OnTap Magazine

YEAST HARVEST IN BREWERIES WITH ITM-3 THE TURBIDITY METER Consumers expect a filtered beer to be a clear, bright, non-hazy product that remains so during its shelf life. Hazy products, unless the style of beer requires it, are often regarded as defective and perhaps even potentially harmful. Therefore, controlling haze formation is an important aspect in beer production. During fermentation, the yeast pitched into the wort multiplies two- to three- fold through respiration of the oxygen dissolved in the wort. The lowest, densest layer consists of dead yeast cells. The middle and still very dense layer consists of living yeast cells with a high fermentation power known as “white yeast”. The upper layer, or light brown yeast, is mixed with beer and is less turbid (Fig. 1) During the first yeast harvest, the bottom two layers are carefully extracted and separated because the white yeast is reused, or even marketed, as so-called “pitching yeast”. During the storage and ageing period, the remaining yeast largely settles out as brown yeast. When the tank is emptied, the brown yeast is carefully separated from the beer as this has a major impact on the beer quality. Many breweries still monitor yeast harvesting manually. The process is controlled by checking the turbidity through a sight glass. The Anderson-Negele Solution Due to differences in the number of yeast cells and in the density of the yeast layers, turbidity measurement can be used to differentiate between the layers. For this purpose, an ITM-3 turbidity meter is installed at the fermentation tank outlet. It continuously measures the turbidity in % and outputs the measured values as a 4...20mA analog signal to the process controller. By simply adjusting the set points, the yeast harvest can now be controlled precisely, reproducibly and automatically. The advantages - Precise, reproducible measurement guarantee a consistent product quality. - Time saving quickly amortize the cost of investment and make production more profitable on a lasting basis. - Favorable price-performance ratio. ITM-3 TURBIDITY MEASUREMENT Applications and specific use: Media with a turbidity > 500EBC / 200 NTU Phase separation of products CIP - return (monitoring of pre-rinse water and cleaning solutions to product leftovers) Rinse Control Yeast harvesting in breweries Leakage control of filter and gaskets ITM-3 YOUR PARTNER FOR ACCURATE MEASUREMENT AND EXPERT SUPPORT INSTRUMENTATION, CONTROL & FACTORY AUTOMATION FOR THE BREWERY INDUSTRY +27 12 998 6326 Fax: 086 508 7575 info@instek.co.za www.instek.co.za 1. 2. 3. 4. 5. 6. 1. Fermentation tank 2. Young beer 3. Light Brown yeast 4. White yeast 5. Dead yeast 6. ITM-3 Turbidity measurement 7. Further processing Fig. 1. Fermentation tank with the measuring point