Papaya seeds as source of extracts with protective effect against the edible palm oil oxidation

Enviado por Fabian

Protective effect against the lipid oxidation in edible vegetable oil of supercritical extracts from papaya(Carica papaya L.) seeds

Abstract

Extracts with protective effect against the lipid oxidationwere obtainedfrom papaya (Carica papaya L.) seeds.Papaya seed extracts were obtained by supercritical fluid extraction (SFE) and Soxhlet extraction (SE). The SFE was performed using carbon dioxide (CO2) at different temperatures and different pressures, after extractions using CO2 added with ethanol(CO2/EtOH) were made.EtOHand hexanewere used in the SE. Theprotective effect against the lipid oxidationof the extracts was evaluated in vegetable edible oil (EO) and compared with the synthetic antioxidant butyl hydroxytoluene (BHT). The highest yield values were achieved in the SE withEtOH (31.46 ± 0.10%) and the SFE withCO2/EtOH(23.75 ± 0.04%).The extracts obtained by SE with EtOH, by SFE with CO2 at 20 MPa (40, 50 and 60 °C)andwithCO2/EtOH (20 MPa, 50°C and 5%of co-solvent)showed the highest protective effect on EO,this effect was higher than that observed for BHT. These results show the papaya seeds as a promissory source of compounds with protective effect against oxidation of vegetable edible oils, so it is an alternative for to replace the synthetic antioxidants used by food industry.

Keywords:Carica papaya L. seeds, supercritical fluid extraction, lipid oxidation.

Introduction

Papaya (Carica papaya L.) is a native fruit of tropical America, actually distributed in many tropical countries. Its global production in 2012 was about 3.52 million t, India and Brazil were the major producers with 1.46 and 0.43 million t respectively, whereas Colombia produced about 46527 t [1]. The fruit is grown mainly for fresh consumption, for juices production and for the papain production. Many processed products are currently produced, however, this use is limited to papaya pulp, discarding the seeds which can reach 15% w/w of the fruit[2]. The papaya seeds have been used in countries from Africa, Asia, Central and South America as a traditional medicine in malaria treatment, as sedative, muscle relaxant and anticonvulsant [3]. The papaya seed extracts have exhibited different biological properties; ethanolic extracts showed antibacterial activity, as well as ovicidal and larvicidal activity[4], aqueous extracts have anthelmintic and antiamoebic activity [4,5], whereas methanolic extracts exhibited a slight antiinflammatory activity in rats [6]. The contraceptive effect of papaya seeds extracts has been well documented; its extracts and fractions possess a high contraceptive efficacy in males rats[7], monkeys[8], rabbits[9] and dogs [10]. The papaya seed extracts also exhibited antioxidant activity (AA), its radical scavenging potential have been evaluated using different radicals[11,12].However, AA of papaya seed extracts in foods or similar matrices have not yet been addressed(verscopus).

Lipid oxidation plays an important role the spoilage in foods, development of undesirable flavours and formation of toxic and carcinogenic compounds. In edible oils,heating and storage stimulates the oxidation development, leading to deterioration in flavor, texture and nutritional value. The use of antioxidants is an efficient mechanism to delay the oxidation; synthetic antioxidant as ter-buthyl hydroquinone (TBHQ), butyl hydroxyanisol (BHA) and butyl hydroxytoluene (BHT) have been widely used due to its low cost and high efficiency. However, they have been questioned about their volatility, thermal instability and possible carcinogenic effects [13,14]. This has generated a need to search and to research alternativesources of antioxidants, particularly from natural matrices, as well the most appropriate technology its obtaining.

The supercritical fluid extraction (SFE) is an alternative, emerging and novel methodology for the antioxidants obtaining, various studies have shown the effectiveness of SFE in obtaining antioxidants with ability to retard the lipid oxidation in foods and other food models[15-17].About this, our research group has explored theSFE from fruit wastes obtaining extracts with AA in foods as cooked beef meat [18], canola oil [19] and linoleic acid emulsion [20]. The results obtained have shown that SFE is an efficient and selective method for obtaining antioxidants with AA in foods.Additionally supercritical fluid extraction has not been applied to papaya seeds

This work explored the possibility to use the papaya seeds as anantioxidants source capable to retard the lipid oxidation on EO. Therefore, different extracts were obtained employing SFE with carbon dioxide (CO2) and withCO2 added with ethanol(EtOH) as co-solvent (CO2/EtOH). The results obtained in the SFE were compared with the Soxhlet extraction (SE) in terms of yield extraction and AA.

