Avocado (Persea americana Mill) pulp and seeds of the cultivar Fuerte, cultivated in the Northeast region of Brazil, were analysed for their proximate composition. The lipid contents of the pulp and seeds were 15.39% and 1.87%, respectively. Hexane extracted oils from pulp and seeds presented similar refractive indices (1.4608 and 1.4592), specific gravity (0.9272 and 0.9300) and peroxide values (1.40 and 1.37), but different acid (2.45 and 4.12), iodine (77.6 and 69.4) and saponification values (178.3 and 231.6), respectively. Gas chromatographic analysis revealed the presence of twenty two and twenty seven fatty acids in pulp and seed oils, respectively. Palmitic acid was the principal saturated acid, present in concentrations of 21.3% in pulp and 20.8% in seed oils. The major difference between these oils was in their mono-unsaturated (C18:1 - 64.3%, for pulp and 15.4% in seed oil) and poly-unsaturated (C18:2 and C18:3 - 9.14% and 0.46%, respectively, in pulp oil and 34.39% and 5.81%, respectively, in seed oil) fatty acids composition.La semilla y pulpa del aguacate (Persea americana Mill), cultivar Fuerte, cultivado en la región del nordeste de Brasil fueron analizados para determinar su composición centesimal. El contenido de lípidos en pulpa y semillas, en la base húmeda fueron 15.39% y 1.87%, respectivamente. Los aceites extraídos de la pulpa y de las semillas por hexano representan similares índices de refracción (1.4608 y 1.4592), densidad específica (0.9272 y 0.9300) e índice de peróxidos (1.40 y 1.37) pero diferentes índices de acidez (2.45 y 4.12), iodo (77.6 y 69.4) y saponificación (178.3 y 231.6), respectivamente. El análisis de cromatografía gaseosa revela la presencia de 22 y 27 ácidos grasos en aceite de pulpa y de semillas, respectivamente. El ácido palmítico fue el principal ácido saturado, presente en concentraciones de 21,3% en pulpa y 20,8% en aceites de semillas. La principal diferencia entre estos aceites fue su contenido de ácidos grasos mono-insaturados (C18:1 -64.3% en aceite de pulpa y 15.4% de semillas) y poli-insaturado (C18:2 y C18:3 -9.14% y 0.46% respectivamente, en aceite de pulpa y 34.39% y 5.81% respectivamente, en aceite de semillas)

Bora, Pushkar S.

Narain, Narendra

Queiroz Paulo, Marçal

Rocha, Rosalynd V.M.

Grasas y Aceites (E-Journal)

Characterization of the oils from the pulp and seeds of avocado(cultivar: Fuerte) fruitsBy Pushkar S. Bora, Narendra Narain*, Rosalynd V.M. Rocha and Marçal Queiroz PauloDepartamento de Tecnología Química e de Alimentos, UniversidadeFederal da Paraíba, 58059-900 João Pessoa-PB, Brazil.e-mail: narain@funape.ufpb.brRESUMENCaracterización de los aceites de la pulpa y semillasde aguacate (cultivar: Fuerte).La semilla y pulpa del aguacate (Persea americana Mill), cul-tivar Fuerte, cultivado en la región del nordeste de Brasil fueronanalizados para determinar su composición centesimal. El conte-nido de lípidos en pulpa y semillas, en la base húmeda fueron15.39% y 1.87%, respectivamente. Los aceites extraídos de lapulpa y de las semillas por hexano representan similares índicesde refracción (1.4608 y 1.4592), densidad específica (0.9272 y0.9300) e índice de peróxidos (1.40 y 1.37) pero diferentes índi-ces de acidez (2.45 y 4.12), iodo (77.6 y 69.4) y saponificación(178.3 y 231.6), respectivamente. El análisis de cromatografía ga-seosa revela la presencia de 22 y 27 ácidos grasos en aceite depulpa y de semillas, respectivamente. El ácido palmítico fue elprincipal ácido saturado, presente en concentraciones de 21,3%en pulpa y 20,8% en aceites de semillas. La principal