JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE
·
2020
·Vol. 101
·期 6
·2552-2560
·
IF 2.614
Hengye Chen,Liuna Wei,Xiaoming Guo,Chengying Hai,Lu Xu,Lei Zhang,Wei Lan,Chunsong Zhou,Yuanbin She,Haiyan Fu
BACKGROUND The quality of tea is influenced by numerous factors, especially l- theanine, which is one of the important markers used to evaluate the sweetness and freshness of tea. Sensitive, rapid, and accurate detection of l -theanine is therefore useful to identify the grade and quality of tea. RESULTS A high-sensitivity, paper-based fluorescent sensor combined with chemometrics was established to detect l- theanine in tea water based on CdTe quantum dots / corn carbon dots and nano tetra pyridel-porphine zinc (ZnTPyP). To verify the reliability of this method, fluorescence spectra and fluorescence-visualized paper-based sensors were compared. The fluorescence spectrum method demonstrated a linear range of 1 to 10 000 nmol L −1 and a limit of detection (LOD) of 0.19 nmol L −1 . In the fluorescence-visualized paper-based sensors there was a linear range of 10–1000 nmol L −1 , and the LOD was 10 nmol L −1 . Partial least squares discriminant analysis (PLSDA) and partial least squares regression analysis (PLSR) were used successfully to determine l -theanine accurately in tea water with this approach. The accuracy of the PLSDA model was 100% both in the training set and the predicting set, and the correlation coefficient between the actual concentration and the predicted concentration was greater than 0.9997 in the PLSR model. CONCLUSION This fluorescence-visualized paper-based sensor, combined with chemometrics, could be applied efficiently to the practical analysis of tea water samples, which provides a new idea to ensure the flavor and quality of tea. © 2020 Society of Chemical Industry
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FOOD CHEMISTRY
·
2021
·
IF 7.514
Shanshan Xu,Xinsheng Zeng,Huiting Wu,Shanshan Shen,Xiaogen Yang,Wei-Wei Deng,Jingming Ning
The aroma profile of raw pu’er tea (RPT) depends on its storage duration (2–10 years) and storage conditions (wet-hot or dry-cold environment). We analyzed the major odorants of RPT samples by performing metabolomic analysis and by using the molecular sensory science approach. Under dry-cold storage conditions, tea leaves had more carotenoid derivatives, glycoside-derived volatiles, and phenolic volatiles, resulting in “fresh,” “floral,” and “sweet” aroma. Under wet-hot storage conditions, tea leaves had more methoxybenzenes, which contributed considerably to their “stale” and “woody” aroma. We identified 11 and 4 compounds as the odor markers of RPTs when stored in dry-cold and wet-hot environments, respectively. Our findings provide a scientific basis for optimal storage that yields the desired aroma profile.
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JOURNAL OF CHROMATOGRAPHY A
·
2020
·
IF 4.049
Xiao-Hua Zhang,Qian Zhou,Zhi Liu,Xiang-Dong Qing,Jing-Jing Zheng,Shu-Ting Mu,Pan-Hua Liu
Retention time shifts in second-order calibration-assisted chromatographic analysis seriously impact the modeling and quantitative accuracies in complex systems. In this work, three second-order methods, i.e. alternating trilinear decomposition (ATLD) algorithm, multivariate curve resolution-alternating least squares (MCR-ALS), alternating trilinear decomposition-assisted multivariate curve resolution (ATLD-MCR), were compared their performance to process liquid chromatographic data in the presence of retention time shifts and overlapped peaks. Firstly, the validation samples contain five tea polyphenols at three concentrate levels within the calibration ranges, helped to understand, visualize and interpret these features of three second-order multivariate methods. Secondly, experimental data were studied concerning the determination of polyphenols in Chinese tea samples by HPLC-DAD. The results showed that all three second-order multivariate methods realized satisfactory quantification for five targeted analytes in Pu-Er ripe tea samples and Green tea samples even with the interference of slight retention time shifts, average recoveries were 91.23% –113.16% for ATLD, 89.96%–115.96% for ATLD-MCR, 90.64%–117.60% for MCR-ALS, respectively. However, ATLD was disappointing in the case of larger time shifts (approx. 4.00 s and 6.40 s) occurring for the quantitative analysis of Black tea and Clinacanthus nutans tea, the average recoveries were just 67.33–84.05%. Relatively, MCR-ALS and ATLD-MCR were more significantly excellent, satisfactory results still can be obtained, the average recoveries for MCR-ALS and ATLD-MCR were in the range of 86.04–117.60% and 89.96–115.96%, respectively.
