Impaginato 75 Adv. Hort. Sci., 2011 25(2): 75-80 Received for publication 24 February 2011. Accepted for publication 18 March 2011. Antioxidant capacity and total phenolic content of hydrothermally-treated ‘Fuerte’ avocado E.R. Daiuto *, J.G.F. Fumes**, R.L. Vieites***, N.C. Cabia**, R.S.D. Castro**** * Department of Horticulture, Faculty of Agronomic Sciences, UNESP, C.P. 237, 18610307 Botu- catu, São Paulo, Brazil. ** Agronomic Engineering, UNESP, C.P. 237, 18610307 Botucatu, São Paulo, Brazil. *** Department of Agribusiness Management and Technology, Faculty of Agronomic Sciences, UNESP, C.P. 237, 18610307 Botucatu, São Paulo, Brazil. **** Food engineer, UNESP, C.P. 237, 18610307 Botocatu, São Paulo, Brazil. Key words: antioxidant capacity, bioactive compounds, Persea americana Mill., refrigeration. Abstract: Avocados possess high nutritional value with proven effectiveness in preventing cardiovascular dis- eases, attributed primarily to their unsaturated fatty acids content. This fruit is also rich in carotenoids and vit- amins, particularly vitamin E. This work evaluates the antioxidant capacity and total phenolic content of hydrothermally-treated Fuerte avocado. Fruits were selected and hydrothermally treated at 45oC for 5, 10, 15 and 20 min. They were then stored in a refrigerator (10 ± 1oC and 90±5% relative humidity) and evaluated over a 15-day period. The total phenolic content increased up to the sixth day of storage, and decreased thereafter, without differences between the treatments. The percentage of antioxidant capacity of the control and the hydrothermally-treated samples for 5 and 10 min increased during storage. Untreated fruits showed the highest percentage of antioxidant capacity. However, the antioxidant capacity of avocado fruits subjected to these treat- ments declined starting on the twelfth day of storage, possibly due to the fruits’ senescence. Hydrothermal treat- ments for 15 and 20 min delayed fruit senescence while the antioxidant capacity continued to increase up to the fifteenth day of storage. No significant correlation was found between antioxidant capacity and total phenolic content. The antioxidant capacity of ripe Fuerte avocado was higher than that of unripe or overripe avocado. 1. Introduction Avocado (Persea americana Mill.) has considerable nutritional quality, with a high content of fibers, pro- teins and mineral salts, particularly potassium and vita- mins, especially vitamin E (USDA, 2007). It also con- tains significant amounts of unsaturated fatty acids, which are beneficial for the prevention of cardiovascu- lar diseases (Tango et al., 2004). Previous studies have also shown that this fruit contains anticarcinogenic lipophilic compounds such as carotenoids (Ding et al., 2007). Wang et al. (2010) pointed out the scantiness of stud- ies on the phytochemical composition of avocados and the lack of knowledge about the total phenolic content and antioxidant capacity of different avocado varieties, or cultivars. The aforementioned authors conducted studies to determine the antioxidant capacity of the pulp, seed and peel of different avocado varieties, but not the Fuerte variety. ‘Fuerte’ avocados are small and are highly valued in European and American markets. Antioxidants, which are compounds that inhibit and/or reduce the effects of free radicals (Soares et al., 2005), can be defined as compounds that protect the cells against the harmful effects of oxygen and nitrogen free radicals that are formed in oxidative processes. High free radical levels generate an imbalance, trigger- ing oxidative stress, the metabolic process responsible for the onset of several types of chronic degenerative diseases. Antioxidants can be obtained by eating food containing vitamins E and C, carotenoids, phenolic compounds, and