diferenciaentre estos aceites fue su contenido de ácidos grasos mono-insa-turados (C18:1 -64.3% en aceite de pulpa y 15.4% de semillas) ypoli-insaturado (C18:2 y C18:3 -9.14% y 0.46% respectivamente, enaceite de pulpa y 34.39% y 5.81% respectivamente, en aceite desemillas).PALABRAS-CLAVE: Aceite – Acidos grasos (composición) –Aguacate – Propiedades físico-químicas.SUMMARYCharacterization of the oils from the pulp and seeds ofavocado (cultivar: Fuerte) fruits.Avocado (Persea americana Mill) pulp and seeds of thecultivar Fuerte, cultivated in the Northeast region of Brazil, wereanalysed for their proximate composition. The lipid contents of thepulp and seeds were 15.39% and 1.87%, respectively. Hexaneextracted oils from pulp and seeds presented similar refractiveindices (1.4608 and 1.4592), specific gravity (0.9272 and 0.9300)and peroxide values (1.40 and 1.37), but different acid (2.45 and4.12), iodine (77.6 and 69.4) and saponification values (178.3 and231.6), respectively. Gas chromatographic analysis revealed thepresence of twenty two and twenty seven fatty acids in pulp andseed oils, respectively. Palmitic acid was the principal saturatedacid, present in concentrations of 21.3% in pulp and 20.8% inseed oils. The major difference between these oils was in theirmono-unsaturated (C18:1 - 64.3%, for pulp and 15.4% in seed oil)and poly-unsaturated (C18:2 a n d  C18:3 -  9 .1 4% an d 0.46 %,respectively, in pulp oil and 34.39% and 5.81%, respectively, inseed oil) fatty acids composition.KEY-WORDS: Avocado – Fatty acids (composition) – Oil –Physico-chemical properties.1. INTRODUCTIONThe avocado fruit belongs to the family ofLauraceae which includes approximately 150species, majority of which are habitat of tropicalAmerica. The fruit distinguishes itself from otherfruits due to its high lipid content and is consumed asfood, and as ingredient in the formulations ofpharmaceutical and cosmetic products. The oilcontent of the fruit depends upon its ecological originand on the cultivar, as for example, in Guatemalanand Mexican cultivars, the oil content varies from 10to 13% and from 15 to 25%, respectively (Biale andYoung 1971) while in the fruits from Carrebean, a lowfat (2.5 to 5%) has been reported (Hatton et al. 1964).According to Soares et al. (1992) adulteration of oliveoil with avocado oil to a level of 35% is undetectable onthe basis of flavor as the avocado oil possesses similarcharacteristics to that of olive oil (Gutfinger & Letan 1974;Freitas et al. 1993). Though some work has beenpublished on the physico-chemical properties (Tango etal. 1972), and the fatty acids composition (Mazliak 1971;Tango et al. 1972; Itoh et al. 1975, Martinez et al. 1988,Southwell et al. 1990,) of the pulp oil obtained from someimportant avocado cultivars, and of the seed oil (Mazliak1971), no comparative study on the characterization ofthe pulp and seed oils of the fruits of the same avocadocultivar is so far available. Furthermore, the fatty acidcomposition of the avocado oil, besides the cultivar andstage of ripening, depends upon the geographical growthlocation (Ahmad and Barmore, 1980). The present workwas therefore undertaken to compare the physical andphysicochemical properties of the oils extracted from thepulp, and seed of the avocado (cultivar: Fuerte), fruits,as well as to compare their fatty acid composition.2. EXPERIMENTALPreparation of the pulp and seed samples ofavocado fruits: Avocado fruits (Lauraceae spp.),cultivar Fuerte were obtained from a farm located inthe vicinity of the city of João Pessoa in the state of«Paraíba» in Brazil. The fruits, were stored at roomtemperature (approx. 