Headspace

Liquids expand when frozen so a space must be left in containers which hold liquid foods. Allow a headspace of ½in/12mm in wide-topped containers and ¾in/18mm in narrow-topped containers. When packing fruit, allow ½in/12mm for all dry packs; ½–1 in/12mm–2.4cm per pint/500ml for wide-topped wet packs; ¾–1in/1.8–2.4cm per pint/500ml for narrow-topped wet packs. Allow double headspace for 2 pint/1 litre containers.