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1.
Food Chem ; 367: 130710, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34343802

RESUMO

The levels of carotenoids and carotenoid esters in pumpkin (C. maxima) slices as affected by hot air drying (60-100 °C, 6-17 h) were assessed via an HPLC-MS/MS method. Among the 25 carotenoids and carotenoid esters identified in pumpkin flesh, xanthophyll diesters (including (all-E)-violaxanthin dipalmitate, lutein 3-O-myristate-3'-O-laurate, lutein 3-O-palmitate-3'-O-laurate, lutein 3-O-myristate-3'-O-palmitate, lutein 3-O-stearate-3'-O-myristate and lutein 3-O-stearate-3'-O-palmitate) accounted for 43% of the total carotenoids (853.6 ± 18.5 µg/g, dried weight). Dihydroxy xanthophylls, especially those containing 5,6-epoxy group, were more heat-labile than carotenes, while xanthophylls were less heat stable than their diester counterparts. The degradation rates (first-order reactions, R2 = 0.983-0.992) for lutein diesters (rate constant: 0.002-0.049 h-1) in pumpkin slices were only 10-20% of that for lutein (rate constant: 0.020-0.243 h-1) during hot air drying, and 76-98% of lutein diesters could be retained in the final dried products.


Assuntos
Carotenoides , Cucurbita , Ésteres , Luteína , Espectrometria de Massas em Tandem
2.
J Colloid Interface Sci ; 566: 33-45, 2020 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-31986307

RESUMO

Persulfate (PS) activation have been extensively considered as a promising technology for removing recalcitrant pollutants, due to their production of radicals with superior oxidation reactivity. However, a catalyst with high reactive and convenient recovery for PS activation still remains to be developed. In this work, the silver-doped bismuth ferrite (Agx-BiFeO3, x = 0.1, 0.2, 0.3 and 0.4) catalysts with variable Ag content were synthesized via a facile sol-gel method and applied as heterogeneous catalyst in PS activation for tetracycline (TC) degradation. Ag0.4-BiFeO3 presented the best catalytic activity compared with other Ag doped BiFeO3 composites, 91% TC could be efficiently removed within 60 min under optimized conditions and the reaction rate constant was 0.0338 min-1. On the basis of the characterization analysis and catalytic test results, Ag could be the effective active site in PS activation and had a significant effect on PS activation. Moreover, the initial pH has negligible effect on the catalytic performance, indicating that Ag0.4-BiFeO3/PS system could work in a wide pH range. The results of electron spin-resonance spectroscopy and radical quenching tests suggested that both SO4- and OH radicals were involved in the Ag0.4-BiFeO3/PS system. The possible mechanism of Ag0.4-BiFeO3 activating PS and the major degradation pathway of TC degradation were proposed. At last, the reusability experiment results proved that Ag0.4-BiFeO3 catalyst still has a high catalytic performance after 4 times used.


Assuntos
Bismuto/química , Compostos Férricos/química , Peróxidos/química , Prata/química , Tetraciclina/química , Catálise , Tamanho da Partícula , Propriedades de Superfície
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