28oC) till they become ripe.Grasas y Aceites 171Vol. 52. Fasc. 3-4 (2001), 171-174The pulp and seeds were removed manually fromthe fruit and the pulp was homogenised in a domesticblender. The seeds were cut into small pieces andtriturated in a mill. The pulp and seed samples werefilled in polyethylene bags and stored in arefrigerator.Proximate analysis of pulp and seeds: Moisture,protein, lipid, ash and, crude fibre contents weredetermined following the standard AOAC (1990)methods. Total carbohydrate content was calculatedfrom the difference. Ten different samples wereanalysed in duplicate.Extraction of the oil: The homogenized avocadopulp and triturated seeds were dried in an oven for 24hours at 50oC. The dried mass was triturated again ina mill and passed through the sieves of 40 meshsizes. The oil was obtained by extraction of the driedpowders with solvent hexane. Three lots for each oilwere prepared.Physical and physicochemical properties of oil:The specific gravity and refractive index were determinedat room temperature (28oC) using specific density bottleand refractometer, respectively. For determination of acid,peroxide, iodine and saponification values, standard AOAC(1990) methods were used. Three different samples ofoil were analysed in duplicate.Fatty acid composítion of seed oil: Fatty acidswere transformed to their methyl esters (FAME)following the method of Hartman and Lago (1973)and were determined by using a gas chromatographHP 5890 Series III (Hewlett Packard) equipped witha flame ionisation detector. 1.5 µl of the FAMEsample was injected and GC separation was carriedout on BP-INNOwax capillary column (HewlettPackard; 30m length, 0.25 mm i.d. and 0.25 µm filmthickness). The carrier gas (helium) head pressurewas maintained at 11.5 psi and the column flow ratewas 1ml/min. The oven temperature was held initiallyat 120oC for 1 min, later increased at 8oC/min to210oC and then maintained at 210oC for 45 min. Thetemperatures of the injection port and of detectorwere 250oC and 280oC, respectively. FAME werepositively identified by matching their retention timedata and mass spectra with those of the authenticstandards obtained from various firms (Sigma;Nu-Chek-Prep, USA) which were also run underidentical analytical conditions using high resolutionGC-MS system (GCQ of Finnigan Mat).3. RESULTS AND DISCUSSIONThe proximate analysis of the avocado pulp andseeds is presented in Table I. Besides moisture, thelipid was the principal constituent of the pulp presentin concentrations of nearly 15.4%. For cultivarFuerte, Tango et al. (1972) reported a higher lipidcontent (22.1 %), while Freitas et al. (1993 ) reporteda recovery of 20% lipid from the pulp of the samecultivar. Lipid concentrations ranging from 15 to 30%in Fuerte, Bacon and Hass cultivars were alsoreported by Biale and Young (1971). In comparisonwith the pulp, the seeds contained only 1.87% lipids.The protein content of the pulp and seeds were 1.01and 1.87% respectively. For California and Floridafruits, the protein content ranged from 1.21 to 2.26%as reported by Hall et al. (1955) and Slater et al.