ANTIOXIDANT CAPACITY AND POSTHARVEST QUALITY OF 'FUERTE' AVOCADOABSTRACT -Antioxidant capacity and quality of the avocado 'Fuerte' were evaluated. The fruits were maintained under room temperature (24 ± 1 ºC) and refrigeration (10 ± 1 ºC and 90±5% UR) during 15 days. Weight loss and respiratory rate were evaluated. Physical and chemical characteristics were determined: titratable acidity (TA), soluble solids (SS), ratio, pH, firmness, polyphenoloxidase (PPO) activity, color (L, a* and b*), total phenolics and antioxidant activity (AA) for DPPH·. In the two storage conditions the breathing pick happened in the 9th day. The fruits maintained under refrigerated temperature presented smaller mass loss and larger firmness than those in room temperature. The respiratory behavior result in the values of TA and content of SS that decreased starting from respiratory pick. The pH values increased as a consequence of the decrease of the TA. Brightness values stayed high, being observed a decrease of the green component color and increase of the yellow in the pulp with the storage PPO activity decreased with the storage. The values of AA varied from 17,6 to 68,7%. Total phenolics content decreases after the breathing pick and growing values of AA were observed even after the 9th day.

JOANA GIFFONI FIGUEIREDO FUMES 3 RESUMOAvaliou-se o efeito da radiação UV-C na conservação pós-colheita do abacate 'Hass'. Frutos selecionados foram submetidos à radiação em luz UV-C por 5, 10, 15 e 20 minutos, mantidos sob refrigeração (10±1ºC e 90±5% umidade relativa) e avaliados durante 15 dias. Determinou-se a perda de massa, taxa respiratória, acidez total titulável (ATT), sólidos solúveis totais (SST), ratio (SST/ATT), pH, firmeza, fenólicos totais e atividade antioxidante por DPPH•. A firmeza e o conteúdo de fenólicos totais diminuíram durante o período experimental nos frutos de todos os tratamentos. Houve correlação significativa moderada (P=0,0; r=0,455) entre atividade antioxidante e compostos fenólico dos frutos. Os tratamentos cuja exposição a luz UV-C foi de 15 e 20 minutos apresentaram porcentagens de atividade antioxidante maiores em relação aos outros tratamentos, entre o 6 e 12 dias de armazenamento, perda de massa inferior ao tratamento controle e valores estáveis de sólidos solúveis durante o período experimental. Estes resultados apontam que a utilização da luz UV-C pode ser uma opção na conservação de abacate 'Hass'.

RESUMOObjetivou-se nesta pesquisa avaliar a capacidade antioxidante e qualidade do abacate 'Hass'. Os frutos foram mantidos sob temperatura ambiente (24 ± 1 ºC e 70±5% UR) e sob refrigeração em 10 ± 1 ºC e 90±5% UR e avaliados durante 21 dias. Determinou-se a perda de massa e taxa respiratória. As características físico químicas avaliadas foram acidez total titulável (ATT), sólidos solúveis totais (SS), ratio, pH, firmeza, atividade da enzima polifenoloxidase (PPO), coloração (L a* b*), fenólicos totais e atividade antioxidante por DPPH·. Nas duas condições de armazenamento o pico respiratório ocorreu no 12º dia Os frutos mantidos sob temperatura refrigerada apresentaram menor perda de massa e firmeza em relação àqueles em temperatura ambiente. Os valores de ATT diminuiram durante o armazenamento e os valores de pH permaneceram estáveis entre 6,8 e 7,1. A luminosidade manteve-se elevada (77,8 a 88,8%), observando-se diminuição dos componentes de cor verde e amarelo na polpa com o armazenamento. A atividade da PPO diminuiu durante o período de armazenamento para os frutos mantidos sob refrigeração, com tendência oposta àqueles mantidos em temperatura ambiente. Os valores de atividade antioxidante e conteúdo de fenólicos totais diminuíram do início ao fim do armazenamento. A atividade antioxidante por DPPH variou de 32,5 a 20,0%. Palavras-chave: Persea americana Mill., capacidade antioxidante, refrigeração, compostos fenólicos ANTI FREE RADICAL SCAVENGER ACTIVITY AND POSTHARVEST QUALITY OF 'HASS' AVOCADO ABSTRACTThe antioxidant capacity and quality of the avocado 'Hass' was evaluated. Fruits were maintained under room temperature (24 ± 1 ºC and 70±5% relative humidity), and under refrigeration (10 ± 1 ºC and 90±5% relative humidity) for a period of 21 days. Weight losses and respiratory rates were also evaluated. Both physical and chemical characteristics were determined: titratable acidity (ATT), total soluble solids (SS), ratio, pH, firmness, polyphenoloxidase (PPO) activity, coloration (L a* b*), total phenolic and antioxidant activity for DPPH·. In both storage conditions, the breathing pick happened on the 12th storage day. Fruits maintained under refrigerated temperature presented smaller mass loss and firmness than those stored under room temperature. The ATT content decreased during storage, whereas the pH values remained stable: between 6,8 and 7,1. Brightness remained high (77.8 to 88.8%), whereas a decrease in the pulp green and yellow color components, during storage, was observed. The PPO activity decreased during storage period in fruits maintained under refrigeration, with an opposed tendency for those maintained under room temperature. Antioxidant activity and the total phenolic content decreased from beginning to end of storage. The antioxidant activity for DPPH varied from 32.5 to 20.0%.

TOTAL PHENOLICS, POLYPHENOLOXIDASE AND COLORATION IN 'HASS' AVOCADO SUBMITTED TO UV-C RADIATIONABSTRACT -The effect of radiation UV-C was evaluated in Hass avocados, regarding the total phenolics content, polyphefenoloxidase (PPO) enzyme activity and coloration. The selected fruits were submitted to the radiation in light UV-C during 5, 10, 15 and 20 minutes being maintained under refrigeration (10 ± 1 ºC and 90±5% relative humidity), and evaluated for 15 days. For the total phenolics content and PPO there were no differences among treatments in the different times of submission to the UV-C light. Total phenolics content and PPO decreased during the experimental period. The values of brightness remained high (85.4 to 88.5) in the storage. The color values a * and b * decreased with the storage in a more intense way in the fruits submitted to the radiation UV-C. There were no significant correlations for the PPO, total phenolics content and coloration.

Recently collected fruits were submitted to doses of 0.2, 0.4, 0.6 and 1.0 kGy of gamma irradiation and exposed to UV‐C light for 5, 10, 15 and 20 min, made into guacamole and stored refrigerated (10 ± 1C and 90 ± 5% relative humidity). The ripened fruit was characterized by pH, titratable acidity and color. The product was also frozen in a domestic freezer at −18C and evaluated after 0, 30, 60 and 90 days. Guacamole prepared from fruits submitted to gamma radiation had lower values of polyphenol oxidase activity, titratable acidity and the more lipids when compared to other treatments. Gamma radiation did not change the sensorial quality of the product compared to the control. Practical Applications This research will have the practical application of showing producers and suppliers of avocados the best ways to prepare guacamole from “Fuerte” avocados and minimize postharvest losses. It shows that gamma and UV‐C irradiation decreased the damage that can occur during storage and it produces guacamole with a higher content of healthy fats. The treatments did not affect the sensorial quality of the product.

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