Estimation of Yeast Glycogen Content from the Mid-Infrared Spectra of Yeast

Abstract

The mid-infrared spectra of dried yeast samples taken from various stages of the fermentation process were recorded. Because differences were small, the second derivatives of the absorbance spectra were taken to enhance spectral features. Differences noted in the carbohydrate peak regions were related to the relative concentrations of yeast glycogen (energy reserve carbohydrate) and yeast mannan (structural cell wall carbohydrate). The absorbance ratios of glycogen peaks to those of mannan were calculated from the second derivative spectra and were correlated to glycogen values for the same set of yeasts assayed by an enzymatic method. The infrared method offers the advantages of being more rapid and simpler to perform than are enzymatic methods.