Estudo da resposta da azeitona de mesa, cultivar Negrinha de Freixo, ao longo do armazenamento em atmosfera com CO2
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2014
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As azeitonas de mesa têm uma grande tradição em Portugal. A Região de Trás-os-Montes e Alto Douro é a principal produtora de azeitona de mesa, nomeadamente da cultivar “Negrinha de Freixo” que integra a DOP “Azeitonas de Conserva Negrinha de Freixo”. Devido ao elevado amargor, as azeitonas não podem ser consumidas direta-mente da oliveira, por isso é necessário ser submetidas a processos de desamerização (perda do amargor) para que fiquem “doces” de modo a possibilitar o seu consumo.
Neste sentido, com o presente trabalho pretendeu-se avaliar o efeito do CO2 na desamerização de azeitonas da cultivar Negrinha de Freixo, assim com nas propriedades físicas e químicas. As azeitonas foram colhidas num olival, em regime de sequeiro, lo-calizado em Suçães, próximo de Mirandela. Posteriormente as azeitonas foram submeti-das a duas condições de armazenamento, ou seja, em atmosfera normal (tratamento con-trolo) e em atmosfera saturada CO2, durante um período de um mês. Durante este perío-do avaliaram-se as diferenças nas propriedades sensoriais, organoléticas e físicas (amar-gor, textura, cor, cheiro e aparência) e químicas (pH, compostos fenólicos totais, com-postos fenólicos individuais, orto-difenois, antocianinas, α-caroteno, β-caroteno e ativi-dade antioxidante) utilizando métodos colorimétricos e de HPLC-DAD. De acordo com os resultados obtidos, ainda que preliminares, verificamos que de um modo geral as azeitonas conservadas sob atmosfera saturada em CO2 apresentaram diferenças signifi-cativas nas propriedades sensoriais e organoléticas, no perfil de compostos fenólicos, no teor em pigmentos e na atividade antioxidante, face às azeitonas mantidas sob atmosfera normal. O perfil fenólico permitiu a identificação de diferentes compostos fenólicos entre os quais se destacam o hidroxitirosol, tirosol, ácido caféico, rutina, verbascosido, luteolina-7-O-glucósido, luteolina-4-O-glucósido e a oleuropeina em quantidades supe-riores a todos os outros. Observou-se uma diminuição mais acentuada da Oleuropeina na atmosfera rica em CO2 e também a maior perda de amargor. Com base nos resultados obtidos, concluímos que a atmosfera rica em CO2 permite uma redução mais acentuada de oleuropeína, composto responsável pelo amargor característico das azeitonas não processadas, mas mantendo as características funcionais e organoléticas das azeitonas, neste último caso verificou-se que o armazenamento sob CO2 contribuiu para o desen-volvimento de frutado a maçã. Este processo de desamerização apresenta potencialida-des para ser uma alternativa aos métodos industriais que usam produtos químicos para a perda de amargor, utilizam volumes de águas elevados e produzem efluentes, enquanto o armazenamento sob CO2 não há este tipo de problema e por isso é mais ecológico.
