Variability assessment in Pongamia pinnata (L.) Pierre germplasm for biodiesel traits

Variability assessment in Pongamia pinnata (L.) Pierre germplasm for biodiesel traits

i n d u s t r i a l c r o p s a n d p r o d u c t s 2 9 ( 2 0 0 9 ) 536–540 available at www.sciencedirect.com journal homepage: www.elsevier.com/lo...

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i n d u s t r i a l c r o p s a n d p r o d u c t s 2 9 ( 2 0 0 9 ) 536–540

available at www.sciencedirect.com

journal homepage: www.elsevier.com/locate/indcrop

Variability assessment in Pongamia pinnata (L.) Pierre germplasm for biodiesel traits N. Mukta ∗ , I.Y.L.N. Murthy, P. Sripal Directorate of Oilseeds Research, Hyderabad, Andhra Pradesh 500 030, India

a r t i c l e

i n f o

a b s t r a c t

Article history:

Wide variability in oil content was observed in 75 germplasm accessions of Pongamia pinnata

Received 16 July 2008

(L.) Pierre collected from Telengana region of Andhra Pradesh, India. Out of these, fatty acid

Received in revised form

profiles of 21 accessions with varying seed oil content were examined. Large variation was

7 October 2008

observed in stearic, oleic and linoleic fatty acid composition i.e. 1.83–11.50%, 46.66–65.35%

Accepted 14 October 2008

and 12.02–32.58% respectively while less variation i.e. 9.25–12.87% was found with palmitic acid content. Saponification number (SN), iodine value (IV) and cetane number (CN) of fatty acid methyl esters of oils varied from 183.3 to 200.91, 74.78 to 100.98 and 50.85 to 59.11

Keywords:

respectively. Fatty acid composition, IV and CN were used to predict the quality of fatty

Pongamia pinnata

acid methyl esters of oil for use as biodiesel. Fatty acid methyl esters of oils of P. pinnata

Germplasm collection

accessions DORPP 49, 72 and 83 were found most suitable (CN more than 56.6) for use as

Oil content

biodiesel and they meet the major specification of biodiesel standards of USA, Germany

Fatty acid profile

and European Standard Organization. The range of variability found for various biodiesel

Biodiesel traits

standards in accessions of P. pinnata can be utilized for the establishment of plantations of promising genotypes through clonal means for increased productivity. © 2008 Elsevier B.V. All rights reserved.

1.

Introduction

Great emphasis is being given to the production of biofuel in view of its enormous economic, social and environmental benefits. In India, the focus on tree borne oilseeds as the source of feed stock for biodiesel production has highlighted the role of Pongamia pinnata (L.) Pierre. P. pinnata (family Fabaceae—Papilionoideae) commonly known as karanja is a medium-sized tree with a short crooked trunk and broad crown of spreading or drooping branches. It is considered to be a native of Western Ghats in India and occurs naturally in most parts of the Indian subcontinent. The tree is valued for shade, ornamental value, seed oil, fodder and green manure. The leaves, roots and flowers are reported to possess medicinal properties (WOI, 1969).



In recent times, the interest in this tree is mainly focused on the use of its seed oil as biodiesel (Shrinivasa, 2001). Fatty acid methyl esters (FAMEs) of seed oils have already been found suitable for use as fuel in diesel engines (Harrington, 1986). Based on this criteria, extensive studies have been carried out on the technical feasibility of karanja oil as a source of fuel (Vivek and Gupta, 2004; Raheman and Phadatare, 2004; Karmee and Chadha, 2005; Meher et al., 2006; Sharma and Singh, 2008; Scott et al., 2008). FAMEs as biodiesel are environmentally safe, non-toxic and biodegradable. With the growing interest in the seed oil of P. pinnata, the need for raising plantations has been realized. In this context, the present study was undertaken to assess the existence of variability for some of the important biodiesel parameters as a prelude to selection of more efficient biodiesel yielders. With

Corresponding author. Tel.: +91 40 24015345x238; fax: +91 40 24017969. E-mail address: [email protected] (N. Mukta). 0926-6690/$ – see front matter © 2008 Elsevier B.V. All rights reserved. doi:10.1016/j.indcrop.2008.10.002

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i n d u s t r i a l c r o p s a n d p r o d u c t s 2 9 ( 2 0 0 9 ) 536–540

this objective the survey, collection and characterization of P. pinnata has been undertaken to assess the variability existing for various economically important parameters for its development as a profitable crop for biodiesel production.

2.

