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.

Biorefinery of Green Biomass─How to Extract and Evaluate High Quality Leaf Protein for Food?

“…76 Other bacterial strains such as E. coli or Erwinia carotocora can also be used to precipitate the green protein without lowering the pH. 91 The mechanism of this microbial precipitation is, however, not known in detail.…”

“…Both chlorophyll and protein solubility decreases when pH is reduced to a range between pH 3 and 6.5, but chlorophyll precipitates to a higher extent than protein, which can be used to produce a white protein fraction. − Alternatively, the pH of the green juice can be reduced by fermentation using lactic acid forming bacteria resulting in precipitation of a green protein fraction, but the fermentation produces lower protein yields than heat fractionation probably due to proteolysis . Other bacterial strains such as E. coli or Erwinia carotocora can also be used to precipitate the green protein without lowering the pH . The mechanism of this microbial precipitation is, however, not known in detail.…”