Tea Varieties Research Articles

An Insight into the Potential of Flavonoids and Furanocoumarins in the Treatment of Psoriasis

Abstract: Psoriasis is a hereditary, immune-mediated illness that can affect the skin, joints, or both. The condition frequently requires the treatment of a wide group of specialists with a variety of specialties. Numerous difficulties are presented by psoriasis, such as its high prevalence, chronicity, disfigurement, disability, and related comorbidities. Natural treatment of psoriasis can be provided by flavonoids and furanocoumarins. Flavonoids, a group of chemical compounds with various phenolic structures, are found in a wide variety of foods, including fruits, vegetables, cereals, bark, roots, stems, flowers, tea, and wine. The health benefits of these natural compounds are well known, and efforts are being made to extract the components known as flavonoids. Furanocoumarin is a subgroup of coumarins with phenolic compounds. It can be divided into two groups: linear generic name psoralens, which include psoralen, xanthotoxin, and bergapten, and angular generic name angelicins, which include sphondin and pimpinellin. The most important plant source is psoralen, which has been used for generations in traditional medicine to treat psoriasis and vitiligo. The creation of alternative psoralen molecules that do not generate the bifunctional adducts that serve as the foundation for DNA crosslinking is one of the future directions for further improving psoriasis treatment. This article focuses on flavonoid and furanocoumarin research and development trends, modes of action, functions, and applications.

The Chemistry, Sensory Properties and Health Benefits of Aroma Compounds of Black Tea Produced by Camellia sinensis and Camellia assamica

Black tea is frequently consumed worldwide and is renowned for having a distinctive scent. The volatile chemicals in tea are responsible for its aroma, which is important for sensory quality. The enzymatic and non-enzymatic processes that produce the compounds endowing black tea with its distinctive aroma are complex. Black tea is well known for its robust and complex aroma, which can vary based on the type of tea leaves used and processing technologies used. During the production of black tea, several intricate biological and chemical processes contribute to the aroma’s development. Different volatile chemicals are generated during the processing of black tea, which includes withering, rolling, fermentation (enzymatic oxidation), and drying. Various methods have been used to analyze and describe the aroma of black tea. Different methods, such as gas chromatography-mass spectrometry, olfactometry, and solid phase extraction, have been used to assess the fragrance of black tea. These methods evaluate characteristics including fruity, flowery, woody, malty, spicy, and smoky flavors. Phenyl ethyl alcohol, one-octen-3-ol, trans-linalool oxide (furanoid), geraniol, and nonanal are major aroma-active compounds in black tea. Sensory analytic techniques are used to assess black tea’s flavor and scent qualities. This assessment helps figure out the tea’s quality, unique characteristics, and even some unpleasant attributes. Black tea is mostly made from Camellia sinensis and Camellia assamica tea varieties. These two varieties, members of the Camellia genus, differ in their development patterns, leaf sizes, and chemical makeup, impacting how black tea’s scent is formed. When evaluating black tea made from Camellia sinensis and assamica, sensory analysis involved assessing the aroma when the tea was dry and, after brewing, noting any differences from other teas. This review focused on how key aromatic compounds are formed during the tea manufacturing process by Camellia sinensis and Camellia assamica black tea.

Exploring the Optimal Extraction Conditions and Antibacterial Effects of Tea Polyphenols

Tea polyphenols are a general term for polyphenols in tea, which are a white amorphous powder that is easily soluble in water. It is well known that it has many functions, such as antioxidant activity, antibacterial activity, inhibitory enzyme activity and other physiological activities. And as a natural compound, tea polyphenols have good environmental friendliness, and as additives, they can help improve the current environmental pollution situation. Tea polyphenols have extensive application value in various industries, but there is currently a lack of research on their antibacterial properties when combined with daily chemical products. Due to the current lack of research in this area, this experiment used shower gel as an example to study the antibacterial effect of daily chemical products which are added tea extract. This article includes two experiments. One is study on the optimal extraction conditions for tea polyphenol, including two variables on temperature and extraction agent concentration. The other one is study on antibacterial effect of tea polyphenol, by combining variables on store temperature and concentration of tea extract solution, a total of 14 experimental conditions are set up, including the extract acting alone, and acting together with diluted shower gel, and the control group (water, diluted shower gel). The experimental study shows that the inherent content of tea polyphenols varies among different tea varieties and tea extracts is with good antibacterial properties. Generally speaking, the extraction effect at 80 degrees Celsius is significantly better than those at 50 degrees Celsius, and the content also changes with the extraction time. And tea extracts extracted with suitable extraction conditions shows the best antibacterial effect when diluted 100 to 200 times. This article aims to find better extraction methods and antibacterial effect, providing a new approach for the industrial application of tea polyphenols as natural bacteriostat.

