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Abstract(s)
Os extratos de plantas são fontes abundantes de compostos fenólicos com propriedades antioxidantes reconhecidas. Dados os benefícios que aportam para a saúde humana, estes assumem grande relevância na indústria alimentar, nomeadamente no desenvolvimento de alimentos funcionais. No entanto, estes compostos de reconhecida instabilidade, podem sofrer alterações durante o processamento dos alimentos onde são incorporados e após processos metabólicos. Neste contexto, a microencapsulação possibilita a proteção destes antioxidantes naturais, permitindo ainda a sua libertação controlada. O presente trabalho teve como objetivo avaliar as propriedades antioxidantes do extrato hidroalcoólico de Rosa micrantha Borrer ex Sm na sua forma livre e microencapsulada quando incorporados num iogurte natural. Para o efeito, foram preparadas microesferas de alginato utilizando uma técnica de microencapsulação por atomização seguida de coagulação. O processo foi otimizado numa primeira fase utilizando a catequina como composto modelo, sendo posteriormente aplicada ao extrato de R. micrantha. Quando comparada com o seu homólogo microencapsulado, a incorporação direta do extrato de R. micrantha conduziu a produtos com atividade antioxidante inicial superior (avaliação para t=0) tendo-se verificado a sua diminuição para t=3 dias o que foi associado à sua degradação. Os iogurtes aditivados com o microencapsulado mostraram um ligeiro incremento da atividade antioxidante para o período em análise tendo sido esta melhoria associada à libertação do extrato a partir das microesferas. Assim, o processo de microencapsulação parece favorecer a manutenção da atividade antioxidante do extrato através da sua proteção na matriz de alginato e posterior libertação faseada no tempo. A observação por Microscopia ótica das microesferas incorporadas na matriz de iogurte permitiu comprovar que os “reservatórios” de alginato se mantêm estáveis para o período em análise apontando para a viabilidade da utilização deste material para a aplicação em estudo. Os estudos de reidratação comprovaram ainda uma boa capacidade de recuperação de água por parte das microesferas liofilizadas, característica importante para a aplicação em desenvolvimento.
Plant extracts are abundant sources of phenolic compounds with recognized antioxidant properties. Given their benefits to human health, they assume a great importance in the food industry, namely in the development of functional foods. However, these compounds of known instability may suffer modifications during food processing and after metabolic processes. In this context, microencapsulation enables the protection of these natural antioxidants, allowing also their controlled release. This study aimed to evaluate the antioxidant proprieties of Rosa micrantha Borrer ex Sm hydroalcoholic extract in its free and microencapsulated form when incorporated into natural yogurt. For this purpose, alginate microspheres were prepared using a spray/coagulation microencapsulation technique. The process was optimized initially using catechin as a model compound, and subsequently applied to R. micrantha extract. When compared with its microencapsulated counterpart, the direct incorporation of the R. micrantha extract led to products with higher initial antioxidant activity (assessment for t=0) followed by a reduction for t=3 days, which was related with its degradation. The yogurts added with the microencapsulated extract showed a slight antioxidant activity increase in the analyzed time period, being this improvement associated with the release of the extract from the microspheres. Thus, the microencapsulation process seems to favor the maintenance of the extract antioxidant activity through its protection on an alginate matrix and its subsequent time-phased release. Microscopic observation of the microspheres incorporated in the yogurt allowed confirming that the alginate “shells” remained stable during the 3-day period of analysis thus pointed out for the viability of using this material for the application under study. Rehydration studies based on freeze-dried microspheres have shown a good ability of water recovery of the produced microparticles, important feature for the application under development.
Plant extracts are abundant sources of phenolic compounds with recognized antioxidant properties. Given their benefits to human health, they assume a great importance in the food industry, namely in the development of functional foods. However, these compounds of known instability may suffer modifications during food processing and after metabolic processes. In this context, microencapsulation enables the protection of these natural antioxidants, allowing also their controlled release. This study aimed to evaluate the antioxidant proprieties of Rosa micrantha Borrer ex Sm hydroalcoholic extract in its free and microencapsulated form when incorporated into natural yogurt. For this purpose, alginate microspheres were prepared using a spray/coagulation microencapsulation technique. The process was optimized initially using catechin as a model compound, and subsequently applied to R. micrantha extract. When compared with its microencapsulated counterpart, the direct incorporation of the R. micrantha extract led to products with higher initial antioxidant activity (assessment for t=0) followed by a reduction for t=3 days, which was related with its degradation. The yogurts added with the microencapsulated extract showed a slight antioxidant activity increase in the analyzed time period, being this improvement associated with the release of the extract from the microspheres. Thus, the microencapsulation process seems to favor the maintenance of the extract antioxidant activity through its protection on an alginate matrix and its subsequent time-phased release. Microscopic observation of the microspheres incorporated in the yogurt allowed confirming that the alginate “shells” remained stable during the 3-day period of analysis thus pointed out for the viability of using this material for the application under study. Rehydration studies based on freeze-dried microspheres have shown a good ability of water recovery of the produced microparticles, important feature for the application under development.