Acid Protease for Alcohol Production
Acid protease is a kind of high-tech product generated by modern
biotechnology. During the alcohol fermentation, adding of acid
protease can effectively hydrolyze the protein and break the
structure link raw materials, increase the efficiency of
glucoamylase, increase the conversion rate of carbon source, and
finally improve the yield of alcohol.
On other hand, the hydrolyze function of the acid protease can
increase the a-amino nitrogen level, improve the growth and
propagation of yeast, increase the fermentation speed, shorten the
fermentation period and increase efficiency of fermentation tanks.
1. Optimum Condition
Acid protease suitable for alcohol production from corn, sorghum,
rye and other starch materials. The optimum pH 2.5-6.0, and
temperature is 30-55.
The dosage of acid protease used is 10-16 U/g raw materials; it
depends on different raw material and fermentation process. In most
cases, each gram raw material need 14U/g acid protease, 280g/ton
acid protease (50000u/g), or 350g/tone acid protease (40000u/g).
(1) Re-activation of acid protease: dissolve the acid protease in
35-40 warm water, soak and activate for 1 hour, stir every 15
(2) Batch fermentation: when the sacrificed slurry reaches 1/3 of
the fermentation tank, add all liquid and residues part at one
(3) Cascade fermentation and semi-continuous fermentation: Depends
on the production volume, add acid protease continuously during
fermentation. For a 30 ton/day (10,000 ton/year) alcohol plant, the
adding rate acid protease is 20 liter/ hour.
(1) As the optimum temperature of acid protease is ~ 40, it is
suggested to use the thermo yeast.
(2) The use of acid protease can shorten the fermentation cycle
greatly to 48--55 hours. After fermentation, discharge the tank
immediately; avoid alcohol lost and increase of acidity.
(3) After the use of acid protease, the number of yeast will
doubled, fermentation speed will greatly increase, so its better to
control the fermentation temperature, the highest temperature
should not be more than 40.