Patent GB-585149-A (GB)
Title: Improvements in or relating to the production of alcohol and glycerol by fermentation
IPC: C12P7/20
Filed: 1942-12-22
Abstract: In the manufacture of ethyl alcohol and glycerol by the fermentation by yeast of a solution containing a yeast-fermentable sugar and buffering substances, the proportion of glycerol produced is increased from about 3 per cent. to 6 to 9 per cent. while the total yield of alcohol plus glycerol may be increased by as much as 2.5 per cent., by first seeding the sugar-containing solution with yeast, allowing the fermentation to proceed initially at a pH less than 7, adding sodium hydroxide in amount between 0.5 and 4 per cent. by weight of the sugar during a period lying between 5 and 30 hours from the time of seeding, and allowing the fermentation to continue. Other alkaline substances may be used, and the addition of the alkali may be deferred until substantially the whole yeast crop has grown. The initial sugar-containing solution may be molasses containing from 65 to 80 per cent. of sugar, and the concentration of sugar in the seeded mass may be 100 to 250, preferably 170 to 200, lbs. per 100 gallons.  Nutrient substances such as ammonium sulphate and diammonium phosphate may be employed, but these may be replaced by ammonium chloride to reduce scaling during evaporation of the spent wash for glycerol recovery.  The sugar-containing solution may be sterilized or pasteurized prior to the addition of the yeast, and it may be made up from spent wash from a previous fermentation which may, or may not, have had the glycerol recovered therefrom.  The alkali may be added intermittently during the period stated but preferably the whole of it is added during a period of about 15 minutes at approximately 10 to 12 hours after the seeding of the wash. Careful temperature control is advisable.  The yeast is preferably removed from the fermented mass, e.g., by a centrifuge, the alcohol distilled off and the glycerol extracted by means of an organic solvent or by the method described in Specification 572,539.ALSO:In the manufacture of ethyl alcohol and glycerol by the fermentation by yeast of a solution containing a yeast-fermentable sugar and buffering substances, the proportion of glycerol produced is increased from about 3 per cent. to 6 to 9 per cent. while the total yield of alcohol plus glycerol may be increased by as much as 2.5 per cent., by first seeding the sugar-containing solution with yeast, allowing the fermentation to proceed initially at a pH less than 7, adding sodium hydroxide in amount between 0.5 and 4 per cent. by weight of the sugar during a period lying between 5 and 30 hours from the time of seeding, and allowing the fermentation to continue. Other alkaline substances may be used, and the addition of the alkali may be deferred until substantially the whole yeast crop has grown. The initial sugar-containing solution may be molasses containing from 65 to 80 per cent. of sugars, and the concentration of sugar in the seeded mass may be 100 to 250, preferably 170 to 200 lbs. per 100 gallons.  Nutrient substances such as ammonium sulphate and diammonium phosphate may be employed, but those may be replaced by ammonium chloride to reduce scaling during evaporation of the spent wash for glycerol recovery.  The sugar-containing solution may be sterilised or pasteurised prior to the addition of the yeast, and it may be made up from spent wash from a previous fermentation which may, or may not, have had the glycerol recovered therefrom.  The alkali may be added intermittently during the period stated, but preferably the whole of it is added during a period of about 15 minutes at approximately 10 to 12 hours after the seeding of the wash.  Careful temperature control is advisable.  The yeast is preferably removed from the fermented mass, e.g., by a centrifuge, the alcohol distilled off, and the glycerol extracted by means of an organic solvent or by the method described in Specification 572,539, [Group III].