Yeast fodder

A suitable means of scale-up for aerobic processes is to measure the dissolved oxygen level that is adequate in small equipment and to adjust conditions in the plant until this level of dissolved oxygen is reached. However, some antibiotic fermentations and the production of fodder yeast from hydrocarbon substrates have very severe requirements, and designers are hard-pressed to supply enough oxygen. 

The situation with regard to ethanol is much clearer there is long industrial experience in the manufacture of ethanol from wood, by fermentation of the sugars in the waste effluents of pulp mills, or of the sugars made by wood hydrolysis ( ). In the years following World War II, wood hydrolysis plants have been unable to compete economically with petroleum-based ethanol synthesis, mainly by hydration of ethylene, and they have been shut down in most countries. However, in the Soviet Union, we understand, there are still about 30 wood hydrolysis plants in operation (10). Many of these are used for fodder yeast production (11) but the wood sugars are also available for ethanol production. 

A two-stage acid hydrolysis process is employed in over 40 Soviet wood hydrolysis plants (15). These plants have an average annual output per plant of 10,000 t of wood sugar. Most of the output is converted to industrial alcohol and fodder yeast. 

The costs of the carbon and energy sources have only a minor influence on the price of the final protein product the price is mainly determined by the manufacturing costs. Even when the substrate may be obtained free, as in the case of sulfite liquor or waste whey, the price of producing the fodder yeast is still considerable (Humphrey, 1967 Tannenbaum and Mateles, 1968). 

Protein content Wheat Beef Cow s Fodder Yeast from... 

Vitamin Beef Milk Fodder Yeast from Daily... 

Biochemical industry, e.g., algae, fodder antibiotic, yeast extracts, enzymes, etc. 

With respect to the product, the solid sorbent can be neutral (placebo) or active. In the first case, the sorbent is used only as a carrier for heat-sensitive and otherwise hard-to-dry materials. Liquid bioproducts such as antibiotics, enzymes, yeasts, amino acids, and the Uke, which, when conventionally dried, can lose up to 70% of their biological activity, are typical examples. Sawdust, activated carbon, and ground straw or hay are typical solid carriers. After drying, the solid sorbent is either separated from the product or left as is for further utilization, as it is in the case of fodder antibiotics [17]. Figure 21.4 shows the co- and countercurrent modes of contacting solid carriers with liquid biomaterials in a spray dryer configuration. 

An example of the special spray dryer construction to drying of a suspension of antibiotics, fodder yeast, amino acids, and enzymes is shown in Figure 45.11 [20], Inside the dryer chamber a sweeper rotates along the wall. The cleaning is made by air of proper parameters, such as pressure and temperature, which is introduced by nozzles installed on the sweeper. The air, or an inert gas, prevents the material from sticking to the wall and cools down to a thermolabile substance. A similar result can be... 

In this way, paraffins are converted with ammonia and oxygen from the air, in the presence of mineral salts, to proteins with the approximate compositions of CH1.7O0.5N02. CO2 and water are also products of this synthesis and heat to the extent of 32 000 kJ/kg dry mass is released. The dense yeast pulp is separated from the unconverted paraffins by centrifugation and then very thoroughly washed. The yellowish product is used as animal fodder. 

In Germany during World War II, yeasts were produced on wood sugars obtained by hydrolysis of wood wastes. However, these uneconomic processes will not be viable in a free economy. In the Soviet Union today, over 900,000 tons of fodder yeast are produced from wood sugars. Several major processors have been trying to develop a direct fermentation of cellulose. However, slow reaction times and low cell yields have caused most processes to be uneconomical. 

The use of simple saccharides or disaccharides to grow fodder or bakers yeast has been common for some time. The carbon atoms are easily assimilable by microorganisms. 

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