Analytical Sciences

The Use of a Gas Chromatography/Milli-whistle Technique for the On-line Monitoring of Ethanol Production Using Microtube Array Membrane Immobilized Yeast Cells

Ming-Ju WU,* Guan-Fu YE,* Ching-Hao WANG,* Hong-Ting Victor LIN,** Chien-Chung CHEN,*** and Cheng-Huang LIN*

*Department of Chemistry, National Taiwan Normal University, 88 Sec. 4, Tingchow Road, Taipei, Taiwan
**Department of Food Science, National Taiwan Ocean University, No. 2, Pei-Ning Road, Keelung 202, Taiwan
***Graduate Institute of Biomedical Materials and Tissue Engineering, Taipei Medical University, 250 Wu-Hsing St., Taipei, Taiwan

Hollow, poly(L-lactic acid) microtube array membranes (MTAM) were used in preparing membranes that contained immobilized yeast cells. To evaluate the performance of the developed system for continuous and fed-batch fermentation, a gas chromatography/milli-whistle device was used to on-line monitor the production of ethanol. The milli-whistle was connected to the outlet of a GC capillary, and when the fermentation gases and the GC carrier gas passed through it, a sound with a fundamental frequency was produced. The online data obtained for frequency-change vs. retention time can be recorded after a fast Fourier transform. In typical bioethanol fermentation, the yeast cells cannot be recycled, whereas the artificial yeast-MTAMs can be. The hollow-MTAM containing immobilized yeast cells significantly enhanced to bioethanol productivity, and represent a novel, promising technology for bioethanol fermentation. Our data indicate that the gas chromatography/milli-whistle device, which is economical and stable, is a very useful detector for long-term monitoring.

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