrates of tropical fruit and tomato paste are also packed in 55-gallon bags and stored in drums for reprocessing and exports. Bag-in-Box concept generally are 5L to 20 L. Aseptic packaging system of bulk essentially constitutes Tinplate container with multilayer laminate with metallised polyester or aluminium foil as a substrate, placed inside. The process is sterilising and filling, steam under pressure. Bags are sterilised by gamma irradiation, filling in an environment of steam or hot sterile air and caps sterilised by Hydrogen peroxide, Chlorine, Iodophor solution or peracetic acid chemical sterilant for cleaning tanks, purged with sterile nitrogen. The sterile product is filled from the top.
The packaging material used for aseptic pack-sterilisation should be:
- Compatible with the product
- Easily removable
- Free of health hazard
- Enviro compatible
- Cost effective
Over the years the industry has witnessed considerable technological advancements encompassing materials, process and machinery and probably markets as well . These could be broadly stated as:
- A recent development is aseptic drinks filling technology – a multi-functional system that provides customers with the capacity to switch between a range of produces from carbonated to still aseptic beverages and vice versa. This new technology uses a counter-pressure volumetric electronic filling valve. It can also fill products with fibres upto 2 mm long and dia 3mm (GAE Group, Germany).
- A new aseptic version that provides new opportunities in the dairy ad beverages industry. The new version enables container decontamination by e-beam with the latest sterilisation module. (SERAC, France)
- Adoption of an octagonal shape to fit contours of hand with a large resealable opening and the metallic effect called Tetra Prisma Aseptic Edge 250ml package. The process development included microfiltration to boost the protein content and direct heating technologies to improve product taste (Tetrapak, China).
- The development addresses the growing market for healthy plant-based alternative beverages instead of added sugar juice drinks. Container selected is strong, unbreakable, transparent and safe with recyclability. The absence of sterilised aluminium foil due to the tightness between the bottleneck and the cap has the added advantage. (Sidel.com)
- The aseptic carton developed uses renewable raw materials to save fossil resources and helps to reduce the impact on the environment. The carton packs come in 1, and 1.5l capacity. Oil based polymers used to laminate the paperboard are combined with cent percent plant based material via a mass balance system. The pack has a carbon foot print lesser of the order of 30-65% and is considered the most sustainable packaging solution. (SIG,Switzerland)
- Signature brand aseptic pack is said to contain 70-80% paperboard from renewable wood sources. The polymer used for laminating the paperboard and making the closure are linked to plant-based material. In this, the polymer used in the pack has an equivalent amount of bio-based feedstock and fossil-based material in the manufacture of the polymer. (SG Combibloc, Switzerland).
- Development of the 2 step sterilisation has the key advantage of being simpler to perform and product dependent parts and moulds can be replaced much faster than on a sterile blow moulder. Preform sterilisation enables the bottle material to be disinfected upstream of the stretch blow moulder. Also, the room within a room design provides both hygienic safety and ease in operation (KHS GmbH, Germany).
- A new aseptic PET line produces one lit. Bottles and newly designed 2L bottles for milk. The new design includes a reference to the customer’s branding on the top part of the container and shapes the PET avoiding may splashing effect during product pouring. The total system combines perform and cap sterilisation, blowing and sealing functions in a single enclosure for a complete sterile filled and capped PET bottle (SIDEL, Italy).
The globe will continue to witness more and more such developments addressing newer challenges and market needs. Aseptic packaging stands to grow and establish further preferences.
* Author is Chairman, SIES School of Packaging and can be contacted at +91 9820141751 and firstname.lastname@example.org