Ripe Tea Research Articles

Polysaccharide Conjugates' contribution to mellow and thick taste of Pu-erh ripe tea, besides Theabrownin

Mellow and thick taste (MTT) is considered to be a typical taste characteristic of high-quality Pu-erh ripe tea. However, the role of polysaccharide conjugates remains unclear. In this study, the infusion of different grades of Pu-erh ripe tea was isolated to fractions by sensory-guided ultrafiltration technology and the key taste substances of MTT in Pu-erh ripe tea were identified and confirmed in the sensory reconstruction experiment. Further separation, purification and structural identification of the polysaccharide conjugates were carried out. Involving in aggregation morphology, the ultrafiltration fraction exhibited obvious MTT than other fractions. The main MTT compound (PRTPS-5), mainly composed of the rhamnose, galactose, arabinose and mannose, had a molecular weight of 22.93 kDa. The main chain of PRTPS-5 comprised α-L-Araf-(1→, →2,4)-α-L-Rhap-(1→, →2)-α-L-Rhap-(1→, α-D-Galp-(1→, →4)-α-D-GalpA-6-OMe-(1→, →4)-α-D-Manp-(1→, →3,6)-β-D-Galp-(1 → and →5)-α-L-Araf-(1 → and contained multiple pectic characteristic peaks. This result had scientific guiding significance for the quality enhancement of Pu-erh ripe tea.

Serum untargeted metabolomics analysis of the preventive mechanism of TAETEA Prebiotea on non-alcoholic fatty liver in rats

Pu-erh tea belongs to the six tea categories of black tea, according to the processing technology and quality characteristics, is divided into two types of raw tea and ripe tea. Raw tea is made from fresh leaves of tea as raw materials, through the process of greening, kneading, sun drying, steam molding and other processes made of tightly pressed tea. Ripe tea is made from Yunnan large-leafed sun green tea, using a specific process, post-fermentation (rapid post-fermentation or slow post-fermentation) processing of loose tea and tightly pressed tea. TAETEA Prebiotea is Puerh Ripe Tea, TAETEA Prebiotea has the effect of increasing insulin level and improving hyperglycemia in mice, and it also has the effect of regulating blood lipids, which can reduce the level of serum total cholesterol (TC) and triglycerides (TG), increase the level of high-density lipoprotein cholesterol (HDL-C), and improve the metabolism of lipids. Therefore, further experiments were conducted by us, and TAETEA Prebiotea was formulated into a suitable dose for the intervention of non alcoholic fatty liver disease (NAFLD) model rats, and at the end of the experiments, the samples of each group of experiments were analyzed and detected by the method of UHPLC-Q-Exactive LC-MS liquid-mass spectrometry methodology, and the relevant metabolites as well as metabolic pathways were analyzed by the method of Non targeted metabolomics analysis. As a result, 71 differential metabolites could be screened, of which 35 differential metabolites were up-regulated after intervention and 36 differential metabolites were down-regulated after intervention. Based on the KEGG pathway enrichment and Pathway Impact bubble diagram analysis, glycine, serine, threonine metabolism, arginine and proline metabolism, protein digestion and absorption, and central carbon metabolism in cancer may be the main metabolic pathways in which TAETEA Prebiotea exerted preventive effects on NAFLD rats, C00148 (Proline), C00300 (Creatine) and C00719 (Betaine) are the differential metabolites that play important regulatory roles.

Effects of Dried Tea Residues of Different Processing Techniques on the Nutritional Parameters, Fermentation Quality, and Bacterial Structure of Silaged Alfalfa.

The effects of dried tea residues on the nutritional parameters and fermentation quality, microbial community, and in vitro digestibility of alfalfa silage were investigated. In this study, dried tea residues generated from five different processing techniques (green tea, G; black tea, B; white tea, W; Pu'er raw tea, Z; Pu'er ripe tea, D) were added at two addition levels (5% and 10% fresh weight (FW)) to alfalfa and fermented for 90 days. The results showed that the tea residues increased the crude protein (CP) content (Z10: 23.85%), true protein nitrogen (TPN) content, DPPH, and ABST radical scavenging capacity, total antioxidant capacity (T-AOC), and in vitro dry matter digestibility (IVDMD) of the alfalfa silage. Moreover, the pH, ammonia-N (NH3-N) content, and acetic acid (AA) content decreased (p < 0.05). The effects of tea residues were promoted on these indicators with increasing tea residue addition. In addition, this study revealed that the influence of dried tea residues on the nutritional quality of alfalfa silage was greater than that on fermentation quality. Based on the nutrient composition, the addition of B or G to alfalfa silage can improve its silage quality, and these tea byproducts have the potential to be used as silage additives.