SN =

 560 × Ai MW

 254 × Di × Ai MWi

where Ai is the percentage, D is the number of double bonds and MWi is the molecular mass of each component. Cetane number (CN) of FAMEs was calculated from the following equation (Krisnangkura, 1986): CN =

Characteristics

Range

Seed oil (%)

<10 10–20 20.1–30 30.1–40 >40

Materials and methods

Exploration trips were conducted during the months of April–May, 2006 to various districts of Andhra Pradesh, India and 75 accessions were collected. A global positioning system (Garmin 12) was used to mark the position of the collected accessions. The area explored lies between 17◦ 03 62 to 17◦ 31 63 N and 77◦ 37 38 to 78◦ 24 91 E covering parts of districts of Mahabubnagar, Nalgonda, Nizamabad and Rangareddy in the Deccan plateau of India. Representative samples consisting of 2–3 kg pods covering all sides of the selected tree were collected. Pods were stored at room temperature. For seed oil content and fatty acid analysis, one kg pods were randomly picked from this lot, threshed and the final sample was randomly drawn from this material. Seed oil content was estimated using standard NMR (Nuclear Magnetic Resonance) technique (AOAC, 1970) for the 75 accessions. Among these, 21 accessions covering all the ranges of oil content were examined for fatty acid composition of the oil using gas chromatography. Pongamia seeds of individual accessions were taken in duplicate and crushed in a mortar and pestle and placed in a test tube and 4 ml of 0.5% sodium methoxide in methanol and 2 ml hexane were added. After shaking, the test tubes were covered and left for 5 min at room temperature. The samples were then heated at 60–65 ◦ C for 20 min in a water bath to form methyl esters. These FAMEs were subjected to gas chromatography analysis. A Thermo Focus GC fitted with a DB225 polar column (30 m, 0.322 mm, 0.25 ␮) and FID was used for the analysis of fatty acid composition. The temperature of oven, injectors and detector blocks was maintained at 210, 230 and 250 ◦ C respectively. Nitrogen was used as carrier gas. Peaks were identified by comparison with relative retention times of the standard FAMEs. Concentration of each fatty acid was recorded by normalization of peak areas using GC post run analysis software, manual integration and reported as % of the particular fatty acid. Saponification number (SN) and iodine value (IV) were calculated from FAME compositions of oil with the following equations (Kalayasiri et al., 1996):

IV =

Table 1 – Frequency distribution of 75 germplasm accessions of Pongamia pinnata for seed oil content.

46.3 + 5458 SN − 0.225 × IV

Oleic and linoleic acid (O/L) ratio was also computed. Correlation coefficients were worked out for the various traits studied. Based on the characteristics studied P. pinnata accessions were classified into low (< x¯ − 1 s), medium (x¯ − 1 s to

Number of accessions 1 11 19 33 11

x¯ + 1 s) and high (> x¯ + 1 s) categories where x¯ and s are mean and standard deviation respectively (Sarkar and Deb, 1984). Data is expressed as mean ± S.D. and subjected to correlation analysis using Microsoft Excel.

3.

Results and discussion

3.1.

Oil content

Oil yield forms the most important trait which will affect the overall commercial success of the efforts for P. pinnata cultivation and its use as an energy crop. Frequency distribution of 75 germplasm accessions of P. pinnata for seed oil content is presented in Table 1. Forty percent of the accessions have exhibited oil content ranging from 9.5 to 30% while 44% exhibited higher oil content in the range of 30.1–40% (Table 1). More than 40% oil content was recorded in 15% of the accessions. The 21 P. pinnata accessions selected for fatty acid analysis covered the whole range of oil content from minimum of 9.5% in DORPP 98 to maximum of 46% in DORPP 49 (Table 2). However, highest seed oil content of 49.8% was reported for seeds collected from Maharashtra state (Manjare et al., 2003). Kaushik et al. (2007) also observed variability in oil content from 32.6 to 44% in accessions collected from Haryana state. Seeds collected from six locations within three agroclimatic zones of Tamil Nadu located in southern India varied for oil content from 26 to 38.2% (Kumar et al., 2003). The two accessions with very high oil content (>43.6%) viz. DORPP 49 and 80 as well as DORPP 39, 51, 72, 76, 83, 85, and 87 with >40% oil content will be valuable for the development of high oil lines.

3.2.

Fatty acid profile

The quality of the oil is a function of its fatty acid profile. Palmitic, stearic, oleic and linoleic fatty acid composition varied widely in the 21 accessions selected for this study (Table 2). Of the accessions DORPP 48 and 66 had high (>61.83%) content of oleic acid (Table 3) while DORPP 39, 86, 87, 88 and 95 had high (>26.85%) linoleic acid content. The maximum values of both the fatty acids reported in the present investigation are considerably higher than those recorded by previous researchers (Scott et al., 2008). Among the saturated fatty acid contents, the accessions DORPP 31, 59, 80, 85 and 86 had the highest (>12.15%) palmitic acid while the lowest (< 5.40%) stearic acid content was noticed in DORPP 59, 80 and 85. Highest (>9.92%) stearic acid content was recorded in DORPP 48 and 86 (Table 3). Oleic/linoleic acid (O/L) ratio among the various P. pinnata accessions varied from 1.43 to 4.9. Accession DORPP 72 exhibited high O/L ratio and low iodine value (Table 2), which indicates higher stability and longer shelf life.

