Fatty Acid Profile of Pometia pinnata J.R.Forst. & G.Forst Seeds Oil as a Potentially Biodiesel Raw Material

Pometia pinnata J.R.Forst. & G.Forst was a tropical native to the Pacific region, it was widely found and cultivated in Indonesia and has gained attention for the yield of the seeds oil. The seed oil of Pometia pinnata was investigated for biodiesel raw material. This study explores the promising potential of Pometia pinnata seed oil as a sustainable source for biodiesel production based on the chemical composition of the fatty acid. The seeds were collected from around Central Java Province, Indonesia, and extracted by the soxhlet method. The profile of fatty acid was characterized by Gas Chromatography. The yield of Pometia pinnata seeds oil was 22.37%. Based on the GC Result, the fatty acid concentration was 48,86% of saturated fatty acid and 51,14% of unsaturated fatty acid. The main content of fatty acid was Arachidate (20:00) and Oleate (18:02). The result verified that Pometia pinnata potentially as a biodiesel raw material. These results can be the basis study for further studies about Pometia pinnata used as biodiesel.


Introduction
Pometia pinnata (J.R.Forst.& G.Forst) was group of Sapindacaceae that origin from tropical South Asia, Southeast Asia, and Melanesia.Pometia pinnata was widely found in Indonesia, Including Papua, Maluku, Sulawesi, Kalimantan, Java, and Sumatra.Pometia pinnata commonly known as Matoa or Crystal longan fruit, it is a medium-sized tree that can grow until 18 M and fruiting after 2-5 years after planting, the tree flowering on July until October that can be harvest in three or four months later.Pometia pinnata is fleshy fruit used for consumption, while, the peel and leaves as antibacterial and antioxidant [1].The fruit is almost round in shape with a length of 1.5-5 cm and a diameter of 1.5-3 cm [2], it was distinguished according to the colour of the exocarp there was red, yellow, green, brown [3].Inside the pericarp, the was round seeds with a light brown to black color and has coated seeds.The seed of Pometia pinnata was the unprocessed part because it was a recalcitrant seed that was easily damaged during storage [4].Biodiesel raw material can be an alternative for utilizing the seeds because there was some Sapindaceae seed were contain several types of fatty acids [5]- [8].
Seeds oil can be used as biodiesel raw material.The seed contain fatty acid that potentially used as industrial raw material.Biodiesel is a renewable alternative fuel made from various raw materials, IOP Publishing doi:10.1088/1755-1315/1317/1/012025 2 primarily fats and vegetable oils was the most widely used feedstocks for biodiesel.It was designed to be used in diesel engines and can be blended with petroleum diesel fuel or used as a standalone fuel.Derived from organic materials, biodiesel offers a promising alternative to traditional fossil fuels.It is importance transcends economic and environmental factors, touching upon issues of energy security, greenhouse gas emissions reduction, and the preservation of ecological balance [9].As a biodiesel raw material, profiles of fatty acid were required to determine that the seed was suitable.The seed oils with a high of C16-C22 was potential as a recources of biodiesel raw material and for industrial oil [6].
Chromatography gas was commonly used for determined the characterized of fatty acid from extracted seed oil [10].Gas chromatography was a powerful technique for fatty acid analysis because it can separate individual fatty acids in a mixture, allowing for precise identification and quantification.The important of knowing fatty acid composition of the feedstock used to produce biodiesel because it was have a significant effect on the quality of the biodiesel product.Biodiesel was typically produced from triglycerides (fats and oils), [11], the composition of these triglycerides, specifically the types of fatty acids they contain, can impact various properties of the biodiesel, including its cetane number, cold flow properties, oxidative stability, and overall performance.The prevoius study of fatty acid component of Pometia pinnata were not found until the present moment, this study then aimed to analyzing the fatty acid of Pometia pinnata with the purpose to make it use as a biodiesel raw material to produce biodiesel.

Oil extraction
Th The materials were used in this study were matoa seeds and petroleum ether as solvents.The seeds were collected from around Central Java Province, Indonesia.The oil extraction was carried out in the UPT Integrated Laboratory of Sebelas Maret University from April to August 2022.
The oil Extraction was carried out using the esterification method, the first step selecting seeds by removing the damaged seeds.The seeds that have been separated from the fruit was cleaned and dried using an oven at 60 o C for 72 hours, than the seeds was mash used blender.Oil extraction seeds starts from weighing 2 grams of the seed powder and putting it into filter paper then placing it in a soxhlet extraction tool, putting petroleum ether in a boiling flask and extracting for 4-6 hours (10 cycles) then start distillation process on 70 o C. The extracted oil was calculated over the sample weight after dried in the oven.

