Hplc analysis of tea

There are two types of Pu-erh tea available on the world market: Raw and Ripe. It is not difficult to tell them apart if the Raw version is relatively young. Researchers have already developed various tools to identify Pu-erh teas. However, they are quite complicated and require advanced statistical analyses. In addition, they are characterized by different levels of accuracy. The aim of the work was to identify relationships or differences that would easily give specific results for identifying types of Pu-erh tea...

Pesticide residue detection in food has become increasingly important. Herein, surface-enhanced Raman scattering (SERS) coupled with an intelligent algorithm was developed for the rapid and sensitive detection of pesticide residues in tea. By employing octahedral Cu2 O templates, Au-Ag octahedral hollow cages (Au-Ag OHCs) were developed, which improved the surface plasma effect via rough edges and hollow inner structure, amplifying the Raman signals of pesticide molecules. Afterward, convolutional neural network (CNN), partial least squares (PLS), and extreme learning machine (ELM) algorithms were applied for the quantitative prediction of thiram and pymetrozine...

The flavor and quality of tea largely depends on the cultivar from which it is processed; however, the cultivar effect on the taste and aroma characteristics of Hakka stir-fried green tea (HSGT) has received little attention. High-performance liquid chromatography (HPLC), gas chromatography-mass spectrometry (GC-MS), and sensory evaluations were used to detect and predict the essential taste and aroma-contributing substances of HSGTs made from Huangdan (HD), Meizhan (MZ) and Qingliang Mountain (QL) cultivars...

Yunnan pickled tea is produced from fresh tea-leaves through fixation, rolling, anaerobic fermentation and sun-drying. In this study, widely targeted metabolomics using UHPLC-QQQ-MS/MS and HPLC analysis were carried out to elaborate its quality formation during the whole process. Results confirmed the contribution of preliminary treatments and anaerobic fermentation to the quality formation. A total of 568 differential metabolites (VIP > 1.0, P < 0.05, FC > 1.50 or < 0...

Blister blight and small leaf spots are important alpine diseases that mainly attack tender tea leaves, affecting tea quality. However, there is limited information on the effect of these diseases on tea's non-volatile and volatile metabolites. Metabolomic analysis based on UHPLC-Q-TOF/MS, HPLC and GC/MS was used to reveal the characteristic chemical profiles of tea leaves infected with blister blight (BB) and small leaf spots (SS). Flavonoids and monolignols were non-volatile metabolites that were enriched and significantly changed...

Interspecific metabolite transfer (ISMT) is a novel approach for plants biofortification. In this study, the effect of tea (Camellia sinensis; Cs), with or without membrane permeabilizers EDTA and Tween, as a donor plant on broccoli, cauliflower and kale sprouts was investigated. As a result, caffeine- and catechin-enriched broccoli, cauliflower and kale microgreens were produced. Kale sprouts were most permeable for catechins from Cs, while cauliflower was most permeable for caffeine. Cs + EDTA significantly increased vitamin C in broccoli and kale...

There are billions of tea drinkers around the world. However, the optimized tea-brewing temperature and time conditions for achieving a higher concentration of antioxidants in tea drinks have not been thoroughly studied. Finding out the optimized brewing conditions can benefit tea drinkers significantly. In this work, we have studied ten antioxidants from seven different popular green, Oolong, black, and scented teas using hot water extraction followed by HPLC analysis. The antioxidant yield was evaluated at 25-100 °C with 5 to 720 min of brewing time...

Tea can be found among the most widely consumed beverages, but it is also highly susceptible to fraudulent practices of adulteration with other plants such as chicory to obtain an illicit economic gain. Simple, feasible and cheap analytical methods to assess tea authentication are therefore required. In the present contribution, a targeted HPLC-UV method for polyphenolic profiling, monitoring 17 polyphenolic and phenolic acids typically described in tea, was proposed to classify and authenticate tea samples versus chicory...

As the main flavor components of tea, the contents of epigallocatechin-3-gallate (EGCG), theanine and caffeine are regulated by ambient temperature. However, whether the biosynthesis of EGCG, theanine and caffeine in response to temperature is regulated by endogenous hormones and its mechanism is still unclear. In this study, tea cuttings cultivated in the phytotron which treated at different temperatures 15℃, 20℃, 25℃ and 30℃, respectively. The UPLC and ESI-HPLC-MS/MS were used to determine the contents of EGCG, theanine, caffeine and the contents of phytohormones in one leaf and a bud...

Green tea is a popular beverage around the world and possesses a unique flavor. The flavor qualities of green tea are closely related to its grade and this relationship has not yet been studied. Three baked green teas with similar flavor were studied, namely, Huangshan Maofeng, Taiping Houkui, and Shucheng Xiaolanhua. A total of 34 odor compounds were identified by solid phase microextraction (SPME) combined with two-dimensional comprehensive gas chromatography-olfactometry-mass spectrometry analysis (GC×GC-O-MS)...

