Optical Absorption Sensors for Evaluation of Yeast Acidification Power

The acidification power test provides a fast and simple method of assessing the ability of cells to perform a successful fermentation. It has been used as a rejection criterion for assessing the technological quality of starter yeast cultures in brewing, cider production, baking, as well as cheese making based on lactic acid bacteria. The cell acidification power responses to pH decrease of the environment after glucose addition. We have prepared novel recognition elements of pH sensors suitable for evaluation of yeast acidification power by absorption of two pH sensitive sulfonphthalein dyes (bromocresol green and bromophenol blue) into hydrogel of poly(2-hydroxyethyl methacrylate-co-ethylene dimethacrylate). The absorption spectra, function ranges, pKa values, and response times for each absorbed dye were evaluated, compared with the free dyes, and further discussed with regard to its application to the acidification power test