Insights on the Nutraceutical Properties of Different Specialty Teas Grown and Processed in a German Tea Garden.

European countries have recently started experimenting with growing and producing their own teas in small quantities, mainly for the specialty tea sector. To characterize European teas, this study investigated a set of five tea types obtained from different Camellia sinensis varieties/cultivars, representing various oxidation grades (green, white, yellow, oolong, black), all grown and processed in the only tea garden in Europe (in Germany) that focuses on all five types. Hot and cold brews were studied by measuring the total phenolic (TPC) and flavonoid contents (TFC), the antioxidant capacity and UV-Vis spectra, also with the objective of discriminating between the different tea types and the different plant varieties. The dried leaves were analyzed to measure the content of essential and toxic elements and by ATR-FTIR spectroscopy to determine a chemical fingerprint for identifying the tea varieties and types. The average levels of TPC (hot brew = 5.82 ± 2.06; cold brew = 5.4 ± 2.46 mM GAEq), TFC (hot brew = 0.87 ± 0.309; cold brew = 0.87 ± 0.413 mM CAEq), and antioxidant capacity (ORAC assay-hot brew = 20.9 ± 605; cold brew = 21.8 ± 8.0 mM TXEq, ABTS assay-hot brew = 15.2 ± 5.09; cold brew = 15.1 ± 5.8 mM TXEq, FRAP assay-hot brew = 9.2 ± 3.84; cold brew = 10.4 ± 5.23 mM AAEq) observed compared well with those from other parts of the world such as China, Africa, and Taiwan. The hazard quotient <1 and the hazard index of 0.14 indicate that there is no non-carcinogenic risk from consumption of these teas. The obtained information is essential for elucidating the characteristics and the impact of tea processing and tea variety on the health benefits of these tea products coming from a single European tea garden. This multifaceted approach would help tea growers in Europe increase their knowledge on the health attributes of the teas they grow, ultimately leading to optimization of the nutraceutical properties of these teas.

Classification of oolong tea varieties based on computer vision and convolutional neural networks.

In the contemporary food industry, accurate and rapid differentiation of oolong tea varieties holds paramount importance for traceability and quality control. However, achieving this remains a formidable challenge. This study addresses this lacuna by employing machine learning algorithms - namely support vector machines (SVMs) and convolutional neural networks (CNNs) - alongside computer vision techniques for the automated classification of oolong tea leaves based on visual attributes. An array of 13 distinct characteristics, encompassing color and texture, were identified from five unique oolong tea varieties. To fortify the robustness of the predictive models, data augmentation and image cropping methods were employed. A comparative analysis of SVM- and CNN-based models revealed that the ResNet50 model achieved a high Top-1 accuracy rate exceeding 93%. This robust performance substantiates the efficacy of the implemented methodology for rapid and precise oolong tea classification. The study elucidates that the integration of computer vision with machine learning algorithms constitutes a promising, non-invasive approach for the quick and accurate categorization of oolong tea varieties. The findings have significant ramifications for process monitoring, quality assurance, authenticity validation and adulteration detection within the tea industry. © 2023 Society of Chemical Industry.