Analysis of Composition of Fatty Acid using Cromatography Gas (GC)
The The fatty acid profile analysis by Cromatography Gas (GC) that was carried out in the Integrated Research and Testing Laboratory (LPPT).Analys of CG used digital scales, waterbath, vortex, fraction tube bottles, eppendorf, and CG tools.The materials used were matoa seed samples, concentrated HCl, diethyl ether and petroleum ether (1:1), methanolic sodium, boron trifluoride methanoate, heptan, and saturated NaCl.
For CG analysis, first take 0.5 mL of sample, add 1.5 mL of methanolic sodium solution then heat at 60°C for 5-10 minutes while shaking, cool the sample, add 2 mL of boron trifluoride methanoate and heat at 60°C for 5-10 minutes, then cooled.Extract with 1 mL Heptan and 1 mL saturated NaCl, take the top layer and put it in eppendorf.The results obtained were then injected as much as 1µL into the GC Agilent 7890B.

Analysis of Composition of Fatty Acid using Cromatography Gas (GC)
The average oil yield of Pometia pinnata was 22.37%, the previouse study was reported the yield of Sapindus saponaria was 42.58% while the Nephelium lappaceum was 31.23% using soxhlet method [5], [6].[12], reported the solvent that used in extraction prosess was impacted to the oil yield, petroleum ether was successfully extract linolenic acid and oleic acid better than hexane on jatropha, soybean, and sunflower oil.In this extraction process was carried out by the soxhlet method using petroleum ether as a solvent.The use of petroleum ether as a solvent aims to produce more and pure oil because it will only dissolve the oil in the seeds, not other components of the matoa seeds.The method used in this extraction was efficient to extract the oil which show the oil of Pometia pinnata seeds was lower than other Sapindaceae seeds.The oil yield in each plant was different, this was influenced by genetic, environmental and interaction factors of it [13].