(1975). Other constituents such as ash, fibre andcarbohydrates were present in smaller quantities inpulp than in the seeds.Table II shows the data on some physical andphysico-chemical properties of pulp and seed oilsextracted with hexane. The refractive index, specificgravity and peroxide values of the pulp and seed oilswere very close to each other. These indices/valuesfor the pulp oil were similar to the ones reported bySoares et al (1991). However, there was aconsiderable difference in the saponification valuesof pulp and seed oils, being 178.3 and 231.6,respectively. Tango et al. (1972) reported a range of167.6 to 190.1 for saponification value. The iodinevalues of the pulp (77.6) and seed (69.4) oils differedvery little from the reported values of 76.5 to 99.7 forthe pulp oil of different avocado cultivars (Tango et al.1972). A high iodine value (133) for the pulp oils ofBacon, Fuerte and Hass cultivars was reported byMartinez et al. (1988).Table IProximate composition (% w/w; average value ±standard deviation) of the avocado pulp and seedsConstituents (%) Pulp SeedMoisture 78.24 ± 2.54 56.04 ± 2.58Lipids 15.39 ± 1.56  1.87 ± 0.31Protein 1.01 ± 0.18  1.95 ± 0.16Ash 0.66 ± 0.09  1.87 ± 0.24Fibre 0.53 ± 0.16  5.10 ± 1.11Carbohydrates (by diff.) 4.17 ± 1.37 33.17 ± 2.73Table IISome physical and physico-chemical propertiesof avocado pulp and seed oilsCharacteristics Pulp oil Seed oilRefractive Index 1.4608 ± 0.0004 1.4592 ± 0.0012Specific Gravity 0.9272 ± 0.0028 0.9300 ± 0.0046Acid Value 1.23 ± 0.02 2.06 ± 0.32Peroxide Value 1.40 ± 0.215 1.37 ± 0.208Iodine Value 77.6 ± 1.54 69.4 ± 1.04Saponification Value 178.3 ± 1.61 231.6 ± 1.40172 Grasas y AceitesFatty acid composition of seed oil: The fattyacid composition of the pulp and seed oil ispresented in Table III. In earlier reports (Mazliak1971), eight fatty acids were reported in the pulp oilof cultivar Fuerte, while SouthweIl et al. (1990)reported the presence of only six fatty acids.However in this study, we could identify as many as22 fatty acids in the pulp oil. A large majority of thesefatty acids in the pulp oil has not been reportedearlier. Only C16:0, C16:1, C18:0, C18:1, C18:2 fatty acids(Martinez et al. 1988; Soares et al. 1991) togetherwith C18:3 (Frega et al. 1990 Southwell et al. 1990)and C14:0, C20:0 in trace amounts (Mazliak, 1971) werereported in the pulp oil of different avocado cultivars.In all the cultivars C18:1 (oleic acid) was aIways theprincipal fatty acid followed by C16:0 (palmitic) andC18:2 (linoleic). Other fatty acids reported to bepresent in trace concentrations were C14:0 (myristic)C18:0 (stearic), C18:3 (linolenic) and C20:0 (arachidic)acids (Gutfinger and Letan, 1974, Itoh et al. 1975,Mazliak 1971, and Tango et al. 1972). Similar tothese reports we also observed that the major fattyacid in the pulp oil was C18:1 followed by C16:0 andC18:2 however, the concentrations of these fatty acidsin the pulp oil were different from the cited reports.This quantitative difference is justifiable in view of thefruits from different geographical origin and otherfactors such as maturity and harvest practices.According to the Mazliak (1971) the concentration ofthe fatty acids C18:1, C16:0 and C18:2 in the Fuertemesocarp oil was 67-72, 13-16.7 and 10.4-11.4%,respectively while Martinez et al. (1988) reported arange of 60-65, 15-19 and 11-12%, respectively for thesame fatty acids in the oil from Becon, Fuerte, and Hasscultivars. Besides, they also reported the presence ofC16:1 (palmitoleic acid) in the concentration of 7.5 to 8.6%Table IIIFatty Acid Composition of Avocado Pulp and Seed OilsFatty Acid% of the total fatty acid*Pulp oil Seed oilSaturated fatty acids:Hexanoic acidHeptanoic acidOctanoic acidNonanoic acidDecanoic acidUndecanoic acidDodecanoic acidTridecanoic acidTetradecanoic acidPentadecanoic acidHexadecanoic acidHeptadecanoic acidOctadecanoic acidNonadecanoic acidEicosanoic acidDocosanoic acidTetracosanoic acidMonounsaturated fatty acids:9-tetradecenoic acid10-pentadecenoic acid9-hexadecenoic