Effects of pile-fermentation on the aroma quality of dark tea from a single large-leaf tea variety by GC × GC-QTOFMS and electronic nose

Aroma is one of the significant quality factors of dark tea (DT). However, for a single large-leaf tea variety, there are few studies analyzing the effect of pile-fermentation on the aroma quality of DT. The GC × GC-QTOFMS, electronic nose (E-nose) and GC-olfactometry (GC-O) techniques were employed to analysis the difference of tea products before and after pile-fermentation. A total of 149 volatile metabolites (VMs) were identified, with 92 VMs exhibiting differential characteristics. Among these, 31 VMs with OAV > 1.0 were found to be correlated with E-nose results (|r| > 0.8). Additionally, GC-O analysis validated seven major differential metabolites. Notably, naphthalene, 2-methylnaphthalene, and dibenzofuran were found to enhance the woody aroma, while (Z)-4-heptenal, 2-nonenal and 1-hexanol were associated with an increase in mushroom, fatty and sweet odors, respectively. Moreover, 1-octen-3-ol was linked to reducing pungent fishy smell. These findings could provide a certain theoretical basis for understanding the influence of pile-fermentation on the aroma quality of dark tea.

Adaptability of Toxoptera aurantii (Hemiptera: Aphididae) to Different Tea Cultivars

The adaptability of phytophagous insects to different host plants is a key determinant of their population propagation. Understanding the feeding behaviour and population dynamics of insects is crucial for elucidating host adaptability and screening for insect-resistant germplasms. Here, we investigated Toxoptera aurantii (Hemiptera: Aphididae) adaptability using electropenetrography and assessed its population growth on seven tea cultivars: Huangjinya (HJY), Qianmei601 (QM601), Fudingdabaicha (FD), Longjing43 (LJ43), Qiancha1 (QC1), Qiancha8 (QC8) and Qiancha10 (QC10). The results showed that the feeding behaviour of T. aurantii differed significantly depending on the tea cultivars. The initial probing of T. aurantii on HJY was the earliest among the seven host plants. Aphids on QC1 and QC10 displayed an increased duration of stylet probing and decreased ingestion of phloem sap, whereas a contrasting trend was observed for aphids on HJY. In addition, the mechanical resistance of T. aurantii fed on HJY and QM601 during the probing phase was significantly lower than that of aphids fed on other cultivars. Population dynamic parameters revealed that the growth rate of T. aurantii reared on HJY was the fastest, and its population quantity within 15 days was markedly higher than that of aphids fed on other cultivars. These findings demonstrate that HJY is the most suitable host plant, whereas QC1 and QC10 are less suitable hosts for T. aurantii, although the aphids successfully survived on all the selected tea cultivars. Our results provide valuable information for the biological control of T. aurantii using resistant tea varieties.

A systemic review on Liubao tea: A time-honored dark tea with distinctive raw materials, process techniques, chemical profiles, and biological activities.

Liubao tea (LBT) is a unique microbial-fermented tea that boasts a long consumption history spanning 1500 years. Through a specific post-fermentation process, LBT crafted from local tea cultivars in Liubao town Guangxi acquires four distinct traits, namely, vibrant redness, thickness, aging aroma, and purity. The intricate transformations that occur during post-fermentation involve oxidation, degradation, methylation, glycosylation, and so forth, laying the substance foundation for the distinctive sensory traits. Additionally, LBT contains multitudinous bioactive compounds, such as ellagic acid, catechins, polysaccharides, and theabrownins, which contributes to the diverse modulation abilities on oxidative stress, metabolic syndromes, organic damage, and microbiota flora. However, research on LBT is currently scattered, and there is an urgent need for a systematical recapitulation of the manufacturing process, the dominant microorganisms during fermentation, the dynamic chemical alterations, the sensory traits, and the underlying health benefits. In this review, current research progresses on the peculiar tea varieties, the traditional and modern process technologies, the substance basis of sensory traits, and the latent bioactivities of LBT were comprehensively summarized. Furthermore, the present challenges and deficiencies that hinder the development of LBT, and the possible orientations and future perspectives were thoroughly discussed. By far, the productivity and quality of LBT remain restricted due to the reliance on labor and experience, as well as the incomplete understanding of the intricate interactions and underlying mechanisms involved in processing, organoleptic quality, and bioactivities. Consequently, further research is urgently warranted to address these gaps.

