YEAST PROTEIN MEASUREMENT USING NEAR-INFRARED REFLECTANCE SPECTROSCOPY

The measurement of total protein in yeast cells is useful for fermenta tion and yeast research as well as for byproduct improvement studies. The protein content of the cell changes with alterations in several fe rmentation and medium parameters and during the course of the cell cyc le. In general, the protein content of the harvested cells is maximise d under conditions ideal for yeast growth. Brewers often sell excess y east as a byproduct and the quality of the yeast, as well as the assoc iated price per unit weight, are often determined by the protein conte nt. Many methods to measure the protein content in yeast cells exist b ut can be impractical for various reasons or prone to error. In this r esearch, a method was developed to measure the protein content of yeas t cells by near infrared reflectance spectroscopy (NIR) - a technique which is finding many applications in brewing and is simple, rapid and amenable to on-line control systems. With this latest application for NIR, it is now possible to measure yeast glycogen, trehalose and prot ein contents on the same sample in less than 30 minutes including a sa mple preparation time of 25 minutes.