Brazilian Archives of Biology and Technology

URI permanente para esta coleçãohttps://thoth.dti.ufv.br/handle/123456789/12090

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2001 - 200922010 - 20142

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Data final: 2019Assunto: search.filters.subject.Qualidade de bebida

Resultados da Pesquisa

Agora exibindo 1 - 4 de 4
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    Stability of phenolic compounds and antioxidant capacity of regular and decaffeinated coffees
    (Instituto de Tecnologia do Paraná - Tecpar, 2014-01) Vicente, Silvio José Valadão; Queiroz, Yara Severino; Gotlieb, Sabina Léa Davidson; Torres, Elizabeth Aparecida Ferraz da Silva
    This study compared the regular and decaffeinated coffees in relation to antioxidant capacity, levels of some antioxidant molecules and stability of these parameters over a six-month period under different storage conditions. The regular coffee samples analyzed right after the industrial production showed higher antioxidant capacity (ORAC and DPPH), the same levels of phenolic compounds and higher levels of phenolic acids than decaffeinated coffee. After six months, the closed packs of both the grades kept under vacuum at 20°C did not show significant changes from the initial results; the open packs stored at 4°C showed small but statistically significant reductions and the open packs stored at 20°C showed higher and statistically significant losses (p < 0.05). Oxygen was the most important factor for these losses but temperature also played an important role. Tests showed that the storage conditions were very important to preserve the quality of coffees regarding the analyzed parameters.
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    Evaluation of arsenic and selenium in brazilian soluble coffee by inductively coupled plasma atomic emission spectrometry with hydride generation
    (Instituto de Tecnologia do Paraná - Tecpar, 2001-10) Santos, Éder José dos; Oliveira, Elisabeth de
    A method for the evaluation of arsenic and selenium in soluble coffee by inductively coupled plasma atomic emission spectrometry with continuous hydride generation to attend the Brazilian food legislation is described. Samples were digested with nitric acid and hydrogen peroxide in a focused microwave system. Slow heating eliminated nitric acid and selenium (VI) was reduced to selenium (IV) by addition of 6 mol/L hydrochloric acid and heating at 90°C under a reflux system. The influence of sample acidity on sensitivity was investigated. Hydrochloric acid 6 mol/L was the most suitable reaction medium. Practical detection limits of 2.0μg/L for As and 1.0μg/L for Se were achieved and attended the Brazilian food legislation. The results of recoveries on spiked samples demonstrate the reliability and accuracy of the procedure.
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    Comparison of high performance liquid chromatography with fluorescence detector and with tandem mass spectrometry methods for detection and quantification of ochratoxin a in green and roasted coffee beans
    (Instituto de Tecnologia do Paraná - Tecpar, 2013-11) Bandeira, Raquel Duarte da Costa Cunha; Uekane, Thais Matsue; Cunha, Carolina Passos da; Rodrigues, Janaina Marques; Cruz, Marcus Henrique Campino de la; Godoy, Ronoel Luiz de Oliveira; Fioravante, Andreia de Lima
    Two analytical methods for the determination and confirmation of ochratoxin A (OTA) in green and roasted coffee samples were compared. Sample extraction and clean-up were based on liquid–liquid phase extraction and immunoaffinity column. The detection of OTA was carried out with the high performance liquid chromatography (HPLC) combined either with fluorescence detection (FLD), or positive electrospray ionization (ESI+) coupled with tandem mass spectrometry (MS–MS). The results obtained with the LC-ESI-MS/MS were specific and more sensitive, with the advantages in terms of unambiguous analyte identification, when compared with the HPLC-FLD.
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    A comparison between enzyme immunoassay and HPLC for ochratoxin A detection in green, roasted and instant coffee
    (Instituto de Tecnologia do Paraná - Tecpar, 2007-03) Fujii, Simone; Ono, Elisabete Yurie Sataque; Ribeiro, Ricardo Marcelo Reche; Assunção, Fernanda Garcia Algarte; Takabayashi, Cássia Reika; Oliveira, Tereza Cristina Rocha Moreira de; Itano, Eiko Nakagawa; Ueno, Yoshio; Kawamura, Osamu; Hirooka, Elisa Yoko
    An indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) for ochratoxin A (OTA) detection in green, roasted and instant coffees was developed using anti-OTA monoclonal antibody. Immunological reagents prepared were OTA-BSA (4.76 μ g/mL), anti-OTA.7 MAb (2x10 3 -fold dilution) and HRP-anti IgG (10 3 -fold dilution). The detection limit was 3.73 ng OTA/g and correlation coefficients (r) between this immunoassay and high performance liquid chromatography were 0.98 for green coffee, 0.98 for roasted and 0.86 for instant. OTA levels detected by ic- ELISA were higher than by HPLC, with ELISA/HPLC ratio of 0.66 - 1.46 (green coffee), 0.96 - 1.11 (roasted) and 0.93 - 1.82 (instant). ELISA recoveries for OTA added to coffee (5 - 70 ng/g) were 81.53 % for green coffee, 46.73 % for roasted and 64.35 % for instant, while recoveries by HPLC were 80.54 %, 45.91 % and 55.15 %, respectively. Matrices interferences were minimized by samples dilution before carrying out the ELISA assay. The results indicate that MAb-based ic-ELISA could be a simple, sensitive and specific screening tool for OTA detection, contributing to quality and safety of coffee products.