Microbial coagulation of alfalfa green juice

Abstract

Of the different bacterial strains isolated from alfalfa raw material, nine were able to coagulate the protein fraction of alfalfa green juice. The two strains showing the highest efficiency were further used for coagulation experiments. They were classified as Erwinia carotovora and Escherichia coli. Juice samples inoculated (1:10 to 1:100) with stationary-phase cultures were efficiently coagulated. The amount of protein recovered was equivalent to that obtained when the juice was heat treated. A minimal incubation temperature of 30 degrees C was required. The protein coagulum appeared after 8 to 10 h of incubation. During this period no bacterial growth was apparent, but glucose was actively fermented. For both strains no extracellular enzymatic activity could be shown in the culture supernatants. The fermentative metabolism during the incubation period seems to be responsible for protein coagulation.