Magonia pubescens ( Sapindaceae ) Seed Oil : Physical and Chemical Properties , Fatty Acid Profile and Biodiesel Production

Magonia pubescens is a tree species originally from the Brazilian Cerrado that bears fruit with winged seeds from which fixed oil can be extracted. This study aimed to analyze the physical and chemical properties of the oil extracted from these seeds and the biodiesel produced thereof. Methods from the Adolfo Lutz Institute, American Oil Chemists Society, and American Society for Testing and Materials were used. Seven fatty acids (oleic, arachidic, gadoleic, palmitic, palmitoleic, linoleic, and stearic acids) were found in the oil. Acidity level (1.119 mg KOH·g), iodine value (77.36 cg I2·g), saponification value (133.36 mg KOH·g), density (0.8796 g·cm), and refractive index (1.3348nD) were low when compared to the high peroxide value (26.14 meq·kg), viscosity (101.46 mm2·s), and moisture (0.88%) of other oils and fats used for biodiesel production. Biodiesel showed density (0.8484 g·cm), viscosity (29.62 mm·s), acidity level (0.752 mg KOH·g), and saponification value (148.89 mg KOH·g).


Introduction
Magonia pubescens (Sapindaceae), known as "Tingui", "Timbo", and "Tingui do Cerrado", is a plant originally from the Brazilian Cerrado also found in Bolivia and Paraguay.It is between four and twelve meters tall, and bears large, globular fruit with winged seeds, which germinate easily.This species is used for initial reforestation of degraded lands, its seeds are used to produce soap, and oil can be extracted there of (Coelho et al., 2012).
In this manner, most of the tests used to evaluate the physical and chemical properties in oil and biodiesel are based on indexes determined by the properties above (Martinez et al., 2014).
Seeking new oil sources for biodiesel production is important, since most oils used for its production are also used in foodstuffs.Therefore, low-cost oil sources that are not used as foodstuff, have appropriate physical and chemical properties, and are locally available should be indetified (Martinez et al., 2014).In the Brazilian context, the use of genetic resources of the Cerrado to develop new products contributes to the exploitation and preservation of species and increases the income of local communities.The seed oil from M. pubescens may represent an innovative source for biodiesel production, without posing a risk of reducing the supply of oil for food.In this manner, this study aimed principally to analyze the potential use of these seed oils for biodiesel production.

Method
The fruits and seeds were collected from July to September 2014 directly from M. pubescens trees in the Cerrado biome in the city of Montes Claros, Minas Gerais, Brazil.The species was identified based on a voucher specimen labeled as number 106750 in the Herbarium at the Institute of Biological Sciences, Federal University of Minas Gerais in Belo Horizonte, Minas Gerais.
The seeds were first peeled and then dried at 105±2 °C for 24 hours in an oven (Nova Ética, model 400-4ND).The cold-pressed oil was mechanically extracted using a hydraulic press.The extraction yield was calculated as a percentage of the weight of seed used.

Analysis of Seeds, Oil, and Biodiesel
The moisture content in the seeds was analyzed according to methods provided by the Adolfo Lutz Institute (IAL,  2008).The moisture content, density, ash content, peroxide value, saponification value, viscosity and refraction index of the oil were analyzed according to methods of the American Oil Chemists Society (AOCS).The density analysis and acidity level testing of the biodiesel followed the standards of the American Society for Testing and Materials (ASTM).

Complementary Analyses of Oil and Biodiesel
Some complementary analyses were carried out using methods different from those provided by the AOCS and ASTM.

Iodine Value (Oil)
The iodine value was calculated based on the composition of fatty acids with unsaturated bonds and their ratio in the oil composition, obtained by gas chromatography analysis, using the Equation 1 (Knothe, 2002).
Where, II = iodine value; Af = the percentage of fatty acid in the composition; 253.81 = weight of two iodine atoms that are theoretically added to a double bond; db = number of unsaturated bonds of the fatty acid; MWF = molecular weight of fatty acid.

Composition of Fatty Acids
The oil composition of fatty acids was analyzed using a gas chromatograph model 7890A GC system (Agilent Technologies, Santa Clara, CA, USA) coupled to a mass spectrometer model 5975C inert XL MSD with triple-axis detector (Agilent Technologies, Santa Clara, CA, USA).The esters were identified by comparing the mass spectrum previously found with the NIST 2.0 library standards Chemstation software (Agilent Technologies, Santa Clara, CA, USA).
Firstly, an oil sample was subjected to derivatization.The process was carried out by adding 20 mg of oil to 5 mL of potassium hydroxide solution at 0.5 mol•L -1 .The mixture was heated under reflux and stirred constantly for one hour.Subsequently, 2 mL of 4:1 v/v hydrochloric acid/methanol was added and the solution was heated under reflux for another hour.After reaching room temperature, 5 mL of distilled water was added.For extraction, three aliquots of 5 mL of dichloromethane were added to the material obtained from derivatization.The organic phase was collected and then anhydrous sodium sulfate was added to remove water.The resulting mixture was filtered through a round-bottom flask and evaporated in a rotary evaporator at 65 °C.The material was solubilized again using dichloromethane as a solvent and placed in a previously weighed penicillin bottle.After spontaneous evaporation of all dichloromethane in a desiccator at room temperature, the yield was jas.ccsenet.

