Poster 3-31

José D. Fontana,^a Mauricio Passos,^a José Luiz F. Trindade,^b and Luiz P. Ramos^b

aBiomass Chemo/Biotechnology Laboratory
Department of Biochemistry
Federal University of Parana
P.O. Box 19046
Curitiba, PR, Brazil 81531l-990

bResearch Center on Applied Chemistry, Federal University of Parana, Curitiba, PR, Brazil

Telephone: +55-41-366-3144, Ext. 180; Fax: +55-41-266-2042; E-mail: jfontana@bio.ufpr.br

Classic mineral catalysts (H₂SO₄ and HCl) are still used for maize and cassava starch depolymerization to produce glucose syrups in Parana State, Brazil, and elsewhere.

Aqueous thermopressurized phosphoric acid is a pioneering technology developed for the selective depolymerization of sugarcane bagasse hemicellulose (heteroxylan), producing a free xylose syrup along with a residual lignocellulose with improved digestibility for ruminants. The process was also employed for dahlia inulin monomerization to fructose syrup, using milder hydrolytic conditions.

Kinetic conditions were established for the depolymerization of cassava starch to maltodextrins and glucose syrups. Thin-layer chromatography and HPLC analyses corroborated that the proper H₃PO₄ strength and thermopressurization range (150–170EC, 3.7–6.8 atm) can be successfully explored for such hydrolytic purposes. Maintaining phosphoric acid in the hydrolyzates is advantageous since neutralization with ammonia generates the key nutrients for industrial fermentations (C, P, N), thus avoiding the additional steps (e.g., gypsum centrifugation and ion exchange) required for classic catalysts. Furthermore, phosphoric acid is an acceptable additive in soft drinks since its acidic taste is compatible and/or synergistic with both natural and artificial sweeteners.

Cassava starch hydrolyzed by this technique was upgraded to high-value single-cell protein (e.g., the pigmented biomass of Xanthophyllomyces dendrorhous or Phaffia rhodozyma), for which the level of astaxanthin (dihydroxy-diketo-$-carotene) may reach 0.5 mg/g dry yeast. This is an ideal complement for animal feed to provide natural color to meat (fish) and poultry (eggs).

[Patent request submitted to INPI-Brazil; funding provided by CNPq-PADCT, PRPPG-UFPR]