acid10-heptadecanoic acid9-octadecenoic acid11-eicosenoic acid13-docosenoic acidPolyunsaturated fatty acids:9,12-octadecadienoic acid9,12,15-octadecatrienoic acid11,14,17-eicosatrienoic acidUnsaturated/Saturated fatty acid ratioPolyunsaturated/Saturated fatty acid ratioOleic/Linoleic acid ratio(C6:0)(C7:0)(C8:0)(C9:0)(C10:0)(C11:0)(C12:0)(C13:0)(C14:0)(C15:0)(C16:0)(C17:0)(C18:0)(C19:0)(C20:0)(C22:0)(C24:0)(C14:1)(C15:1)(C16:1)(C17:1)(C18:1)(C20:1)(C22:1)(C18:2)(C18:3)(C20:3)22.9270.12 ± 0.064±Tr0.075 ± 0.015±Tr±0.284 ± 0.096Tr0.062 ± 0.02821.312 ± 0.5500.033 ± 0.0010.762 ± 0.021±±0.086 ± 0.004Tr0.065 ± 0.03567.4330.115 ± 0.0520.071 ± 0.0042.391 ± 0.1880.106 ± 0.00464.436 ± 0.6660.249 ± 0.0360.065 ± 0.0129.6149.147 ± 0.0300.467 ± 0.016±3.360.427.0432.4950.800 ± 0.0450.290 ± 0.0970.278 ± 0.0520.217 ± 0.006TrTr0.278 ± 0.0510.166 ± 0.0110.537 ± 0.0522.334 ± 0.11020.847 ± 0.8431.725 ± 0.0221.185 ± 0.0110.610 ± 0.3410.043 ± 0.0201.114 ± 0.0231.685 ± 0.04520.7120.251 ± 0.0020.321 ± 0.1591.786 ± 0.3250.372 ± 0.08317.410 ± 0.0580.448 ± 0.2770.124 ± 0.04346.72638.892 ± 0.5856.577 ± 0.0281.257 ± 0.0302.071.440.45 * Tr - Traces (concentration less than 0.06% of the total fatty acids).Vol. 52. Fasc. 3-4 (2001) 173against  the value of 3-5. 1 % reported by Mazliak (1971).However, a higher concentration (72.2%) of C18:1 fattyacid in avocado pulp oil was reported by SouthweIl et al.(1990). In our study, the principal fatty acids and theirconcentrations in the pulp oil were:C18:1-64.43%, C16:0-21.31%,C18:2-9.15% and C16:1-2.39% (Table III). In addition tothese, C6:0, C8:0, C13:0, C14:1, C15:1, C17:1, C:18:0, C18:3,C20:0, C20:1, C22:1 and C24:0 were present inconcentrations varying from 0.06 to 0.76%, and C7:0,C9:0, C14:0, C15:0, C17:0, C22:0 in trace quantities (lessthan 0.06% of the total fatty acids).Saturated fatty acids constituted about 22.93% ofthe total fatty acids of the pulp oil while in the seed oilwas about 32.45%. All saturated fatty acids from C6to C24 except for C21 and C23 were identified in theseed oil. The C16 fatty acid (20.85% of total fattyacids) was also the principal saturated fatty acid ofthe seed oil followed by fatty acids C15, C17, C24, C18and C22 which were present in concentrations of2.33, 1.72, 1.68, 1.18 and 1.11% of total fatty acids,respectively. Other saturated fatty acids werepresent in concentrations ranging from 0.16% (C13)to 0.80% (C6) while C10, C11, and C20 fatty acids werepresent in trace quantities.Both the oils constituted the same mono-unsaturated fatty acids, but quantitatively theircomposition was different. Fatty acids C18:1 (64.43%in pulp and 17.41% in seed oil) and C16:1 (2.39% inpulp and 1.78% in seed oil) were the principal acids.Mazliak (1972) reported 67-72 % C18:1 and 3-5.1 %C16:1 fatty acids in the mesocarp and 25% C18:1 and3.2% C16:1 fatty acids in the avocado seed oil.Avocado seed oil contained high concentrationsof C18:2 (38.89%) and C18:3 (6.57%) fatty acids. Theconcentration of these fatty acids in the pulp oil wasrelatively low (9.14% and 0.46%, respectively). Afavourable C18:2/C18:3 fatty acid ratio of the avocadoseed oil could possibly be responsible for reducingthe triglycerides and HDL in blood plasma as wasobserved by Werman et al. (1991) in a nutritionalstudy with rats. In our study, the unsaturated tosaturated fatty acids ratios were 3.36 and 2.07 andpolyunsaturated to saturated fatty acids were 0.42and 1.44, respectively for the pulp and seed oils.However, for the pulp oil of the same cultivar, Slateret al. (1975) reported higher values for these ratios(7.4 and 0.73, respectively). In