Yeast nucleate effect

If the conclusion drawn is correct, a similar behaviour of other negative hydrophilic sols as to the influence of indifferent salts on the relative viscosity was to be expected. Indeed the electroviscous effect has been found to exist in all cases investigated, viz.t gtim arabic soluble starch mucilage of semen lini and of carrageen, sodium thymus nucleate and sodium yeast nucleate. Pecularities shown by some of these examples will be discussed later p. 223 10 and p. 227 11. 

Fig. 36. Neutralisation of the electroviscous effect for a 0.83% sol of Na yeast nucleate (42° C). Beyond 13.3 m. eq. per 1. Luteo—s (= Co(NH3)oCl3) flocculation occurs. This figure should be compared with Fig. 34 from which it appears that, notwithstanding the fact that yeast nucleate belongs to the low viscous, thymus nucleate to the very high viscous type of macromolecular colloids, the character of the bundle of curves is the same and also CoCNHaloClg causes flocculation with both (and this occurs with both with CaClg also at higher concentrations, see p. 270).

A variety of physical actions also contribute to the stimulating effect of alcoholic fermentation by suspended solids. By providing nucleation sites for gas bubbles, suspended solid particles have been suggested to promote the elimination of CO2 from the fermentation medium—thus limiting its inhibitive effect on yeasts. This effect is very limited at tank pressures found in dry white winemaking. Suspended solids are also thonght... 

An interesting development in this field is the recent report by Dameron et al. (88) of the biosynthesis of quantum-sized CdS crystals in the yeast cells Candida glabrata and Schizo saccharomyces pombe. Exposed to Cd ions these cells synthesize certain peptides with an enhanced sulfide production. Small CdS crystals are formed inside the cells. These crystallize in the rock salt structure (and not in the thermodynamically stable hexagonal configuration). The organism controls particle nucleation and growth, so that uniformly sized CdS particles of about 20 A are formed. They show pronounced quantum-size effects. This is the first example of the biosynthesis of quantum-sized semiconductor crystallites. It constitutes a metabolic route for the detoxification of Cd " -infected living cells (see also 89). 

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