To the meat inspector, a sour ham is one which has a tainted or “off”
odor, that is, any odor which deviates from the normal. The odor may be
very slight, so slight that at times only the trained meat inspector
can detect it. When slight, the odor is elusive and hard to define, but
when pronounced it has a distinctly putrefactive quality. When not very
pronounced, the odor possesses, as a rule, a slightly sour quality,
chemically speaking, and at times this sour quality may be quite
marked; hence the term “sour ham,” or “sour” has originated. In a badly
soured ham—using the term “sour” in the packing-house sense to denote
any ham that is tainted—the odor loses this sour quality and becomes
distinctly putrefactive in nature.