P135: Optical non-intrusive measurement of dissolved oxygen and pH in a simulated fermentation process of wine

Optical oxygen and pH sensors developed by Ocean Optics use a glass like sol-gel thin film which is sensitive to these analytes. The thin film is coated on flexible patches that can be employed inside the fermentor wall and optically interrogated non-intrusively. For oxygen sensing, this glass film has ruthenium compound embedded in the host sol-gel matrix. The fluorescence of the ruthenium is quenched depending on the oxygen level. Ocean Optics phase fluorometer is used to measure this rate of fluorescence quenching and computes it for the amount of oxygen present. Multimode optical fibers are used for transportation of light from an LED source to the sensor and from the sensor to phase fluorometer. For pH sensing, the sol-gel film is doped with colorimetric indicator dye, and is then overcoated with a thin, optically reflective film. Absorbance at specific wavelengths is correlated to pH level through a simplified algorithm. This new oxygen and pH sensing system yields an inexpensive solution for monitoring the dissolved oxygen and pH during the process of fermentation in winery and brewery industries. This study monitors the consumption of oxygen and changes in pH in grape juice left to ferment with yeast and yeast nutrient at a controlled temperature.