Aseptic packaging is defined as the filling of a commercially sterile product into a sterile container under aseptic conditions and hermetically sealing the containers so that reinfection is prevented.
What does this mean?
As per the definition, we are trying to eliminate all the possible way of contamination of product by the microbes. Suppose let us consider following condition of product storage with an aim to maximize the shelf life of the product (I will try to take all day to day example from our kitchen)
We saw few factors which affects the shelf life of a processed and packed food. These are the product to be packed, packaging material and the packaging / filling condition. So, if we eliminate microbes from all these factors, the products’ shelf is increased. This is the basic principle of Aseptic packaging. The term “aseptic” is derived from the Greek word “septicos” which means the absence of putrefactive micro-organisms
Sterilization of Products
In aseptic processing, the design to achieve commercial stability is based on the well-founded principles of thermal bacteriology and integrated effect of time/temperature treatment on spores of micro-organisms. Pre-sterilization of a product usually consists of heating the product to the desired UHT temperature, maintaining this temperature for a given period in order to achieve the desired degree of sterility, with subsequent cooling, usually to ambient temperature and sometimes to an elevated temperature to achieve right viscosity for filling. Heating and cooling should be performed as rapidly as possible to achieve the best quality, depending upon the nature of the product. A fast heat exchange rate is desired for cost reasons.
Sterilization of Aseptic Packaging Materials and Equipment
Initially, heat was used as the sterilant for aseptic systems as a natural extension of thermal processing. Product supply lines and fillers are commonly sterilized by ‘moist’ heat in the form of hot water or saturated steam under pressure. ‘Dry’ heat, in the form of superheated steam or hot air, may also be used to sterilize equipment. However, due to the relatively high dry heat resistance of bacterial endospores, the time-temperature requirements for dry heat sterilization are considerably higher than those for moist heat sterilization
Hydrogen peroxide is the most commonly chemical sterilant. Other chemicals used are various acids, ethanol, ethylene oxide and peracetic acid. Hydrogen peroxide is not an efficient sporicide when used at room temperature. But, the sporicidal activity increases substantially with increasing temperatures. General practice of aseptic packaging is the use of hydrogen peroxide (at concentrations of 30 to 35%) as a sterilant for packaging materials and then being exposed to hot air (60°C to 125°C) to dissipate residual hydrogen peroxide
Gamma-radiation, due to excellent penetrating powers, is used as sterilant for the bulk packages at commercial irradiators. A dose of approximately 1.5 Megaradians (Mrad) is commonly used to decontaminate containers for acid and acidified food.
For proper sterilization of product, time temperature combination is very much required. We need to ensure that each and every particle of the product is exposed to required temperature and for required time. So, after bringing brought to the sterilisation temperature, it flows into a holding tube. The tube provides the required residence time at the sterilisation temperature and also ensure that the fastest moving particle through the holding tube will receive a time/temperature process sufficient for sterilisation. A deaerator is used to remove air to prevent undesirable oxidative reactions, which occur as the product temperature is increased during the process. The deareation is generally carried by keeping product under vacuum. The sterilised product is accumulated in an aseptic surge tank prior to packaging which is further pumped into the surge tank and is removed by maintaining a positive pressure in the tank with sterile air or other sterile gas.
Seals and Closures
Any aseptic system must be capable of closing and/or sealing the package hermetically to maintain sterility during handling and distribution. The integrity of the closure and seal is very important to avoid contamination post packing.
Aseptic packaging v/s canning
Though basic objectives are same, there is fundamental difference between aseptic packaging technology and canning. In canning product and packaging is sterilized after sealed packaging of the product. The canning process begins with treating the food prior to filling. Initial operations inactivate enzymes so that these will not degrade the product during processing. The package is cleaned, and the product is introduced into the package, usually hot. Generally, air that can cause oxidative damage is removed from the interior. The package is hermetically sealed and then subjected to heating. The package must be able to withstand heat up to about 100°C for high acid products and up to 127°C for low acid products, which must receive added heat to destroy heat-resistant microbial spores. Packages containing low-acid (above pH 4.5) food must withstand pressure as well. Although conventional canning renders food products commercially sterile, the nutritional contents and the organoleptic properties of the food generally suffer in the processing. Moreover, tinplate containers are heavy in weight, prone to rusting and are of high cost.
Virtual plant tour
The very latest generation of Aseptic bag in box fillers for bulk filling of liquids into flexible packaging