Plant Pre-requisites

  • All relevant equipment operating manuals, recommended maintenance schedules, as well as generally accepted good manufacturing practices etc. are followed.
  • The aseptic block needs to be able to run at nominal speed.
  • The upstream units need to be able to provide the required quantity and quality of packaging material needed for the microbiological validation.
  • The downstream units need to be able to handle the required quantity of filled and closed bottles produced during the microbiological validation in a way that ensures the integrity of the sealed bottles.
  • To run the validation, the packaging material must meet the correct specifications. (see appendix 2).

Validation Format

  • Only one format is chosen for microbiological validation: Usually this is the one with the lowest treatment time available i.e., the smallest bottle because it runs at highest speed and represents the most critical condition.
  • In agreement with both parties, also the main contractual format or the one with the most difficult shape or geometry may be selected as the validation format.
  • If the microbiological performance has been proven with this format all other formats perform equal or better. In this case, no further microbiological tests with other formats are required.

Low Acid versus High Acid Products

  • This guideline distinguishes between procedures for low acid products and high acid products (according to the FDA definition).
  • Low acid products : pH > 4.6
  • High acid products : pH ≤ 4.6
  • If a low acid validation is passed, the line is also validated for high acid products, if all parameters of the aseptic block remain the same.

Validation Medium

  • If the intention is to sell the tested production volume once the aseptic system has been validated, the intrinsic quality of the product must follow the customer's specifications.
  • For the microbiological validation of low acid aseptic lines a culture medium is used to enable visual inspection. Alternatively, the customer’s product may be used, e.g. UHT milk or others.
  • For the microbiological validation of high acid aseptic lines a clear product (e.g. apple juice) is used to enable visual inspection.

Thermal Treatment of the Product

  • As heat treatment for high acid products is not sufficient for killing all kinds of microorganisms including heat resistant spores, the temperature/time regime affects the final results of the validation. It is recommended to apply the highest temperature and longest holding time which the process unit allows for in order to minimize this influence. For explanation of heat treatment see appendix 3.
  • It is recommended to detect thermophilic spore formers in the raw product just before the heat treatment as well as in the aseptic storage tank and in the filled bottles.

Sample Size

The validation is based on three runs of the dedicated numbers of bottles and product:

Validation Sequence

Three consecutive days are chosen to run the tests according to the following sequence:

Fill Level of the Bottles

  • Half fill the bottles in order to shorten the incubation time because of a higher oxygen level in the headspace.
  • If bottle handling (transport, stacking) is critical, the fill level may be increased up to the necessary level e.g. 80% of the nominal volume.
  • If nitrogen is used in commercial production, the validation should also include nitrogen dosing.
  • If the customer wants to have sellable product, the bottles may be filled with product up to the nominal volume.