Meaning
Geometric ratios used to compare the contact area of packaging to the quantity of food contained within determine the concentration of migrating substances. Performing surface to volume ratio calculations is necessary because smaller containers have more plastic surface area per kilogram of food than larger ones. This difference means that the same material may be safe for a large tub but exceed migration limits for a small portion pack.
Geometric Scaling
Size reduction increases the relative intensity of chemical leaching. During the design of a new bottle, surface to volume ratio calculations show how the migration of additives will change as the container gets smaller. A hundred milliliter container has a much higher ratio than a two liter bottle, leading to higher levels of migrants in the smaller volume.
Exposure Intensity
Contact area determines the total amount of chemical that can transfer.
Compliance Adjustment
Regulatory limits for specific migrants are often calculated using a standard ratio of six square decimetres per kilogram. When actual surface to volume ratio calculations differ from this standard, the laboratory must adjust the results to reflect the real world exposure. This ensures that the safety assessment is accurate for the specific size of the packaging being sold.