other compounds (Ali et al., 2008). Phenolic compounds are responsible for most of the antioxidant activity in fruits, making them a natural source of antioxidants (Heim et al., 2002). The pheno- lic content in food and plants depends on a number of intrinsic factors such as the genus, species and cultivar, and on extrinsic factors such as agronomic and envi- ronmental factors, handling and storage (Thomas-Bar- berán and Espín, 2001). Avocado is a climacteric fruit which ripens a few days after harvest (Hardenburg et al., 1986; Seymour and Tucker, 1993) and whose postharvest behavior can be influenced by temperature and storage time. The lit- erature contains several studies about the increase in 76 the conservation period of avocado, involving the eval- uation of storage temperature, the use of modified atmosphere with the application of wax, gamma irradi- ation and thermal treatment to prevent chilling injury (Zauberman et al., 1973; Castro and Bleinroth, 1982; Seymour and Tucker, 1993; Germano et al., 1996; De Oliveira et al., 2000; Sanches, 2006; Morgado, 2007; Donadon, 2009). Thermal treatment has been applied postharvest to solve the problem of contamination by fungal diseases and insect infestation in fruit (Fawcett, 1922 apud Couey, 1989) or to reduce problems caused by low stor- age temperatures (Kluge et al., 2006). To this end, ther- mal treatments are performed prior to refrigeration, in the form of conditioning, or during refrigerated storage, in the form of intermittent warming. Thermal condi- tioning consists of exposing fruits briefly to moderate (15 to 25oC) or high temperatures (37 to 53oC) before putting them in refrigerated storage (Kluge et al., 2006). Daiuto and Vieites (2008) conducted a study on Hass avocado to evaluate the polyphenol oxidase (PPO) and peroxidase (POD) content in unripe and ripe fruits hydrothermally treated at 45oC for 10 min and stored at 9oC (±1). The enzyme inactivation in ripe fruits subjected to the treatment was 78 to 94% com- pared to untreated fruits. Daiuto et al. (2010) evaluated the weight loss and respiratory rate of ‘Hass’ avocado by subjecting it to different physical treatments (ther- mal, UV and gamma radiation) and reported a decrease in the intensity of the fruit’s respiratory peaks. The evaluation of antioxidant capacity has become increasingly important to determine the effectiveness of natural antioxidants in protecting vegetable products against oxidative damage and loss of their commercial and nutritional value. Therefore, the present research focused on an evaluation of the antioxidant capacity and total phenolic content of ‘Fuerte’ avocado subject- ed to hydrothermal treatment. 2. Materials and Methods ‘Fuerte’ avocados were harvested carefully at the point of physiological maturation and according to their oil content. The fruits, which were selected with a view to uniform size, color and absence of injuries and defects, were hydrothermally treated in a water bath at 45°C for 5, 10, 15 and 20 min (four treatments), after which they were stored under refrigeration (10±1°C and 90±5% relative humidity). Fruits not subjected to the hydrothermal treatment were used as control. The fruits of these five treatments were evaluated at three- day intervals for two weeks. Fruit extraction The extraction process was performed with a sol- vent mixture of ethanol:water (80:20 v/v). Fruit extracts were obtained in triplicate. Aliquots of 3.0 g of pulp were weighed and placed in Falcon tubes, to which were added 30 ml of an ethanol:water mixture (80:20 v/v). The tubes containing pulp and solvent were then processed at room temperature in a Turrax crushing disperser for several minutes, and then cen- trifuged at 5000 X G for 15 min. The extracts were fil- tered and stored in dark vials at 8ºC for