Microbial spoilage of whole sheep livers.

When liver treated with antibiotics to inhibit microbial growth were held at 10 degrees C, the initial high pH (6.4) declined as lactic acid accumulated throughout the storage period of 10 days. The glycogen content also declined, but the glucose concentration in the tissues remained high. When livers were allowed to spoil at 10 degrees C, distinct but variable floras developed within the tissues, in the drip, and on the upper surface. Deep-tissue floras were composed of anaerobic and facultative organisms (Lactobacillus, Enterobacter, Aeromonas); surface floras were generally dominated by strictly aerobic organisms (Pseudomonas, Acinetobacter); drip floras contained variable proportions of organisms of all three types, but the facultatively anaerobic Enterobacter were usually present as a major component. Spoilage occurred after 4 to 6 days with the development of visible discrete colonies on the upper surface without spoilage odors being evident. Changes in tissue and drip composition due to microbial activity could be detected only when spoilage had reached an advanced stage.