For packaging food in tinplate containers with white BPA-NI varnish, it is important to consider the following aspects based on the information provided:

  1. Sanitary Requirements and Certificates: Make sure that the containers comply with sanitary requirements and have the necessary certificates. This includes sanitary registration to produce food contact packaging and at least one ISO 9001 certificate. It is also advisable to have BRC and environmental registrations, as well as health certificates for coatings that comply with European and FDA standards.
  2. Varnishes and Coatings: Varnishes used in packaging must be included in the positive list of the FDA or other European health regulatory agencies. This is essential to ensure that packaging is safe for food contact.
  3. BPA-NI Varnish: The varnish used must be of the BPA-NI type, which means that it does not contain bisphenol-A. This is an important requirement for food safety and to avoid exposure to potentially harmful chemicals.
  4. Varnish Quality Control: Varnish loading should be checked to ensure that the proper amount of varnish is applied and polymerization should be checked to confirm that the chemical process has been properly completed. It is also important to check the porosity to ensure that the coating is waterproof.
  5. Curing Conditions: It is necessary to maintain optimum curing conditions for the varnish, which may require keeping the tinplate in the curing oven at a specific temperature for a specific time.
  6. Post-Processing Handling: After sterilization, it is important to control the cooling rate and the final temperature to prevent the containers from remaining wet for longer than is desirable. It may also be necessary to perform drying operations with hot air currents at the cooling outlet to remove residual moisture.
  7. Safety Precautions: When handling containers, appropriate safety precautions should be taken, especially if the containers are suspected to be commercially unsterile.

Remember that the selection of the right varnish and compliance with sanitary and quality procedures are essential to ensure the safety and integrity of the packaged product.