Advances in Chemical Engineering and Science, 2012, 2, 519-523 Published Online October 2012 (
Chemical Composition of the Cashew Apple Bagasse and
Potential Use for Ethanol Production
Flávia Cristina dos Santos Lima1, Flávio Luiz Honorato da Silva2, Josivanda Palmeira Gomes3,
José Mariano da Silva Neto1
1Department of Chemical Engineering, Center of Sciences and Techn o l o gy, Federal Universi t y of C a m p i na Gran de,
Campina Grande, Brazil
2Department of Chemical Engineering, Center of Technology, Federal University of Paraiba, João Pessoa, Brazil
3Department of Agricultural Engineer in g, Center o f Science and Technology, Federal University of Campina Grande,
Campina Grande, Brazil
Received August 23, 2012; revised September 25, 2012; accepted October 5, 2012
On the world scene, the energy requirements are mainly based on fossil fuels, however, these compounds reserves are
finite and their exploitation has caused serious environmental problems. As a consequence, the demand for alternative
renewable sources has been intensified in substitution the rising demand for energy and raw materials. The biomass is
emerging as one of the few sources that have potential to meet these challenges of sustainability, as is currently the
largest energy resource in the world, and only carbon-rich material available on the planet, apart from fossils. Form, the
cashew crop has great potential for technological development of alternative sources of energy, from its industrial waste
processing cashew adding value to the product. In this sense, this paper aims to study the characterization of the cashew
apple bagasse and to verify (by acid prehydrolysis) the potentia l of this material for ethanol produ ction. Initially it was
carried out physicochemical characterization of cashew bagasse used (pH, moisture content, soluble solids, sugars,
cellulose, hemicellulose and lignin). Following it was carried prehydrolysis at 105˚C for 1 h to obtain fermentable
sugars. Analyses of the samples were carried out on HPLC the results showed the saccharification of biomass with
glucose (1537.49 mg/L), xylose (3823.22 mg/L) and arabinose (7131.11 mg/L) as well as the capacity of the biomass
for ethanol production.
Keywords: Pre-Hydrolyze; Ethanol; Cashew Apple Bagasse
1. Introduction
The world’s energy needs are based on fossil fuels,
however, the impending shortage of fossil oil and envi-
ronmental problems that its holding concerned, it has
aroused in the scientific community interest in new al-
ternative energy sources renewable and sustainable [1,2].
In this context, the biomass comes as one of the sources
having this potential, because when produced sustainably,
can dramatically reduce emissions of greenhouse gases
compared to fossil fuels, as the only carbon-rich material
available on the planet [3,4], which can be used for
energy, heat, liquid and gaseous fuels, and also serves as
a raw material for chemicals and materials.
Brazil is enjoying a comfortable position in the world
with the technology of ethanol production. In this sector,
the United States is currently the largest prod ucer, except
that the bioethanol produced from corn (cost three times
higher than derived from cane sugar), followed by Brazil
which uses cane sugar, with an ethanol production of
27.7 billion liters, respectively, in the harvest of 2008/
2009 [5].
The lignocellulosic biomass represent an abundant
source of sugars by biotechnological processes can be
converted to products of industrial interest such as ethanol.
This biofuel is currently produced from virtually raw beet
and starch, cane sugar and maize, respectively. However,
researchers are developing new processes for the most
economically viable use of the component of lignocellu-
losic biomass such as agricultural residues (straw and
bagasse of sugar cane, wheat straw and corn stover) and
forest residues (dust and waste wood), for production of
fuel ethanol (second generation ethanol) [6, 7].
In Brazil, the cashew nut harvest (2008/2009) ac-
counted for 11% of world production, which represents
more than 6 million tons of cashew [8]. However, in the
Northeast, cashew agroindustry has an outstanding role
in the local economy, because, in industrial processes
40% (w/w) of bagasse is normally discarded by the in-
opyright © 2012 SciRes. ACES
dustry [9]. So sustainably this culture has great potential
for technological development of alternative energy
sources, from their industrial waste processing, besides
being used as a support for cells in alcoholic fermenta-
tion of juice cashew [10].
The cashew bagasse is a lignocellulosic waste that is
composed mainly of cellulose, hemicellulose and lignin.
For these residues are bioconverted it is necessary to
subject them to physical pretreatments and/or chemicals
prior to hydro lysis in order to produce ethanol. Su ch pre-
treatment aimed at removing lignin and hemicellulose,
reducing the crystallinity of the cellulose and increasing
the porosity of these materials so as to make the pulp
more susceptible to hydrolysis. Among the various op-
tions for pre-treatment, the use of dilute acid in addition
to removing the selective hemicellulose produces li-
queurs (prehydrolysis) with high content of pentoses and
reduced lignin content [8,11].
