GB346361A - Improvements in or relating to producing yeast - Google Patents

Abstract

Yeast is manufactured by the aeration method with periodical addition of the nutrients, the propagation of the yeast being divided into partial fermentations of increasing volume directly following each other and each of which constitutes a fully accomplished fermentation phase. At the beginning of each phase the entire nutrient solution required for that phase is supplied to the yeast and the propagation is in every one of such phases carried on up to the full consumption of the fermentable sugar introduced at the beginning of the phase. The yeast produced in one phase is used without separation as starting yeast for the next phase, and the quantity of nutrient substance supplied to the yeast at the beginning of each phase is calculated so that the quantity of yeast increases in each phase, through all stages of fermentation for a determined amount increasing from phase to phase, which is determined by the ideal condition that the quantity of yeast ought to increase throughout logarithmically with the time, corresponding to the fundamental equation q=aed t where q is the amount of yeast present after the time t, a the quantity of yeast employed for starting the propagation, e the base of the natural logarithm and d the factor of growth, which according to the quantity and yield of yeast aimed at lies between the limits 0,05 and 0,22. The total duration of the propagation process being advantageously chosen from 16-36 hours in from 5-9 phases. Ripening intervals may be inserted at the end of the phases following the preliminary fermentation prior to further supply of nutrient substances and the duration of these intervals increases with the progress of the fermentation procedure. Specification 299,336, [Class 14 (ii), Beverages &c.], is referred to.