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FOOD CHEMISTRY
·
2023
·
IF 8.8
Xingle Guo,Xiaojiao Zheng,Xu Guo,Junxue Wu,Xu Jing
Emulsive liquid–liquid microextraction (ELLME), a simple, rapid, and environmentally friendly technique, was established to identify chiral prothioconazole and its chiral metabolite in water, juice, tea, and vinegar using ultra-high-performance liquid chromatography (UPLC). Environmentally friendly extractant was mixed with pure water to prepare a high-concentration emulsion, which was added to samples to complete the emulsification and extraction in 1 s. Afterward, an electrolyte solution was added to complete the demulsification without centrifugation. ELLME did not use dispersants compared to the familiar dispersive liquid–liquid microextraction (DLLME), thus reducing the use of toxic solvents and avoiding the effect of dispersants on the partition coefficient. The linear range was from 0.01 to 1 mg/L. The limit of detection was 0.003 mg/L. The extraction recoveries ranged from 82.4 % to 101.6 %, with relative standard deviations of 0.7–5.2 %. The ELLME method developed has the potential to serve as an alternative to DLLME.
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FOOD CHEMISTRY
·
2023
·
IF 8.8
Xuexue Zheng,Tengfei Hu,He Xie,Xingchang Ou,Jianan Huang,Chao Wang,Zhonghua Liu,Qin Li
Fu brick tea (FBT) is popular for its unique ‘fungal flower’ aroma, however, its key odor-active compounds are essentially unknown. In this study, the odor-active compounds of “stale-fungal” aroma (CJX), “fresh-fungal” aroma (QJX), and “fermentation-fungal” aroma (FJX) types FBT were extracted and examined by headspace solid phase microextraction (HS-SPME) combined with gas chromatography-mass spectrometry (GC–MS) and gas chromatographyolfactometry (GC-O). A total of 43 volatile and 38 odor-active compounds were identified by these methods. Among them, the content of dihydroactindiolide (4596–13189 µg/L), (E) -linalool oxide (2863–6627 µg/L), and benzyl alcohol (4992–6859 µg/L) were highest. Aroma recombination experiments further verified that these odor-active compounds could be simulated the overall aroma profile of FBT successfully. Furthermore, omission experiments confirmed that 15, 20, and 15 key odor-active compounds in CJX, QJX, and FJX FBT, respectively. This study will provide a theoretical basis for comprehensively understanding the formation of characteristic aromas in FBT.
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ANALYTICAL LETTERS
·
2023
·
IF 2
Xinlei Zhang,Wenbao Jia,Xinru Tang,Qing Shan,Qiyan Chen,Can Cheng,Jinfa Shao,Yongsheng Ling,Daqian Hei
Teas of the same type in a small growing area are generally similar, and identification of their detailed geographic origin is challenging and interesting. In this study, a convenient method for distinguishing Pu-erh teas from nearby locations was developed by combining two spectroscopic techniques with chemometric methods. The distinction was based on the difference in the mineral elements and organic metabolites from tea infusions. First, Pu-erh tea was infused with water at 90 °C for 30 min. Total reflection X-ray fluorescence and ultraviolet-visible (UV-Vis) spectroscopies were used to determine the elements (P, S, K, Ca, Mn, and Ni) and organic metabolites (caffeine and polyphenols), respectively. Chemometric methods were applied to classify the origin based on the component. The proposed method was used to test samples collected from 10 mutually adjacent high-altitude villages in Mengku, Lincang, Yunnan, China. The developed user-friendly method was successfully used for the rapid evaluation of the composition, enabling the identification of the geographic origins of Pu-erh tea. Mn, caffeine, and polyphenols were found to be the key origin markers. Compared to principal component analysis, linear discriminant analysis models exhibited high discrimination performance with 100% predictive ability to distinguish the geographic origins of Pu-erh teas over a small production area. This rapid and simple method may be used to solve classification problems in tea quality control and management.