no longer than a week prior to analysis. Total polyphenol analysis The total phenolic content was determined by the Folin-Ciocalteu spectrophotometric method, as described by Singleton et al. (1999), using gallic acid as standard. An aliquot of 0.5 ml of the resulting extracts was then transferred to a test tube and 2.5 ml Folin-Ciocalteu reagent diluted in water 1:10 was added. The mixture was allowed to rest for 5 min, after which 2 ml of sodium carbonate 4% was added and the tubes were left to stand for 2 hr in the dark. The absorbance was measured in a spectrophotometer oper- ating at a wavelength of 740 nm. A blank sample was subjected to the same procedure and conditions. The results are expressed in µg GAE/100 g-1 of dry weight. DPPH radical scavenging activity The radical scavenging activity was determined by DPPH method (Mensor et al., 2001). Tocopherol and BHT at a concentration of 90 µg ml-1 were used as standards. The reaction mixture consisted of 500 µl of fruit extract, 3.0 ml of ethanol 99%, and 300 µl of the DPPH radical in a solution of ethanol 0.5 mM, which was incubated for 45 min at room temperature in the dark. The negative control was prepared by replacing the volume of extract for an equal volume of the extrac- tion solvent. A processing time of 45 min was defined after determining the half maximal effective concentra- tion, Ec50. To determine the stabilization time, read- ings of the antioxidant in five concentrations (1, 2, 3, 4 and 5 g) were taken at 15-min intervals (Sanches- Moreno et al., 1998). According to Do Rufino et al. (2007), in subsequent experiments with the same fruit, readings can be limited to the previously established time (Ec50 time), accompanied by the initial reading of the control. The blank was prepared by substituting the volume of the DPPH solution for an equal volume of solvent. The free radical scavenging activity was determined in the form of Antioxidant Activity (AA), using the equation: AA (%) = 100- [(Aa – Ab) x 100] / Ac, where: Aa = absorbance of the sample; Ab = absorbance of the blank; and Ac = absorbance of the negative control. All the analyses were performed in triplicate and accompanied by a control. A variance analysis was performed using Tukey’s test for multiple comparisons of the averages, at a sig- nificance level of 5%. The data were then subjected to a regression analysis and to Pearson’s correlation for the two parameters evaluated, using the SAS version 77 9.2 software program. 3. Results and Discussion Table 1 presents the average and standard deviation of total polyphenols identified in ‘Fuerte’ avocado. Although the four treatments produced similar results, a difference was detected as a function of storage time (p=0.007). Total polyphenol content was higher in the control treatment. Mean values of 45.7, 47.0, 47.1 and 47.2 µg GAE/100 g-1, respectively, were obtained in 5, 10, 15 and 20 min hydrothermal treatment, while the control showed 49.8 GAE/100g-1. The lowest value obtained was 42.7 µg on the first day of analysis and the highest was 62.1 µg for the control treatment on the sixth day of analysis. The composition of phenolic compounds in fruit may be mod- ified as a function of the environment and postharvest fac- tors, including processing and storage. Processing and storage can induce prolonged enzymatic and chemical oxidation of phenolic compounds, contributing to their reduction (Kaur and Kapoor, 2002). Many studies have shown that phenolic compounds generally decrease in cli- macteric fruit such as tomatoes, bananas, mangos and guavas during ripening (Haard and Chism, 1996; Lak- shimnarayana et al., 1970; Mitra and Baldwin, 1997; Sel- varaj and Kumar, 1989). The total phenolic content increased up to the sixth day of storage, decreasing thereafter due to the