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A voltammetric tool for the evaluation of propolis antioxidant activity

Publication . Falcão, Soraia; Tomás, Andreia; Freire, Cristina; Vilas-Boas, Miguel

Propolis (bee glue) is a sticky dark-colored material that honeybees collected from parts of plants, buds and exudates, and used as construction and defense material in the hive. This resinous substance is a rich source of phenolic compounds, and its chemical composition is strongly influenced by its phytogeographic origin. This research outlines the evaluation of the redox profile and the quantification of the total antioxidant capacity in Portuguese propolis from different origins and potential floral sources Populus x canadensis Moench and Cistus ladanifer L through cyclic voltammetry and differential pulse voltammetry. Although several oxidation processes were showed by propolis samples, which were dependent of the resin origin, common oxidation potentials within the majority of samples of a region were detected, suggesting an analogous chemical composition in respect of electroactive species. Based on the quantification of the total electroactive antioxidant power, it was found that propolis with higher antioxidant activity was from coast center, followed by north ~ Azores Archipelago > central interior > Madeira Island > south.

2016Journal article

Open access

Gamma and electron-beam irradiation as viable technologies for wild mushrooms conservation: effects on macro- and micro-elements

Publication . Fernandes, Ângela; Barreira, João C.M.; Antonio, Amilcar L.; Rafalski, Andrzej; Morales, Patricia; Férnandez-Ruiz, Virginia; Oliveira, Beatriz; Martins, Anabela; Ferreira, Isabel C.F.R.

The consumption of mushrooms is increasing all over the world as a result of their sensorial and nutritional qualities. Among their nutrients, mushrooms present high levels of macro- and micro-elements. The qualitative composition in these elements is, however, often unknown. Mushrooms are known also as being very perishable products. Gamma rays or electron-beam irradiation has been applied to improve their shelf life and decrease health hazards caused by microorganisms. In addition, the effects of irradiation on the physicochemical and nutritional parameters of wild mushrooms have been studied by our research group. Nevertheless, the effects on essential macro- and micro-elements of these natural matrices are still unknown. The effects of gamma and electron-beam irradiation on the macro- and micro-elements profiles were evaluated in Boletus edulis, Hydnum repandum and Macrolepiota procera. The same elements were detected in the three species with some quantitative differences. The profiles obtained allowed the definition of proper dietary intakes, thus preventing undesirable effects derived from consuming mushrooms in quantities that exceed threshold levels of these minerals. The applied irradiation doses did not show a systematic effect on the macro- and micro-elements profiles, except for the 10 kGy. Accordingly, irradiation treatment, using gamma rays or electron beam up to 6 kGy, is a suitable technique to disinfest and/or decontaminate wild mushrooms, independently of their species or physical state.

2016Journal article

Restricted access