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|Título:||Carotenoids and α-tocopherol determination in common aromatic herbs|
Composição de Alimentos
|Resumo:||Aromatic herbs have long been recognised for their pleasant flavour and therapeutic properties. Nowadays there is an increasing interest on their study, especially in what concerns to their bioactive compounds with potential health benefits. The objective of this study was to analyse seven aromatic herbs regarding their content on carotenoids (zeaxanthin, lutein, β-cryptoxanthin, lycopene, α-carotene and β-carotene) and α-tocopherol. Samples were acquired in supermarkets of Lisbon in the dried form. The following aromatic herbs were selected for the study: basil (Ocimum basilicum L.), marjoram (Origanum majorana L.), oregano (Origanum vulgare L.), peppermint (Mentha piperita L.), rosemary (Rosmarinus officinalis L.), tarragon (Artemisia dracunculus L.) and thyme (Thymus vulgaris). Carotenoids were extracted from samples with hexane/ethanol, 4:3 (v/v). In the case of peppermint, thyme, basil and tarragon, two sample preparation procedures were compared, with and without saponification with methanolic KOH (10%, w/v) during 4 h. Ultra-High Performance Liquid Chromatography with diode array detection (UHPLC-DAD) was used for quantification. An Acquity UPLC® BEH C18 guard column (5.0 mm x 2.1 mm I.D., 1.7 µm particle size) and an Acquity UPLC® BEH C18 analytical column (50 mm x 2.1 mm I.D., 1.7 µm particle size) were selected for the separation. The mobile phase was a gradient of solvent (A) ultrapure water and solvent B [acetonitrile/methanol (containing 0.05 M ammonium acetate)/dichloromethane (75:20:5, v/v/v)]. The run time was 22 min and the flow-rate was 0.5 mL/min. Saponification is a common step for the determination of carotenoids in foods from plant origin because it allows the hydrolysis of carotenoid esters and carotenol esters, and eliminates chlorophylls and other interfering substances like unwanted lipids. However in the analysis of peppermint, thyme, basil and tarragon, saponification degraded carotenoids. Lutein was found in all the studied aromatic herbs (from 389 to 20739 µg/100 g of sample, for tarragon and thyme, respectively) and zeaxanthin in all except one. Remarkable amounts of lutein were found in thyme, indicating this particular herb as an excellent source of this carotenoid. The highest content of β-carotene was found for peppermint (1149 µg/100 g of sample) followed by marjoram (359 µg/100 g of sample). The quantification of β-carotene in rosemary, peppermint, marjoram and oregano indicates that these aromatic herbs present provitamin A activity. α- tocopherol was quantified in rosemary (9.3 mg/100 g of sample) and oregano (8.1 mg/100 g of sample). Comparing all the analysed herbs, rosemary presented the highest concentrations of α-tocopherol and zeaxanthin, and considerable concentrations of lutein. The intake of aromatic herbs may contribute for the total daily intake of antioxidants, which have positive health benefits, like prevention of cardiovascular disease and cancer, and may help to reduce the addition of sugar and salt to foods; therefore their consumption shall be encouraged and promoted.|
|Aparece nas colecções:||DAN - Apresentações orais em encontros internacionais|
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