Phytochemical profiles and antioxidant activity of brown rice varieties.

The phytochemical content and antioxidant activity of eight varieties of brown rice (BR) are reported. The total phenolic contents of BR ranged from 72.45 to 120.13mg of gallic acid equiv./100g. The phenolics from bound fraction contributed 40.6-50.2% of the total phenolic content. The total flavonoid contents of BR ranged from 75.90 to 112.03mg catechin equiv./100g. The flavonoids from the bound fraction contributed 26.9-48.2% of total flavonoids. Trans-ferulic acid was the predominant phenolic acid in BR. Total trans-ferulic acid content ranged from 161.42 to 374.81µg/100g. The percentage of trans-ferulic acid in bound fraction ranged from 96.4% to 99.2%. Only α- and γ-tocopherols and -tocotrienols were detected in BR with α-tocopherol and γ-tocotrienol being the predominant. The total peroxyl radical scavenging capacity (PSC) of BR ranged from 18.29 to 40.33mg vitamin C equiv./100g. The bound fraction contributed 67.2-77.2% of total PSC.

Organochlorine pesticides and pyrethroids in Chinese tea by screening and confirmatory detection using GC-NCI-MS and GC-MS/MS.

One hundred and one tea samples including green tea, dark tea, scented tea, black tea, and oolong tea were screened and confirmed for the contamination of 31 organochlorine pesticides (OCPs) and 19 pyrethroids (PYs) by gas chromatography-negative chemical ionization-mass spectrometry (GC-NCI-MS) and gas chromatography-tandem mass spectrometry (GC-MS/MS). 50 pesticides, 3 deuterium-labeled PYs, and 24 (13)C-labeled OCPs were separated well with the limits of detection (LODs) ranging from 0.02 to 4.5 µg/kg for GC-NCI-MS, and the positive samples were verified by GC-MS/MS with LODs of 0.1-5.0 µg/kg. High detection rates for some PYs, such as 63.4% for bifenthrin (not detected (ND)-3.848 mg/kg), 55.4% for λ-cyhalothrin (ND-3.244 mg/kg), 46.5% for cypermethrin (ND-0.499 mg/kg), and 24.8% for fenvalerate (ND-0.217 mg/kg), were found in the 101 tea samples. Endosulfan, DDTs, HCHs, and heptachlor, the persistent OCPs, were frequently detected with rates of 63.4% (ND-1.802 mg/kg), 56.4% (ND-0.411 mg/kg), 24.8% (ND-0.377 mg/kg), and 15.8% (ND-0.100 mg/kg), respectively.