Content Of Tea Polyphenols Research Articles

Different Treatments on the Physicochemical Properties and Volatile Components of Tea Wine During Storage Period

Tea wine has garnered significant attention due to its unique fusion of tea and wine flavors, as well as its alleged health benefits. This study aimed to investigate the effects of various treatments on the physicochemical properties of tea wine, including viable cell counts, pH, acidity, total ester content, tea polyphenol content, and volatile flavoring substances during the storage period. The findings indicated that tea wine subjected to low-temperature plasma (LTPS) treatment exhibited superior quality maintenance and an enhanced tea polyphenol content compared to untreated, UV-treated, and HTHP-treated tea wine. Analysis of volatile compounds revealed that the LTPS group exhibited the highest relative content of alcohols and esters (89.72%) during storage, thereby enhancing the fruity and sweet aroma of the tea wine. This study provides a theoretical basis for the application of low-temperature plasma technology in the storage of tea wine.

Development of antioxidant arabinoxylan-tea polyphenol composite films for enhanced preservation of fresh grapes

In this study, arabinoxylan (AX) was used as a substrate, and tea polyphenol (TP) as a functional additive to create degradable, non-polluting, and antioxidant packaging materials. The effects of different TP concentrations on light transmittance and antioxidant activity of the AX-TP composite films were analyzed. The colors of the films gradually deepened with increasing TP content. The maximum scavenging rate of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals using the AX-TP composite film solution of 59.13 ± 2.19 % was achieved at the TP concentration of 2.0 %. AX-TP composite films with different TP concentrations were applied to the surfaces of grapes, and the sensory quality, shriveling and decay rates, titratable acid, and weight loss rate of grapes during storage were evaluated using data from different experimental groups. The AX-TP composite films coated on grapes reduced the transpiration of water in the fruit and delayed grape spoilage, demonstrating an excellent preservation effect. These results show that AX-TP composite films increase the shelf life of fresh grapes.

Simple Sequence Repeat Marker-Based Genetic Diversity and Chemical Composition Analysis of Ancient Camellia sinensis in Jiulong County, Sichuan Province, China.

The ancient tea plant germplasm resources are rich in genetic diversity and provide an important basis for the genetic diversity in tea germplasm resources. To explore the genetic diversity of ancient tea plant germplasm resources in Jiulong County, Sichuan Province. 59 ancient tea tree germplasm resources were analyzed using simple sequence repeat (SSR) molecular markers and chemical composition analysis. The results showed that a total of 83 alleles were amplified by 23 pairs of SSR primers, with an average observed allele number (Na) of 3.6 and an effective allele number (Ne) of 2.335. The average Shannon information index (I) and the polymorphic information content (PIC) of the primers were 0.896 and 0.446, respectively. The results of the UPGMA cluster analysis showed that 59 ancient tea tree samples could be classified into five different subgroups. Based on the results of chemical composition analysis, two specific tea germplasm resources with high amino acid content, 10 excellent germplasm resources with tea polyphenol content over 20% and some other tea germplasm resources were identified. This study reveals that Jiulong's ancient tea tree germplasm exhibits significant genetic diversity and includes valuable tea tree planting resources. These findings provide a foundational framework for the conservation, detailed exploration and sustainable utilization of these resources.

Non-Destructive Detection of Tea Polyphenols in Fu Brick Tea Based on Hyperspectral Imaging and Improved PKO-SVR Method

Tea polyphenols (TPs) are a critical indicator for evaluating the quality of tea leaves and are esteemed for their beneficial effects. The non-destructive detection of this component is essential for enhancing precise control in tea production and improving product quality. This study developed an enhanced PKO-SVR (support vector regression based on the Pied Kingfisher Optimization Algorithm) model for rapidly and accurately detecting tea polyphenol content in Fu brick tea using hyperspectral reflectance data. During this experiment, chemical analysis determined the tea polyphenol content, while hyperspectral imaging captured the spectral data. Data preprocessing techniques were applied to reduce noise interference and improve the prediction model. Additionally, several other models, including K-nearest neighbor (KNN) regression, neural network regression (BP), support vector regression based on the sparrow algorithm (SSA-SVR), and support vector regression based on particle swarm optimization (PSO-SVR), were established for comparison. The experiment results demonstrated that the improved PKO-SVR model excelled in predicting the polyphenol content of Fu brick tea (R2 = 0.9152, RMSE = 0.5876, RPD = 3.4345 for the test set) and also exhibited a faster convergence rate. Therefore, the hyperspectral data combined with the PKO-SVR algorithm presented in this study proved effective for evaluating Fu brick tea’s polyphenol content.

