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close this bookRenewable biological systems for alternative sustainable energy production. (FAO Agricultural Services Bulletin - 128) (1997)
close this folderChapter 3 - Production of fuel alcohol from cellulosic biomass
close this folder3.4 Use of immobilized yeast cells in alcohol fermentation's
View the document(introduction...)
View the document3.4.1 Preparation of immobilized yeast cells
View the document3.4.2 Continuous plant operation using immobilized yeast cells
View the document3.4.3 Fermentation processes used in ethanol production
View the document3.4.4 Flash fermentation using immobilized yeast cells

3.4.1 Preparation of immobilized yeast cells

Of the various methods used for continuous fermentation, that employing the use of immobilized yeast cells was selected. Methods of yeast immobilization evaluated included collagen casting, acetic acid-lactic acid cellulose microencapsulation, chitosan/glutar-aldehyde molding, carrageenan-entrapping method, and calcium alginate gel-entrapping. Of these, the calcium alginate gel-entrapping method was preferred because of its high enzymatic activity, simple manner of preparation, and stability.

Preparation of a uniform calcium alginate gel, necessitated maintaining the viscosity of the mixture of calcium alginate and yeast cells between 1000 and 2000 cps. The addition of a nonionic surfactant and an unsaturated fatty acid at the time of gelling was also found to improve cell retention and enzyme activity. Preparation of immobilized yeast cells is outlined in Fig 3-15.


Figure 3.15 - Immobilization of yeast cells