Evaluation of optimal QuEChERS conditions of various food matrices for rapid determination of EU priority polycyclic aromatic hydrocarbons in various foods.

Optimal QuEChERS (quick, easy, cheap, effective, rugged and safe) conditions with good accuracy, repeatability and precision were established to rapidly extract the European Union (EU) priority polycyclic aromatic hydrocarbons (PAHs) from various food matrices (Category: Poultry and Meat, Fish and seafood, Grains, Soy beans and products, Root vegetables and Coffee). The QuEChERS conditions combined with the established high performance liquid chromatography-fluorescence detection conditions were used to rapidly determine the PAHs in 19 popular cooked foods in Taiwan and their corresponding original materials. These conditions also meet the EU and Taiwan Food and Drug Administration specifications. Charcoal grilled, gas stove grilled and smoked foods had higher PAHs contents, while fried and electric oven-baked/baked foods had lower PAHs contents. In addition to the effects of cooking methods, the contamination of original materials by PAHs in the environment should also have an important impact on the contents of PAHs in these cooked foods.

Comparison and establishment of appropriate methods to determine EU priority PAHs in charcoal-grilled chicken drumsticks with different treatments and their dietary risk assessments.

Three major polycyclic aromatic hydrocarbons (PAHs) analytical methods, gas chromatography-mass spectrometer (GC-MS), high performance liquid chromatography-photodiode-array detector (HPLC-PDA) and HPLC-fluorescence detector (FLD) were compared to analyze the European Union (EU) priority PAHs. In addition to the highest sensitivity, HPLC-FLD could be developed to rapidly determine the PAHs. A QuEChERS method was also established to rapidly extract the PAHs from chicken drumsticks. The method detection limits (0.004-0.25 ng/g), method quantification limits (0.01-0.75 ng/g), recoveries (67-114%), and coefficients of variations for intra- (1-15%) and inter- (1-21%) assays for the determination of the PAHs were in compliance with the EU and Taiwan Food and Drug Administration (TFDA) requirements. The PAHs contents in charcoal-grilled chicken drumsticks (without skin, with skin, and skin removal after processing) at different processing times were also determined by the developed methods. Although the risk assessment results for all samples showed a low level of concern, the presence of skin and long-term grilling had a greater impact on PAHs levels and dietary risks. Therefore, excessive processing should be avoided, and the skin of chicken drumsticks should be removed before and after charcoal-grilling to reduce the risk of PAHs intake.

Antioxidant effect and active components of litchi (Litchi chinensis Sonn.) flower.

The effects of scavenging 2, 2-diphenyl-2-picrylhydrazyl hydrate (DPPH) radicals and inhibiting low-density lipoprotein (LDL) oxidation, and phenolic quantities were used for the activity-guided separation to identify the effective components of litchi flower. The acetone extract of the flower with notable antioxidant capacities was suspended in water and sequentially partitioned with n-hexane, ethyl acetate (EA) and n-butanol. The EA partition with the highest phenolic levels and antioxidant capacities was subjected to silica gel column chromatography. Thirteen fractions (Fr. 1-13) were collected; Fr. 10-12 with higher phenolic levels and antioxidant effects were applied to Sephadex LH-20 column chromatography. Each fraction was further separated into three sub-fractions and the second ones (Fr. 10-II, 11-II, and 12-II) were the best, which two major compounds could be isolated by semi-preparative high performance liquid chromatography (HPLC). Through Mass (MS) and Nuclear Magnetic Resonance (NMR) measurements, they could be identified as (-)-epicatechin and proanthocyanidin A2. Their contents in the litchi flower were 5.52 and 11.12 mg/g of dry weight, respectively. The study was the first time to reveal the effective antioxidant components of litchi flower.