Arbuscular mycorrhizal fungi enhance nitrogen assimilation and drought adaptability in tea plants by promoting amino acid accumulation.

The development and quality of tea plants (Camellia sinensis (L.) O. Ktze.) are greatly hampered by drought stress (DS), which affects them in a number of ways, including by interfering with their metabolism of nitrogen (N). Arbuscular mycorrhizal fungi (AMF) are known to enhance water and nutrient absorption in plants, but their specific effects on tea plant N metabolism under DS and the associated regulatory mechanisms remain unclear. This study aimed to evaluate the impact of Claroideoglomus etunicatum inoculation on N assimilation in tea plants (C. sinensis cv. Fuding Dabaicha) under well-watered (WW) and DS conditions, and to explore potential molecular mechanisms. After 8 weeks of DS treatment, root mycorrhizal colonization was significantly inhibited, and the biomass of tea shoots and roots, as well as the contents of various amino acids (AAs) were reduced. However, AMF inoculation significantly increased the contents of tea polyphenols and catechins in leaves by 13.74%-36.90% under both WW and DS conditions. Additionally, mycorrhizal colonization notably increased N content by 12.65%-35.70%, various AAs by 11.88%-325.42%, and enzymatic activities associated with N metabolism by 3.80%-147.62% in both leaves and roots. Gene expression analysis revealed a universal upregulation of N assimilation-related genes (CsAMT1;2, CsAMT3;1, CsGS1, CsNADH-GOGAT, CsTS2, CsGGT1, and CsADC) in AMF-colonized tea roots, regardless of water status. Under DS condition, AMF inoculation significantly upregulated the expressions of CsNRT1;2, CsNRT1;5, CsNRT2;5, CsNR, CsGS1, CsGDH1, CsGDH2, CsTS2, CsGGT1, CsGGT3, and CsSAMDC in tea leaves. These findings suggest that AMF improved tea plant adaptability to DS by enhancing N absorption and assimilation, accompanied by the synthesis and accumulation of various AAs, such as Glu, Gln, Asp, Lys, Arg, GABA and Pro. This is achieved through the upregulation of N metabolism-related genes and the activation of related enzymes in tea plants under DS condition. These findings provide valuable insights into the role of AMF in regulating tea plant N metabolism and enhancing stress tolerance.

Microbial diversity across tea varieties and ecological niches: correlating tea polyphenol contents with stress resistance.

Microorganisms exhibit intricate interconnections with tea plants; however, despite the well-established role of microorganisms in crop growth and development, research on microbes within the tea plant remains insufficient, particularly regarding endophytic microorganisms. In this study, we collected samples of leaves and rhizosphere soils from 'Zhuyeqi', 'Baojing Huangjincha#1', 'Baiye#1', and 'Jinxuan' varieties planted. Our analyses revealed significant variations in tea polyphenol contents among tea varieties, particularly with the 'Zhuyeqi' variety exhibiting higher levels of tea polyphenols (>20% contents). Microbiome studies have revealed that endophytic microbial community in tea plants exhibited higher host specificity compared to rhizospheric microbial community. Analyses of across-ecological niches of the microbial community associated with tea plants revealed that soil bacteria serve as a significant reservoir for endophytic bacteria in tea plants, Bacillus may play a crucial role in shaping the bacterial community across-ecological niche within the tea plants with higher tea polyphenol levels. In the aforementioned analyses, the microbial community of 'Zhuyeqi' exhibited a higher degree of host specificity for leaf endophytic microorganisms, the topological structure of the co-occurrence network is also more intricate, harboring a greater number of potential core microorganisms within its nodes. A closer examination was conducted on the microbial community of 'Zhuyeqi', further analyses of its endophytic bacteria indicated that its endophytic microbial community harbored a greater abundance of biomarkers, particularly among bacteria, and the enriched Methylobacterium and Sphingomonas in 'Zhuyeqi' may play distinct roles in disease resistance and drought resilience in tea plants. In summary, this study has shed light on the intricate relationships of tea plant varieties with their associated microbial communities, unveiling the importance of microorganisms and tea varieties with higher tea polyphenols, and offering valuable insights to the study of microorganisms and tea plants.

