Comparative study of different methods of hydrolysis and fermentation for bioethanol obtaining from inulin and inulin rich feedstock (original) (raw)
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Fuel Ethanol Bioproduction from Inulin Rich Feedstock
Due to its important environmental benefits, bioethanol promise to be a good biofuel substitute for gasoline. To make it competitive with other fuels, the production costs should be reduced by using alternative raw materials. Inulin rich feedstock, like dahlia (Dahlia hortensis) and Jerusalem artichoke (Helianthus tuberosus) tubers or chicory (Cichorus intybus) roots would be a cheap and convenient source for fermentable sugars for bioethanol production. These are suitable crops for European countries and in low-requirements environmental conditions. Two processes were studied for conversion of inulin rich feedstock to fermentable sugars:"acid-based" and "enzymebased" hydrolysis. The fermentable sugars (mainly fructose and low amounts of glucose) are then fermented using different alcohol-tolerant Saccharomyces cerevisiae yeast strains. Direct fermentation of inulin to ethanol was also performed, as some Kluyveromyces spp. yeast strains were found to have the ability to ferment inulin. This paper highlights the ongoing developments in fuel ethanol bioproduction from inulin rich feedstock, with focus on inulin hydrolysis which is the major problem of the overall process.
Inulin-Containing Biomass for Ethanol Production Carbohydrate Extraction and Ethanol Fermentation
Applied Biochemistry and Biotechnology, 2006
The use of stalks instead of tubers as a source of carbohydrates for ethanol production has been investigated. The inulin present in the stalks of Jerusalem artichoke was extracted with water and the effect of solid-liquid ratio, temperature, and acid addition was studied and optimized in order to attain a high-fructose fermentable extract. The maximum extraction efficiency (corresponding to 35 g/L) of soluble sugars was obtained at 1/6 solidliquid ratio. Fermentations of hydrolyzed extracts by baker's yeast and direct fermentation by an inulinase activity yeast were also performed and the potential to use this feedstock for bioethanol production assessed. The results show that the carbohydrates derived from Jerusalem artichoke stalks can be converted efficiently to ethanol by acidic hydrolysis followed by fermentation with Saccharomyces cerevisiae or by direct fermentation of inulin using Kluyveromyces marxianus strains. In this last case about 30 h to complete fermentation was required in comparison with 8-9 h obtained in experiments with S. cerevisiae growth on acid extracted juices.
Biofuel production from Jerusalem artichoke tuber inulins: a review
Jerusalem artichoke (JA) has a high productivity of tubers that are rich in inulins, a fructan polymer. These inulins can be easily broken down into fructose and glucose for conversion into ethanol by fermentation. This review discusses tuber and inulin yields, effect of cultivar and environment on tuber productivity, and approaches to fermentation for ethanol production. Consolidated bioprocessing with Kluyveromyces marxianus has been the most popular approach for fermentation into ethanol. Apart from ethanol, fructose can be dehydrated to 5-hydrolxymethylfurfural followed by catalytic conversion into hydrocarbons. Findings from several studies indicate that this plant from tubers alone can produce ethanol at yields that rival corn and sugarcane ethanol. JA has tremendous potential for use as a bioenergy feedstock.
Biomass and Bioenergy, 2014
Keywords: Jerusalem artichoke Inulin Enzymatic hydrolysis Optimization Response surface methodology (RSM) ABE fermentation a b s t r a c t In this study, a central composite design and response surface methodology were used to study the effect of various enzymatic hydrolysis variables (temperature, pH, substrate concentration and enzyme loading) on the enzymatic hydrolysis of Jerusalem artichokederived inulin. It was found that a quadratic model was able to predict inulin conversion as a function of all four investigated factors. The model was confirmed through additional experiments and via analysis of variance (ANOVA). Subsequently, numerical optimization was used to maximize the inulin conversion (94.5%) of Jerusalem artichoke powder within the experimental range (temperature of 48 C, pH of 4.8, substrate concentration of 60 g l À1 , and enzyme loading of 10 units g À1 substrate for 24 h). The enzymatic hydrolyzate of Jerusalem artichoke was fermented via solventogenic clostridia to acetoneebutanoleethanol (ABE).