Ultrasound-Assisted Extraction as a Technique for Preparing Improved Infusions as Functional Beverage Bases

Right after water, tea is one of the most popular beverages in the world. The composition of a tea drink is determined by, among other things: the degree of fermentation and the fineness of the tea leaves, as well as the brewing time and temperature. The purpose of this study was to verify the hypothesis that the extraction of selected elements from dried tea during infusion preparation was improved by using ultrasound under laboratory conditions. The effect of increasing the extraction time was also analyzed. The effectiveness of ultrasound was evaluated by measuring the content of selected elements in the extract of teas that were treated with ultrasound compared to a control group. The effectiveness of the application of ultrasound was evaluated by measuring the content of individual elements at intervals of 1 min, 5 min and 10 min comparing the application of ultrasound with the classical technique of tea brewing. In addition, the results were related to measurements of the amounts of overall concentrations of selected ions after the dried tea mineralization procedure. Samples of extracts and mineralizates were analyzed for elemental composition using an ICP-OES iCAP Dual 6500 Thermo® spectrometer. The use of ultrasound was shown to have a positive effect on the extraction process, and the efficiency of the process depended on the tea variety and the extraction time. The percentage of extraction relative to the results of the total amount of extracted ions was also calculated. Analyzing the effect of ultrasound on the leaching of minerals from tea leaves during infusion preparation is another step toward optimizing the tea brewing extraction process and a way to improve the nutritional value of tea infusions as a functional beverage base. The application of ultrasound in the extraction process of tea infusions may be a good solution to support traditional methods of extracting infusions for both research and technological purposes.

Widely targeted metabolomics reveals the effect of different raw materials and drying methods on the quality of instant tea.

Instant teas are particularly rich in tea polyphenols and caffeine and have great potential as food ingredients or additives to improve the quality of food and enhance their nutritional and commercial value. To determine the relationships between raw material, drying method, and sensory and other quality attributes, instant teas were prepared from three tea varieties, namely black, green and jasmine tea, using two drying methods, namely spray-drying (SD) and freeze-drying (FD). Both the raw tea material and drying method influenced the quality of the finished instant teas. Black tea was quality stable under two drying, while green tea taste deteriorated much after SD. Jasmine tea must be produced from FD due to huge aroma deterioration after SD. FD produced instant tea with higher sensory quality, which was attributed to the lower processing temperature. Chemical compositional analysis and widely targeted metabolomics revealed that SD caused greater degradation of tea biochemical components. The flavonoids content changed markedly after drying, and metabolomics, combined with OPLS-DA, was able to differentiate the three varieties of tea. Instant tea preparations via SD often lost a large proportion of the original tea aroma compounds, but FD minimized the loss of floral and fruity aroma compounds. Changes in the tea flavonoids composition, especially during drying, contributed to the flavor development of instant tea. These results will provide an practicle method for high-quality instant tea production through choosing proper raw tea material and lowering down drying temperature with non-thermal technologies like FD.

INFLUENCE OF STEVIA PRODUCTS ON BIOCHEMICAL AND ORGANOLEPTIC PROPERTIES OF TEA, COFFEE AND HERBAL DRINKS

The need for natural antioxidants and phenolics additives is constantly growing, there are a number of aspects that need to be studied before the introduction of technology into production. Therefore, in presented work was studied the antioxidant properties of Stevia products that exist on the European market with comparison them to extracts of in vitro cultures of Stevia plants. The highest antioxidant activity was observed in leaf crops (89%) of in vitro cultures of Stevia rebaudiana which further were selected as components for the development of beverages based on tea, herbs and coffee with improved organoleptic properties. It was estimated that antioxidant activity in different varieties of tea, herbal drinks and coffee was lower compared to the same kinds plus 10% S. rebaudiana leaf culture extracts to be added to beverages. The profile of phenolic compounds in Stevia, tea and coffee consists of a wide range of compounds of phenolic nature, which includes phenolic acids, anthocyanins, flavonoids, catechins but shown different composition. Organoleptic evaluation of beverages (black, green, aronia, hibiscus, chamomile, mint, mate teas, yoga-tea, lapacho, Coffea arabica) and its change under the influence of Stevia additives has been presented.