Materials and methods

2.1. Samples, chemicals and standards

Alimentos SAS S.A. (Bogotá-Colombia) provided the papaya seeds, them were a waste product from papaya fruit processing. The refined, bleached and deodorized vegetable edible oil (EO), without antioxidants, was supplied by Duquesa S.A. (Bogotá-Colombia). This oil is a mixture of edible palm, soy and sunflower oils, composed of 70% of triglycerides (TG) with unsaturated fatty acids, as there are 60% oleic, 35% linoleic acid and 5% others, and 30% of TG with saturated fatty acids (stearic acid). The papaya seeds and the EO were stored in dark at -20 and -80 °C, respectively, until use.

The CO2 (99.9% purity)was purchased from White Martins Praxair Inc (Joinville-SC, Brazil). Ethanol (EtOH), isooctane, tricloroacetic acid (TCA) and chlorhydric acid (HCl) were purchased from VetecQuímicaFinaLtda (Rio de Janeiro-RJ, Brazil). Thiobarbituric acid (TBA), hexanal (HEX) and nonanal (NON) were obtained from Alfa Aesar (Lancashire, UK). Ferrous chloride dihydratewas purchased from Merck (Darmstadt, Germany). 1,1,3,3-tetraetoxypropane (TEP) and butylatedhydroxytoluene (BHT) were purchased from Sigma-Aldrich Chemical Co. (St. Louis-MO, USA). Chloroform and hexanewere obtained from Synth (Diadema-SP, Brazil).The solid-phase microextraction fibers were purchased from SupelcoSigma-Aldrich(St. Louis-MO, USA). All reagents and solvents used were either analytical or HPLC grade.

2.2. Papaya seeds preparation

The papaya seeds were cleaned using running water, subsequently these were dried at room temperature for 72 h until final moisture 0.3%. The dried seeds were crushed using a knife mill (De Leo, Porto Alegre-RS, Brazil) and then the particles were separated by size in a vertical vibratory sieve shaker (BertelMetalurgic Ind. Ltda., Caieiras-SP,Brazil). The material with particle size between 0.300 and 0.850mm (+50/-18 US Standard size sieves) was used in all extractions,the mean particle diameter was 0.496 ± 0.003 mm calculated based on mean size distribution[21]. Finally the ground samples were stored in plastic bags at -20 ºC until the extractions.

2.3. Supercritical fluid extraction (SFE)

The SFE of papaya seeds was performed in a dynamic extraction unit [22,23]. The equipment contains a pressurized CO2 reservoir, a cold bath (Thermo Haake C10, Karlsruhe,Germany) kept at -10 °C in order to keep the CO2in liquid state, an air driven pump (Maximator M111, WalkenriederStraßeZorge, Germany), a stainless steel jacketed extraction column (329 mm length, 20.42 mm inner diameter and internal volume of 100 mL), pass valves, flow regulators and manometers. The extraction temperature was controlled by a thermostatic bath (Thermo Haake DC30 Karlsruhe, Germany). A co-solvent pump (Constametric 3200, Thermo Separation Process, Riviera Beach-FL, USA) was connected to the extraction line in order to supply the modifier (organic solvent at high-pressure) at pre-established flow rate, to mix with CO2 flow before the extraction vessel.The extraction procedure was previously established [24]; sample of papaya seeds (10 g)was place inside the extraction column to form the fixed bed of particles, then the process variables (temperature, pressure and solvent flow rate) were achieved and the continuous flow of solvent was allowed.The mixtures supercritical solvent-extracts were separated to ambient pressure using a pressure regulator valve and the extracts were collected in amber flasks. Each extraction was performed during 180 min (according to previous kinetics assays), finally the extracts wereweighted in an analytical balance (SHIMADZU Model AY220, São Paulo-SP, Brazil), flushed with nitrogen stream, sealed, and stored at -20 °C.

The SFE assays were divided in two groups:

(1) CO2assays using the supercritical solvent at different temperatures (40, 50 and 60 ºC), and differentpressures (10, 20and 30MPa),and a CO2flow rate of 0.5 ± 0.05 kg/h. The extraction temperatures and pressures were selected based on previous experience and the maximum operational conditions of extraction unit.
(2) Assays with CO2/EtOH, where the EtOH was added to supercritical CO2in concentrations of 2, 5 and 8% w/w. This group of assays was performed at 50 °C, 20MPa and constant CO2/EtOH flow rate of 0.5 ± 0.048 kg/h. Thetemperature and pressure were chosen considering theextraction yield and AA results of assay group (1). After the extraction the EtOH was removed in rotary evaporator at 40 °C (Fisatom model 802, São Paulo-SP, Brazil).

