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CHAPTER IV

PRESENTATION, ANALYSIS, AND INTERPRETATION OF RESULTS

The results of the experiment regarding the parametric evaluation of

selected fermentation parameters specifically fermentation time and yeast

loading of bioethanol production from ripe carabao mango peelings are clearly

presented, analyzed and interpreted in this section of the study.

1. Properties of Ripe Carabao Mango Peelings Before and After Pre-

treatment

Lignocellulosics are naturally resistant to degradation and are

hydrolytically stable and structurally robust mainly because of cross linking

between polysaccharides like cellulose and hemicellulose and lignin by means of

ester and ether linkages (Verma et al., 2011). Thus, so as to increase the yield of

fermentable sugars, such components of the biomass must be solubilised and

separated through appropriate pre-treatment.

In this study, the chemical properties of untreated and pre-treated ripe

carabao mango peelings particularly in terms of hemicellulose, holocellulose,

alpha cellulose, lignin (acid soluble lignin and acid insoluble lignin), and

extractives, were determined so as to show the effects of the dilute acid pre-

treatment on the substrate. These are evidently presented in Table 4.

After the pre-treatment, alpha cellulose composition almost tripled from

25.94%0.005 to 73.21%0.006. Such high increase only implies that the

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Parametric Evaluation of Selected Fermentation Parameters of BioethanolProduction from Ripe Carabao Mango (Mangifera Indica L.) Peelings

Chapter I The Problem and its BackgroundAmul, K.M.L., Carpio, R.M. Toledo, A.R.M.

crystalline structure of the cellulose was disrupted, the accessible area for the

cellulase swelled, and the lignin and hemicellulose were separated from the

cellulose itself. Therefore, alpha cellulose was then become more susceptible to

enzymatic degradation prior to fermentation. On the other hand, Zhang et al.

(2004) once stated in their study that variations on the degree of polymerization

and crystallinity of cellulose from species to species exist and such have shown a

significant impact on acidic and enzymatic hydrolysis.

Table 4

Chemical Properties of Untreated and Dilute Acid Pre-treated

Ripe Carabao Mango Peelings

ChemicalProperties

Compositional Analysis (%)

UntreatedPeelings

Dilute Acid Pre-treated Peelings

Alpha Cellulose** 25.940.005 73.210.006

Holocellulose** 32.100.009 76.010.002

Hemicellulose** 6.160.005 2.810.007

Acid Soluble Lignin** 7.790.0015 5.570.0008

Acid Insoluble Lignin** 20.050.009 48.880.017

Extractives* 41.510.007 15.710.001Note: * - Moisture free basis; ** - moisture free and extractive free basis

Also, a noticeable increase in holocellulose from 32.10%0.009 to 76.01%

0.002 also dictates that more saccharifiable materials were present upon the

completion of the process. (add research study about this)

However, since hemicellulose is easier to hydrolyze than the other

components such as cellulose, some of it may have been converted to sugar

monomers and soluble oligomers during the dilute acid pre-treatment.

Furthermore, it was indicated in the study conducted by Harmsem et al. (2010)

that the presence of acid highly improves the solubility of hemicellulose in water.

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Parametric Evaluation of Selected Fermentation Parameters of BioethanolProduction from Ripe Carabao Mango (Mangifera Indica L.) Peelings

Chapter I The Problem and its BackgroundAmul, K.M.L., Carpio, R.M. Toledo, A.R.M.

From that, it can be assumed that part of the hemicellulose was removed by

water used in neutralizing the substrate before undergoing saccharification and

fermentation process. As a result, a 54.44% decrease (i.e. from 6.16%0.005 to

2.81%0.007) in the hemicellulose component of the peelings was observed.

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