Brewing Health Benefits: A Comparative Study Of Black, Herbal, And Green Tea On Rat Physiology

This study compared the physiological effects of black, herbal, and green tea in rats to determine prospective health advantages. Animals were divided into eight groups of six male rats each. In the morning and evening, the negative control group was intubated with 1ml of distilled water, with rat chow and water. The remaining six groups got each type of tea (black, herbal, and green) in the morning and evening for 14 days while physiological data were recorded. Green tea showed the most significant lipid profile and liver function improvement among the three tea varieties. The findings imply that all three tea varieties may have health advantages, particularly in enhancing liver health and lipid profiles. The highest impacts on lipid profile and body weight reduction were specifically shown with green tea.

Compositions and Antioxidant Activity of Tea Polysaccharides Extracted from Different Tea (Camellia sinensis L.) Varieties.

Tea polysaccharide (TPS) is a bioactive compound extracted from tea. It has raised great interest among researchers due to its bioactivity. However, few studies focused on the diversity of TPS in its compositions and antioxidant activity. This study collected 140 different tea varieties from four tea germplasm gardens in China, and their TPSs in tea shoots were extracted. The extraction efficiency, composition contents, including neutral sugar, uronic acid, protein, and tea polyphenols, and the scavenging abilities of hydroxyl radical (·OH) and superoxide radical (O2-·) of 140 TPSs were determined and analyzed. The results showed significant differences in the compositions and antioxidant activities of TPS extracted from different tea varieties. By applying hierarchical clustering analysis (HCA), we selected nine tea varieties with high TPS extraction efficiency and 26 kinds of TPS with high antioxidant capacity.

Differential Effects of Organic Inputs on Soil Fertility and Growth of Tea Plants

The objective of the experiment was to evaluate how newly planted biclonal Tocklai stock tea varieties (TS 462, TS 463, TS 520, and TS 589) respond to compost in a series of treatment including control (without application), cow dung, vermicompost, municipal solid waste compost, and homemade kitchen waste compost applications. A total of 20 tea plants (5 plants of each tea variety) were planted in plastic buckets of equal size (16 litres). 300 gm. of compost was applied to each plant continuously at an interval of 25 to 30 days for the initial six months, and then compost application was discontinued for the next six months. Data were collected before, during, and after compost application. The highest growth in plant height (11cm to 51 cm), number of leaves (33 to 95), and number of branches (8 to 15) were recorded in the tea plants of the TS 463 variety. The pH of soil samples was found in the range of 4.72 to 6.61. The pH level of the acidic soil was slightly increased by the compost application. The average SOM% ranged from 6.88% to 11.94%, and it was found that a good SOM% was supportive of the good growth of the tea crop. N% was found between 0.85% and 0.217%, and P levels were found between 18 ppm and 50 ppm. The suitable N% and P levels affect plant growth most significantly in terms of the number of leaves and the number of stems. SOM% was found to be highest in vermicompost-treated soil, N% and P levels were optimal in home-made kitchen waste compost, and K levels were highest in cow dung-treated soil. Therefore, it can be concluded that an integrated compost application can be recommended for ideal growth and good plant health status for sustainable tea production.

Genomic analysis of Colletotrichum camelliae responsible for tea brown blight disease

BackgroundColletotrichum camelliae, one of the most important phytopathogenic fungi infecting tea plants (Camellia sinensis), causes brown blight disease resulting in significant economic losses in yield of some sensitive cultivated tea varieties. To better understand its phytopathogenic mechanism, the genetic information is worth being resolved.ResultsHere, a high-quality genomic sequence of C. camelliae (strain LT-3-1) was sequenced using PacBio RSII sequencing platform, one of the most advanced Three-generation sequencing platforms and assembled. The result showed that the fungal genomic sequence is 67.74 Mb in size (with the N50 contig 5.6 Mb in size) containing 14,849 putative genes, of which about 95.27% were annotated. The data revealed a large class of genomic clusters potentially related to fungal pathogenicity. Based on the Pathogen Host Interactions database, a total of 1698 genes (11.44% of the total ones) were annotated, containing 541 genes related to plant cell wall hydrolases which is remarkably higher than those of most species of Colletotrichum and others considered to be hemibiotrophic and necrotrophic fungi. It’s likely that the increase in cell wall-degrading enzymes reflects a crucial adaptive characteristic for infecting tea plants.ConclusionConsidering that C. camelliae has a specific host range and unique morphological and biological traits that distinguish it from other species of the genus Colletotrichum, characterization of the fungal genome will improve our understanding of the fungus and its phytopathogenic mechanism as well.