This liquor resulting from the pre-hydrolysis is consti-
tuted by compounds such as pentoses (xylose and arabi-
nose) at high concentrations and hexoses (glucose, man-
nose, galactose, etc.) components of the hemicellulose.
During the pretreatment the acid s used as catalysts in the
process release protons that act on glycosidic bonds be-
tween the monomers polymeric sugar chains, causing the
breaking of these bonds releasing a number of undesir-
able compounds in the fermentation process, leading to
partial degradation of pentoses and hexoses, generating
furfural and 5- hydroxym et hy lfu rfural (5-HM F) [1 2].
In this context, this work was to study the characteri-
zation of the cashew apple pomace and by acid hydroly-
sis pre-determine their potential for ethanol production.
2. Materials and Methods
The investigation was conducted at the Laboratories of
Porous Media, Particulate Systems and Biochemical En-
gineering at the Chemical Engine ering Academic Unit in
the Science and Technology Center of the Universidade
Federal de Campina Grande—Paraíba state.
2.1. Obtaining a Raw Material
Fresh cashew apple bagasse was used, obtained from
FRUTNAT, a fruit juice production company located in
the city of Campina Grande/Paraiba/Brazil.
2.2. Preparation of Raw Material
The cashew apple bagasse was washed twice in water at
60˚C, and then water at room temperature until reaching
˚Brix 0. After washing, it was placed into aluminum trays
and dried in an air circulating oven at 55˚C for 48 hours,
depending (Figures 1(a)-(c)). It was then immediately
ground in a knife mill, sieved through 40 mesh sieves and
stored in polyp ropy l ene bags for subsequent use.
2.3. Acid Prehydrolysis of Cashew Apple Bagasse
Dried cashew residue was treated with a dilute acid solu-
tion (95% pure sulfuric acid—VETEC/PA), and prehy-
drolysis liquor was obtained at 105˚C for 1 h in a pres-
surized 700 mL stainless steel reactor, using a weight
ratio of 1:6 (10 0 g of sample/600 g o f H2SO4 at 3%v/v).
2.4. Characterization of Cashew Apple Bagasse:
Physicochemical Analysis
Samples of cashew bagasse dry and prehydrolysis were
taken to be its characterization, which was to analyze
(moisture, pH, soluble solids, reducing sugars, cellulose,
hemicellulose and lignin). Table 1 gives the references
of the methodologies used for physicochemical charac-
2.5. Characterization of Prehydrolysis Liquor
Levels of sugars and furan compounds (HMF and Fur-
fural) were determined by high performance liquid
chromotography (HPLC) equipped with a ProStar 210
pump (Varian); Manual injector with a 20 µL loop;
ProStar 356 refractive index detector (Varian) and 284
nm UV-visible (aldehydes); Hi-Plex H stainless steel
analytical column (300 mm × 7.7 mm; Varian), applying
the following operating conditions: Column temperature
of 40˚C; Mobile phase: 0.005 M H2SO4 with a flow rate
of 0.6 mL/min; Analysis time: 15 and 60 minutes for
(a) (b) (c)
Figure 1. Cashew apple bagasse: (a) In nature; (b) Drying
at 55˚C; (c) Dry.
Table 1. Methods used in the characterization of cashew
apple bagasse.
Parameters Analyzed Methodology
Moisture [13]
pH [13]
Soluble Solids [13]
Cellulose [14]
Lignin [14]
Hemicellulose [14]
Reducing Sugars [15]
Copyright © 2012 SciRes. ACES
sugar and aldehyde content, respectively. Internal stan-
dard solution for sugars: glucose, xylose, arabinose and
sucrose (Sigma 99.99% HPLC grade), congeners 5-hy-
droxymethylfurfural—HMF (Aldrich 99.98%) and fur-
fural (Vetec 99.9 UV/HPLC) were used to quantify the
component s of liquor.
3. Results and Discussion
The physicochemical characterization of cashew bagasse
dry and prehydrolyzed shown in Table 2, aims to ana-
lyze its composition with respect to nutrient content and
for future comparison with the bagasse hydrolyzate.
