A new method of optical detection of yeast acidification power.

We describe here a newly developed method for a contact-free optical pH measurement in yeast suspensions supplemented with glucose, and containing the pH sensitive triphenylmethane dye bromocresol green. It is suitable for performing the acidification power test (based on measuring the rate of pH drop of yeast suspension caused by active extrusion of acidity from cells after glucose addition) used for assessing yeast vitality in fermentation industries. Using this methodology we monitored the pH in yeast suspensions in the course of acidification in the pH range of 3.5-5.3. Optical pH measurement allows simultaneous testing of several samples, minimizes the sample volume, simplifies sample handling and reduces the hands-on time in sample processing.