Yeasts production

K. marxianus var. fragilis which utilizes lactose, produces a food-giade yeast product from cheese whey or cheese whey permeates collected from ultrafiltration processes at cheese plants. Again, the process is similar to that used with C. utilis (2,63). The Provesteen process can produce fragiUs yeast from cheese whey or cheese whey permeate at cell concentrations ia the range of 110—120 g/L, dry wt basis (70,73). 

Bakers Yeast Production. Bakers yeast is grown aerobicaHy in fed-batch fermentors under conditions of carbohydrate limitation. This maximizes the yield of yeast biomass and minimizes the production of ethanol. Yeasts grown under these conditions have exceUent dough leavening capabHity and perform much better in the bakery than yeast grown under anaerobic conditions. 

R w Until the 1930s, grain worts were used as the principal carbon and energy sources for yeast production. Since then, cane and... 

Fermentation Processes. The efficient production of penicillin, yeasts, and single-ceUed protein by fermentation requires defoamers to control gas evolution during the reaction. Animal fats such as lard [61789-99-9] were formerly used as a combined defoamer and nutrient, but now more effective proprietary products are usually employed. Defoamer appHcation technology has also improved. For example, in modem yeast production faciHties, the defoamers are introduced by means of automatic electrode-activated devices. One concern in the use of defoamers in fermentation processes is the potential fouHng of membranes during downstream ultrafiltration (qv). SiHcone antifoams (43,44) seem less troubled by this problem than other materials. 

For the yeast process from n-alkanes, which of the following contributes most to the cost of yeast production, and which contributes least (Tables 4.7 4.11 and 4.12 are helpful). 

Table 2.2. Effect of aeration rate on baker s yeast production ...

Whole cells are grown for a variety of reasons. The cells may perform a desired transformation of the substrate, e.g., wastewater treatment the cells themselves may be the desired produce, e.g., yeast production or the cells may produce a desired product, e.g., penicillin. In the later case, the desired product may be excreted, as for the penicillin example, and recovered in relatively simple fashion. If the desired product is retained within the cell walls, it is necessary to lyse (rupture) the cells and recover the product from a complex mixture of cellular proteins. This approach is often needed for therapeutic proteins that are created by recombinant DNA technology. The resulting separation problem is one of the more challenging aspects of biochemical engineering. However, culture of the cells can be quite difficult experimentally and is even more demanding theoretically. 

Yeast extract and other yeast products Meat extract (Marmite)... 

The main limitation to the clinical use of the MAOIs is due to their interaction with amine-containing foods such as cheeses, red wine, beers (including non-alcoholic beers), fermented and processed meat products, yeast products, soya and some vegetables. Some proprietary medicines such as cold cures contain phenylpropanolamine, ephedrine, etc. and will also interact with MAOIs. Such an interaction (termed the "cheese effect"), is attributed to the dramatic rise in blood pressure due to the sudden release of noradrenaline from peripheral sympathetic terminals, an event due to the displacement of noradrenaline from its mtraneuronal vesicles by the primary amine (usually tyramine). Under normal circumstances, any dietary amines would be metabolized by MAO in the wall of the gastrointestinal tract, in the liver, platelets, etc. The occurrence of hypertensive crises, and occasionally strokes, therefore limited the use of the MAOIs, despite their proven clinical efficacy, to the treatment of atypical depression and occasionally panic disorder. 

The "cheese effect" is a well-established phenomenon whereby an amine-rich food is consumed while the patient is being treated with an irreversible MAOI. Foods which cause such an effect include cheeses, pickled fish, yeast products (red wines and beers, including non-alcoholic varieties), chocolate and pulses such as broad beans (which contain dopa). It appears that foods containing more than 10 mg of tyramine must be consumed in order to produce a significant rise in blood pressure. Furthermore, it is now apparent that there is considerable variation in the tyramine content of many of these foods even when they are produced by the same manufacturer. Therefore it is essential that all patients on MAOIs should be provided with a list of foods and drinks that should be avoided. 

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. 

The production of yeast protein from wood sugars for use as a food for humans and animals became of national importance in Germany. In 1933 and 1934 the German Ministry of Nutrition made arrangements for yeast production from wood sugar at Tornesch. The yield of dry yeast with 50% crude protein was reported to be 25% of the weight of the dry, bark-free wood and the yeast utilized both hexoses and... 

F. K. Skoog, Food Yeast Production and Utilization in Germany. PB Report 2041 (1945). 

Ammonium sulfate occurs in trace concentrations in the upper atmosphere. It is widely used as a fertilizer for rice and other crops. It is a source of sulfur for the soil. It is also used as an additive to supply nutrient nitrogen in fermentation processes (e.g., yeast production from molasses). It also is used for fireproofing timber and plastics, and in treatment of hides, and leather production. 

The trihasic salt is a water softener emulsifier and a nutrient for yeast production and wine fermentation. 

Though baker s yeast production is a rather complex process, its kinetics are well known [67, 68]. Software developed by Kristiansen [68] for simulation of this... 

Temperature Ihe temperature in a bioreactor is an important parameter in any bioprocess, because all microorganisms and enzymes have an optimal temperature at which they function most efficiently. For example, optimal temperature for cell growth is 37 °C for Escherichia coli and 30 °C for Saccharomyces sp, respectively. Although there are many types of devices for temperature measurements, metal-resistance thermometers or thermistor thermometers are used most often for bioprocess instrumentation. The data of temperature is sufficiently reliable and mainly used for the temperature control of bioreactors and for the estimation of the heat generation in a large-scale aerobic fermentor such as in yeast production or in industrial beer fermentation. 

The RQ control, where the sugar-feeding rate is controlled so as to maintain the RQ value at approximately 1.0, is the distinct control method in aerobic fed-batch cultivation such as with baker s yeast production. By keeping the RQ at 1.0 during the fed-batch operation, cell production with a high yield will be achieved. 

Here, n, v, and p represent a specific growth rate, a specific substrate consumption rate, and a specific product formation rate, respectively. and are the mean values of data used for regression analysis and a, bp and C are the coefficients in the regression models that are determined based on selected operating data in a database. This model was linked with the dynamic programming method and successfully applied to the simulation and onhne optimization of glutamic acid production and Baker s yeast production. 

Food and feed yeast production employ several molds in [he family Cryplocvccaceae Candida ulilis, C. tropicalis. and C. japonica, which are cultrvated on plant wastes (wood sugars, molasses, stillage), and C. lipolytica, which converts hydrocarbons to yeast protein... 

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