Yeasts recovery

Taking the idea of yeast recovery one step further is continuous fermentation. This incorporates a vessel or vessels inoculated with yeast through which the fermentable substrate is passed continuously. The flow is designed to ensure that all the sugar is fermented before it exits the final fermenter as beer. This beer is clarified to remove any entrained yeast cells and a percentage of the yeast is recycled back into the system. 

Fig. 20.9 A beer and yeast recovery system. 1. Fermenter 2. Beer clarifier 3. Surge tank 4. Yeast suspension tank 5. Filter aid mixer 6. Yeast (autolysis) tank 7. Rotary vacuum filter 8. Top feed applicator 9. Precoat applicator 10. Yeast suspension spray 11. Defoamer 12. Vacuum pump 13. Beer recovery tank 14. Pasteurizer 15. Yeast drier A. Wort preparation B. Beer treatment C. Dried yeast. (Based on drawing of Alfa-Laval Ltd.)...

The recovery of recombinant chymosin from a yeast fermentation broth showed that large-scale hydrophobic interaction chromatography could... 

Many other recovery alternatives have been proposed that iaclude ion exchange (qv), pyrolysis, and wet combustion. However, these have not gained general acceptance. A limited number of calcium-based mills are able to utilize their spent pulpiag liquors to produce by-products such as lignosulfates for oil-weU drilling muds, vanillin, yeast, and ethyl alcohol (see PETROLEUM Vanillin). 

Abfallerzeugnis, n. waste product. Abf everWertung,/. utilization of waste. Abfall-fett, n. waste fat or grease, -gummi, n. waste rubber, scrap rubber, -gut, n. waste material (to be treated for recovery), -hefe, /. waste yeast, -holz, n. waste wood, abfallig, a. falling off, sloping, etc. (see abfallen) deciduous adverse. 

The process is used mostly for industrial separations, such as the removal of yeast from beer or the recovery of emulsified cutting oils. It has been proposed as a pretreatment to RO for fouling waters, but the economics do not yet look attractive. 

Microbial cell recovery is carried out in a continuous disc-stack centrifuge. The centrifuge is operated at 5000 rpm for separation of baker s yeast. At a feed rate of 601/min, 50% of the cells are recovered. At constant speed, solid recovery is inversely proportional to flow rate. 

Table 17.1. Mass balance of G3PDH recovery from baker s yeast in direct process integration...

Bauer and co-workers (Rottenbacher, 1985 Rottenbacher et ah, 1987) carried out anaerobic fermentation under nitrogen gas at 18-20°C in a gas-tight closed circuit with a partial condenser followed by a gas adsorber for ethanol and water vapour recovery. The highest rate of ethanol production was about 50gh with a bed of 2.4 kg of extruded cylindrical baker s yeast pellets of diamefer 800 rm. This rate is less... 

When sugar that is produced by the Scholler process is fermented by the acid-producing organism, the yield is only 35% of the total sugar. If the solution is first fermented by yeast, however, a 37 % yield of alcohol is produced, and from the residual liquor fermented by the butyric acid organism, a 15.5% yield of acids is produced, making a total recovery of 52.5%. 

Whole cells of yeast [BMIMllPFgl/buffer (two-phase) Recovery of ra-butanol from fermentation broth 33... 

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