According to the results shown in Table 1 shows that
the analysis of dry bagasse resulted in 9.29% ± 0.07%
moisture, however, [16] analyzing the cashew stalk resi-
due dried in a vacuum oven at 65˚C found 6.99% mois-
ture. For the analysis of the pH value of 4.23 ± 0.01 was
found no significant difference with the values reported
by [16,17] at pH 4.01 and 4.52. For soluble solids was
found to be the result of 0, this is because the pulp was
well washed to remove the remaining sugar prior to dry-
ing. Now for the AR value was higher than that reported
by [18] who studied the efficiency of solvents in the ex-
tractives content in pulp of the cashew apple, finding the
dry bagasse at 55˚C the value 0.31%.
Analyzing prehydrolyzed the bagasse it is found that
the values of moisture, pH, Brix and AR found for dry
pomace cashew are similar to those found in [19] to
study the acid hydrolysis of bagasse from the stalk of the
cashew, which was reported at 14.51% moisture, pH 1.77
and 0.10% of ˚Brix.
A comparison of the chemical composition of dry ba-
gasse cashew pre-treated is shown in Table 3.
In terms of cellulose, hemicellulose and lignin, the pulp
of the cashew apple dry values were similar to that found
by [8] 19.21% ± 0.35%, 12.05% ± 0.37% and 38.11% ±
Table 2. Physicochemical characterization of the cashew
apple bagasse in natura and after pretre atment.
analyzed Cashew
bagasse dry Bagasse of cashew
Moisture (%) 9.29 ± 0.07 23.85 ± 0.05
pH 4.23 ± 0.01 1.70 ± 0.04
Soluble solids (˚Brix) 0.00 ± 0.00 0.00 ± 0.00
Reducing Sugars (%) 0.56 ± 0.02 1.80 ± 0.08
Table 3. Comparison between the chemical composition of
dried and crushed cashew pretreated.
Parameters analyzed Cashew
bagasse dry Bagasse of cashew
Cellulose (%) 18.31 ± 0.07 31.50 ± 0.02
Hemicellulose (%) 27.18 ± 0.01 19.30 ± 0.09
Lignin (%) 23.91 ± 0.02 32.21 ± 0.07
0.08% for the cashew apple bagasse in nature, [20]
38.4%, 10.2% and 2.8% for soybean hulls, however, [21]
studied the same residue found 36%, 12.5% and 18.2%.
It was observed for wheat straw 31, 26 and 24%, re-
spectively [22]. The values related to lignin were higher
than those found by different authors. As can be seen the
cashew bagasse dry compared to other residues men-
tioned, appears to be quite promising for bioconversion
products of hig h a dde d val ue such as ethanol.
Bagasse from cashew stalk when subjected to pre-hy-
drolysis with dilute acid changes most of the hemicellu-
lose fraction monosaccharides by hydrolysis (xylose, ara-
binose, and others). Consequently, the pulp prehydrolyzed
has a browning in relation to the dry material due to the
formation of degradation products of carbohydrates under
acid catalysis [23] as shown in Figure 2(b). It can be seen
in Table 3 , values for cellulose, hemicellulos e and lignin.
Compared to the straw marabout 39.5%, 15.9% and 31.6%
of cellulose, hemicellulose and lignin, respectively [24]
can be observed that the amount of pulp was higher,
however, hemicell ulose and l igni n were si m il ar.
As can be seen in Table 4, the pre-hydrolysis with
dilute acid not only solubilizing hemicellulose, but also
has the power to convert it into fermentable sugars, the
resulting liquor is composed of sugars (glucose, xylose
and arabinose), making it an important residue which can
be used for producing ethanol, as shown in Figure 3 as a
4. Conclusion
Depending on the results presented here, we can conclude
Figure 2. Peduncle of cashew bagasse (a) dry and (b)
Table 4. Concentration (mg/L) and sugar compounds toxic
liquor bagasse prehydrolyzed of the cashew apple.
Component Content (mg/L)
Glucose 1758.66
Xylose 5458.70
Arabinose 7640.72
Acetic acid 5.66
HMF 49.17
Furfural 0.04
Copyright © 2012 SciRes. ACES
Figure 3. Percentage of sugar in the liquor prehydrolyzed
bagasse peduncle of c a shew.
that the cashew bagasse biomass has great potential for
bioprocess after prehydrolysis, is a promising raw mate-
rial for bioethanol production, with 12% of hexoses, and
88% pentoses.
5. Acknowledgements
The authors would like to express thanks to Their Bra-
zilian agencies MCT/CNPq/CTBio for financial support
through the Notice MCT/CNPq/CTAgro/CTBio No. 39/
2007-Vanguard Technologies for the Production of Eth-
anol and Biod iesel (Case No. 5528 15/2007-1). CNPq for
doctoral fell o w ships and underg rad uat e r esearch.
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