onset of senescence (Fig. 1). Daiuto et al. (2010) found that the average respiratory peak of ‘Hass’ avocado subjected to different physical treatments occurred on the ninth day of storage, after which senescence set in. This decrease can be attributed to a series of chemical and enzyme amend- ments that occur during the accelerated process of matu- ration of this fruit. These changes may include glycoside hydrolysis by glycosidases, phenol oxidation by phe- noloxidases, and polymerization of free phenolic content (Robards et al., 1999). The average antioxidant capacity measured in the treatments varied from 21.1% (20 min treatment) to 28.5% (control). The lowest value obtained was 17.6% on the first day of analysis and the highest was 67.6% on the twelfth day of analysis in the control treatment (Table 2). The overall average, taking into account the days of stor- age time, indicated an increase in antioxidant capacity. Table 1 - Average and standard deviation of the total polyphenol content in hydrothermally-treated ‘Fuerte’ avocado as a function of treatment and storage day Treatments Storage days 0 3 6 9 12 15 Overall average per treatment Control 5 min 10 min 15 min 20 min Overall average per storage day 42.7±2.7 42.7±2.7 42.7±2.7 42.7±2.7 42.7±2.7 42.7B±2.7 41.8±2.7 51.8±12.8 58.5±2.7 51.6±5.1 49.3±1.7 50.6AB±8.8 62.1±20.5 42.3±13.5 48.0±4.6 58.4±9.1 54.6±10.1 53.1A±13.0 54.2±1.3 52.9±15.4 48.8±6.5 41.4±15.8 45.3±6.8 48.5AB±10.3 36.5±9.3 42.7±3.7 44.1±7.5 42.8±4.5 45.6±2.9 42.4B±6.1 61.7±3.5 42.2±6.0 39.8±15.1 45.6±6.0 45.4±7.9 46.9AB±10.8 49.85±13.2 45.75±9.9 47.05±9.5 47.15±9.4 47.25±6.5 Upper case letters compare overall averages on each storage day Table 2 - Average and standard deviation of antioxidant capacity of hydrothermally-treated ‘Fuerte’ avocado as a function of hydrothermal treat- ment and storage day Treatments Storage days 0 3 6 9 12 15 Overall average per treatment Control 5 min 10 min 15 min 20 min Overall average per storage day 17.6aB±1.1 17.6aB±1.1 17.6aB±1.1 17.6aB±1.1 17.6aB±1.1 17.6±1.1 9.3aB±2.0 24.7aAB±1.0 15.4abA±4.0 13.2aAB±4.3 17.7aAB±2.5 16.1±5.9 20.6abB±7.2 10.8bB±6.4 15.7abA±7.4 38.4aA±5.4 32.6AB±13.3 23.6±12.9 26.6aB±6.8 25.1aAB±9.7 34.3aA±16.9 9.3aB±4.5 10.81B±3.8 21.2±12.9 67.6aA±1.4 43.2aA±33.6 16.9bA±0.7 13.2bAB±0.7 7.2bB±4.8 29.6±17.5 29.4aAB±3.6 29.6aAB±12.6 31.7aA±12.2 33.4aAB±8.4 40.9aA±34.6 33.0±15.7 28.5±19.5 25.1±16.6 21.9±11.2 20.9±13.4 21.1±17.8 Lower case letters compare averages per treatment per day. Upper case letters compare averages of each treatment on each storage day. Fig. 1 - Total phenolic content (µg GAE/100g-1) of hydrothermally- treated ‘Fuerte’ avocado (overall average of storage days). 78 The highest percentages of antioxidant capacity were obtained in the fruit without hydrothermal treatment. The percentage of antioxidant capacity declined in ther- mally-treated fruits starting on the twelfth day of stor- age, possibly due to senescence. The fruits thermally treated for 15 and 20 min showed values of 33.4 and 40.9%, respectively, after 15 days of storage. However, the values declined between the sixth and twelfth day of storage. This tendency for the percentage of antioxidant capacity to decrease may be a result of the thermal treatment, but the profile pre- sented here with low values at nine and 12 days may be a consequence of the heterogeneity of fruit samples. This may explain the results of this research, which indicated that the antioxidant capacity of pulp thermally treated for 15 and 20 min increased up to the fifteenth day of stor- age. With a less intense respiratory peak, the degradation reactions were also diminished. Arancibia-Avila et al. (2008) reported that total polyphenols, flavonoids and anthocyanins were significantly higher (p < 0.05) in ripe durian fruit than