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Dairy processing: Aseptic processing and packaging systems
Aseptic packaging

Aseptic packaging is a procedure consisting of sterilization of the packaging material or container, filling with a commercially sterile product in a sterile environment, and producing containers that are tight enough to prevent recontamination (hermetically sealed).

Aseptically packaged ultra-high temperature (UHT) milk should also give almost complete protection against light and atmospheric oxygen. The package should therefore be of barrier type or similar.

The term 'aseptic' implies the absence of any unwanted organisms from the product, package or other specific areas. The term 'hermetic' is used to indicate suitable mechanical properties to exclude the entry of bacteria into the package or, more specifically, to prevent the passage of microorganisms and gas or vapour into or from the container.

Packaging material

  • Establish a program to ensure that the packaging materials received meet the criteria identified in the scheduled process
    • Include visual examination of the packaging material to identify damage and defects
  • Store all packaging material in a clean and sanitary manner to minimize the risk of contamination and physically damaging the materials

Sterilant

The aseptic packaging machine ensures the sterilization of the container and provides a sterile environment for filling. The most commonly used sterilants, depending on the application, are hydrogen peroxide (H2O2) or a combination of H2O2 and peracetic acid.

  • Use sterilants to sterilize the package that are safe and suitable for use in dairy processing facilities
  • Follow the manufacturer's recommendation if dilution of the sterilant is required

During the sterilization of the packaging material by H2O2 or other sterilants, a residue of these sterilants may be left on the material and can subsequently contaminate the filled product.

  • Rinse the treated aseptic packages with water to remove sterilant residues when necessary
    • Ensure the rinse water is sufficiently sterile (that is, commercially sterile) so that it does not result in loss of asepsis throughout the entire shelf-life of the product
  • Perform residue testing at an appropriate frequency to ensure sterilant residues are at or below the level specified by the scheduled process

Depending on the type of packaging equipment, different means of applying the sterilants are used for example, spray, vapour, roller system, immersion bath, etc.

  • Have the person responsible for the scheduled process (for example a process authority) validate that the sterilant can achieve commercial sterility

Headspace gas

Nitrogen gas or other media may be used to create a headspace in the formed package.

  • Filter or treat headspace gas to remove or destroy microorganisms

Packaging/filling room air quality

In order to minimize airborne contamination from other areas of the processing plant:

  • Maintain the packaging/filling aseptic zone under positive pressure relative to the rest of the facility
  • Maintain the packaging/filling room under negative pressure relative to the aseptic zone of the packaging machine
  • Conduct microbial analysis of air quality at a frequency that is sufficient to substantiate the air quality is appropriate
    • Keep records of results on file
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