Title:
Enzymatic Hydrolysis of Carbohydrates from Steam Exploded Olive Tree Pruning
Author(s):
Sáez, F., Ballesteros, I., Ballesteros, M., Manzanares, P., Negro, M.J., González, A., Álvarez, C., Oliva, J.M.
Document(s):
Paper
Abstract:
Olive tree pruning is a suitable raw material for ethanol production, and it has been also shown to be an interesting biomass to obtain high value-added products as oligosaccharides and antioxidants, which can have a positive effect on both the integral use of this agricultural residue and the improvement of ethanol yields. However its high extractives content could cause condensation reactions between extractives and acid insoluble lignin during pretreatment, hindering the enzymatic hydrolysis of pretreated material. Previous to steam explosion pretreatment, a water extraction stage of olive tree pruning was carried. The aim of this work is, on one hand to enhance enzymatic hydrolysis of cellulose contained in water insoluble solid after steam explosion of olive tree pruning and, on the other hand, to study the oligosaccharides released during the pretreatment. The steam explosion pretreatment conditions (190 ºC, 25 min) were selected in a previous work, which result in both high sugars recovery and cellulose fibres with enhanced digestibility to enzymatic attack. At these conditions, more than 80% of both total glucose and xylose present in the olive tree pruning become available, considering sugars in extractives, in the liquid fraction and those released by enzymatic hydrolysis of the solids (WIS) from steam exploded olive tree pruning. First, the liquid fraction was analyzed for free sugars, degradation products (furans, phenols) and acetic acid content. On the other hand, the fraction with oligosaccharides was purified by means of chromatographic techniques to know the degree of polymerization (DP) and finally was incubated with several hydrolytic enzymes (glucoamylase, xylanases and cellulases) to produce a selective hydrolysis of the oligomers present in it, and facilitate the identification of hydrolysis products. In order to obtain the highest sugars yield in the solid fraction, the effect of different substrate loading (water insoluble solids, WIS) (5, 10, 15, 17, 20 %, w/w), in the enzymatic process has been studied. Several enzyme dosages (15, 20, 30, 40 mg protein/g glucan) of cellulases mixed with hemicellulases were investigated.
Keywords:
analysis, hemicellulose, olive tree, pretreatment, steam explosion
Topic:
Biomass Conversion Technologies for Heating, Electricity and Chemicals
Subtopic:
Biochemical conversion
Event:
19th European Biomass Conference and Exhibition
Session:
VP2.6.15
Pages:
1743 - 1747
ISBN-13:
978-88-89407-55-4
ISBN-10:
88-89407-55-7
Paper DOI:
10.5071/19thEUBCE2011-VP2.6.15
Price:
FREE