in unripe or overripe fruit (Durio zibethinus Murr., cv. Mon Thong). The overall average antioxidant capacity during the storage period was 17.6, 16.1, 23.6, 21.2, 29.6, and 33.0% for the different treatments, indicating the ten- dency for antioxidant capacity to increase as the fruits ripened. The total phenolic content is not necessarily involved in the quantification of antioxidant activity (Jacóbo-Velasquéz and Cisneros-Zevallos, 2009). The correlation analysis of antioxidant capacity and phenolic compounds in Fuerte avocado did not reveal significant results (p=0.992 and r=0.001). Arancibia-Avila et al. (2008) found a correlation of 0.98 between the total phe- nolic content and antioxidant capacity of durian fruit. These authors concluded that the high polyphenol con- tent was the main factor responsible for the fruit’s antioxidant capacity. Wang et al. (2010) found a signifi- cant correlation between the total phenolic content and antioxidant capacity (≥ = 0.79) of avocados of different cultivars. The two parameters evaluated by these authors showed no correlation with the chlorophyll and carotenoids content (r<0.1). Furthermore, for these authors the high correlation found between procyanidins and the polyphenol content and antioxidant capacity suggests that this compound is the main polyphenol con- tributing to the antioxidant capacity of avocado. In the present research, the low correlation found for the eval- uated parameters may indicate that another food metabo- lite is responsible for the antioxidant activity of avocado. It should be noted that vitamin E is a powerful antioxi- dant which may also contribute to the antioxidant capac- ity of avocado fruits. In a study of the effect of heat treatment on the antioxidant capacity of vegetables, Melo et al. (2009) found that several events that occur during this treatment explain changes in the antioxidant activity of foods, which may be increased, reduced or unaltered. In situa- tions in which the antioxidant activity of food increases, heat treatments favor the partial oxidation of the bioac- tive compound with the highest ability to donate a hydrogen atom to a radical starting from the hydroxyl group, and/or the aromatic structure of the polyphenol is more able to withstand the displacement of the unpaired electron around the ring. Moreover, heat treatments may favor the formation of new compounds such as Maillard reaction products (reductones), which exhibit antioxi- dant activity (Nicoli et al., 1999). Because refrigeration is the most efficient method for controlling fruit matura- tion, it may have contributed to maintaining the antioxi- dant capacity of the fruits during the storage period. The heat treatment had a negative effect on the maintenance of the fruit’s antioxidant capacity compared to that of the control. The longer the fruit is exposed to a hydrother- mal treatment, the higher the loss of its antioxidant capacity. 4. Conclusions The total phenolic content increased up to the sixth day of storage, decreasing thereafter, without differ- ences between the treatments. The antioxidant capacity of the control fruit and the fruit hydrothermally treated for 5 and 10 min increased throughout the storage peri- od. The highest percentages of antioxidant capacity were obtained for the fruit without heat treatment. The percentage of antioxidant capacity of these treatments declined starting on day 12 of storage, possibly due to senescence. Hydrothermal treatments of 15 and 20 min delayed senescence, with antioxidant capacity continu- Fig. 2 - DPPH antioxidant activity of hydrothermally-treated Fuerte avocado. Legend: T = thermal treatment Considering all the treatments, the highest antioxidant capacity was found in the control treatment, followed by the 5-min thermal treatment. Figure 2 shows increasing values of antioxidant capacity over storage time in the control and the 5- and 10-min hydrothermal treatments. 