Effect of citric acid and citrate on the shelf stability of canned liver paste processed at reduced F(0) values

Citric acid and the combination of citric acid and citrate, in a few cases enriched with potassium sorbate, were tested for their stabilizing effect in a canned liver paste processed at reduced F(0) values. pH values of the rest products ranged from 5·24 to 5·76; a(w) values varied from 0·950 to 0·972. F(0) values of 0·05, 0·30 and 0·85 were applied. Before sterilization, the paste doughs were contaminated with mixtures of bacterial spores. Heated packages were challenged by incubation at 30 and 55°C for up to about 2 years. Incubated packages with the standard formulation at an F(0) of 0·05 showed the first blown cans at 30°C after 24 days. Starting from this point, at this F(0) value products with a variable, but increased, bacteriological stability were observed. At an F(0) of 0·30 a perfectly stable product at 30°C was observed after addition of 0·14% w/w citric acid only (product pH 5·69). Moreover, all tested combinations of additives at F(0) values of 0·30 and 0·85 yielded stable products at this incubation temperature. At the higher F(0) value a clear effect with respect to delaying thermophilic spoilage was observed. The effect of the application of potassium sorbate-in combination with both other additives-at F(0) values of 0·30 and 0·85 proved to be negligible.