What is head space?
1) It is the empty space between the top package content and the brim. It is a must, a necessity to all containers. Get a bottle of juice. Pay for the glass bottle, cap, juice and lastly, pay for the empty space.
2) Provided to allow expansion of product during heat processing and prevent spilling. High temperature makes the product molecules excited, pushing each other apart thus making the volume much bigger. A tightly sealed container with no empty space is likely to explode when heated.
3) The place where aerobic microorganisms grow in case the package is not air tight. Container should always be airtight unless something went wrong back in the process.
4) It is either filled with natural mixture of gases, partial vacuum – done by capping while still hot or pumping the air our mechanically, or filled with carbon dioxide – the case of carbonated beverages and sparkling wines. A bottle fruit jam has a slightly recessed cover – a sign of vacuumed head space . Soft drinks plastic cap are slightly embossed as proof of carbonation.
5) Allows the partial insertion of filling tools like funnel and automated filling tube. Inserting the filler mechanism reduces spills.
6) Cheating might be done by means of head space. Intentionally increasing the head space decreases the product contents.
7) Contrary to item “6”. A mean to immediately identify under-filled products. True only for transparent packages like glass and plastic bottles.
8) Make the “shake well before using” instruction possible. How can you shake a viscous ketchup if sufficient head space was not provided? Transfer to a larger container and shake. Transfer is not necessary cause head space always exists.
I never know if there is a rule of thumb regarding the height or volume needed for the head space. Please enlighten me!