Saccharification and ethanol fermentation of apple pomace
- Worcester Polytechnic Inst., MA
Apple pomace (the pulp residue from pressing apple juice) is an abundant waste product and presents an expensive disposal problem. A typical (50,000 gal. juice/day) apple juice company in central Massachusetts produces 100 tons of pomace per day. Some of it is used as pig feed, but it is poor quality feed because of its low protein content. Most of the pomace is hauled away (at a cost of $4/ton) and landfilled (at a cost of $10/ton). If 5% (w/w) conversion of pomace to ethanol could be achieved, the need for this company to purchase No. 6 fuel oil (1000 gal/day) for cooking during processing would be eliminated. Our approach was to saccharify the pomace enzymatically, and then to carry out a yeast fermentation on the hydrolysate. We chose to use enzymatic hydrolysis instead of dilute acid hydrolysis in order to minimize pH control problems both in the fermentation phase and in the residue. The only chemical studies have concerned small subfractions of apple material: for example, cell walls have been analyzed but they constitute only 1 to 2% of the fresh weight of the apple (about 15 to 30% of the pomace fraction). Therefore, our major problems were: (1) to optimize hydrolysis by enzyme mixtures, using weight loss and ultimate ethanol production as optimization criteria; (2) to optimize ethanol production from the hydrolysate by judicious choice of yeast strains and fermentation conditions; and (3) achieve these optimizations consistent with minimum processing cost and energy input. We have obtained up to 5.1% (w/w) of ethanol without saccharification. We show here that hydrolysis with high levels of enzyme can enhance ethanol yield by up to 27%, to a maximum level of 6% (w/w); however, enzyme treament may be cost-effective only a low levels, for improvement of residue compaction. 3 figures, 4 tables.
- OSTI ID:
- 6056237
- Report Number(s):
- CONF-820580-
- Journal Information:
- Biotechnol. Bioeng. Symp.; (United States), Vol. 12; Conference: 4. symposium on biotechnology in energy production and conservation, Gatlinburg, TN, USA, 11 May 1982
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
APPLES
ENZYMATIC HYDROLYSIS
ETHANOL
PRODUCTION
AGRICULTURAL WASTES
ANIMAL FEEDS
FERMENTATION
SACCHARIFICATION
ALCOHOLS
BIOCONVERSION
CHEMICAL REACTIONS
DECOMPOSITION
FOOD
FRUITS
HYDROLYSIS
HYDROXY COMPOUNDS
LYSIS
ORGANIC COMPOUNDS
ORGANIC WASTES
SOLVOLYSIS
WASTES
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