Nano-Tubular Cellulose for Bioprocess Technology Development

Delignified cellulosic material has shown a significant promotional effect on the alcoholic fermentation as yeast immobilization support. However, its potential for further biotechnological development is unexploited. This study reports the characterization of this tubular/porous cellulosic material, which was done by SEM, porosimetry and X-ray powder diffractometry. The results showed that the structure of nano-tubular cellulose (NC) justifies its suitability for use in “cold pasteurization” processes and its promoting activity in bioprocessing (fermentation). The last was explained by a glucose pump theory. Also, it was demonstrated that crystallization of viscous invert sugar solutions during freeze drying could not be otherwise achieved unless NC was present. This effect as well as the feasibility of extremely low temperature fermentation are due to reduction of the activation energy, and have facilitated the development of technologies such as wine fermentations at home scale (in a domestic refrigerator). Moreover, NC may lead to new perspectives in research such as the development of new composites, templates for cylindrical nano-particles, etc

Domestic refrigerator wine making.

<p>(a) Fermentation kinetics observed at 1°C of freeze dried mixture of invert sugar and NC-yeast biocatalyst. (b) Fermentation kinetics at 1°C of freeze dried mixture of grape must and NC-yeast biocatalyst. (c) Fermentation kinetics observed at 1°C of freeze dried mixture of raisins and NC-yeast biocatalyst. Fermentation kinetics using free freeze dried cells are also shown in all Figures (a), (b) and (c). (d) SEM micrograph of the freeze dried mixture of grape must and NC-yeast biocatalyst (scale bar corresponds to 20 µm).</p

“Glucose pump”.

<p>(a) Cell is immobilized on cellulose fiber by hydrogen bonding. (b) Glucose also attached on the surface of the cellulose fiber by hydrogen bonding. (c) Glucose is transferred inside the cell. (d) Glucose is biochemically converted inside the cell. (e) After glycolysis, alcoholic fermentation and other processes, ethanol and other fermentation products are produced and transferred to the solution, and another cycle begins.</p

Quality of the wine produced in the refrigerator using mixture of freeze dried grape must and freeze dried biocatalysts.

<p>(a) Effect of temperature on esters and alcohols formation during alcoholic fermentation of mixtures of freeze dried grape must and freeze dried biocatalysts. Tr: compounds <1 µg/L (traces), nd: not detected. FDNCB: Freeze dried NC-yeast biocatalyst, FFDC: Free freeze dried cells. (b) Effect of temperature on the ratio of esters-to-alcohols formed during alcoholic fermentation of mixtures of freeze dried grape must and freeze dried biocatalysts. (c) Effect of temperature on the (%) percentage of ethyl acetate and amyl alcohols on total volatiles formed during alcoholic fermentation of mixtures of freeze dried grape must and freeze dried biocatalysts. Plots show means of three replicates with standard errors. (d) Sensory evaluation of commercial wine and wines produced by freeze dried free cells and freeze dried NC-yeast biocatalyst.</p

Nano-tubular cellulose (NC) and promotion of the alcoholic fermentation.

<p>(a) Fermentation kinetics observed at 25°C and 15°C by free cells and cells immobilised on NC (NC-yeast biocatalyst). (b) Arrhenius plot for evaluation of the activation energy and the pre-exponential factor of alcoholic fermentation performed with free and NC-yeast biocatalyst. (c) Activation energies and reaction rate constants of the fermentations made using free cells (FC) and cells immobilised on NC (IC).</p

Nano-tubular cellulose (NC) in food, environmental and health care applications.

<p>(a) Removal of bacteria and yeasts from water (22–26°C). (b) SEM micrograph of <i>L. casei</i> flocculation in NC that was sampled from the bioreactor, which was pumped at low temperature (5°C) with its liquid culture for cold pasteurization (scale bar corresponds to 10 µm).</p