Effect of Drying Method and Temperature on the Quality of Cascara Tea

This study aims to determine the effect of the drying method and optimum temperature on the quality of coffee skin tea (cascara). This research was conducted at the Laboratory of Food Processing Technology and Agricultural Products, Department of Agricultural Products Technology, Faculty of Agriculture, Santo Thomas Catholic University, Medan. This research was conducted in March 2023 until completion. This research was conducted using a completely randomized design (CRD), which consisted of 2 factors. The first factor is the drying method (P), namely L : P1 = 4 hours, P2 = 6 hours, P3 = 8 hours and P4 = 10 hours. The second factor is the effect of drying temperature on the quality of tea from coffee skin (T), namely: T1 = 40°C, T2 = 50°C, T3 = 60°C and T4 = 70°C. The results showed that the drying method had a very significant effect (p<0.01) on the yield, water content, polyphenol content, organoleptic value of taste, organoleptic value of aroma and color organoleptic value of cascara tea produced. The longer drying time, the yield and organoleptic value of flavor increase, while the water content, polyphenol content, organoleptic value of aroma and organoleptic value of cascara tea produced decreases. The drying temperature has a very significant effect (p<0.01) on yield, moisture content, polyphenol content, the organoleptic value of taste, the organoleptic value of aroma, and organoleptic value of color. The higher the drying temperature, the higher the yield and taste organoleptic value, while the water content, polyphenol content, aroma organoleptic value and color organoleptic value decreased. The interaction of the drying method and temperature treatment had a significant effect (p<0.015) on the moisture content, polyphenol content, and aroma organoleptic value of cascara tea but had no significant effect (p>0.05) on yield, taste organoleptic value, and color organoleptic value of coffee skin tea (cascara). The best quality of cascara tea was obtained in the treatment combination P1T4.

Mechanisms of single and mixed microbial fermentation to improve summer-autumn green tea

To investigate the effect of individual and collaborative fermentation on summer-autumn green tea (SAGT) quality. Liquid fermentation with individual inoculation of Aspergillus cristatus (ACFT), Aspergillus niger (ANFT) and mixed inoculation of A. cristatus/A. niger (MFT), respectively, with SAGT extracts (CT) as raw materials. The volatile organic compounds (VOCs), characteristic non-volatile compounds and sensory evaluation of tea samples were determined. The results showed a significant decrease in the content of tea polyphenols, carbohydrates and nongalloylated catechins (C, EC) and a significant increase in the amount of VOCs in MFT compared to ANFT and ACFT. The results of metabolic pathway analysis and sensory evaluation showed that ACFT went through the terpene and phenylpropanoic acid metabolic pathway, which produced large amounts of α-terpineol, phenethyl alcohol, and methyl salicylate, which in turn conferred ACFT with distinctly sweet, floral, and herbal aroma. ANFT produces large amounts of linalool oxides I and II, mainly through the linalool oxide metabolic pathway, making ANFT a distinctive aged and woody aroma. MFT may be due to the strong woody aroma of linalool oxides masking other weaker and better aromas, thus giving MFT a significant woody, herbal and stale aroma. This study provides new insights and a theoretical basis for mixed fungal fermentation to improve the quality of SAGT.

Enzymatic quality enhancement of oolong tea based on grade difference analysis

The quality of oolong tea in summer and autumn is generally lower than in spring, resulting in a loss of economic benefits. We found that this was due to the higher tea polyphenol content and lower sugar and amino acid content of summer and autumn oolong teas. Here, we used cellulase, protease and tannase for targeted enzymatic hydrolysis of low-quality teas to reduce the tea polyphenol content while increasing the soluble sugar and amino acid contents. By optimizing the ratio, concentration and treatment temperature of the added enzymes, the soluble sugar and amino acid contents of low- and middle- quality tea were increased by 6%-128% and 12%-88%, respectively. The ester catechin content was reduced by 12% and the total catechin content was reduced by 41%. The aroma of middle- and low-quality tea was transformed into the characteristics of high-quality tea. Therefore, directed enzymatic degradation is a promising technology for tea quality improvement.

Process Optimization and Quality Components Analysis of γ-Aminobutyric Acid Pickled Tea.