Table olives are a great tradition in Portugal. The region of “Trás-os-Montes e Al-to Douro” is the major producer of table olives, namely Cv. “Negrinha de Freixo” that integrates the DOP "Azeitonas Conservadas Negrinha de Freixo”. Outstanding the high bitterness of olives, this fruit can’t be consumed directly from the olive tree, so it is33 necessary to submit them to loss of bittering process of loss of bitterness to make them "sweet" in order to enable its for consumption. In this sense, the present work aims to assess the effect of CO2 in the submit them to loss of bittering process of olives (Cv. “Negrinha de Freixo”), and evaluate this effect in physical and chemical properties. Ol-ives were harvested in an orchard in conditions of rainfed, located in “Mirandela” in the Northeast of Portugal. After the olives were subjected at two storage conditions, in normal atmosphere (control treatment) and saturated CO2 atmosphere, during a period of one month and three weeks. During this period it was assessed differences in sensory properties, physical and organoleptic (bitterness, texture, color, smell) and chemical proprieties (pH, β-carotene, total phenolic compounds, individual phenolic compounds, ortho-diphenols, anthocyanins, α-carotene, and antioxidant activity) using colorimetric methods and HPLC-DAD. According to the results we found that generally the olives stored under saturated atmosphere in CO2 significant differences in sensory and organo-leptic properties, phenolic profile, pigment content and antioxidant activity, as com-pared to olives kept under normal atmosphere. The phenolic profile allowed the identi-fication of various phenolic compounds among, hydroxytyrosol, tyrosol, caffeic acid, rutin, verbascoside, luteolin-7-O-glucoside, luteolin-4-O-glucoside and oleuropein. There was a greater reduction in the Oleuropein atmosphere rich in CO2 and also a greater loss of bitterness. Based on these results, we conclude that the CO2-rich atmos-phere allows a sharper reduction of oleuropein (compound responsible for the character-istic bitterness of the olives not processed), but preserve the functional and organoleptic characteristics of olives, in relation to the latter characteristic was verified that storage under CO2 contributed to the developement of fruity apple. This process of submit them to loss of bittering process has potential to be an alternative to industrial methods that use chemicals to loss of bitterness, consuming high volumes of water and produces effluents; while the CO2 storage it is more ecologic.
Table olives are a great tradition in Portugal. The region of “Trás-os-Montes e Al-to Douro” is the major producer of table olives, namely Cv. “Negrinha de Freixo” that integrates the DOP "Azeitonas Conservadas Negrinha de Freixo”. Outstanding the high bitterness of olives, this fruit can’t be consumed directly from the olive tree, so it is33 necessary to submit them to loss of bittering process of loss of bitterness to make them "sweet" in order to enable its for consumption. In this sense, the present work aims to assess the effect of CO2 in the submit them to loss of bittering process of olives (Cv. “Negrinha de Freixo”), and evaluate this effect in physical and chemical properties. Ol-ives were harvested in an orchard in conditions of rainfed, located in “Mirandela” in the Northeast of Portugal. After the olives were subjected at two storage conditions, in normal atmosphere (control treatment) and saturated CO2 atmosphere, during a period of one month and three weeks. During this period it was assessed differences in sensory properties, physical and organoleptic (bitterness, texture, color, smell) and chemical proprieties (pH, β-carotene, total phenolic compounds, individual phenolic compounds, ortho-diphenols, anthocyanins, α-carotene, and antioxidant activity) using colorimetric methods and HPLC-DAD. According to the results we found that generally the olives stored under saturated atmosphere in CO2 significant differences in sensory and organo-leptic properties, phenolic profile, pigment content and antioxidant activity, as com-pared to olives kept under normal atmosphere. The phenolic profile allowed the identi-fication of various phenolic compounds among, hydroxytyrosol, tyrosol, caffeic acid, rutin, verbascoside, luteolin-7-O-glucoside, luteolin-4-O-glucoside and oleuropein. There was a greater reduction in the Oleuropein atmosphere rich in CO2 and also a greater loss of bitterness. Based on these results, we conclude that the CO2-rich atmos-phere allows a sharper reduction of oleuropein (compound responsible for the character-istic bitterness of the olives not processed), but preserve the functional and organoleptic characteristics of olives, in relation to the latter characteristic was verified that storage under CO2 contributed to the developement of fruity apple. This process of submit them to loss of bittering process has potential to be an alternative to industrial methods that use chemicals to loss of bitterness, consuming high volumes of water and produces effluents; while the CO2 storage it is more ecologic.
Descrição
Dissertação de Mestrado em Engenharia Agronómica
Palavras-chave
Azeitona , Atmosfera , Composição química , Características organoléticas , Atividade antioxidante , Oleuropeína