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SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
·
2019
·
IF 2.931
Kui Chen,Weixia Qing,Weiping Hu,Minghua Lu,Yong Wang,Xiuhua Liu
In this work, we reported an economical plant-based hydrothermal method for one-pot green synthesis of water-soluble carbon dots (Tea-CDs) by using waste tea extract as a carbon source. The synthesized Tea-CDs were characterized by UV–visible, fluorescence, FT-IR, TEM, XPS and XRD. The Tea-CDs were found to remove hydroxyl and superoxide anion radical in vitro. In addition, the Tea-CDs exhibited bright blue fluorescence under UV-light (λ ex = 365 nm), and the fluorescence could be effectively quenched by CrO 4 2− and Fe 3+ ions. Meanwhile, the fluorescence of Tea-CDs-CrO 4 2− and Tea-CDs-Fe 3+ systems could be again easily recovered by ascorbic acid (AA) and L-cysteine (L-Cys). As an on-off-on fluorescent nano-sensor of the Tea-CDs, the sensitive detection of CrO 4 2− , Fe 3+ , AA and L-Cys were all performed, showing that the good linear relationships between fluorescence intensity of Tea-CDs and concentration of all testing samples. Finally, the sensors successfully detected CrO 4 2− , Fe 3+ , AA and L-Cys in commercially available real samples with satisfactory recovery ranges. The prepared sensors offer distinct advantages including low cost, simple handling, good sensitivity and high selectivity.
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PLANT DISEASE
·
2019
·Vol. 103
·期 10
·
IF 3.583
Yuchun Wang,Fei Xiong,Qinhua Lu,Xinyuan Hao,Mengxia Zheng,Lu Wang,Nana Li,Changqing Ding,Xinchao Wang,Yajun Yang
Several Pestalotiopsis -like species cause gray blight disease in tea plants, resulting in severe tea production losses. However, systematic and comprehensive research on the diversity, geographical distribution, and pathogenicity of pathogenic species associated with tea plants in China is limited. In this study, 168 Pestalotiopsis -like isolates were obtained from diseased tea plant leaves from 13 primary tea-producing provinces and cities in China. Based on a multilocus (internal transcribed spacer, translation elongation factor 1-α, and β-tubulin gene region) phylogenetic analysis coupled with an assessment of conidial characteristics, 20 Neopestalotiopsis unclassified isolates, seven Pestalotiopsis species, including two novel ( Pestalotiopsis menhaiensis and Pestalotiopsis sichuanensis ), four known ( Pestalotiopsis camelliae , Pestalotiopsis chamaeropis , Pestalotiopsis kenyana , and Pestalotiopsis rhodomyrtus ) and one indistinguishable species, and three Pseudopestalotiopsis species, including two known ( Pseudopestalotiopsis camelliae-sinensis and Pseudopestalotiopsis chinensis ) and one indistinguishable species, were identified. This study is the first to evaluate Pestalotiopsis chamaeropis on tea plants in China. The geographical distribution and pathogenicity tests showed Pseudopestalotiopsis camelliae-sinensis to be the dominant cause of gray blight of tea plants in China. In vitro antifungal assays demonstrated that theobromine not only derepressed mycelial growth of the 29 representative isolates but also increased their growth. Correlation analysis revealed a linear positive relationship between the mycelial growth rate and pathogenicity ( P = 0.0148).
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FOOD RESEARCH INTERNATIONAL
·
2024
·
IF 7
Qiwei Wang,Jialing Xie,Lilei Wang,Yongwen Jiang,Yuliang Deng,Jiayi Zhu,Haibo Yuan,Yanqin Yang
Processing technology plays a crucial role in the formation of tea aroma. The dynamic variations in volatile metabolites across different processing stages of fresh scent green tea (FSGT) were meticulously tracked utilizing advanced analytical techniques such as GC-E-Nose, GC–MS, and GC × GC-TOFMS. A total of 244 volatile metabolites were identified by GC–MS and GC × GC-TOFMS, among which 37 volatile compounds were concurrently detected by both methods. Spreading and fixation stages were deemed as pivotal processes for shaping the volatile profiles in FSGT. Notably, linalool, heptanal, 2-pentylfuran, nonanal, β -myrcene, hexanal, 2-heptanone, pentanal, 1-octen-3-ol, and 1-octanol were highlighted as primary contributors to the aroma profiles of FSGT by combining odor activity value assessment. Furthermore, lipid degradation and glycoside hydrolysis were the main pathways for aroma formation of FSGT. The results not only elucidate the intricate variations in volatile metabolites but also offer valuable insights into enhancing the processing techniques for improved aroma quality of green tea.
