Bioprocess Engineering

, Volume 12, Issue 1–2, pp 41–46 | Cite as

Apparent yield stress of xanthan solutions and broths

  • L. G. Torres
  • F. Flores
  • E. Galindo


Apparent yield stress is a very useful rheological property which is important in determining the extent of mixing in xanthan fermentations as well as the suspending ability of the gum solutions. Using a previously developed stress relaxation technique, three commercial products, one home-made product and one dehydrated-reconstituted fermentation broth (DRFB) were characterized in terms of the apparent yield stressτ y of solutions containing different polymer concentrations and when mono and divalent salts or sucrose were added and also when exposing the samples to heat treatment in the case of DRFB. Sodium, potassium, calcium, magnesium, acetate, pyruvate, the mean molecular weight (MMW) and the molecular weight distribution (MWD) were determined. Although the four products showed differences in their chemical characteristics, the pyruvic acid content and the mean molecular weight played the main role in determining the yield stress patterns. With no salt added, the slope of theτ y vs gum concentration plot was a strong and inverse function of the pyruvate content. With NaCl 0.5%, the mentioned slope correlated linearly with the MMW. The three commercial xanthans showed very similar MWD. Xanthan broths showed an exponential, rather than a linear (as it was the case for end-products) function ofτ y in terms of xanthan concentration. No significative differences were found in τy depending on the type of salt. Sucrose decreasedτ y and this effect was more pronounced in DRFB than in a solution of a commercial xanthan.


Fermentation Molecular Weight Distribution Fermentation Broth Pyruvic Acid Stress Pattern 
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  1. 1.
    Galindo, E.: Xanthan gum: a microbial polysaccharide obtained from sucrose, having extraordinary properties and a variety of applications. GEPLACEA Bulletin 5 (September) (1988) 1–8Google Scholar
  2. 2.
    Elson, T. P.;Cheesman, D. J.;Nienow, A. W.: X-Ray studies of cavern sizes and mixing performance with fluids possesing a yield stress. Chem. Eng. Sci. 41 (1986) 2555–2562Google Scholar
  3. 3.
    Hanks, R.;Ricks, B.: Laminar-turbulent transition in flow of pseudoplastic fluids with yield stress. J. Hidronautics 8 (1974) 163–166Google Scholar
  4. 4.
    Darby, R.; Melson J.: How to predict the friction factor for flow of Bingham plastics. Chem Eng (Dec) (1981) 59–61Google Scholar
  5. 5.
    Steff, J.;Morgan, R.: Pipeline design and pump selection for non-Newtonian fluid foods. Food Technol. 40 (1986) 78–85Google Scholar
  6. 6.
    Hannote, M.;Flores, P.;Torres, L.;Galindo, E.: Apparent yield stress estimation in xanthan gum solutions and fermentation broths by a low-cost viscosimeter. The Chem. Eng. J. 45 (1991) B49-B56Google Scholar
  7. 7.
    Galindo, E.; Salcedo, G.; Ramírez, M. E.: Preservation ofXanthomonas campestris on agar slopes: Effects on xanthan production. Appl. Microbiol. Biotechnol. (1994) 634–637Google Scholar
  8. 8.
    Torres, L. G.;Brito, E.;Galindo, E.;Choplin, L.: Viscous behaviour of xanthan aqueous solutions from a variant strain ofXanthomonas campestris. J. Ferment. Bioeng. 75 (1993) 58–64Google Scholar
  9. 9.
    Galindo, E.;Torrestiana, B.;García-Rejón, A.: Rheological characterization of xanthan fermentation broths and their reconstituted solutions, Biopr. Eng. 4 (1989) 113–118Google Scholar
  10. 10.
    Montes, A. L.: Bromatologia. Vol I. Universitaria de Buenos Aires (Edit.), (1966) ArgentinaGoogle Scholar
  11. 11.
    Mc Comb, E. A.;Mc Cready, R. M.: Determination of acetyl in pectin and acetylated carbohydrate polymers. Hydroxamic acid reaction. Anal. Chem. 29 (1957) 819–821Google Scholar
  12. 12.
    Hadjivassiliou, A. A.;Rieder, S. V.: The enzymatic assay of pyruvic and lactic acid. A definitive procedure. Clin. Chim. Acta 19 (1968) 357–361Google Scholar
  13. 13.
    Herbst, H.;Schumpe, A.;Deckwer, W.-D.: Xanthan production in stirred tank fermentors: Oxygen transfer and scale-up. Chem. Eng. Technol. 15 (1992) 425–434Google Scholar
  14. 14.
    Graham, H. D.: Microdetermination of Keltrol (xanthan gum) J. Dairy Sci. 54 (1971) 1622–1628Google Scholar
  15. 15.
    Sanford, P. A.;Pittsley, J. E.;Knutson, C. A.;Watson, P. R.;Cadmus, M. C.;Jeanes, A.: Variation inXanthomonas campestris NRRL B-1459: Characterization of xanthan products of differing pyruvic acid content, In: Sanford P. A. and Laskin, A. (Eds.) ACS Symp. Ser: Extracellular Microbial Polysaccharides, vol. 45, (1977) American Chemical Society, Washington, D.C., pp. 192–209Google Scholar
  16. 16.
    Peters, H-U.;Suh, I. S.;Deckwer, W.-D.: Modeling of batchwise xanthan production. Can J. Chem. Eng. 70 (1992) 742–750Google Scholar
  17. 17.
    Flores, F.;Torres, L. G.;Galindo, E.: Effect of the dissolved oxygen tension during cultivation ofX. campestris on the production and quality of xanthan gum. J. Biotechnol. 34 (1994) 165–173Google Scholar

Copyright information

© Springer-Verlag 1995

Authors and Affiliations

  • L. G. Torres
    • 1
  • F. Flores
    • 1
  • E. Galindo
    • 1
  1. 1.Depto. de Bioingenieria, Instituto de BiotecnologiaUniversidad Nacional Autónoma de MéxicoCuernavaca, MorMéxico

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