2.4 Soxhlet extraction (SE)

The SE was performed using EtOHand hexane as solvents. Sample of papaya seeds (10 g)wasplaced inside a thimble made by thick filter paper and loaded into the 250 mLSoxhlet extractor. The solvent (150 mL) was used at the boiling temperature for 8 h extraction. After the extraction the organic solvent was removed in rotary evaporator at 40 °C. Finally the extraction yield and the AA were evaluated.

2.5 Protective effect against lipid oxidation in an vegetable edible oil

The protective effect against lipid oxidation of edible oil (antioxidant activity-AA) of SFE and SE extracts was evaluated in EO and compared to the AA of the a synthetic antioxidant butylatedhydroxytoluene (BHT) [19,25-27].

2.5.1 OE oxidation

Samples of EO without antioxidants (20 g each one) were placed inside amber flasks and a ferrous chloride solution was added at a Fe+2 concentration of 3.5 mg/kg of EO. Then the extracts obtained, each separately,were added to the EO samples at a final concentration of 300 mg/kg EO [28], and the mixtures were homogenized for 2 min using a Vortex (AP 56 Phoenix, Araraquara-SP, Brazil). Control sample (EO without antioxidants) and EO with BHT were similarly prepared and immediately analyzed (zero-day). The antioxidant-doped samples, control sample and EO with BHT were subject to oxidation by heating to 60 ± 2 °C in an oven for 15 days, under stirring and bubbling for 1 min with oxygen, every 12 h. The EO oxidation was determined by cuantifying some lipid oxidation products, such as linoleic acid hydroperoxides (LHP), hexanal (HEX), nonanal (NON) and the thiobarbituric acid reactive species (TBARS). The results were presented as the difference of LHP, HEX, NON, and TBARS content between the 0 and 15 days, respectively. For all assays six replicates of EO oxidation were analyzed.

2.5.2 Measurement of LHP

The LHP formation was measured by the conjugated dienes method [27,29,30]. Briefly, 50 mg of oxidized EO were diluted in isooctane and the absorbance was measured at 234 nm (VARIAN Cary 50 Conc), Palo Alto-CA, USA). The concentration of linoleic acid hydroperoxides was calculated using its molar extinction coefficient (?=26000 M-1 cm-1) [31] and the results was expressed as mmoles of LHP per kilogram of EO (mmol LHP/kg).

2.5.3 Measurement of HEX and NON

The decomposition of LHP to HEX and of oleic hydroperoxides (OHP) to NON was measured by headspace-solid phase microextraction-gas chromatography (HS-SPME-GC)[25,32,33].

2.5.3.1 HS-SPME.

500 mg oxidized EO were placed in a 20 mL amber headspace vial, then a magnetic stirrer was added and the vial was capped with a rubber septum and aluminium cap. The vial was placed in a water bath at 50 ± 1 °C with continue stirring at 700 rpm and the sample was equilibrated for 20 min. Later the divinilbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS, 50/30 µm) fiber was exposed to the headspace and the volatile compounds were adsorbed for 30 min. The isolated compounds were analyzed by gas chromatography with flame ionization detection (GC-FID).

2.5.3.2 GC-FID analysis

The gas chromatograph was a GC Agilent Technologies 6820 GC System (Palo Alto-CA, USA), equipped with a split/splitless injector with a 0.75 mm i.d. glass splitless liner, a DB-5 column (30 m, 0.25 mm i.d., 0.1 µm film thickness, Agilent J&W Scientific, Folsom-CA, USA) and a flame ionization detector. The oven temperature was programmed starting at 30 °C for 2 min, increasing from 30 to 60 °C at 2 °C/min and from 60 to 280 °C at 20 °C/min, holding for 2 min. Helium gas was used as carrier gas at a flow rate of 1.8 mL/min. The temperatures of the injector and the detector were 250 and 300 °C, respectively. Splitless mode was used for the compound desorption in the GC injector for 2 min. HEX and NON were identified by co-elution and comparison to standards. The results were expressed as arbitrary area units for mg of EO (AU/mg).