Optimizing Acid Hydrolysis of Jerusalem Artichoke-Derived Inulin for Fermentative Butanol Production
BioEnergy Research, 2014
In this study, a central composite design and response surface methodology were used to study the effect of various hydrolysis variables (temperature, pH, and time) on the acid hydrolysis of Jerusalem artichokederived inulin using three different mineral acids (HCl, H 2 SO 4 , and H 3 PO 4 ). Numerical optimization was used to maximize the sugar yield of Jerusalem artichoke powder within the experimental range for each of the mentioned acid. The influence of each acid on the formation of hydroxymethylfurfural (HMF; a known by-product and inhibitor for fermentative organisms) was also investigated. H 2 SO 4 was found to have a better potential for sugar yields compared to two other acids (HCl and H 3 PO 4 ) since it can hydrolyze the highest amount of inulin (98.5 %) under optimal conditions (temperature of 97°C, pH of 2.0, and time period of 35 min) without producing inhibiting HMF concentrations. The sulfuric hydrolysate of Jerusalem artichoke was fermented via solventogenic clostridia to acetonebutanol-ethanol (ABE). An ABE yield of 0.31 g g −1 and an overall fermentation productivity of 0.25 g l −1 h −1 were obtained, indicating the suitability of this feedstock for fermentative ABE production.
Dry method for preparation of inulin biomass as a feedstock for ethanol fermentation
African Crop Science Journal, 2011
Sisal leaves which constitute only 2% of the sisal plant have been used in the production of pulp and fiber; the remaining 98% which is mostly of the sisal bole is largely regarded as waste. The bole's high inulin fraction (24-36%) is of particular significance due to its chemical functionality and relative ease of fermentation. utilisationThe objective of this study was to identify properties and pertinent characteristics for developing industrially viable methods of extracting inulin from sisal bole in a readily utilisable form. Inulin was extracted using the dry method 'baking', whereby sisal boles were chopped into chips of defined sizes 1.5-6 cm, before drying at 70-150 °C. The dried bole chips were milled to sieved powder of 90-2000 µm. Particle sizes and temperature for total sugars were determined using the dinitrosalicylic (DNS) colorimetric method. Prior to fermentation, the inulin was hydrolysed using sulphuric acid to give a total sugar yield of 5-16% wt/wt depending on drying temperature. In general, high temperatures, e.g. 150 o C led to low sugar recovery (10.3% wt/wt), while low temperatures, e.g. 70 o C gave high sugar recovery (16.3% wt/wt). The fine inulin powder (<250 µm) was richer sugar content (~16%), whereas coarse particles (>400 µm) gave low sugar levels (~9%). The hydrolysed inulin was fermented using Saccharomyces cerevisiae for 57 hours giving consistent ethanol yields depending on initial sugar levels.
Bioethanol production from Jerusalem artichoke by acid hydrolysis
Rom Biotech Lett, 2011
The hydrolysis of inulin from Jerusalem artichoke (JA) slices by HCl under different regimes of temperature and hold (contact time) time was investigated. Final reducing sugars concentration in the hydrolyzates depended on temperature, pH, hydromodule (JA:water) and hold time. Acid hydrolysis at higher temperature and longer hold time increased the degradation of fructan to fructose and increased the concentrations of inhibitory compounds such as 5-hydroxymethylfurfural (HMF). Acid hydrolysis at 126 o C, hydromodule 1:1 and pH 2, resulted in less than 0.2 g/L HMF at both hold times (30 min and 60 min.). Fermentation of the hydrolyzates obtained by hydrolysis at 126 o C, hydromodule 1:1, pH 2 and hold time 60 min, resulted in the highest ethanol yield of 7.6 % w/w, which corresponds to volumetric productivity of ethanol 1.52 g /Lh and 94.12 % (w/w) of theoretical yield of ethanol.
Biocatalytic strategies for the production of high fructose syrup from inulin
Bioresource technology, 2018
The consumption of natural and low calorie sugars has increased enormously from the past few decades. To fulfil the demands, the production of healthy sweeteners as an alternative to sucrose has recently received considerable interest. Fructose is the most health beneficial and safest sugar amongst them. It is generally recognised as safe (GRAS) and has become an important food ingredient due its sweetening and various health promising functional properties. Commercially, high fructose syrup is prepared from starch by multienzymatic process. Single-step enzymatic hydrolysis of inulin using inulinase has emerged as an alternate to the conventional approach to reduce complexity, time and cost. The present review, outlines the enzymatic strategies used for the preparation of high fructose syrup from inulin/inulin-rich plant materials in batch and continuous systems, and its conclusions.