Profile of Fatty Acid Composition
The fatty acid profile was crucial for biodiesel properties because it was directly influences the fuel overall quality and performance.Biodiesel was typically produced from renewable feedstocks like vegetable oils or animal fats, which consist of various fatty acid molecules.The composition of these fatty acids plays a significant role in determining the following biodiesel properties like kinematic viscosity, cetane number, cold flow properties, and flash point.Carbon chain length and fatty acid saturation can affected to the quality of biodiesel [14]- [16].Analysis of the fatty acid of Pometia pinnata seeds oil was carried out using GC.The result of the GC was a chromatogram that showed the composition of the fatty acids and concentrations (Fig. 1).The results of the chromatogram can show the retention time or time the compound was detected, the relative abundance or amount (%) of the compound in the sample and the type of compound found in the sample.Fatty acid analysis was carried out on the fragmentation peaks which were identified as fatty acid compounds based on their similarity to standard compounds.Based on the cromatogram (Fig. 1) there was 37 types of fatty acids found in the Pometia pinnata seeds.There was 11 fatty acid with short chain carbon (C6-12) and most of them was have <0.1% concentation except M Butyrate (3.89) and M Hexanoate (2.07) and 7 fatty acid with very long chain carbon (>C22) that have <0.1% concentation.Fatty acid with <0.1% was fatty acid that have low carbon not detected (ND).Biodiesel was made from fatty acid with carbon C16-C22, the lenght carbon of fatty acid was affected to quality of biodiesel properties.Fatty acids consist of saturated and unsaturated fatty acids.Saturated fatty acids are fatty acids whose hydrocarbon chains do not have double bonds, while unsaturated fatty acids are fatty acids that have double bonds.Unsaturated fatty acids have lower melting point values than saturated fatty acids.The presence of a double bond in the fatty acid structure will result in a different cis configuration if the double bond was located on the same side as the hydrogen group and a trans configuration if the double bond is located on the opposite side [17].The total concentration of saturated fatty acids in Pometia pinnata seeds was 48,86% and 51,14% of unsaturated fatty acids with the main fatty acid content namely methyl arachidate and methyl oleate respectively 36.12% and 23.38%.According to the length of the carbon chain, fatty acids are carboxylic acids with saturated or unsaturated aliphatic chains.Fatty acids can be divided into four groups, namely short chain fatty acids (<C6), medium chain fatty acids (C6-C12), long chain fatty acids (C13-C21) and very long chain fatty acids (C22).Moreover, fatty acids can contain different numbers of double bonds in their aliphatic chains at different positions.
The main fatty acid content was methyl arachidate (36.12%) and methyl oleate (23.38%), both of them was fatty acid with long chain carbon.Methyl arachidate has flash point value on 215°C while the methyl oleate has flash point value on 218 °C.Methyl arachidate and methyl oleate can be stored minimal at -20°C.Methyl arachidate was unsaturated fatty acid, while methyl oleate was saturated fatty acid.The saturation level of biodiesel can affect to the biodiesel properties.Blending the saturated fatty acids and unsaturated fatty acids in biodiesel was carried out to produce biodiesel products with desired characteristics for different applications and climates.
To produce high-quality biodiesel with desirable properties, biodiesel producers often carefully select feedstocks and optimize their processing methods to control the fatty acid profile.By doing so, they can address issues related to oxidative stability, kinematic viscosity, cetane number (CN), and cold flow properties (CFP), making biodiesel a more viable and environmentally friendly alternative to traditional diesel fuels.Fatty acids play a crucial role in the characteristics of biodiesel, which is a renewable and environmentally friendly alternative to traditional diesel fuel.The specific fatty acids found in biodiesel can influence various properties of the fuel.
Oxidation of biodiesel was chemical properties of fuel that affected to the engine performance and emission [18].The value of oxidative stability of biodiesel affects the stability during storage process [19].Unsaturated fatty acids, such as those in vegetable oils, can contribute to lower oxidative stability.Biodiesel made from oils with a higher content of unsaturated fatty acids may be more prone to oxidation and degradation over time, leading to fuel instability and the formation of harmful byproducts [20].[21], the presence of Oleate in biodiesel will improve biodiesel perfomance at the low temperature, and have a fositive impact in oxidation stability.The concentration of Oleate and the proportion of saturated fatty acid was conducted that Pometia pinnata seeds oil potentially have a positive contribution to the oxidative stability.
The type and composition of fatty acids in biodiesel can affect its viscosity.The standart kinematic viscosity in biodiesel based on ASTM D6751-12 was 1.9-6.0mm2/s.High viscosity can lead to poor fuel atomization and combustion, potentially causing engine deposits and reduced fuel efficiency [22].Biodiesel made from oils with a higher content of long-chain saturated fatty acids tends to have higher viscosity.The increase of carbon double bonds will incresing the kinematic viscosity value, which is biodiesel with more unsaturated fatty acid have a lower kinematic viscosity.Pometia pinnata seeds oil have more unsaturated fatty acid (51,14%) than saturated fatty acid (48,86%) but with a slight difference, it will affected to the value of kinematic viscosity.[23], the kinematic viscosity more affected by the molecular weight of fatty acid alkyl ester than the number of carbon double bonds, in the other hand, [24], the molecular weight of fatty acid methyl ester was not affected to the kinematic viscosity value, it was the oxygen content in the biodiesel molecule that was responsible in kinematic viscosity.
The cetane number was a measure of the ignition quality of diesel fuels.Fatty acids with higher saturation levels, tend to have higher cetane numbers, which means they ignite more readily and improve combustion efficiency.Based on [25], Palmitic (16:00) and Stearic (18:00) have positive relationship with the CN wich mean it will increase the CN value.In the other side, Linoleic (18:02), Oleic (18:01), and Linoleic (18:03) that have negative affected to CN value.Reseach by (Miraboutalebi et al., 2016), the concentration of Palmitoleic (> 0.8%) and Linoleic (> 36.5%)prediction have low CN value, while Oleic (> 59.285%) have medium CN value.Pometia pinnata have Palmitoleic (0.89%), linoleic (3.25%) and Oleic (23.36%), the concentration of it was remains lower than the prediction level that potentially decreasing the CN value.
Cold flow properties included of cloud point, pour point and cold filter plugging point.The composition of fatty acids can influence the cold flow properties of biodiesel.Fatty acids with longer carbon chains and saturated structures can lead to higher cloud points and pour points, making the fuel less suitable for cold weather use.Generally, biodiesel have CFP higher than petro diesel (Dwivedi & Sharma, 2013) for example the pour point value of biodiesel was 15-40 O C. The CFP value of biodiesel was by the level of unsaturated fatty acid, biodiesel with more concentration of unsaturated fatty acid (Lauric, Oleic and Linoleic) have positive factor to the CFP value [26].Pometia pinnata have higher Oleic acid (23.36%) it will improves the CFP of biodiesel.
Fatty acid methyl ester was chain of saturated and unsaturated compounds, it have difference prospects and consequences on biodiesel properties.An increase of chain length of saturated acid will increases viscosity, in the other side, it will affected to the CFP of biodiesel.However, the increases of chain length improves the CN value.To optimize the characteristics of biodiesel, it was essential to consider the fatty acid composition, source material, and treatment during the production process.Different feedstocks have varying fatty acid profiles, allowing producers to tailor biodiesel properties to meet specific requirements and environmental standards.

Conclusion
Pometia pinnata seeds oil was potentially uses as biodiesel raw material, the yield of the seeds oil was 22.37% with the main content of fatty acid was Arachidate (20:00) and Oleate (18:02).Based on the fatty acid composition of saturated and unsaturated concentration, it was promising as a biodiesel.For futher studies was needed to estimated the biodiesel properties of Pometia pinnata, specially for oxidation stability, kinematic viscosity, cetane number and cold flow properties that important which affects to the engine performance.

Figure 1 .
Figure 1.Chromatogram results of matoa seed fatty acids using gas chromatography
*) based on database of National Institute of Standards and Technology (NIST) and National Center for Biology Information (NCBI)