GIFSQ Tools · Module 10 — Packaging & Shelf-Life · Tool 185 of 500
Work out the headspace in a pack from the package and product volumes, and how much oxygen that headspace holds at the gas mix you use.
Try sample values — fills the form with the worked example below.
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Headspace (mL)
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Headspace (%)
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Oxygen in headspace (mL)
Equation: Headspace (mL) = package volume − product volume. Headspace (%) = headspace ÷ package volume × 100. Oxygen in headspace (mL) = headspace × oxygen (%) ÷ 100.
Method: Headspace volume balance for rigid and flexible packs. The oxygen figure is the amount present at packing, before any product uptake or film transmission.
Assumptions: volumes are measured at the same temperature; the product volume is the volume it occupies in the pack, not its mass.
Limitations: headspace changes as the product settles, gas dissolves or the film flexes; the oxygen figure falls over storage as the product and microbes consume it.
Rounding: headspace volume to 1 decimal place; percentages to 2 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Method: Headspace volume balance for rigid and flexible packs. The oxygen figure is the amount present at packing, before any product uptake or film transmission.
Assumptions: volumes are measured at the same temperature; the product volume is the volume it occupies in the pack, not its mass.
Limitations: headspace changes as the product settles, gas dissolves or the film flexes; the oxygen figure falls over storage as the product and microbes consume it.
Rounding: headspace volume to 1 decimal place; percentages to 2 decimal places; intermediates unrounded.
This is a calculation aid, not a laboratory report — confirm against your accredited method before citing a value.
Worked example: A 500 mL pack holding 400 mL of product: headspace = 500 − 400 = 100.0 mL (20.00%); at 21% oxygen the headspace holds 100 × 0.21 = 21.00 mL of oxygen.
Enter values above to see results.
Large headspace means more oxygen to remove or flush; MAP packs are usually flushed to under 1% residual oxygen. Tool 185 of 500 — GIFSQ