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Table 2 – Variability for oil content, fatty acid composition and biodiesel traits in 21 germplasm accessions of Pongamia pinnata. Accession no.

a

30.7 40.8 31.4 46.0 41.0 39.2 19.8 20.3 25.0 43.2 43.1 43.7 36.1 41.3 40.3 11.0 42.4 19.3 23.4 9.5 12.1 31.4 2.66 12.21 9.5–46

Oleic/linoleic ratio

Palmitic

Stearic

Oleic

Linoleic

12.70 9.86 9.40 11.60 10.85 12.38 11.78 11.28 10.66 11.84 11.54 12.87 10.06 9.78 12.45 12.15 9.25 9.79 9.77 10.12 10.68 10.99 0.25 1.16 9.25–12.87

5.40 5.94 10.06 7.13 6.49 4.38 9.37 7.26 9.03 8.87 9.51 1.83 8.51 9.37 5.13 11.50 9.13 8.42 8.78 6.26 8.53 7.66 0.49 2.25 1.83–11.5

57.20 46.66 65.08 55.50 61.33 60.75 57.98 65.35 56.88 58.94 56.58 56.81 60.28 56.39 58.25 47.88 47.70 51.92 51.99 60.14 57.32 56.71 1.12 5.12 46.66–65.35

19.30 32.58 15.41 18.08 15.30 15.86 20.85 16.09 23.40 12.02 18.31 22.68 16.62 15.87 19.02 28.45 27.17 29.85 29.44 23.47 23.45 21.11 1.25 5.75 12.02–32.58

Percentages may not add to 100% due to the noninclusion of other constituents.

2.96 1.43 4.29 3.07 4.00 3.83 2.78 4.06 2.43 4.90 3.09 2.50 3.63 3.68 3.06 1.68 1.75 1.74 1.77 2.56 2.46 2.94 0.21 0.97 1.43–4.9

Saponification number

190.3 190.8 200.1 185.5 188.6 187.8 200.8 200.6 200.6 184.2 192.7 189.6 191.4 183.3 190.8 200.9 187.0 200.5 200.5 200.5 200.6 193.67 1.42 6.51 183.30–200.91

Iodine value

Cetane number

86.4 101.0 86.4 82.7 82.9 83.4 89.9 87.9 93.5 74.8 84.0 92.2 84.3 79.5 86.8 94.6 92.1 100.8 100.1 96.6 94.0 89.24 1.56 7.17 74.78–100.98

55.5 52.2 54.1 57.1 56.6 56.6 53.3 53.7 52.5 59.1 55.7 54.3 55.8 58.2 55.4 52.2 54.8 50.9 51.0 51.8 52.4 54.4 0.51 2.35 50.85–59.11

i n d u s t r i a l c r o p s a n d p r o d u c t s 2 9 ( 2 0 0 9 ) 536–540

DOR PP 31 DOR PP 39 DOR PP 48 DOR PP 49 DOR PP 51 DOR PP 59 DOR PP 65 DOR PP 66 DOR PP 67 DOR PP 72 DOR PP 76 DOR PP 80 DOR PP 81 DOR PP 83 DOR PP 85 DOR PP 86 DOR PP 87 DOR PP 88 DOR PP 95 DOR PP 98 DOR PP 99 Mean S.E.M.± S.D. Range

Fatty acid composition (%)a

Seed oil content (%)

31, 59, 80, 85, 86 48, 86 48, 66 39, 86, 87, 88, 95 48, 51, 66, 72 65, 66, 67, 86, 88, 95, 98, 99 39, 88, 95, 98 49, 72, 83 39, 49, 51, 65, 66, 67, 72, 76, 81, 83, 98, 99 31, 39, 49, 51, 65, 66, 67, 72, 76, 81, 83, 87, 88, 95, 98, 99 31, 49, 51, 59, 65, 67, 72, 76, 80, 81, 83, 85, 88, 95, 98, 99 31, 48, 49, 59, 65, 66, 67, 76, 80, 81, 83, 85, 98, 99 31, 49, 59, 65, 67, 76, 80, 81, 83, 85, 98, 99 31, 39, 48, 49, 51, 59, 76, 80, 81, 85 31, 48, 49, 51, 59, 65, 66, 67, 76, 80, 81, 85, 86, 87, 99 31, 39, 48, 51, 59, 65, 66, 67, 76, 80, 81, 85, 86, 87, 99 48, 87, 88, 95 59, 80, 85 39, 86, 87 51, 72 39, 86, 87, 88, 95 72, 83, 87 72, 83 88, 95, 98 Fatty acid content (%) Palmitic Stearic Oleic Linoleic Oleic/linoleic acid ratio Saponification number Iodine value Cetane number

49, 80 31, 39, 48, 51, 59, 65, 66, 67, 72, 76, 81, 83, 85, 87, 88, 95 86, 98, 99 Seed oil content (%)

Low (< x¯ − 1 s) Character

Table 3 – Classification of Pongamia pinnata DORPP accessions in respect of their traits.