Pickled tea is an anaerobically fermented tea common in Thailand, Myanmar and Yunnan minority areas. γ-aminobutyric acid (GABA) is non-protein amino acid with multiple bioactives, which can be easily produced under anaerobic conditions. During the processing of pickled tea, controlling the process parameters is effective for the production of GABA-rich products; however, the precise parameters remain to be clarified. In the present study, the fresh leaves of Camellia sinensis (L.) Kuntze (C. sinensis) 'FudingDabai', C. sinensis 'MabianLv No. 1', C. sinensis 'Wuniuzao' and C. sinensis 'Fuxuan No. 9' were used as raw materials to process GABA-rich pickled tea. Single-factor and orthogonal experiments were conducted to determine the best tea cultivars and optimize the best processing parameters via comparing the content of GABA, tea polyphenols (TPs) and other biochemical components of GABA-rich pickled tea. The results of the signal-factor experiment showed that the fresh leaves of C. sinensis 'MabianLv No. 1' had the highest GABA content of 2.61 mg·g-1 after treatment with vacuum for 6 h; therefore, C. sinensis 'MabianLv No. 1' was selected as the raw material for the subsequent experiments. Orthogonal experiments showed that the highest GABA content of 2.53 mg·g-1 was found in the pickled tea with 8 h of vacuum treatment, 20 min of rolling after microwave fixing, 20 min of spreading and 20 d of anaerobic fermentation at room temperature. Further, the sensory evaluation showed that it possesses a strong sour taste with a slight sweetness and a light yellow color and better comprehensive quality. This indicates that these parameters are optimal for the processing of GABA-rich pickled tea. This study will provide scientific basis for the subsequent production of high GABA tea.

Tea polyphenol reinforced polyacrylamide hydrogel as a regenerative adsorbent for low-concentration methylene blue

To remove the low-concentration methylene blue (MB) residues from liquid waste, we attempt to fabricate a hydrogel with good reusability and good removal efficiency. In this work, polyacrylamide (PAAm) hydrogel initially synthesized through polymerization and subsequently soaked in tea polyphenol (TP) aqueous solution to yield PAAm/TP hydrogels. The hydrogels were detected by Fourier transform infrared spectrometer, scanning electronic microscope, zeta electric potential instrument, full-automation surface area and porosity instrument, swelling degree, and universal testing machine. The results confirmed the successful preparation of PAAm/TP hydrogels with mesoporous structure. Compared to pure PAAm hydrogel, TP-reinforced PAAm hydrogel exhibited good mechanical properties and low swelling degree. Furthermore, PAAm/TP hydrogels were employed as an adsorbent for low-concentration MB owing to low specific surface area and mesoporosity. The effects of adsorption time, TP concentration, hydrogel level, starting MB level, pH value, and inorganic salts on MB adsorption were researched. PAAm/TP hydrogels had higher adsorption efficiency for low-concentration MB than pure PAAm hydrogel. The kinetic data of the PAAm/TP hydrogel coincided with the quasi-second-order model (R2 = 0.9997), and the adsorption rate was mainly governed by internal diffusion. The adsorption process highly followed the Freundlich isotherm model (R2 = 0.9755). Furthermore, the hydrogel demonstrated stability and excellent recyclability. Notably, the removal efficiency remained above 50 % even after five consecutive adsorption-desorption cycles. The mechanism analysis manifested that the MB adsorption was stimulated by electrostatic attraction, hydrogen bonding, and π-π stacking interreactions. Hence, the prepared PAAm/TP hydrogels brought a green and effective method for removing low-concentration MB from wastewater.

Polyphenol content, antioxidant and anti-inflammatory activities of Georgian wine and green Tea

This comprehensive study explores the health-promoting properties of Georgian green tea and red wine, focusing on their antioxidant and anti-inflammatory activities, as well as polyphenol content. Utilizing the DPPH and FRAP methods, we observed impressive results, with green tea showcasing a remarkable FRAP activity of 61.2 % of ascorbic acid activity set as 100 %, surpassing red wine at 18.2 %. Comparative assessments against ascorbic acid for antioxidant activity and Sodium diclofenac for anti-inflammatory effects further underscored green tea's prowess. Intriguingly, green tea exhibited a substantial anti-inflammatory activity of 20 % of Sodium diclofenac also set as 100 %, outshining red wine at 3.7 %. Polyphenol content, a key contributor to health benefits, revealed green tea's concentration at 7.5 % (w/w), red wine's - 4.4 % g/l. These findings highlight the potential of green tea and red wine as a potent source of bioactive compounds with implications for cellular health, inflammation mitigation, and chronic disease prevention. The results prompt a closer look at dietary choices, advocating for the incorporation of green tea to harness its multifaceted health benefits. As we delve into the molecular richness of these beverages, our findings provide valuable insights into the potential therapeutic avenues offered by these popular and culturally significant drinks.

