2.3 Ethanol and hydrogen production by separate hydrolysis and fermentation (SHF)
The sugar available for fermentation after the pretreatment and hydrolysis of biomass can be either heterogeneous like sucrose and glucose when originated from lignocellulosic biomass.
Thus, the main bulk of biomass used for ethanol production are two types of sugars, the disaccharide sucrose and the monosugar glucose, both of them can easily be fermented to ethanol by the traditional baker’s yeast, S.cerevisae.
The medthod is
A pretreated peel in 0.01 M phosphate buffer with pH 6 was used as the SHF medium.
The SHF experiments started with the inoculation of pineapple peel with the addition of the enzyme solution in 50 mL working volume for 0-96 h.
Therefore, a filter steriled hydrolysate produce from pineapple peel under optimal condition was used as fermentation medium with no nutrient supplementation.
Afterward free and immobilized cell of S. cerevisiae and E. aerogenes with a loading of 20% (w/v) was operated under anaerobic condition and a temperature controlled at 30o C.
The samples were collected every 6 h for 4 days (96 h) to determined sugar concentration and the production of ethanol and hydrogen.
S. cerevisiae, commercial ethanol-producing bacteria, has many advantages over other known ethanol producing microorganisms. The most important are high ethanol yields, ethanol tolerance, high robustness and high resistance to toxic inhibitors.
It is necessary to further optimize culture condition or improve production technique. Therefore, immobilized cell technology was selected to increase the production of ethanol and H2 in this study.