The Alternaria species are considered to produce a plethora of several mycotoxins constituting a risk factor for both human and animal health. This work aimed mainly to explore the cytotoxicity of a combined mixture of altenuene (ALT), alternariol (AOH), tenuazonic acid (TeA), and altenuisol (AS) toxins produced by pathogenic A. alternata toward human oral epithelial cells (PCS-200-014), lung fibroblast cells (WI-38), and male albino rats. The sequencing of the multi-locus, RNA polymerase second largest subunit ( rpb2 ), glyceraldehyde-3-phosphate dehydrogenase ( gapdh ), and Alternaria major allergen gene ( Alt a 1 ) was performed to infer relationships among isolated Alternaria species...

BACKGROUND: Cardiovascular disease medications such as aspirin (ASP), statins like atorvastatin (ATR), and blood pressure-lowering drugs including ACE inhibitors like ramipril (RAM) have been included in the World Health Organization (WHO) Essential Medicines List (EML) for many years. Therefore, there is a strong demand to develop a simple, rapid, and sensitive analytical method that can detect and quantitate the ternary mixture of these analytes in pharmaceutical preparations in a short run time...

Different Senecio species, especially S. inaequidens - a neophyte native to South Africa - have widely spread across Europe and now are found worldwide. The entire genus is known to contain toxic pyrrolizidine alkaloids (PAs), which renders them a possible health hazard to humans and livestock. As they can enter the food chain or occur as contaminants in herbal crops and phytopharmaceutical formulations (e.g. teas), efficient and straightforward assays for their qualitative and quantitative analysis are in high demand...

Many tannase-based industrial applications are currently being developed to successfully break down tannins in teas and juices. However, so far, no study has demonstrated the potential application of tannase to reduce tannin levels in Hibiscus sabdariffa tea. The D-optimal design was utilized to predict the optimal conditions for maximizing anthocyanins and decreasing tannin content in Hibiscus tea. Then, the effects of Penicillium commune tannase were evaluated by examining the physicochemical parameters and α-amylase inhibitory action of untreated and treated Hibiscus tea, as well as quantifying catechin content changes using HPLC...

Tea aroma components are often stored as glycosidically bound forms in the tea plant ( Camellia sinensis ). However, the determination of these glycosides in tea samples is far from optimal. In the present study, we developed a high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for simultaneous quantification of eight primary aroma glycosides within 10 min. After systematic optimization of multiple reaction monitoring (MRM) parameters, the proposed method was highly sensitive and accurate...

Characteristic metabolites including tea polyphenols, amino acids, catechins, caffeine, sugars and anthocyanins were fully analyzed by high performance liquid chromatography (HPLC), gas chromatography tandem mass spectrometry (GC-MS) and ultra-high performance liquid chromatography (UHPLC)-ESI-tandem mass spectrometry (MS/MS), and showed significant differences among Zijuan tea from different plantations in Yunnan province (YN-ZJ), Qijiang (QJ-ZJ) and Ersheng (ES-ZJ) district, China, indicating that Zijuan is significantly influenced by growth conditions...

High-performance liquid chromatography (HPLC), headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS) and ultra-high performance liquid chromatography-Q-Exactive HF-X mass spectrometer (UHPLC-Q-Exactive HF/MS) were carried out to reveal dynamic changes of volatile and non-volatile compounds during the withering process of black tea. A total of 118 volatile organic compounds (VOCs) and 648 metabolites were identified in fresh and withered tea-leaves, respectively. Among them, 47 VOCs (OAV > 1...

An effective, sensitive, and rapid method was developed for the quality control evaluation of the standard decoction of Smilax glabra Roxb (SGR). SGR is a primary ingredient of the traditional functional foods of turtle jelly and SGR tea. Chemometrics, Network Pharmacology, and molecular docking were used to screen for six quality markers. Multiple extraction parameters were optimized. HPLC-UV/CAD-QAMS was used to rapidly quantify the six quality markers (neoastilbin, astilbin, neoisoastilbin, isoastilbin, quercitrin, and isoengeletin) in 10 batches of the standard decoction of SGR samples...

The flavor and aroma quality of green tea are closely related to the harvest season. The aim of this study was to identify the harvesting season of green tea by alcohol/salt-based aqueous two-phase system (ATPS) combined with chemometric analysis. In this paper, the single factor experiments (SFM) and response surface methodology (RSM) optimization were designed to investigate and select the optimal ATPS. A total of 180 green tea samples were studied in this work, including 86 spring tea and 94 autumn tea. After the active components in green tea samples were extracted by the optimal ethanol/(NH4 )2 SO4 ATPS, the qualitative and quantitative analysis was realized based on HPLC-DAD combined with alternating trilinear decomposition-assisted multivariate curve resolution (ATLD-MCR) algorithm, with satisfactory spiked recoveries (86...

The oxidative decomposition/degradation of two main tea flavanols, EGCG/GCG and ECG/CG, was studied in alkaline solution under ultrasonic-assisted thermal conditions. The study employed HPLC-ESI-ToF-MS to identify the products generated by atmospheric oxygen oxidation and various base-catalyzed reactions. Strong basic condition led to accelerated hydrolysis and oxidation of EGCG/GCG and ECG/CG and yielded gallic acid, de-galloyl flavanols and corresponding o-quinone derivatives. Meanwhile, peroxidation or base-catalyzed cleavage and rearrangement occurred extensively on C- and B-rings of flavanol and generated various simpler aldehydes or acids...