Browsing by Author "Rangel, Joana"
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- Contents of carboxylic acids and two phenolics and antioxidant activity of dried Portuguese wild edible mushroomsPublication . Ribeiro, Bárbara; Rangel, Joana; Valentão, Patrícia; Baptista, Paula; Seabra, Rosa M.; Andrade, Paula B.The organic acids and phenolics compositions of nine wild edible mushrooms species ( Suillus bellini, Tricholomopsis rutilans, Hygrophorus agathosmus, Amanita rubescens, Russula cyanoxantha, Boletus edulis, Tricholoma equestre, Suillus luteus, and Suillus granulatus) were determined by HPLC-UV and HPLC-DAD, respectively. The antioxidant potential of these species was also assessed by using the DPPH¥ scavenging assay. The results showed that all of the species presented a profile composed of at least five organic acids: oxalic, citric, malic, quinic, and fumaric acids. In a general way, the pair of malic plus quinic acids were the major compounds. Only very small amounts of two phenolic compounds were found in some of the analyzed species: p-hydroxybenzoic acid (in A. rubescens, R. cyanoxantha, and T. equestre) and quercetin (in S. luteusand S. granulatus). All of the species exhibited a concentration-dependent scavenging ability against DPPH¥. T. rutilansrevealed the highest antioxidant capacity.
- Efeito do processamento na composição em ácidos orgânicos em castanhas das cultivares Judia e LongalPublication . Pereira, J.A.; Ribeiro, Bárbara; Rangel, Joana; Valentão, Patrícia; Andrade, Paula B.; Bento, Albino; Seabra, Rosa M.Com o presente trabalho pretendeu-se, por um lado, proceder à quantificação dos ácidos orgânicos das cultivares de castanha, Judia e Longal, e por outro verificar o efeito das formas mais comuns de processamento (castanhas assadas, cozidas e fritas) na variação destes ácidos, por HPLC/UV.
- Efeito do processamento na composição em ácidos orgânicos em castanhas das cultivares Judia e Longal.Publication . Pereira, J.A.; Ribeiro, Bárbara; Rangel, Joana; Valentão, Patrícia; Andrade, Paula B.; Bento, Albino; Seabra, Rosa M.Com o presente trabalho pretendeu-se, por um lado, proceder à quantificação dos ácidos orgânicos das cultivares de castanha, Judia e Longal, e por outro verificar o efeito das formas mais comuns de processamento (castanhas assadas, cozidas e fritas) na variação destes ácidos, por HPLC/UV. Os resultados mostraram que em ambas as cultivares foram identificados sete ácidos orgânicos, nomeadamente: ácido oxálico, ácido cis-aconitico, ácido cítrico, ácido ascórbico, ácido málico, ácido quinico e ácido fumárico. O maior teor em ácidos orgânicos foi observado em frutos não processados da Cv. Longal, com 251,2±80,7 mg/kg de matéria seca. O ácido ascórbico foi o ácido orgânico mais abundante. Todos os processos de processamento levaram a uma redução superior a 46% no teor destes compostos.
- Effect of the conservation procedure on the contents of phenolic compounds and organic acids in Chanterelle (Cantharellus cibarius) MushroomPublication . Valentão, Patrícia; Andrade, Paula B.; Rangel, Joana; Ribeiro, Bárbara; Silva, Branca M.; Baptista, Paula; Seabra, Rosa M.To check the influence of the conservation procedure in the chemical composition of chanterelle mushroom, phenolic compounds and organic acids of samples preserved under four different conditions (drying, freezing, conservation in olive oil and in vinegar) were determined. Phenolics and organic acids were analyzed by HPLC-DAD and HPLC-UV, respectively. The results showed that chanterelle is characterized by the presence of six phenolic compounds (3-, 4-, and 5-O-caffeoylquinic acid, caffeic acid, p-coumaric acid, and rutin) and five organic acids (citric, ascorbic, malic, shikimic, and fumaric acids). Samples preserved in olive oil also exhibited hydroxytyrosol, tyrosol, luteolin, and apigenin, whereas conservation in vinegar led to the detection of hydroxytyrosol, tyrosol, and tartaric acid in the analyzed samples. The conservation procedures to which chanterelle samples were subjected seem to affect the qualitative and quantitative phenolics and organic acids profiles.
- Influence of two fertilization regimes on the amounts of organic acids and phenolic compounds of tronchuda cabbage (Brassica oleracea L. Var. costata DC)Publication . Sousa, Carla; Valentão, Patrícia; Rangel, Joana; Lopes, Graciliana; Pereira, J.A.; Ferreres, Frederico; Seabra, Rosa M.; Andrade, Paula B.A phytochemical study was undertaken on tronchuda cabbage ( Brassica oleracea L. var. costata DC) cultivated under conventional and organic practices and collected at different times. Six organic acids (aconitic, citric, ascorbic, malic, shikimic, and fumaric acids) were identified and quantified by HPLC-UV. Qualitative and quantitative differences were noted between internal and external leaves. Analysis of the phenolics of the internal leaves was achieved by HPLC-DAD, and the phenolic profile obtained was revealed to be distinct from that of the external leaves. By this means were identified and quantified 11 compounds: 3- p-coumaroylquinic acid, kaempferol 3-O-sophoroside-7-O-glucoside, kaempferol 3- O-(caffeoyl)sophoroside-7- O-glucoside, kaempferol 3- O-(sinapoyl)sophoroside-7- Oglucoside, kaempferol 3- O-(feruloyl)sophoroside-7- O-glucoside, kaempferol 3- O-sophoroside, two isomeric forms of 1,2-disinapoylgentiobiose, 1-sinapoyl-2-feruloylgentiobiose, 1,2,2¢-trisinapoylgentiobiose, and 1,2¢-disinapoyl-2-feruloylgentiobiose. In general, internal leaves exhibited more constant chemical profiles.
- Organic acids in two Portuguese chestnut (Castanea sativa Miller) varietiesPublication . Ribeiro, Bárbara; Rangel, Joana; Valentão, Patrícia; Andrade, Paula B.; Pereira, J.A.; Bölke, Hanna; Seabra, Rosa M.The organic acids composition of two different chestnut (Castanea sativa Miller) varieties (Judia and Longal) were determined by HPLC/UV. In order to check the influence of the processing over these compounds, samples treated in three distinct manners (roasted, boiled and fried) were also analysed. The results showed that chestnut is characterized by the presence of seven organic acids: oxalic, cisaconitic, citric, ascorbic, malic, quinic and fumaric acids. The organic acid quantitative profile allows the distinction of the two varieties. Longal variety samples presented higher organic acids contents than those from Judia variety. The contents of the pair malic plus quinic acids may be useful for the discrimination of the two varieties. Roasting, boiling and frying procedures lead to significant reduction of total organic acids contents.
- Phenolic profile and antioxidative properties of the beefsteak fungus Fistulina hepaticaPublication . Silva, Branca M.; Ribeiro, Bárbara; Rangel, Joana; Baptista, Paula; Seabra, Rosa M.The phenolic composition of the edible beefsteak fungus Fistulina hepatica was determined by HPLC/DAD. The results showed a profile composed by caffeic, p-coumaric and ellagic acids, hyperoside and quercetin. Ellagic acid was the main compound in this species. Beefsteak fungus was also investigated for its capacity to act as a scavenger of DPPH radical and reactive oxygen species (superoxide radical, hydroxyl radical and hypochlorous acid). Good results were obtained against DPPH and superoxide radicals and hypochlorous acid but a prooxidant effect was observed for hydroxyl radical.