Theabrownins in dark tea form complexes with tea polysaccharide conjugates.

Theabrownins (TBs) are one of most important quality components in dark tea, but have not been produced industrially. In this study, the aqueous extract was obtained from Pu-erh ripe tea, one kind of dark tea. Caffeine, theaflavin, catechin and saponin were removed by trichloromethane, ethyl acetate and n-butanol in turn to obtain a TB isolate. The TB isolate was subjected to column chromatography using a macroporous resin HPD-750 and eluted with a gradient of 0-700 g kg-1 ethanol aqueous solution. Four fractions were obtained, and named as TBs-FC1, TBs-FC2, TBs-FC3 and TBs-FC4. These four fractions contained polysaccharides and no small molecules such as catechins, caffeine and theaflavins as well as average molecular weights of 123.000 kDa, 23.380 kDa, 89.870 kDa and 106.600 kDa. It was revealed that they were complexes of TBs and tea polysaccharide conjugates (TPCs). Ultraviolet-visible (UV-visible) and infrared (IR) spectra showed the properties of TBs and TPCs. Their zeta potentials ranged from -13.40 mV to -38.80 mV in aqueous solutions at pH 3.0-9.0. This study reveals that TBs do not exist in free state but in combined state in dark tea, which provide the theoretical basis for the industrialization of TBs. © 2024 Society of Chemical Industry.

A novel method for Pu-erh tea face traceability identification based on improved MobileNetV3 and triplet loss

Ensuring the traceability of Pu-erh tea products is crucial in the production and sale of tea, as it is a key means to ensure their quality and safety. The common approach used in traceability systems is the utilization of bound Quick Response (QR) codes or Near Field Communication (NFC) chips to track every link in the supply chain. However, counterfeiting risks still persist, as QR codes or NFC chips can be copied and inexpensive products can be fitted into the original packaging. To address this issue, this paper proposes a tea face verification model called TeaFaceNet for traceability verification. The aim of this model is to improve the traceability of Pu-erh tea products by quickly identifying counterfeit products and enhancing the credibility of Pu-erh tea. The proposed method utilizes an improved MobileNetV3 combined with Triplet Loss to verify the similarity between two input tea face images with different texture features. The recognition accuracy of the raw tea face dataset, ripe tea face dataset and mixed tea face dataset of the TeaFaceNet network were 97.58%, 98.08% and 98.20%, respectively. Accurate verification of tea face was achieved using the optimal threshold. In conclusion, the proposed TeaFaceNet model presents a promising approach to enhance the traceability of Pu-erh tea products and combat counterfeit products. The robustness and generalization ability of the model, as evidenced by the experimental results, highlight its potential for improving the accuracy of Pu-erh tea face recognition and enhancing the credibility of Pu-erh tea in the market. Further research in this area is warranted to advance the traceability of Pu-erh tea products and ensure their quality and safety.

Mellow and Thick Taste of Pu-Erh Ripe Tea Based on Chemical Properties by Sensory-Directed Flavor Analysis.

The mellow and thick taste is a unique characteristic of pu−erh ripe tea infusion, and it is closely related to the chemical composition of pu−erh ripe tea, which is less studied. This paper clarifies and compares the chemical composition of pu−erh ripe tea to that of the raw materials of sun−dried green tea, and uses membrane separation technology to separate pu−erh ripe tea into the rejection liquid and the filtration liquid. The results show that microorganisms transformed most physicochemical components, except caffeine, during the pile fermentation. It was found that total tea polyphenols, soluble proteins, total soluble sugars, theabrownin, and galloylated catechins became enriched in the rejection liquid, and the rejection liquid showed a more obvious mellow and thick characteristic. Taste interactions between crude protein, crude polysaccharide, and theabrownin were determined. They illustrated that the mellow and thick taste of pu−erh ripe tea with the addition of theabrownin increased from 4.45 to 5.13. It is of great significance to explore the chemical basis of the mellow and thick taste in pu−erh tea for guiding the pu−erh tea production process and for improving the quality of pu−erh tea.

