Bacteriological studies on sulfid spoilage of canned vegetables
Iowa Agriculture and Home Economics Experiment Station Research Bulletin: Volume 9, Issue 117
Sulfid spoilage of canned vegetables is characterized by the marked blackening of the contents and the production of hydrogen sulfid by the organism responsible. Externally the can manifests no characteristics of spoilage; it does not swell or spring.
The condition constitutes a new type of thermophilic spoilage due to insufficient processing. It has caused losses in both the sweet corn and pea canning industries of the middle western states. The general characteristics of the spoilage have led to the designation of "sulfid spoilage" for this type.
Sulfid spoilage in canned sweet corn has been shown to be caused by a thermophilic sporulating heat resistant anaerobe. Study of the cultural and physiological characters of the organism indicates that it is an undescribed species, for which the name Clostridium nigrificans has been proposed.
Processing at 118°C. (245 °F.) for 70 minutes has not proved effective in destroying the spores of Clostridium nigrificans in No. 2 cans of sweet corn.
In the-light of experimental evidence now available, it seems desirable in the control of Clostridium nigrificans to elminate the foci of infection in the cannery and prevent the presence of spores in the product. Prevention of contamination in the plant by avoiding' the use of raw materials harboring the organism may offer a way of control if it can be shown that the organism is carried into the cannery on certain raw materials.
The effect of Clostridium nigrificans on different canned vegetables has been pointed out. It would seem that there is little possibility of the organism causing spoilage in vegetables other than peas and sweet corn. In a large number of cases the acidity of the canned product is sufficient to prevent growth of the organism.
Clostridium nigrificans occurs in the soil, in manure and on sugar and probably finds its way into the cannery in these materials, where it may set up a focus of infection.