2.5.3 Measurement TBARS

The TBARS were measured based on previous literature reports [34,35], with slight modifications. To 100 mg EO in 50 mL falcon tubes 26 mM BHT, 26 mMthiobarbituric and 0,3 M tricloroacetic in 0,2 M HCl were subsequently added. The mixture was stirred in a vortex for 30 s and heated in a boiling water bath for 40 min. After the tubes were cooled to room temperature, a 5 mL aliquot of the aqueous phase was mixted with 5 mL chloroform and stirred in a vortex for 30 s, followed by centrifugation (HettichZentrifugen, Universal 320R, Tuttlingen, Germany) at 5500 rpm for 20 min. The aqueous phase was taken and its absorbance was measured at 532 nm (VARIAN Cary 50 Conc, Palo Alto-CA, USA). The results were expressed as mg of malondialdehyde per kilogram of EO (mg MDA/kg) calculated from a standard curve of MDA (36 nM to 185 nM) obtained from hydrolysis of 1,1,3,3-tetraetoxypropane.

2.6 Statistic analysis

All experiments (SFE, SE and AA) were performed by six replicate. The results were reported as the mean and the standard deviation. In the assay group (1) of SFE a 32 factorial design was used. A two ways analysis of variances (ANOVA) with 95% confidence was carried out with the purpose of determining significant differences between the treatments and the effect of process variables. All analysis were performed using the software R (Version 2.13.0).

Results and discussion

3.1. Extraction yield

The extraction yields obtained by SFE (with CO2 and CO2/EtOH) and SE (with hexane and EtOH) are presented in table 1, as also CO2density at the extraction conditions used. The highest extraction yield was obtained in the SE withEtOH(31.46 ± 0.10%), this yield was higher than that obtained with hexane (22.16 ± 0.16%) and reported in literature for the SE with petroleum ether (29.16 ± 0.88%)[36].

In SFE with CO2 the highest extraction yield was obtained at 60 °C/30 MPaand 50 °C/20 MPa (20.50 ± 0.29 y 20.42 ± 0.62%, respectively)with CO2 densities of 0.8302 and 0.7857 g/mL respectively. The ANOVA showed no significant difference between these values (p < 0.05).The extraction yields obtained at 40 °C/20MPa, 60 °C/20MPaand50 °C/30 MPa (19.41 ± 0.50, 19.63 ± 0.64 y 19.56 ± 0.34%,respectively),were close to that obtained at 50 °C/20 MPa, the ANOVA indicated no significant differences between these yields.On the other hand, the lowest extraction yield was obtained at 60 °C/10 MPa (0.51 ± 0.04%),which is due to the low supercritical CO2 density (0.2914 g/mL).

The effects of extraction conditions on extraction yield are show in the yield isotherms (figure 1).The increased in the extraction pressure, at constant temperature, produced in the enhancement on the extraction yield due to increase the CO2 density. The variation in the pressure of 10 to 20 MPa increased substantially the extraction yield;at 40 °C the increase was 4.2 times, at 50 °C 12.7 times, whereas at 60 °C was 38.8 times.The pressure variation from 20 to 30 MPahad a slight or no effect on extraction yield.The temperature effect is more complex; at 10 MPathe increased in extraction temperature produced a decreased in the yield (from 4.59 ± 0.61 to 0.51 ± 0.04%)due to the reduction in CO2 density(from 0.6290 to 0.2914 g/mL). At 20 the increased in the temperature shows no effect on the yield, the ANOVA suggest these yields no show significant differences (see table 1). At 30 MPa the increased in the temperature provided an increment on the yield, despite the reduction in CO2 density. This behavior was caused by the enhancementin the solutes vapor pressure with temperature, which was moresignificant than the reduction in the solvent density. These effects produceda crossover in the yield isothermsas shown in figure 1, the crossover pressure for the system studied is between 17 and 25MPa. A similar behavior was also evidenced in the SFE from other fruits seeds as guava andpeach [20,37] and others natural solid matrices[18,23,24].

A two-ways ANOVA (p < 0.05) was performed to observe the effect of process variables (temperature and pressure) on SFE with CO2 yield. According to the analysis pressure (p < 0.00001), temperature (p= 0.0238) and temperature-pressure interaction (p= 0.00001) have a significant effect on SFE yield.The low p-value observed for the pressure indicates this variable have a greater effect on extraction yield.