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FOOD CHEMISTRY
·
2024
·
IF 8.5
Jingtao Zhou,Muxue Qin,Junyu Zhu,Bernard Ntezimana,Xinfeng Jiang,De Zhang,Zhi Yu,Yuqiong Chen,Dejiang Ni
Fermentation is a key process in Congou black tea, but there is limited research on the changes in flavor factors and their interrelationships during different fermentation stages under industrial production. This study applies sensory evaluation and metabolomics techniques to explore the interactions between flavors. Sensory evaluation indicated that the 4-h fermented sample exhibited the best overall performance. The experiment of adding aroma substances further revealed the significant effects of sweet aroma and green odor on taste of sweetness and astringency. Additionally, 532 flavor compounds were identified using high-resolution liquid chromatography-mass spectrometry and gas chromatography–mass spectrometry. Moreover, significant differences were observed in the volatile compounds derived from flavonoids, amino acids, and fatty acids of samples with different fermentation degrees. Furthermore, weighted co -expression network analysis of flavor compounds showed that the oxidation of polyphenols, especially catechins, plays an important regulatory role in content changes of volatile and other non-volatile compounds during fermentation.
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JOURNAL OF SEPARATION SCIENCE
·
2016
·Vol. 39
·期 7
·1331-1338
·
IF 2.741
Weiqian Liang,Juntao Wang,Xiaohuan Zang,Chun Wang,Zhi Wang
In this work, a porous carbon derived from amino-functionalized material of Institut Lavoisier (C-NH 2 -MIL-125) was prepared and coated onto a stainless-steel wire through sol–gel technique. The coated fiber was used for the solid-phase microextraction of trace levels of phthalate esters (diallyl phthalate, di- iso -butyl ortho -phthalate, di- n -butyl ortho -phthalate, benzyl- n -butyl ortho -phthalate, and bis(2-ethylhexy) ortho -phthalate) from tea beverage samples before gas chromatography with mass spectrometric analysis. Several experimental parameters that could influence the extraction efficiency such as extraction time, extraction temperature, sample pH, sample salinity, stirring rate, desorption temperature and desorption time, were investigated. Under the optimal conditions, the linearity existed in the range of 0.05–30.00 μg/L for green jasmine tea beverage samples, and 0.10–30.00 μg/L for honey jasmine tea beverage samples, with the correlation coefficients ( r ) ranging from 0.9939 to 0.9981. The limits of detection of the analytes for the method were 2.0–3.0 ng/L for green jasmine tea beverage sample, and 4.0–5.0 ng/L for honey jasmine tea beverage sample, depending on the compounds. The recoveries of the analytes for the spiked samples were in the range of 82.0–106.0%, and the precision, expressed as the relative standard deviations, was less than 11.1%.
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FOOD CHEMISTRY
·
2024
·
IF 8.5
Zhi Li,Shuangying Li,Liushan Jiang,Jingwen Niu,Yue Zhang,Linchun Nie,Qingxiang Zhou,Chunmao Chen
As a typical kind of new pollutants, there are still some challenges in the rapid detection of antibiotics. In this work, a sensitive fluorescent probe based on boron-doped carbon dots (B-CDs) in combination with thermo-responsive magnetic molecularly imprinted polymers (T-MMIPs) was constructed for the detection of oxytetracycline (OTC) in tea drinks. T-MMIPs were designed, fabricated and employed to enrich OTC at trace level from tea drinks, and B-CDs were utilized as the fluorescent probe to detect the concentration of OTC. The proposed method exhibited good linear relationship with OTC concentration from 0.2 to 60 μg L −1 and the limit of detection was 0.1 μg L −1 . The established method has been successfully validated with tea beverages. Present work was the first attempt application of T-MMIPs in combination with CDs in detection of OTC, and demonstrated that the proposed method endowed the detection of OTC with high selectivity, sensitivity, reliability and wide application prospect, meanwhile offered a new strategy for the method establishment of rapid and sensitive detection of trace antibiotics in food and other matrices.
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