The occurrence and probabilistic risk assessment of 3-MCPDEs and GEs in infant formulas from Chinese market employing Monte Carlo simulation technique.

3-monochloropropane-1,2-diol esters (3-MCPDEs) and glycidyl esters (GEs) are food contaminants and have arisen continuous attention due to their toxicity, especially towards infants. Current risk assessment of these contaminants was mostly employing deterministic approaches, lacking quantitative characterization of the likelihood, incidence, or severity of the risks involved. Herein, 3-MCPDE and GE levels in 46 representative infant formulas (IFs) from Chinese market were determined by GC-MS/MS. Then, combining the occurrence data and consumption data from China National Food Consumption Survey, the Monte Carlo simulation-based probabilistic model for risk assessment of 3-MCPDEs and GEs in IFs from Chinese market was established. The results showed that all P90 (90th percentiles) hazard quotient values were below 1, demonstrating 3-MCPDEs didn't pose health risks to most populations aged 0-36 months old. However, for 0-12 months old groups, P10 (10th percentiles) margin of exposure values were all below 25000, indicating GEs may pose potential risks to 10% of this group. Uncertainty analysis revealed that the probabilistic model had considered uncertainties of model input and distribution, and realized refined assessment. This study is the first report on probabilistic assessment of 3-MCPDEs and GEs in IFs, which also provided references for the formulation of related regulatory limits in China.

Sensory-Guided Identification and Characterization of Kokumi-Tasting Compounds in Green Tea (Camellia sinensis L.).

The chemical substances responsible for the kokumi taste of green tea infusion are still unclear. Here, we isolated the kokumi compound-containing fractions from green tea infusion through ultrafiltration, and the major kokumi compounds were characterized as γ-Glu-Gln and γ-Glu-Cys-Gly (GSH) through ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS). The results indicated that peptides and amino acids were essential compounds in the kokumi-enriched fractions for conducting the sense of kokumi. L-theanine had an enhancing effect on the kokumi taste of green tea infusion, which was confirmed in the sensory reconstitution study. Thus, peptides, especially γ-Glu-Gln and GSH, are the major kokumi compounds in green tea infusion, which has the potential of improving the flavor of tea beverages.

Another perspective to explain green tea cream: Utilizing engineered catechin-caffeine complex.

Green tea cream, the precipitate formed in cooled green tea infusion, appears a negative effect on flavor. To explain the mechanism of green tea cream, complexations between four catechins (CATs) and caffeine (CAF) were engineered and characterized. Dynamic light scattering, high performance liquid chromatography, scanning electron microscopy, fourier-transform infrared spectroscopy, UV-visible absorption spectrum, and x-ray diffraction were used to reveal the differences between ester catechins and non-ester catechins in the dynamic complexation process, particle shape, and precipitate mechanism with caffeine. The results indicated that CATs and CAF affected each other's microenvironment in aqueous solution and Guanidine hydrochloride (GH) weakened the effect both in solution and precipitate. In addition, the 1:1 complex structure of EGC-CAF was first proved, the hydrogen bond, CH…π and π…π interaction were the forces of CAT-CAF complexes by XRD. These results provided a new perspective to the mechanism analysis of green tea cream.

Construction of Sensory/Mass Spectrometry Feedback Platform for Seeking Aroma Contributors during the Aroma Enhancement of Congou Black Tea.

Baking is widely accepted for aroma enhancement of black tea, and studies have mainly focused on the aroma or chemical substances under a specified baking condition. Understanding of the feedback between aroma substances and characteristics is urgently needed. Therefore, a mutual feedback platform (SES/MS) combined sensory evaluation system (SES) with gas chromatography-mass spectrometry (GC-MS) was established. Based on this platform, we found that baking at 90 °C for 4 h or 5 h could maintain the primary aroma attributes and increase characteristic aroma attributes-these were considered to be the best baking conditions for Yunnan congou black tea. Meanwhile, 47 volatiles were identified, among which, pyrrole and benzaldehyde appeared to have a caramel aroma, and 2-furanmethanol and α-terpineol presented a baked aroma. This study reveals the dynamic change of aroma profiles and compounds during the aroma enhancement, and provides an optional template for researchers, focused on the relationship between quality and aroma attributes of teas.