Chemical profile of a novel ripened Pu-erh tea and its metabolic conversion during pile fermentation

Ripened Pu-erh tea is a unique tea type produced from microbial fermentation. Recently, a novel ripened Pu-erh tea (NPT) produced using a patented pile fermentation method has become increasingly popular due to its improved flavor and enriched bioactive gallic acid (GA). However, the detailed chemical features of NPT and their formation during pile fermentation remain unclear. Herein, untargeted metabolomics revealed enrichment of GA, amino acids, free sugars and reduction in catechins and flavonol glycosides in NPT. Mainly, GA was 1.99 times higher in NPT than traditional Pu-erh tea (p < 0.001). The metabolic changes were tracked during pile fermentation, and possible pathways were mapped. GA enrichment may be produced from enhanced hydrolysis of galloyl catechins and phenolic acid esters. Degradation of flavonol glycosides and formation of other metabolites were observed. This study will advance our understanding of conversions during pile fermentation and provide new insights into directional manufacturing of high-quality ripened tea.

RETRACTED ARTICLE: Empirical analysis of Pu'er tea price bubble measurement based on GSADF method

This article has been retracted from publication in the Taylor & Francis journal, Acta Agriculturae Scandinavica, Section B — Soil & Plant Science. Following publication, concerns were raised by multiple third-parties around the content of the special issue and the decision-making process. Following an investigation by the Taylor & Francis Publishing Ethics & Integrity team in full cooperation with the Editor-in-Chief, it was confirmed that this article included in Special Issue titled “ Envisage Computer Modelling and Statistics for Agriculture”, guest edited by Gunasekaran Manogaran was not peer-reviewed appropriately, in line with the Journal's peer review standards and policy. As the stringency of the peer review process is core to the integrity of the publication process, the Editor and Publisher have decided to retract all of the articles within the above-named Special Issue. The journal has not confirmed if the authors were aware of this compromised peer review process. The journal is committed to correcting the scientific record and will fully cooperate with any institutional investigations into this matter. The authors have been informed of this decision. We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines.

Comparison of three second-order multivariate calibration methods for the rapid identification and quantitative analysis of tea polyphenols in Chinese teas using high-performance liquid chromatography

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.

Physicochemical properties and biological activities of a high-theabrownins instant Pu-erh tea produced using Aspergillus tubingensis

High-theabrownins (TB) instant Pu-erh tea was produced via a novel submerged fermentation (SF) by Aspergillus tubingensis and compared with samples produced commercially via the conventional solid-state fermentation (SSF). All tea samples were assessed for physicochemical properties and biological activities (cytotoxicity toward cancer cells; antioxidant capacity). TB content of SF tea was nearly 4-fold compared to SSF teas. SF instant Pu-erh tea had significantly higher levels of theabrownins, total polyphenols, total flavonoids, caffeine and theobromine compared to the SSF ripe tea, but had significantly lower levels of gallic acid, total catechins, epicatechin, epicatechin gallate, theaflavins, thearubigins, amino acids, total carbohydrate and polysaccharides. The free radical scavenging ability of SF-produced tea was lower than of the teas made via SSF. At suitable combinations of concentration and contact time, the instant Pu-erh tea had anticancer and antioxidative effects in vitro. The cytotoxic effect and the intracellular reactive oxygen species scavenging capacity of SF tea was mainly associated with theabrownins.

Effects of High Voltage Pulsed Electric Field on Antioxidant Activity of Tea Polyphenols for Yunnan Pu’er Tea

In order to improve the antioxidant activity of Pu’er tea, the authors use different high voltage pulsed electric field (HPEF) to deal with the third grade Pu’er ripe tea, extract the tea polyphenols and determine antioxidant activity of tea polyphenols in each tea samples by four indexes, namely the ability of scavenging hydroxyl radical (·OH), the ability of scavenging superoxide anion (O2·–), the ability of scavenging radical DPPH and total reducibility. Then antioxidant activity of tea polyphenols is analyzed by stepwise regression analysis on Matlab, establish the mathematical model of its antioxidant activity and voltage, frequency. The results show that HPEF could decrease the content of tea polyphenols in Pu’er ripe tea, and promote it to translate into Theabrownines (TBs) and so on. The suitable conditions of HPEF can improve the antioxidant activity of Pu’er tea to a certain extent. This study provides a new physical method for improving the antioxidant activity of Pu’er tea polyphenols, and provides technical support for the extraction and development of natural antioxidants in Pu’er tea.

