3. Sterilizing for too long a period.
4. Lack of sizing whole products for the container.
Sometimes there is a natural shrinkage that cannot be prevented. This is due to the fact that vegetables contain air in their tissues and when this air is driven off by the heat, the boiling water in the jar rushes in to fill its place. In consequence we have an apparent shrinkage in the amount of water. So be careful to do the blanching as correctly as possible to drive out the air; however, the product will keep just as well in a jar half full of water as if entirely covered with liquid. The contents of the jar whether food or air are sterile.
SHRINKAGE OF GREENS
Shrinkage of greens or pot herbs during the canning process is usually due to insufficient blanching. The proper way to blanch all greens or pot herbs is in a steamer or in a vessel improvised to do the blanching in live steam above the water line. If this is not done much of the mineral salts and volatile oil contents will be extracted by the water and lost.
LOSS OF LIQUID DURING CANNING
A loss of liquid in canning with a hot-water-bath outfit may be caused by one or more of the following:
1. Not having the water in the sterilizing vat cover the tops of the jars by at least one inch.
2. Not providing a suitable platform to hold the jars off the bottom of the sterilizing vat, permitting circulation of water under as well as around the jars.
3. Not having the wire bail that goes over the glass tops of jars sufficiently tight.