calculated dichlorom
The carrie 220 °C.Th at a rate of interface te

Biodie
The biodie 6 mol of constantly distilled w turbidity d

Results
The  On comparing M. pubescens oil with other oily inputs used for biodiesel production (Table 1), it is possible to observe that oleic acid is the main acid found in this oil (56.9%), and is the second most frequently found in soybean oil (25.09% to 26.55%).Arachidic acid (11.3%) and gadoleic acid (9.5%) are, respectively, the second and third most prevalent in M. pubescens oil, although they represent less than 1% of fatty acids in soybean oil.
On the other hand, linoleic acid, whose content in soybean oil is higher, ranging from 51.04% to 55.4%, is lower in M. pubescens oil (3.7%).
The palmitic acid found in M. pubescens oil (8.2%) is also found in palm oil, although at higher levels (43.03% and 45.6%) in the latter.Oleic acid is abundantly found in M. pubescens oil (56.9%), while it is the second most commonly found (38.5% to 39.47%) in palm oil.The linoleic acid found in M. pubescens oil (3.7%) is the main fatty acid in sunflower oil (51.17% to 52.01%).Cotton seed oil also has a great quantity of this fatty acid (57.4%).

Physical and Chemical Properties of M. pubescens Oil
Physical and chemical properties of oils are determined by their conservation status, chain length, and degree of unsaturation of their fatty acids.Some properties are related to only one of these properties, e.g., the iodine number, which depends on the degree of unsaturation and the saponification value, which is determined by the carbon chain length.The combination of degree of unsaturation and chain length is critical for density, viscosity, and refraction.The oil conservation status can be assessed by tests such as acidity value and peroxide value.

Saponification and Iodine Value
M. pubescens oil has a lower saponification value (133.36 mg KOH•g -1 ) compared with other oils used as raw materials for biodiesel production, such as soybean (190.1 to 194.2 mg KOH•g -1 ), animal fat (196.3 to 195.7 mg KOH•g -1 ), palm (199.1 to 200.1 mg KOH•g -1 ), canola (184.0 to 191.0 mg KOH•g -1 ), and sunflower (187.7 to 195.3 mg KOH•g -1 ), and is also lower than linseed (179.4 mg KOH•g -1 ) and acai (189.1 mg KOH•g -1 ), as shown in Table 2.  M. pubescens oil consists of 20.8% fatty acids such as gadoleic and arachidic containing 20 carbon atoms.The presence of long chain fatty acids justifiesa lower saponification value when compared with soybean, canola, sunflower, and animal fats that have fewer long chain fatty acids (Table 1).
Table 1 shows that M. pubescens oil has seven fatty acids and four of them are slightly unsaturated (palmitoleic, linoleic, oleic, and gadoleic).However, only linoleic acid has two double bonds and represents only 3.7% of the fatty acids.The remaining three fatty acids have only one degree of unsaturation.When compared with other oils, the fatty acid composition may have contributed to alower iodine value, as linoleic acid, which is unsaturated, is abundantly found in soybean (51.04% to 55, 4%) and sunflower oil (51.17% to 52.01%), which presented higher iodine indexes than M. pubescens oil.