79 ing to increase up to the fifth day of storage. No signif- icant correlation was found between the antioxidant capacity and the content of phenolic compounds. The antioxidant capacity of ripe ‘Fuerte’ avocado was high- er than that of unripe or senescent fruit. Acknowledgements The authors gratefully acknowledge the company Jaguacy (Bauru, SP, Brazil) for its support of this study, and the Brazilian research funding agencies FAPESP (São Paulo Research Founda- tion) and CAPES (Federal Agency for the Support and Evaluation of Postgraduate Education) for their financial support. References ALI S.S., KASOJU N., LUTHRA A., SINGH A., SHARAN- ABASAVA H., SAHUA A., BORA U., 2008 - Indian medicinal herbs as sources of antioxidants. - Food Research Internation- al, 41(1): 1-15. ARANCIBIA-AVILA P., TOLEDO F., PARK Y.-S., JUNG S.-T., KANG S.-G., HEOD B.G., LEE S.-H., SAJEWICZ M., KOWALSKA T., GORINSTEIN S., 2008 - Antioxidant pro- perties of durian fruit as influenced by ripening. - Food Scien- ce and Technology , 41(10): 2118-2125. CASTRO J.V., BLEINROTH E.W., 1982 - Conservação do aba- cate em atmosfera controlada e à temperatura ambiente. - Boletim do Instituto de Tecnologia de Alimentos, 19(2): 165- 182. COUEY H.M., 1989 - Heat treatment for control of postharvest diseases and insect pests of fruits. - Hort Science, 24(2): 198- 202. DAIUTO E.R, VIEITES R.L., 2008 - Atividade da peroxidase e polifenoloxidase em abacate da variedade Hass, submetidos ao tratamento térmico. - Revista Iberoamericana de Tecnologia Postcosecha, 9(2): 106-112. DAIUTO E.R., VIEITES R.L., TRECOMOLDI M.A., CITADINI RUSSO V., 2010 - Taxa respiratória de abacate ‘hass’ sub- metido a diferentes tratamentos físicos. - Rev. Iber. Tecnología Postcosecha, 10(2): 101-109. DE OLIVEIRA M.A., DOS SANTOS C.H., HENRIQUE C.M., RODRIGUES J.D., 2000 - Ceras para conservação pós colhei- ta de frutos de abacateiro fuerte, armazenados em temperatu- ra ambiente. - Scientia Agricola, 57(4): 777-780. DING H., CHIN Y.W., KINGHORN A.D., D’AMBROSIO S.M., 2007 - Chemopreventive characteristics of avocado fruit. - Seminars in Cancer Biology, 17(5), 386-394. DO RUFINO M.S., ALVES R.E., DE BRITO E.S., DE MORAIS S.M., DE SAMPAIO C.G.; PÉREZ-JIMÉNEZ J., SAURA- CALIXTO F.D., 2007 - Metodologia Científica:Determinação da Atividade Antioxidante Total em Frutaspela Captura do Radical Livre DPPH. - Comunicado Técnico on line. (http://www.cnpat.embrapa.br/cnpat/cd/jss/acervo/Ct_127.pdf) DONADON J.R., 2009 - Distúrbio fisiológico provocado pelo frio e prevenção com tratamentos térmicos em abacates. - Faculdade de Ciências Agrárias e Veterinárias, UNESP, Câmpus de Jaboticabal, Doutor em Agronomia (Produção Vegetal), pp. 204. GERMANO R.M.A., DE A., ARTHUR V., WIENDL F.M., 1996 - Conservação pós-colheita de abacates Persea americana Mill., variedades Fortuna e Quintal, por irradiação. - Sci. Agríc., 53(2-3): 249-253. HAARD N.F., CHISM G.W., 1996 - Characteristics of edible plant tissues, pp. 943-1011. - In: FENNEMA O.W. (ed.) Food Chemistry. - Third edition, Marcel Dekker, New York, USA. HARDENBURG R.E., WATABA A.E., WANG C.Y., 1986 - The commercial storage of fruits, vegetables, and florist and nurs- ery stocks. - Agricultural Handbook, USDA, Beltsville, USA, pp. 130. HEIM K.E., TAGLIAFERRO A.R., BOBILVA D.J., 2002 - Flavonoid antioxidants: chemistry, metabolism and structure- activity relationships. - Journal of Nutritional Biochemistry, 13: 572-584. JACÓBO-VELASQUÉZ D.A., CISNEROS-ZEVALLOS L., 2009 - Correlations of antioxidant activity against phenolic content revisited: A new approach in data analysis for food and medi- cinal plants. - J. Food Sci., 74(9): 107-113. KAUR C., KAPOOR H.C., 