Effects of Pu-erh ripened tea on hyperuricemic mice studied by serum metabolomics.

To evaluate effects of Pu-erh ripened tea in hyperuricemic mice, a mouse hyperuricemia model was developed by oral administration of potassium oxonate for 7 d. Serum metabolomics, based on gas chromatography-mass spectrometry, was used to generate metabolic profiles from normal control, hyperuricemic and allopurinol-treated hyperuricemic mice, as well as hyperuricemic mice given Pu-erh ripened tea at three doses. Pu-erh ripened tea significantly lowered serum uric acid levels. Twelve potential biomarkers associated with hyperuricemia were identified. Pu-erh ripened tea and allopurinol differed in their metabolic effects in the hyperuricemic mice. Levels of glutamic acid, indolelactate, L-allothreonine, nicotinoylglycine, isoleucine, l-cysteine and glycocyamine, all involved in amino acid metabolism, were significantly changed in hyperuricemic mice treated Pu-erh ripened tea. Thus, modulating amino acid metabolism might be the primary mechanism of anti-hyperuricemia by Pu-erh ripened tea.

Volatile components of essential oils extracted from Pu-erh ripe tea by different extraction methods

ABSTRACTPu-erh ripe tea is one of the main tea products in China, which has a unique woody, chestnut fragrance flavour, distinct from other teas. Because of the largely excessive production capacity, it is now possible and necessary to utilise it to produce tea essential oil. In this study, the extraction efficiency of Soxhlet extraction (Soxhlet), ultrasonic-assisted extraction (UAE), simultaneous distillation extraction (SDE), and steam distillation extraction (SD) for extraction oil of Pu-erh ripe tea was investigated. GC-MS and HS-SPME/GC-MS were then applied to identify the volatile compounds in the essential oils and tea samples. The results showed that the extraction ratios of the essential oil were 0.81±0.01 g/kg (Soxhlet), 0.36±0.01 g/kg (UAE), 0.11±0.01 g/kg (SDE), and 0.59±0.01 g/kg (SD). GC-MS identified 40, 38, 35, and 47 volatile compounds in the essential oils extracted by the different methods, whereas 55 compounds were identified by HS-SPME/GC-MS. Therefore, when both the essential oil extraction rate and oil flavour are considered, the best method is SD.

Profiling elements in Puerh tea from Yunnan province, China

ABSTRACTPuerh tea, as the most representative Chinese dark tea, has attracted global interest in recent years. Profiling the levels of metal elements in Puerh tea is very important since its presence is related to human health. In this study, 41 elements in 98 Puerh tea samples from Yunnan province, China including Puerh raw tea and Puerh ripe tea were evaluated by microwave digestion combined with inductively coupled plasma mass spectrometry . The content of toxic elements, essential elements and rare earth elements of Puerh tea from different regions was discussed in detail. The concentrations of Ba, Cr, As, Pb, Bi, Fe, Zn, V, Mn, Be, Ag and Tl showed significant differences (p < 0.05) by ANOVA analysis. Principal component analysis and linear discriminant analysis were used to describe the relationship of Puerh tea from different regions. This study provided a comprehensive database for Puerh tea quality control and intake risk assessment.

Pu-erh ripened tea resists to hyperuricemia through xanthine oxidase and renal urate transporters in hyperuricemic mice

To investigate the effects of Pu-erh ripened tea on lowering uric acid levels and identify its possible mechanisms, three different doses of the tea, with allopurinol as a positivecontrol, were administered intragastrically to hyperuricemic mice. Hyperuricemia was induced in the mice by oral administration of potassium oxonate for 7days. Serum levels of uric acid, liver xanthine oxidase (XOD) and adenosine deaminase (ADA) activities, and expression of renal mURAT1, mGLUT9, mOAT1 and mOCT1 protein and mRNA were measured. Pu-erh ripened tea, at all doses, significantly lowered serum uric acid levels. At the high and medium doses, it also markedly inhibited liver XOD and ADA activities. Furthermore, mURAT1 and mGLUT9 expression levels were significantly down-regulated by Pu-erh ripened tea treatment. These results suggested that Pu-erh ripened tea can resist to hyperuricemia, possibly by inhibiting, concurrently, uric acid production and renal urate reabsorption.

