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Abstract(s)
Rubus ulmifolius Schoot (Rosaceae), conhecida como amora silvestre, é um arbusto perene encontrado em habitats silvestres e cultivados da Europa, Ásia e África do Norte. Tradicionalmente é conhecido pelas suas propriedades medicinais, incluindo atividade antioxidante. Neste trabalho, caracterizaram-se quimicamente dois extratos fenólicos obtidos a partir de botões florais de R. ulmifolius, decocção e extrato hidroalcoólico, tendo sido identificados vários compostos fenólicos, maioritariamente derivados de elagitaninos nomeadamente, os isómeros sanguiin H-10 e lambertianina.
Comparativamente à decocção, o extrato hidroalcoólico apresentou um conteúdo em compostos fenólicos superior e uma maior atividade antioxidante. A sua forma liofilizada foi a escolhida para microencapsular pela técnica de atomização seguida de coagulação tendo-se produzido microesferas de alginato que foram posteriormente incorporadas num iogurte natural. Os resultados obtidos mostraram que ambas as formas (extrato livre e microencapsulado) revelaram maior atividade antioxidante que o controlo e que originaram produtos com melhor preservação dessa atividade ao longo do tempo.
Em síntese, os resultados obtidos demonstraram o potencial antioxidante do extrato hidroalcoólico de R. ulmifolius e a eficiência da microencapsulação para a sua preservação, abrindo assim possibilidades para a sua exploração em aplicações na indústria alimentar.
Rubus ulmifolius Schoot (Rosaceae), known as wild blackberry, is a perennial shrub found in wild and cultivated habitats in Europe, Asia and North Africa. Traditionally, it is considered to have different medicinal properties, including antioxidant activity. In the present work, phenolic extracts obtained from R. ulmifolius flower buds were chemically characterized and incorporated (directly or microcapsulated) into yogurts in order to achieve antioxidant benefits. Various phenolic compounds were identified in both decoction and hydroalcoholic extract of flowers, being ellagitannin derivatives the most abundant ones, namely sanguiin H-10 isomer and lambertianin. Comparatively to the decoction form, the hydroalcoholic extract presented both higher antioxidant activity and higher phenolic content, being its lyophilized form used to microencapsulate. A spray-coagulation technique was chosen to produce alginate based microspheres which were then successfully incorporated into a natural yogurt. The achieved results pointed out that the yogurt containing the microencapsulated extract gave rise to slightly higher antioxidant activity, and that both forms (free and microencapsulated extract) gave higher activity than the control. Furthermore, both forms contributed to preserve antioxidant activity along time. The results obtained demonstrated the antioxidant potential of R. ulmifolius hydroalcoholic extract and the effectiveness of the microencapsulation technique, thus opening new perspectives for the exploitation of these natural phenolic extracts in food applications.
Rubus ulmifolius Schoot (Rosaceae), known as wild blackberry, is a perennial shrub found in wild and cultivated habitats in Europe, Asia and North Africa. Traditionally, it is considered to have different medicinal properties, including antioxidant activity. In the present work, phenolic extracts obtained from R. ulmifolius flower buds were chemically characterized and incorporated (directly or microcapsulated) into yogurts in order to achieve antioxidant benefits. Various phenolic compounds were identified in both decoction and hydroalcoholic extract of flowers, being ellagitannin derivatives the most abundant ones, namely sanguiin H-10 isomer and lambertianin. Comparatively to the decoction form, the hydroalcoholic extract presented both higher antioxidant activity and higher phenolic content, being its lyophilized form used to microencapsulate. A spray-coagulation technique was chosen to produce alginate based microspheres which were then successfully incorporated into a natural yogurt. The achieved results pointed out that the yogurt containing the microencapsulated extract gave rise to slightly higher antioxidant activity, and that both forms (free and microencapsulated extract) gave higher activity than the control. Furthermore, both forms contributed to preserve antioxidant activity along time. The results obtained demonstrated the antioxidant potential of R. ulmifolius hydroalcoholic extract and the effectiveness of the microencapsulation technique, thus opening new perspectives for the exploitation of these natural phenolic extracts in food applications.
Description
Mestrado em cooperação com a Universidade de Salamanca