Glucose In Fermentation Process Research Articles

Monitoring of glucose in fermentation processes by using Au/TiO2 composites as novel modified electrodes

This paper demonstrates an effective method of monitoring glucose in fermentation processes based on the development of enzyme-free glucose electrochemical sensors. The sensing electrodes were manufactured by preparing size-controlled Au nanoparticles (NPs), in the form of colloidal solutions, which were dispersed on TiO2 substrates, and then deposited on commercial carbon screen printed electrodes. The as-synthesized samples were fully characterized by transmission electron microscopy, X-ray diffraction, atomic absorption spectroscopy, and UV–visible diffuse reflectance spectroscopy to obtain information about their morphological, structural, and electronic properties. Particularly, the ability to control the size of Au NPs in the colloidal solution by using different reducing agents and stabilizers is presented here. The Au/TiO2-based modified sensors were assembled and tested for glucose monitoring in an alkaline solution. Results of cyclic voltammetry showed the high electrocatalytic activity of these sensors toward glucose oxidation, whereas no response was detected toward ethanol. This suggests the possibility of using this type of sensor for glucose monitoring in the fermentation processes without ethanol interference. The efficient sensing properties of Au NP-embedded TiO2 composites may be ascribed to the higher electrocatalytic activity of smaller Au NPs stabilized on TiO2.

Infrared and near-infrared technology for the food industry and agricultural uses: on-line applications

Mid-infrared and near-infrared spectroscopy are well-known analytical tools for the food industry but they have different properties. On comparison, due to its lower absorption coefficients, near-infrared allows quantitative analysis, especially on solid samples, whereas, due to its high selectivity, mid-infrared is most suitable for qualitative analysis. The aim of this article is to present general guidelines for the choice of a technology according to the type of problem, of their use in two specific cases. The first example describes the most appropriate system for the quantification of individual sugars in a liquid mixture. Fourier transform/infrared spectroscopy is used to detect fructose and glucose in fermentation processes with standard errors of prediction respectively equal to 2.4 and 3.6 g/l. The second example describes a tool for solid product control at a high speed: near-infrared coupled with optical fibres is selected to detect sugar in fruit at a rate of three fruits per second.

Determination of glucose in fermentation processes by means of an on-line coupled flow-injection system using enzyme sensors based on chemically modified electrodes

The application of an inexpensive, easy-to-make and disposable biosensor, based on a chemically modified graphite electrode with an adsorbed and cross-linked layer of glucose dehydrogenase, as a detector in a flow-injection system for on-line monitoring of glucose in fermenters is described. The performance of the sensor as a function of time is investigated, and used for assaying glucose in a wine fermentation process. It is concluded that the sensor operates satisfactorily during at least 3 days of continuous use. No interference from ethanol is encountered. With regard to practical applications, special emphasis is placed on the interfacing of the fermenter and the analytical system.

Monitoring of glucose in fermentation processes using a commercial glucose analyser

A commercial glucose analyzer, originally designed for monitoring of blood glucose in patients, was tested for use in fermentation processes. The system operates in such a way that the measured value is updated every 90 seconds. The measuring range of the system is 0–5 g glucose/l and the accuracy is ±7%. The response time was found to be approximately 6 min. The system was used to follow fermentations with two different microorganisms, Saccharomyces cerevisiae and Escherichia coli in media containing up to 5 g/l of glucose. The performance was fully satisfactory and the values had a very good correlation with off-line analyses.