US EPA

1618825 

Journal Article 

ALCOHOL PRECIPITATION OF XANTHAN GUM FROM PURE SOLUTIONS AND FERMENTATION BROTHS 

Flahive, JJ; Foufopoulos, A; Etzel, MR 

1994 

1 

Separation Science and Technology
ISSN: 0149-6395
EISSN: 1520-5754 

29 

13 

1673-1687 

WOS:A1994PF43900002 

Xanthan gum was precipitated from pure solutions and
fermentation broths using either ethanol, isopropanol, or tert-butanol. The compositions of the
precipitate and supernatant phases were determined as a function of alcohol concentration and
used to construct binodal solubility curves with tie lines. Xanthan did not precipitate at bulk-
mixture alcohol concentrations below 37.5% (wt) for ethanol, 35% for isopropanol, and 31% for
tert-butanol. As the alcohol concentration increased beyond this point, the precipitates first
were heavy gels with low xanthan concentrations. At higher alcohol concentrations, the
precipitates were compact and fibrous. The maximum xanthan concentration in the precipitate was
14.5% at 60% ethanol, 23.5% at 50% isopropanol, and 33.5% at 40% tert-butanol in the pure
solution precipitation experiments. At alcohol concentrations beyond 75%, the precipitates were
brittle and needle-like, which made separation from the supernatant difficult. The results for
the fermentation broth experiments were very similar to those of the pure solution experiments.
Thus, precipitation using ethanol required the highest alcohol usage and resulted in the lowest
xanthan concentration in the precipitate. Conversely, tert-butanol required the least alcohol for
precipitation and formed the precipitates highest in xanthan concentration. 

XANTHAN GUM; PRECIPITATION; FERMENTATION BROTHS; BINODAL SOLUBILITY CURVE; ETHANOL; ISOPROPANOL; TERT-BUTANOL