In order to improve the yields and AA (section 3.2) of extracts obtained from the SFE with CO2, papaya seeds were subjected to extraction with CO2 added with EtOH as co-solvent, the extraction conditions selected were 50 °C/20 MPa. Theresults obtained (table 1) show that the extraction yield increased with the EtOH addition (2, 5 and 8%) compared to the SFE with CO2,however, the yields obtained using CO2 and CO2 with 2% EtOH were not significantly different. This increase in the extraction yield is due to the increase in the concentration of intermediate polarity compounds in the extracts, which have a limited solubility in pure CO2. At the same time the co-solvent addition could stimulate the disruption of solute/solid matrix interactions, accompanied by the substitution in the active sites with molecules of co-solvent and solubilization of the compounds, as well as the diffusion of solutes in the matrix by swelling[38].

The extraction yield obtained using CO2/EtOH show a maximum at 5% EtOH (23.75 ± 0.04%). The increased in the EtOH concentration from 2 to 5% produced an enhancedin the yield (from 21.02 ± 0.05 to 23.75 ± 0.04%). However the increased from 5 to 8 % decreased the yield (from 23.75 ± 0.04 to 22.52 ± 0.04%), this effect may be due to increase in the hydrogen bonds formation between molecules of EtOH at 8% of co-solvent, which decrease their interaction with polar solutes molecules [38]. A similar behavior had been observed in other studies, EtOH concentration upper 5% decreases the extraction yield from Cordiaverbenacealeaves [24]andtamarillo (SolanumbetaceumSendtn) epicarp[18].

In comparison with the SE with hexane, the yields obtained by SFE with CO2 were lower, however, the yields obtained using CO2/EtOH (5 and 8% EtOH) were higher. Moreover, the yields obtained in this study were higher than those reported for the SFE of brazilian papaya seeds (2.5% at 80 ° C/20 MPa)[39]. Compared to SFE yields obtained from other fruit seeds our yields were higher than those reported for guava seeds (17.30 ± 0.10% at 40 °C/30 MPa and 10% EtOH) [20], grape seeds (11.5 % at 40 °C/20 MPa) [40] and pomegranate seeds (14% at 60 °C/40 MPa)[41].

The results obtained show that papaya seeds are a good source of extracts which can be obtained using SFE with significant yields. These extract are 100% free of solvent or with a little among of EtOH (a generally recognized as safe "GRAS" solvent). This features allows considering the use of these extracts in products intended for human or animal consumer, an option is its use as antioxidants in food protection against lipid oxidation. Considering this the protective effect against lipid oxidation in vegetable edible oilwas evaluated.

3.2 Protective effect against lipid oxidation of vegetable edible oil

The extracts obtained from papaya seeds were added to EO in order to assess their ability to delay the lipid oxidation. The AA results of the papaya seeds extracts and BHT are shown in table 2.The extracts obtained with CO2 at 20 MPa showed the highest AA in EO, the extract obtained at 50 °C showed the highest efficiency to attenuate the linoleic acid hydroperoxides (LHP), hexanal (HEX), nonanal (NON) and thiobarbituric acid reactives species (TBARS) formation. This extract decreased the LHP formation in 83% compared to CONTROL, while the NON and TBARS production was attenuated in 77 and 87%, respectively, compared to CONTROL.Although the ability of this extract to minimize the formation HEX was low, 24% compared to CONTROL, this was higher than observed for most of the extracts obtained by SFE and the extract obtained by SE with hexane. Meanwhile the extracts obtained at 40 °C and 60 °C showed a similar ability to reduce the LHP, NON and TBARS formation compared to extract obtained at 50 °C, however its efficiency to delay the HEX formation was lower. The extract obtained at 40 °C delay the LHP, HEX, NON and TBARS formation in a 84, 16, 75and 78%, respectively, compared to CONTROL. While the extract obtained at 60 °C minimizes the formation of these products in a 84, 19, 75 and 77%, respectively. The ANOVA show no significant differences in HPL and TBARS concentration in the EO samples added with the extracts obtained at 20 MPa.The extracts obtained at 30 MPa also showed protective effect on EO, these delayed the HPL, NON and HEX formation, although their ability to attenuate the TBARS formation was low.

Moreover a slight pro-oxidant effect was observed for the extracts obtained at 40 °C/10MPa and 50 °C/10 MPa which stimulated the HEX formation. The PO samples added with this extracts showed a HEX content 1.22 and 1.12 times, respectively, greater than that observed in the CONTROL. The ANOVA indicates significant differences in the HEX content in the PO samples added with the extracts and the CONTROL. This pro-oxidant effect may be associated with redox reaction between the compounds present in the extracts and Fe+3 ions present in the PO. Probably these compounds reduced the Fe+3 to Fe+2 which catalyzes the breakdown of LHP to HEX and alkoxy radicals [42,43], these radicals are lipid autoxidation initiators which increase the LHP speed production and the HEX formation.