Acidity Level, Peroxide Value, and Moisture Content
The acidity level of M. pubescens oil (1.119 mg KOH•g -1 ) is suitable for biodiesel production.Although there are no official regulations for properties of oils used as raw material for biodiesel production, the acidity level is expected to be below 2 mg KOH•g -1 (Kwiecien et al., 2009).
The peroxide value found in M. pubescens oil (26.139 meq•kg -1 ) was higher than that found in the literature for soybean (0 to 3.21 meq•kg -1 ) and palm oils (0.6 to 2.19 meq•kg -1 ), which are raw materials considered of great importance for biodiesel production.The only oil that showed a peroxide value greater than that of M. pubescens was acai (177.1 meq•kg -1 ) (Table 3).The peroxide value is related to storage time, temperature, exposure to light, foreign materials, the extraction process used to extract the oil, and may also vary depending on the origin of seeds used in the extraction process (Almeida et al., 2013; Mata et al., 2011; Pantoja et al., 2013; Sidibé et al.,  2010).
Analyses were carried out immediately after oil extraction, so the high peroxide value found is not related to storage time, but may be related to the extraction process employed.In this manner, it is important to carry out studies for the evaluation of other extraction processes, in order to obtain oils with lower peroxide values.
The refractive index of M. pubescens oil (1.3348 nD) is lower than that reported in the literature for soybean (1.4671 and 1.4680 nD), sunflower (1.4668 and 1.4679 nD), corn (1.4657 nD), and castor oils (1.4792 nD), and higher than that of linseed oil (1.2 nD) (Table 4).The refractive index depends on the degree of unsaturation of the fatty acids of the oil, the oxidized compounds and polymers present, and also varies according to the heat treatment the oil undergoes.Each type of oil, therefore, shows a different refractive index (Ghanei et al., 2011;  Jorge et al., 2005; Moradi et al., 2012; Santos et al., 2013).
The ash content found in M. pubescens oil was 0.012%, which is similar to that reported in the literature for palm (0.01%) and souari nut oils (0.01%), and less than that found in babassu oil (0.03%) (Costa Neto et al., 2000).
The transesterification also reduced the density of M. pubescens oil from 0.8796 g•cm -3 to 0.8484 g•cm -3 in biodiesel.In spite of being a value higher than that found in mineral diesel (0.838 g•cm -3 ), it is lower than that determined by the ANP and suggested for biodiesel from other sources (Table 5).
The biodiesel acidity level (0.752 mg KOH•g -1 ) was higher than the limit established by the ANP and the ASTM D6751, which suggesta maximum of 0.5 mg KOH•g -1 .The level found is also higher compared with biodiesel produced from other sources, such as soybean (0.16 and 0.24 mg KOH•g -1 ), canola (0.16 to 0.32 mg KOH•g -1 ), cotton (0.09 mg KOH•g -1 ), and sunflower oils (0.14 and 0.34 mg KOH•g -1 ).However, it was lower than that found in biodiesel produced from reused oil (3.3 to 15.7 mg KOH•g -1 ) and castor oil (1.03 to 1.60 mg KOH•g -1 ) (Table 5).The acidity level of biodiesel is related to the biodiesel production process.Transesterification using oils from the same source, but modification of reaction conditions such as temperature, stirring, molar ratio between catalyst and alcohol, results in biodiesel with different acidity levels (Canoira et al., 2010; Jacobson et  al., 2008; Martinez et al., 2014).
There are no official regulations for saponification values in biodiesel.The saponification value of biodiesel from M. pubescens oil was 148.89 mg KOH•g -1 , which is below the saponification values reported in biodiesel produced from different sources of oil such as soybean (190.7 mg KOH•g -1 ), rapeseed (185.0 and 197.07 mg KOH•g -1 ), sunflower (186.0 and 190.23 mg KOH•g -1 ), and palm oil (205.0 mg KOH•g -1 ) (Table 5).
In Brazil, it is tried to diversify the oil sources for the fabrication of biodiesel through the Brazilian National Program of Production and Use of Biodiesel, which also encourages the inclusion of family farming in the cultivation of these inputs with the goal of promoting social development.However, due to the variation in price and low availability of other raw materials, soybean oil remained the main source used in recent years (Santos  Alves et al., 2017; César & Batalha, 2010; Zonin et al., 2014).It is also necessary to consider that soy is an important foodstuffs, so it is imperative to find new oil plants with potential for biodiesel production and that do not represent sources of food, as the M. pubescens (No, 2011; Suarez et al., 2009).
Other studies must be carried out in order to verify the possibility of cultivation, economic and productive variables such as productivity per hectar and oil content per hectar, since these conditions have not yet been evaluated and this work verified that M. pubescens oil has physical and chemical properties appropriate for biodiesel production, with the exception of the peroxide value.Therefore, further studies too should be carried out to evaluate other extraction processes to achieve suitable peroxide values and allow for a better use of seeds.Chromatographic analysis showed that the qualitative composition of fatty acids in the oil is similar to that of other oils used for biodiesel production.M. pubescens oil is suitable for producing biodiesel, however, transesterification conditions should be evaluated to obtain biodiesel with more suitable physical and chemical properties.

Table matogram M. pu
%.The quantity r cleaning and a mass spectro cid profile of v (Knothe et al., y of oil extracte heating the s meter (GC-M vegetable oils , 2002).Most by GC-MS

Table 1 .
Fatty acid composition in M. pubescens oil and other oils

Table 2 .
Saponification and iodine index M. pubescens oil and other oils

Table 3 .
Acidity index, humidity and peroxide index M. pubescens oil and others oils

Table 4 .
Viscosity 20 °C, specific mass 20 °C and refractive index M. pubescens oil and others oils

Table 5 .
Characterization of biodiesel M. pubescens and comparison with others sources