The Promotion Effects on Pu\'er Tea Aroma of High Voltage Pulsed Electric Field

In order to explore how to improve the aroma of geographical indications products in Yunnan-Pu’er Tea Using Electronic Nose System, the aroma components of Five-star Pu’er ripe tea of Fuyuanchang (2005 vintage) was defected, which treated by different High voltage Pulsed Electric Field (HPEF). And Principal Component Analysis (PCA), Linear Discriminant Analysis (LDA) and loadings analysis (Loading) were take on by Winmuster software, then combining response curve peak transuded comparison, the orthogonal test of the results from the experiment was done. The result proved that the content of aroma composition changed prominently after HPEF processing. The three kind of aroma component which include alcohol, organic sulfide and short-chain alkane increased significantly. In the condition of 18 kV/180 Hz/30 min, the three kinds of aroma composition increased the most and the average increase was 12.5%; and under the condition of 12kV/150Hz/45 min, the increase come secondly with the average of 11.1%. In addition, the other promoted condition of HPEF included 18 kV/120 Hz/60 min, 12 kV/120 Hz/60 min and 18 kV/120 Hz/30 min and the first condition was better than the others. The electric field voltage was the essential determinant which effected the content of aroma composition.

Discrimination Based on Volatile Compounds and Differential Analysis of Chinese Dark Tea

&lt;p&gt;Simultaneous distillion and extraction (SDE)/gas chromatographymass spectrometry (Gc-Ms) detection coupled with partial least squares-discriminate analysis (PLS-DA) were used to discriminate Chinese dark teas (CDTs). A total of 84 volatile compounds were taken to conduct the cluster analysis. 9 kinds of CDTs could be divided into 3 groups in consistent with the manufacturing processes. Besides, ingredients that were related with the quality of CDT, such as free amino acid, soluble sugar and catechines were analyzed. Differential trends were disclosed between Pu-Er raw tea and Pu-Er ripe tea as well as raw dark green tea (RDGT).&lt;/p&gt;

Simultaneous determination of free amino acids in Pu-erh tea and their changes during fermentation

Pu-erh ripened tea is produced through a unique microbial fermentation process from the sun-dried leaves of large-leaf tea species (Camellia sinensis (Linn.) var. assamica (Masters) Kitamura) in Yunnan province of China. In this study, the changes of amino acid profiles during fermentation of Pu-erh tea were investigated, based on the improved HPLC–UV method with PITC pre-column derivatization for the simultaneous determination of twenty free amino acids. Results showed that aspartic acid, glutamic acid, arginine, alanine, theanine and tyrosine were the major amino acids in tea samples. Fermentation significantly influenced on the amino acid profiles. The total free amino acid contents significantly decreased during fermentation (p<0.05). Meanwhile, low amount of acrylamide were detected. Its concentration increased after 7-days’ fermentation and then decreased gradually. The results provided the useful information for the manipulation of fermentation process according to the changes of amino acids and acrylamide contents in Pu-erh ripened tea.

Design of Turning and De Blocking Machine or the Fermentation of Ripe Puer Tea Heap

The fermentation of puer ripe tea once generally requires about raw materials 10t. In the meantime, it needs workers manually to turn 4-5 times. This will require not only intensive labor, but also improving the degree of cleaning. For turning operations in fermentation process of puer tea, in order to reduce labor intensity of workers, through researching the entire turning and fermentation process, we design roller double-helix arrangement blade- type turning machine for the fermentation of tea heap and make innovative design of turning device and optimal design of key working parts. In this study the designed turning machine which is mainly composed of turning devices, transport equipment and power devices, through organic complexes of various parts, complete turning operations of puer tea.

The Design of Automatic Stirring Ripe Tea Fermenter for Puer Tea

Traditional ripe tea fermentation is directly stacking puer tea material on the ground of fermentation workshop relying on natural environment to ferment. The way of fermentation, which has poor degree of sanitation, makes fermentation process influenced by environmental change and difficult to ensure product quality and stability. To solve this problem, we design a ripe tea fermenter for puer tea. There is a certain distance between fermenter and the ground and the spindle of fermenter is designed, so as to achieve automatically agitation instead of manually turning process. It can monitor and control temperature and humidity of tea in the fermenter, so that in the fermentation process puer tea will be in a stable environment, improving fermentation process and the quality of temperature fermentation.