Prediction of Tea Varieties’ “Suitable for People” Relationship: Based on the InteractE-SE+GCN Model

This study proposes an improved link prediction model for predicting the “suitable for people” relationship within the knowledge graph of tea. The relationships between various types of tea and suitable target groups have yet to be fully explored, and the existing InteractE model still does not adequately capture a portion of the complex information around the interactions between entities and relationships. In this study, we integrate SENet into the feature layer of the InteractE model to enhance the capturing of helpful information in the feature channels. Additionally, the GCN layer is employed as the encoder, and the SENet-integrated InteractE model is used as the decoder to further capture the neighbour node information in the knowledge graph. Furthermore, our proposed improved model demonstrates significant improvements compared to several standard models, including the original model from public datasets (WN18RR, Kinship). Finally, we construct a tea dataset comprising 6698 records, including 330 types of tea and 29 relationship types. We predict the “suitable for people” relationship in the tea dataset through transfer learning. When comparing our model with the original model, we observed an improvement of 1.4% in H@10 for the WN18RR dataset, a 7.6% improvement in H@1 for the Kinship dataset, and a 5.2% improvement in MRR. Regarding the tea dataset, we achieved a 4.1% increase in H@3 and a 2.5% increase in H@10. This study will help to fully exploit the value potential of tea varieties and provide a reference for studies assessing healthy tea drinking.

Molecular mechanism of lycopene cyclases regulating carotenoids ratio in different branches during tea leaf and flower development

Carotenoids are essential components in tea quality, contributing to leaf color and aroma. However, little information about carotenoids in different tea cultivars and their biosynthesis regulation mechanism during leaf development is known. Here we analyzed carotenoids by HPLC in the buds and leaves of 113 tea cultivars harvested on the same day. By profile clustering, carotenoids were divided into five groups. Same group cultivars displayed divergence in the total content of carotenoids but a similar molar ratio. To figure out the molecular mechanisms of this phenomenon, we further characterized all functional lycopene cyclases, which are the branch point of the carotenoid biosynthesis pathway. Two β-lycopene cyclases (CsLCYB1 and CsLCYB2) and one ε-lycopene cyclase (CsLCYE1) were cloned. Subcellular localization analysis showed that all cloned CsLCYs were localized in plastids. Enzyme activity assays in E. coli indicated both CsLCYBs catalyzed lycopene into β-carotene, and CsLCYE1 produced δ-carotene and ε-carotene. We found CsLCYB1 and CsLCYE1 predominantly expressed in leaf, while CsLCYB2 was mainly expressed during flowering stages. Suppression by antisense oligonucleotides reduced CsLCYB1 and CsLCYE1 transcripts and led to reduction of both β,β-branch and β,ε-branch carotenoids in leaf. The expression levels of CsLCYB1 showed a significant positive correlation with β,β-branch carotenoids in leaf. Our study provides carotenoid profiles of different tea cultivars, which can assist tea producers in selecting cultivars of interest. Meanwhile, we proposed the molecular mechanism of carotenoids reflecting the tenderness of tea plant leaf from a metabolic flux perspective, and suggested lycopene cyclase that could be applied to the breeding of tea varieties with different branch carotenoids.

Chemical Analysis of Various Tea Samples Concerning Volatile Compounds, Fatty Acids, Minerals and Assessment of Their Thermal Behavior.

