Chemical and biological investigation of green tea has been generally performed while using different infusions that are prepared without consideration of the effects of sample preparation conditions. In this study, for the first time, the effects of green tea brewing conditions on the antioxidant activity and chemical profiles of metabolome and catechin compounds were examined at 60 °C and 95 °C for a period of 5–300 min. The antioxidant capacities of the tea infusions, which were assessed as per 2,2-diphenyl-1-picryl-hydrazyl hydrate (DPPH) radical scavenging activity, depended more on temperature than time. Metabolomics study that was based on ultra-high performance liquid chromatography-quadrupole-time-of-flight mass spectrometry (UHPLC-QTOF/MS) revealed that the metabolic profiles, including 33 differential metabolites, were significantly changed by temperature and time, with the effects of time being more evident at 95 °C starting after 30 min. Infusions that were brewed at 95 °C for greater than 30 min yielded distinct profiles in the hierarchical clustering analysis. The quantification of eight catechins by UHPLC-QqQ/MS showed that the total catechin level peaked at 95 °C brewing at 10 min, after which the levels of four epi-forms of catechins decreased and those of four non-epi-forms increased, implying the epimerization of catechins over time. These results suggest that the brewing conditions for sample preparation of green tea should be put into careful consideration in studies where green tea extracts are applied as aqueous infusions.
This paper studies the modification of petroleum asphalt with enzymatic hydrolysis lignin (EHL) epoxy resin. EHL epoxy resin was successfully synthesized by EHL, a novel eco-material with high chemical reactivity. Different amounts of EHL epoxy resin were compounded into AH-70 paving asphalt. The effect of EHL epoxy resin on modified asphalt was examined by penetration, soften point, thin film oven test (TFOT), ductilily tests. The results showed that EHL epoxy resin had marked effect on the high-temperatrue property of increasing softening point at the content of 2-9wt% and it had significantly effect on the low-temperature properties and aging resistance with EHL epoxy resin content of 2-9wt% in modified asphalts. TG analysis indicated that EHL epoxy resin had the high mass loss temperature than pure asphalt. Anti-aging property of asphalt was improved by compounding EHL epoxy resin with asphalt.
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