Medium (x¯ − 1 s to x¯ + 1 s)

High (> x¯ + 1 s)

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A significant negative correlation was observed between palimitic and stearic acid content (r = −0.469*). Oleic acid had a highly significant positive correlation with O/L ratio (r = 0.830**) while with linoleic acid it had a significant negative correlation (r = −0.816**).

3.3.

Biodiesel traits

Saponification number, IV and CN of fatty acid methyl esters of oils were empirically determined and they varied from 183.3 to 200.9, 74.78 to 100.98 and 50.9 to 59.11 respectively (Table 2). CN is the ability of fuel to ignite quickly after being injected and a higher value indicates better ignition quality of fuel. Biodiesel standards of USA (BS, 1999, 2002), Germany (BS, 1994) and European Organization (BS, 2003) have set this value as 47, 49 and 51 respectively. Iodine value is the degree of unsaturation. With increase of CN, IV decreases which means degree of unsaturation decreases. This situation will lead to the solidification of FAMEs at higher temperature. Hence US Biodiesel standards (BS, 1999) have specified the upper limit of CN as 65. IV less than 115 is the lowest maximum limit among the three biodiesel standards set by European Standard Organization (BS, 2003). In the present investigation, values for the three standards fell within these limits in the case of 21 accessions studied. Among the FAMEs of Pongamia, 3 accessions have CN value higher than 56.6. However, the highest minimum value among the three biodiesel standards is only 51 and all the accessions studied satisfy this limit with respect to CN. Pongamia species, which qualify the specification of CN, also meet the specification of IV. The iodine value ranged from 74.8 to 101.0 indicating that Pongamia oil is a semidrying type. Besides these parameters, the concentration of linolenic acid and acids containing four double bonds in FAMEs should not exceed the limit of 12 and 1% respectively in accordance with European standard organization (BS, 2003). P. pinnata FAMEs do not contain fatty acids with four double bonds. Azam et al. (2005) also reported that fatty acid methyl ester of oil of P. pinnata was found most suitable for use as biodiesel since it meets the major specification of biodiesel standards of USA, Germany and European Standard Organization. Correlation studies showed a highly significant and positive correlation with cetane number (r = 0.747**) while SN (r = −0.878**) and IV (r = −0.574**) showed a significant negative correlation with oil content. Oleic/linoleic ratio showed a highly significant positive correlation with CN (r = 0.743**) and negative correlation with IV (r = −0.872**). Saponification number showed a highly significant positive correlation with IV (r = 0.651**) and negative correlation with CN (r = −0.853**). Highly significant negative correlation between IV and CN (r = −0.951**) was also noticed.

4.

Conclusions

FAMEs as biodiesel are environmentally safe, non-toxic and biodegradable. In the light of US biodiesel standard (BS, 2002), in which the minimum value for CN is 47, all the P. pinnata accessions exhibit a desirable fatty acid profile for biodiesel purposes. Biodiesel quality may be considered better if CN is higher. In this study, CN of the FAMEs of the oils ranged from

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50.85 to 59.11 with a mean value of 54.4. P. pinnata accession DORPP 49 has been identified as the ideal biodiesel type while DORPP 72 and 83 are found as most promising and potential biodiesel types. Presently, the selection criteria for promising material for large scale plantations includes high seed yield coupled with high oil content. In addition to these parameters, the oil quality aspect should receive due attention with more efficient values for biodiesel standards adding to the overall efficacy of the biofuels. Though oil quantity and quality are greatly affected by environment and the material evaluated is heterogenous, significant variability has been recorded for most of the traits evaluated which can be utilized for selection of elite material in future. P. pinnata plantations are gaining importance due to the less crop husbandary management practices required in comparison to jatropha. Selection of appropriate genotypes which take into account the biodiesel standards viz. high cetane number besides high seed yield and oil content will result in more efficient biofuel types leading to accrual of higher benefits when such large scale plantations are considered. The establishment of plantations of promising genotypes through clonal means can also result in increased productivity. In the present investigation, genotypes DORPP 49, 72 and 83 were most efficient biodiesel types identified for further utilization and development.

Acknowledgment The authors are grateful to the Indian Council of Agricultural Research, New Delhi for financial grant provided under the Ad hoc Network Project on Tree Borne Oilseeds.

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