Packaging foods in glass
Practical Action
Second hand bottles must be thoroughly inspected, both by looking for chips etc and also by
smelling the containers to make sure that they have not been used for storing kerosene or
poisonous chemicals (insecticides etc). All contaminated containers should be removed and
not used for foods.
Second hand containers should be soaked in a 1% solution
of caustic soda with detergent to remove old labels. The
interior should be cleaned with a bottle brush (Figure 1) and
then rinsed thoroughly. Rinsing is time consuming and can
be speeded up using a bottle rinser (Figure 2).
Many foods that are packaged in glass are then heat
processed and for these it is usual to hot-fill the containers
(fill at 80°C or above). Glass has to be heated and cooled
carefully to avoid the risk of breakage and therefore it is
usual to pre-sterilise containers before hot filling. This can
be done by placing bottles/jars in a large pan of warm water
and heating it to boiling. The containers are boiled for 10
minutes and then removed for immediate filling and sealing.
Figure 1: Bottle brush
Alternatively a steamer (Figure 3) can be constructed and
bottles/jars steamed for 1-2 minutes. This uses less energy and
saves considerable amounts of time compared to using boiling
water. However, care is needed to make sure that the containers
are not heated too quickly, as they will break. Any weak
containers will also break at this stage and bottle sterilisation
should therefore be carried out away from the food production
area to avoid the risk of contamination by broken glass.
Tongs as shown in Figure 3 should be used in all cases when
handling hot containers.
Figure 2: A bottle rinser
For foods that are cold filled and then heat processed it is not
necessary to pre-sterilise the container. For cold filled foods that
are not subsequently heated it is essential to make sure that the jar or bottle is sterilised by
one of these methods to prevent contamination of the product by any micro-organisms on
the glass.
Filling
Most foods that are packaged in glass are
either liquids, such as drinks and syrups or
thicker pastes such as sauces, chutneys etc.
There are basically two types of filling
equipment: those used for solid foods and
others for liquid foods.
Figure 3: A steamer
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