2001 - Anti-oxidant activity and total phenolic - the millenniun’s health. - International Journal of Food Science and Technology, 36(7):703-725. KLUGE R.A., DE AZEVEDO R.A., JOMORI M.L.L., EDAGI F.K., JACOMINO A.P., GAZIOLA S.A., DEL AGUILA J.S., 2006 - Efeitos de tratamentos térmicos aplicados sobre frutas cítricas armazenadas sob refrigeração. - Ciência Rural, 36(5): 1388-1396. LAKSHIMNARAYANA S., SUBHADRA N.V., SUBRA- MANYAM H., 1970 - Some aspects of developmental physiol- ogy of mango fruit. - J. Hortic. Sci., 45: 133-142. MELO E.A., MACIEL M.I.S., LIMA V.L.A.G., SANTANA A.P.M., 2009 - Antioxidant capacity of vegetables submitted to thermal treatment. Nutrire - Rev. Soc. Bras. Alim. e Nutr., 34(1): 85-95. MENSOR L.L., MENEZES F.S., LEITÃO G.G., REIS A.S., DOS SANTOS T.C., COUBE C.S., LEITÃO S.G., 2001 - Screening of Brazilian plant extracts for antioxidant activity by the use of DPPH free radical method. - Phytotherapy Research, 15: 127- 130. MITRA S.K., BALDWIN E.A., 1997 - Mango, pp. 85-162. - In: MITRA S.K. (ed.) Postharvest physiology storage of tropical and subtropical fruit. CAB Internacional, New York, USA, pp. 431. MORGADO C.M.A., 2007 - Conservação pós-colheita de abacates ‘Geada’ e ‘Quintal’, em diferentes pontos de colheita, com o uso de diferentes temperaturas e proteções. - Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista, Jaboticabal, Monografia, 89. NICOLI M.C., AGNESE M., PARPINEI M., 1999 - Influence of processing on the antioxidant properties of fruit and vegetables. - Trends in Food Science and Technology, 10(3): 94-100. ROBARDS K., PRENZLER P.D., TUCKER G., SWATSITANG P., GLOVER W., 1999 - Phenolic compounds and their role in oxidative processes in fruits. - Food Chemistry, 66: 401-436. SANCHES J., 2006 - Efeito de injuries mecânicas na qualidade pós-colheita de abacates. - PhD Thesis, Faculdade de Ciências Agrárias e Veterinárias, Universidade Estadual Paulista, Jaboticabal, Brazil. SANCHES-MORENO C., LARRAURI J.A., SAURA-CALIXTO F., 1998 - A procedure to measure the antiradical efficiency of polyphenols. - J. Sci. Food and Agric., 76(2): 270-276. SELVARAJ Y., KUMAR R., 1989 - Studies on fruit softening enzymes and polyphenol oxidase activity in ripening mango (Mangifera indica L.) fruit. - J. of Food Sci. and Technology, 26(4): 218-222. SEYMOUR G.B., TUCKER G.A., 1993 - Avocado, pp. 53-76. - In: SEYMOUR G.B., J.E. TAYLOR, and G.A. TUCKER (eds.) Biochemistry of fruit ripening. Chapman & Hall, London, UK. SINGLETON V.L., ORTHOFER R., LAMUELA-RAVENTÓS R.M., 1999 - Analysis of total phenols and other oxidation substrates and antioxidants by means of Folin-Ciocalteau reagent. - Methods of Enzymology, 299: 152-178. SOARES D.G., ANDREAZZA A.C., SALVADOR M., 2005 - Avaliação de compostos com atividade antioxidante em células da Levedura Saccharomyces cerevisiae. - Revista Brasileira de 80 Ciências Farmacêuticas, 41(1): 95-100. TANGO J.S., CARVALHO C.R.L., SOARES N.B., 2004 - Carac- terização física e química de frutos de abacate visando a seu potencial para extração de óleo. - Revista Brasileira de Fruti- cultura, 6(1):17-23. TOMÁS-BARBERÁN F.A., ESPÍN J.C., 2001 - Phenolic com- pounds and related enzymes as determinants of quality in fruits and vegetables. - J. Sci. Food Agri., 81: 853-879. USDA, 2007 - National Nutrient Database for Standard Refer- ence, Release 20. - Department of Agriculture, Agricultural Research Service Nutrient Data Laboratory, http://www.ars.usda.gov/ba/bhnrc/ndl. WANG W., BOSTIC T.R., GU L., 2010 - Antioxidant capacities, procyanidins and pigments in avocados of different strains and cultivars. - Food Chemistry, 122: 1193-1198. ZAUBERMAN M.S., SCHIFFMANN-NADEL M., YANKO U., 1973 - Susceptibility to chilling injury of three avocado culti- vars stages of ripening. - HortScience, 8(4): 511-513.