a. Factors Causing Ham Souring. Ham souring is a complicated condition for
which there is no one cause, but instead a group of causes are responsible for this
condition. The following factors must be present in order for ham souring to develop:
(1) Portals of entry. Some common examples are agonal (at time of death)
invasion, sticking, eviscerating, sawing bones, pumping vessels, and the scalding vat.
(2) Ability of bacteria to grow at curing cellar temperatures. There must be
a temperature of 34 to 38F (1.11 to 3.33C) for twenty to sixty days.
(3) Types of bacteria capable of producing souring. Types of bacteria,
which do produce souring, must be present.
(4) Proper oxygen requirements. Proper oxygen requirements for bacteria
must be present.
(5) Halophilic characteristic. Bacteria must be halophiles ("salt lovers") or
they must be able to adjust to high salt concentrations.
Resistance to nitrate and nitrite. Bacteria must be resistant to nitrate
b. Preventive Measures. Some of the effective measures used in preventing
ham souring are:
Bacteriologically controlled pickle solution.
Adequate chilling and refrigeration.
Processing of carcass and placement in chill room as rapidly as
Careful sawing of the shank bone.
c. Characteristics. Ham souring may develop either in the flesh of the ham or
in the bones in the ham and will impart a characteristic putrid odor.