Given the yield and AA results, 50 °C/20 MPa was selected as the extraction condition to carry out the SFE with CO2/EtOH (table 2). The EtOH addition as co-solvent not improved the AA of extracts. The extracts obtained with CO2/EtOH presented a lower ability to delay the HPL, HEX, NON and TBARS formation compared to the extract obtained using CO2 (50 °C/20 MPa), with exception of the extract obtained with 5% EtOH which showed more efficient to retard the TBARS formation. Although the EtOH addition probably allowed extracting moderately polar compounds, increasing the extraction yield, these substances possess a low protective effect onEO.

Relative to the AA of extracts obtained using SE, the ethanolic extract showed good AA while the hexane extract showed low AA. The extract obtained using EtOH retarded the LHP, HEX, NON and TBARS formation in 76, 23, 71 and 77%, respectively. The extract obtained with hexane reduced the LHP, NON and TBARS formation in 63, 59 and 45% respectively. However, this extract shown a pro-oxidant effect on PO stimulating the production HEX. The extract obtained by SE with EtOH showed a similar ability to delay the NON, HEX and TBARS formation compared with some extracts obtained by SFE with CO2 at 20 and 30 MPa.

The results suggest that the extracts obtained by SE with EtOH and SFE with CO2 at 20 MPaand CO2/EtOH (5% of co-solvent) have compounds that can delay the oxidation initial products formation in EO(as LHP and OHP), these antioxidants compounds also reduces the LHP and OHP conversion to final products (as HEX and NON). In addition the low TBARS concentration observed in EO samples added with these extracts indicates that the antioxidants moreover retard the TBARS precursorsformation (as dihidrohydroperoxides,tetrahydroperoxidesendoperoxides and epoxides).These result shows that the papaya seeds extracts controlling the EO lipid oxidation in all stages, reducing the potentially hazardous products concentration for the oil consumer health [44,45].

The extracts obtained by SE with EtOH and by SFE with CO2 at 20 MPa and CO2 added with 5% EtOH showed a greater AA compared to observe in the synthetic antioxidant BHT. This result indicates that papaya seeds are a good source of antioxidants which could be an alternative replacement for synthetic compounds such as BHT. These natural antioxidants could be extracted using SFE with significant yields, this would involve the implementation of new extraction technologies in the use of our natural resources, particularly in the use of agro-industrial waste.

Conclusions

The results obtained in this work show that the papaya seeds (C. papaya L.) are an important source of compounds with ability to delay lipid oxidation in EO. These compounds can be extracted using SFE with CO2 and CO2/EtOH and SE with EtOH with very good yields. The extracts obtained using CO2 (20 MPa), CO2/EtOH (5% co-solvent) and EtOH (by SE) ??are an option in the search of compounds intended to replace the synthetic antioxidants currently used in the food preservation. Finally, this work proposes obtaining antioxidants from papaya seeds using SFE as an alternative use for this agroindustrial residue.

Acknowledgments

The authors thank to the DirecciónInvestigación Bogotá (DIB) at the Universidad Nacional de Colombia (Project: 201010021085), to Alimentos SAS S.A. (Bogotá-Colombia), Duquesa S.A. (Bogotá-Colombia) and CNPq

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Figure Caption

Figure 1.Yields Isotherms (40, 50 and 60 °C) of papaya seeds extracts obtained using supercritical carbon dioxide at 10, 20 and 30 MPa.

Table caption

Table 1. Extraction yields of papaya seeds extracts obtained by supercritical fluid and Soxhlet extraction.

Table 2. Antioxidant activity of papaya seeds extracts from different extraction methods and BHT in edible palm oil.

Autor:

Henry I. Castro-Vargasa,

Luz P. Restrepo-Sáncheza, Sandra R. S. Ferreirab,

WolframBaumannc, Fabián Parada-Alfonsoa,*

aChemistryDepartment, Universidad Nacional de Colombia, Carrera 30 No 45-03, Bogotá D.C., Colombia.

bChemicalandFoodEngineeringDepartment, Universidade Federal de Santa Catarina, EQA/UFSC, CEP 88040-900, Florianópolis, Santa Catarina, Brazil.

cChemistryDepartment, Universidad de los Andes, Carrera 1 No 18a-12, Bogotá D.C., Colombia.