FATTY ACID COMPOSITION AS A CRITERION FOR RAPESEED APPLICATION FOR FUEL PRODUCTION

Monika Bojanowska
Department of Chemistry , Agricultural University of Lublin, Poland

ABSTRACT

The objective of the study was the identification, on the basis of its chemical composition, of a spring rapeseed cultivar most suitable for rapeseed oil production for use in fuels. The study involved the following spring rapeseed cultivars – Bosman, California, Capio, Liciassic, and Pomorzanin, harvested in the years 2003 and 2004. On the basis of conducted research, it was stated that rapeseed of the Bosman cultivar is characterized by the most favourable composition of unsaturated fatty acids in terms of fuel production.

Key words: rapeseed, fatty acids.

INTRODUCTION

The growth of rapeseed production in the world and in the European Union is stimulated primarily by the possibility of rapeseed oil use as a food product as well as in the production of non-nutrition products such as greases, lubricant oils, or Diesel fuel. Interest in rapeseed is related in particular to the possibility of using rapeseed oil for the production of renewable fuels for vehicles [3, 5]. This is determined by the rapid development of road transport that has a harmful effect on the natural environment, especially through the emission of great amounts of CO₂, compounds of sulphur and heavy metals, and aggravates the problems related to the greenhouse effect [2, 4]. In this situation it is more and more common to make use of energy generated from biomass – wood, straw, and oil contained in the seeds of oil-bearing plants [1]. Hence, the growth of the biofuel producing branch in the European market is very dynamic. Over the last few years, such countries as France, Germany, Great Britain or the Czech Republic increased their rapeseed production areas several-fold, mainly due to the advantages resulting from biofuels production on the basis of rapeseed oil [9, 13]. In Poland the area of rapeseed production does not increase, and the lack of suitable legislation and economic incentives that would permit rapid development of that branch of activity inhibit the growth of rapeseed production, even though there exist natural conditions and possibilities of its increase. However, the prospects for rapeseed producers are favourable. It is estimated that the demand of the Polish market for the raw material will systematically grow [7, 10]. This is determined by the necessity of introducing, in conformance with the EU Directive No. 2003/30/EC dated 8^th May, 2003, liquid biofuel production on the basis of bio-components of plant origin, as well as by increased demand of the fodder producing industry for high-protein materials – pomace, extracted meal. Therefore, forecasts for the coming years provide for an increase in rapeseed production area in Poland even up to 1 million hectares, and the projected yields of rapeseed should be on the level of 2.3-3.2 Mg · ha^-1 [8].

The objective of the study was the identification, on the basis of its chemical composition, of a spring rapeseed cultivar most suitable for rapeseed oil production for use in fuels.

MATERIAL AND METHOD

The study involved the following spring rapeseed cultivars – Bosman, California, Capio, Liciassic, and Pomorzanin, harvested in the years 2003 and 2004. The material was rapeseed collected from experimental plots of the Institute of Agrophysics, PAS, in Lublin. The harvest was performed in the final period of rapeseed ripening, i.e. after the completion of “seed filling with oil”. The content of crude oil in rapeseed was determined by means of the extraction method. Fatty acid composition was determined with the help of a gas chromatography apparatus, INCO 505 M with TZ 4620 integrator, made by the Czech firm Laboratorni Pristroje Praha. The diagrams obtained permitted the identification of the following fatty acids – saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), and polyunsaturated fatty acids (PUFA). The identification was made in conformance to the standards of Applied Science Laboratories.

RESULTS AND DISCUSSION

Analysing the particular years of the study it was noted that the year 2004 was characterized by more favourable conditions of rapeseed “filling with oil”. The mean content of oil in the rapeseed was
43.3-46.1%. Among the tested rapeseed cultivars, in both years of the study the highest content of oil was recorded for rapeseed of the Bosman cultivar – 41.4% to 46.1% (fig. 1).

The content of saturated fatty acids in rapeseed harvested in 2003 varied within the range of 3.47-5.2%. Notably lower content of those acids was recorded for all the rapeseed cultivars in 2004 – 1.87-3.4%. The least variation in this respect was observed during the two years in the seeds of the Liciassic cultivar (fig. 2).

Dominant among the saturated fatty acids is the palmitic acid (C₁₆) which constitutes 76.9-96.0% of their total content. Only in 2004, in the Liciassic cultivar, it accounted for less than 50% of the total content of saturated fatty acids. That cultivar, compared to the other ones, was characterized in both the years of the study by a lower content of palmitic acid (tab. 1).

In 4 rapeseed cultivars the content of unsaturated fatty acids in the two years of the study varied within a close range of 96.3-98.4%. A notably lower content of those acids was characteristic of the Pomorzanin cultivar – 64.9 to 74.6% (fig. 3).

Dominant among the unsaturated fatty acids are 18-carbon acids:

• oleic acid, with content values ranging from a minimum of 64.9% (Pomorzanin, 2003) to a maximum of 89.6% (Bosman, 2004) (fig. 4);

• linoleic acid, with content values from 5.3% (Bosman, 2004) to 20.7% (California, 2003), respectively (fig. 5);

• linolenic acid, with content values from 1.3% (Bosman, 2004) to 9.9% (Capio, 2003), respectively (fig. 6).

With respect to their content of unsaturated fatty acids, the tested rapeseed cultivars can be classified as follows:

Oleic acid:
2003 – Pomorzanin< California< Capio< Liciassic < Bosman
2004 – California < Pomorzanin < Capio < Liciassic < Bosman

Linoleic acid:
2003 – Bosman < Capio < Pomorzanin < Liciassic < California
2004 – Bosman < Capio < Liciassic < Pomorzanin < California

Linolenic acid:
2003 – Liciassic < Bosman < California < Pomorzanin < Capio
2004 – Bosman < Liciassic < California < Capio < Pomorzanin

Most vegetable oils contain over 50% of esters of mono- and polyunsaturated fatty acids in their composition. The content of those acids determines, among other things, the viscosity of fuel. Moreover, monounsaturated acids in rapeseed oil, and oleic acid in particular, are highly valuable for the production of stable fuels [12]. On the other hand, the presence of unsaturated acids with multiple bonds in RME molecules is the cause of their susceptibility to oxidation, which makes them less stable, especially during fuel storage. Thanks to the presence of the ester groups and of unsaturated bonds rapeseed fuel differs chemically from petroleum based fuels [6]. The common feature of both types of fuels is the presence of long carbon chains, which makes it possible for the two types of fuels to be mixed at any ratio required.

The chemical composition of rapeseed, and primarily the composition of fatty acids in rapeseed oil, determine the quality of the fuels produced [11]. Therefore, high importance is ascribed to the rapeseed cultivar from which rapeseed oil is produced for use in fuels.

CONCLUSIONS

1. The fatty acid profile is a feature dependent on the rapeseed cultivar.

2. Oil content in spring rapeseed is a feature characterized by high stability. In 2004, the oil content of all rapeseed cultivars varied around a similar level.

3. Rapeseed of the Bosman cultivar is characterized by the most favourable composition of unsaturated fatty acids in terms of fuel production.

REFERENCES

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Accepted for print: 12.12.2006

Responses to this article, comments are invited and should be submitted within three months of the publication of the article. If accepted for publication, they will be published in the chapter headed 'Discussions' and hyperlinked to the article.