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Percorrer por autor "Oliveira, M Beatriz P P"

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  • Chemical characterization and bioactive properties of a coffee-like beverage prepared from Quercus cerris kernels
    Publication . Pinto, Diana; Diaz Franco, Santiago; Silva, Ana Margarida; Cupara, Snezana; Koskovac, Marijana; Kojicic, Ksenija; Soares, Sónia; Rodrigues, Francisca; Sut, Stefania; Dall'Acqua, Stefano; Oliveira, M Beatriz P P
    In the present study, a coffee-like beverage was prepared from Quercus cerris seeds. Seeds presented 60.4% carbohydrates (of which 26.9% is fiber), 6.3% proteins and 4.0% fat. In the coffee-like beverage, the TPC and TFC were 2070.2 mg GAE per L and 285.3 mg CEQ per L, respectively. The IC50 values determined using FRAP and DPPH assays were, respectively, 203.1 mg L-1 and 271.6 mg L-1. Concerning the reactive species scavenging capacity, the extract was more effective against O2˙-, HClO and ˙NO (namely, IC50 = 17.24 ± 0.24 μg mL-1, IC50 = 9.25 ± 0.92 μg mL-1 and IC50 = 0.65 ± 0.06 μg mL-1). Qualitative and quantitative analyses by 1D- and 2D-NMR and LC-MS indicated high levels of ellagic acid and gallotannin or ellagitannin derivatives. The optimal range of non-cytotoxic concentrations in Caco-2 and HT29-MTX cell lines was between 0.1 and 1.0 μg mL-1. This is the first study that evaluates the Q. cerris seed extract as a beverage.
    2019-04-17Artigo científico Acesso aberto Ver mais
  • Improving the extraction of Ara h 6 (a peanut allergen) from a chocolate-based matrix for immunosensing detection: Influence of time, temperature and additives
    Publication . Alves, Rita C.; Pimentel, Filipa B; Nouws, Henri P.A.; Silva, Túlio H B; Oliveira, M Beatriz P P; Delerue-Matos, Cristina
    The extraction of Ara h 6 (a peanut allergen) from a complex chocolate-based food matrix was optimized by testing different temperatures, extraction times, and the influence of additives (NaCl and skimmed milk powder) in a total of 36 different conditions. Analyses were carried out using an electrochemical immunosensor. Three conditions were selected since they allowed the extraction of the highest levels of Ara h 6. These extractions were performed using 2g of sample and 20ml of Tris-HNO3 (pH=8) containing: a) 0.1M NaCl and 2g of skimmed milk powder at 21°C for 60min; b) 1M NaCl and 1g of skimmed milk powder at 21°C for 60min; and c) 2g of skimmed milk powder at 60°C for 60min. Recoveries were similar or higher than 94.7%. This work highlights the importance to adjust extraction procedures regarding the target analyte and food matrix components.
    2017-03-01Artigo científico Acesso aberto Ver mais