relation to oleic-Iinoleic acid ratio, a parameter responsible for theshelf life of the oils, the avocado pulp oil (7.4) had amuch higher ratio than the seed oil (0.447).To detect adulteration of avocado oil with avocadoseed oil, Werman et al. (1996) have reported a thinlayer chromatographic method. Alternatively basedon these findings, we also suggest that theconcentrations of C18:2 and C18:3 fatty acids and theirratio (about 6 in seed oil and 18 in the pulp oil) couldpossibly be used for determining the authenticity ofavocado oils of Fuerte cultivar.REFERENCESAhmad, E. M. and Baarmore, C.R. (1982). Avocado inTropical and Subtropical Fruits (eds. Steven Nagy andPhilip E. Shaw), AVI Publishing Inc. WestportConnecticut.AOAC (1990). Official Methods of Analysis. 15th ed.Association of Official Analytical Chemists,Washington DC.Biale, J. B. and Young, R. E. (1971). The avocado pear. In:«The Biochemistry of Fruits and Their Products». A.C.Hulme (ed), Academic Press, NY.Frega, N., Bocci, F., Lercker, G. and Bortolomeazzi, R.(1990). Lipid composition of some avocado cultivars.Ita. J. Food Sci. 3, 197-204.Freitas, S. P., Lago, R. C. A; Jablonca, F. H. and Hartman,L. (1993). Aqueous enzymic extraction of avocado oilfirom fresh pulp.  Revue Francaise des Corps Gras;40(11/12), 365-371.Gutfinger, T. and Letan, A. (1974). Studies ofunsaponifiables in several vegetable oils. Lipids. 9,658-663 (Fr).Hartman, L. and Lago, R. C. A. (1973). Rapid preparation offatty acid methyl esters from lipids. LaboratoryPractice. 22, 475-476.Hatton Jr., T. T., Harding, P. L. and Reeder, W. F. (1964).Seasonal changes in Florida avocados. Proc. Fla.State Hortic. Soc. 72, 349-353.Itoh, T., Tamura, T., Matsumato, T. and. Dupaigne, P.(1975). Studies on avocado oil in particular on theunsaponifiable sterol fraction. Fruits 30, 687-695.Mazliak, P. (1971). Avocado lipid constituents. Fruits 26,615-623.Martínez, N. L., Camacho, R. F., Rodriguez, V. S. and Moreno,H. M.V. (1988). Extraction and characterization ofavocado oil. Grasas y Aceites, 39, 272-277.Popenoe, W. (1920). Manual of Tropical and SubtropicalFruits. MacMillan Co. NY.Soares, S. E., Filho, J. M., Turatti, J. M. and Tango, J. S.(1991). Caracterização Física, Química e Avaliação daEstabilidade do óleo de abacate (Persea americanaMill.) nas diferentes etapas do processo de refinação.Ver. Farm. Bioquím. Univ. S. Paulo. 27, 70-82.Soares, S. E., Mancini Filho, J., Modesta, R. C. della.(1992). Sensory detection limits of avocado oil inmixtures with olive oil. Revista Española de Ciencia yTecnologia de Alimentos. 32(5), 509-516.SouthweIl, K. H., Harris, R. V. and Swetman, A. A. (1990).Extraction and refining of oil obtained from driedavocado fruit using a small expeller. Trop. Science. 30,121-131.Tango, J.S., Da Costa, S. L, Antunes, A. J. and Figueredo,L.B. (1972). Composition of fruit oil of different varietiesof avocado grown in Sáo Paulo. Fruits 27, 143-146.Werman, M. J., Neeman, I. and Mokady, S. (1991).Avocado oils and hepatic lipid metabolism in growingrats. Food and Chemical Toxicology. 29, 93-99.Werman, M. J., Mokady, S. and Neeman, I. (1996). Asimple and sensitive method for detecting avocadoseed oil in various avocado oils. J. Amer. Oil ChemistsSoc. 73(5), 665-667.Recibido: Diciembre 1999Aceptado: Enero 2001174 Grasas y Aceites

Caracterización de los aceites de la pulpa y semillas de aguacate (cultivar: Fuerte)

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Caracterización de los aceites de la pulpa y semillas de aguacate (cultivar: Fuerte)

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