Tea is the most consumed drink worldwide due to its pleasant taste and various beneficial effects on human health. This paper assesses the physicochemical analysis of different varieties of tea (leaves, flowers, and instant) after prior drying and fine grinding. The thermal decomposition behavior of the tea components shows that the tea has three stages of decomposition, depending on temperature. The first stage was attributed to the volatilization of water, while the second stage involved the degradation of volatiles, polyphenols, and fatty acids. The degradation of cellulose, hemicellulose, and lignin content occurs at the highest temperature of 400 °C in the third stage. A total of 66 volatile compounds, divided into eight classes, were identified in the tea samples. The volatile compounds were classified into nine odor classes: floral, fruity, green, sweet, chemical, woody, citrus, roasted, and alcohol. In all flower and leaf tea samples, monounsaturated (MUFAs), polyunsaturated (PUFAs), and saturated fatty acids (SFAs) were identified. A high content of omega-6 was quantified in acacia, Saint John's Wort, rose, and yarrow, while omega-3 was found in mint, Saint John's Wort, green, blueberry, and lavender samples. The flower and leaf tea samples studied could be a good dietary source of polyphenolic compounds, essential elements. In instant tea samples, a low quantity of polyphenols and major elements were identified. The physicochemical analysis demonstrated that both flower and leaf teas have high-quality properties when compared to instant tea.

Tea's anti-obesity properties, cardiometabolic health-promoting potentials, bioactive compounds, and adverse effects: A review focusing on white and green teas.

Tea is one of the most commonly consumed beverages in the world. Morocco, Japan, and China have consumed green tea for centuries. White tea, which is a variety of green teas, is very popular in China and is highly revered for its taste. Presently, both teas are consumed in other countries around the world, even as functional ingredients, and novel research is constantly being conducted in these areas. We provide an update on the health benefits of white and green teas in this review, based on recent research done to present. After a general introduction, we focused on tea's anti-obesity and human health-promoting potential, adverse effects, and new approaches to tea and its bioactive compounds. It has been found that the health benefits of tea are due to its bioactive components, mainly phenolic compounds. Of these, catechins are the most abundant. This beverage (or its extracts) has potential anti-inflammatory and antioxidant properties, which could contribute to body weight control and the improvement of several chronic diseases. However, some studies have mentioned the possibility of toxic effects; therefore, reducing tea consumption is a good idea, especially during the last trimester of pregnancy. Additionally, new evidence will provide insight into the possible effects of tea on the human gut microbiota, and even on the viruses responsible for SARS-CoV-2. A beverage such as this may favor beneficial gut microbes, which may have important implications due to the influence of gut microbiota on human health.

The arginine decarboxylase gene CsADC1, associated with the polyamine pathway, plays an important role in tea cold tolerance

Arginine decarboxylase (ADC) is an important enzyme responsible for polyamine (PA) synthesis in plants. In our study, 5 tea varieties were used to investigate the relationship between ADC and cold tolerance in field experiments. A strong and positive correlation was found between cold stress-regulated expression levels of CsADC1 and arginine (Arg) content (R2 > 0.75) in tea mesophyll cells and cold tolerance in 5 tea varieties. An exogenous supply of Arg significantly enhanced cold tolerance. To further clarify the location of CsADC1, the full-length cDNA of the CsADC1 gene was cloned and located in the cell nucleus. Moreover, cold stress significantly promoted the production of MDA in CsADC1-silenced leaves compared with WT plants, which exhibited poor cold tolerance. In contrast, under cold conditions, higher Fv/Fm and lower MDA were detected in CsADC1-overexpressing Arabidopsis than in the WT plants. Furthermore, CsADC1-silenced leaves inhibited the expression levels of the PA metabolism genes CsAIH, CsCPA, CsSPDS, CsSPMS1 and CsSPMS2 under cold stress; thus, significantly lower (p < 0.05) putrescine (Put), spermidine (Spd) and spermine (Spm) content was d etected in CsADC1-silenced tea leaves under cold stress. Taken together, our results indicated that CsADC1, as a positive regulator, played an important role in cold tolerance, which may be due to modulation of polyamine pathways in the cold stress response.