Effects of Gnaphalium affine Extract on the Gel Properties of •OH-Induced Oxidation of Myofibrillar Proteins.

This study aimed to investigate the effect of Gnaphalium affine extract (GAE) (0.04, 0.2 and 1 mg/g protein) on the gel properties of porcine myofibrillar proteins (MPs) in a simulated Fenton oxidation system, using tea polyphenols (TPs) at similar concentrations of 0.04, 0.2, and 1 mg/g protein, respectively, as a contrast. The findings revealed that as the TP concentration increased, the water retention of MP gels decreased significantly (p < 0.05). In contrast, MP gels containing medium and high concentrations of GAE exhibited significantly higher water retention than those with low concentrations of GAE (p < 0.05). When the concentration of GAE was increased to 1 mg/g protein, the strength of MP gels was significantly reduced (p < 0.05) by 33.32% compared with the oxidized control group, suggesting that low and medium GAE concentrations support MP gel formation. A texture profile analysis indicated that an appropriate GAE concentration improved gel structure and texture. Dynamic rheological characterization revealed that low concentrations of TP (0.04 mg/g protein) and low and medium concentrations of GAE (0.04 and 0.2 mg/g protein) strengthened the protein gel system. Conversely, high concentrations of TP and GAE (1.0 mg/g protein) damaged the protein gel system or even promoted the collapse of the gel system. Scanning electron microscopy revealed that higher TP concentrations disrupted the gel, whereas low and medium GAE concentrations maintained a more continuous and complete gel network structure compared with the oxidized control group. This indicates that an appropriate GAE concentration could effectively hinder the destruction of the gel network structure by oxidation. Therefore, based on the obtained results, 0.2 mg/g protein is recommended as the ideal concentration of GAE to be used in actual meat processing to regulate the oxidization and gel properties of meat products.

Fermented or not fermented: a comparative study of the biological activities and microbiomes of a non‐fermented green tea and a five‐year‐old fermented tea prepared from young leaves of Shan tea

SummaryCamellia sinensis var. shan is a special tea variety in Vietnam that is in high demand, especially its fermented products. This study compared the total polyphenol content (TPC), antioxidant activity, cytotoxicity, and microbiome of a green Shan tea and a five‐year‐old fermented Shan tea. Folin–Ciocalteu, DPPH and SRB assays were used for TPC, antioxidant activity and cytotoxicity evaluation. The isolated microbes were morphologically and molecularly identified. The TPC (126.59 mg g−1) and antioxidant activity (IC50 of 284.82 μg mL−1) of the green tea were significantly higher than those of the fermented tea. However, the latter showed a significantly higher cytotoxicity against liver cancer cells (inhibiting 73.84% cells at 1 mg mL−1). Notably, the green tea had a negligible number of microbes, but the fermented tea had a much richer microbiome with Aspergillus restrictus (4.7 × 104 CFU g−1), A. ruber (1.76 × 103 CFU g−1), A. pseudoglaucus (1.32 × 103 CFU g−1), A. cibarius (8.8 × 102 CFU g−1), Bacillus cereus (1.13 × 104 CFU g−1), Peribacillus frigoritolerans (4.0 × 102 CFU g−1) and B. amyloliquefaciens (2.0 × 102 CFU g−1) present. These microbes are either harmless or beneficial, except for B. cereus (can cause food poisoning at &gt;106 CFU g−1). The fermented tea would appear to have some advantages over the green tea. However, the presence and density of B. cereus should be monitored.

Changes and dynamics of the main quality components in tea leaves of 4 tea cultivars during the shading process

The purpose of this study was to analyze the relationship between different shading conditions, picking time for main quality components of tea. The main quality components of 4 tea cultivars [Camellia sinensis (L.) O. Kuntze], including the separated tea shoot tissues (leaves, buds, stems), under 4 shading rates during the traditional 20-day shading period were examined. Results showed the Chlorophyll contents after 12 days of shading treatment were significantly higher than control, but after that it ceased increasing significantly Initially, the theanine, total free amino acid, caffeine, and tea polyphenol contents showed decreased trend but then leveled off after 12 days. The increase of free amino acids, caffeine, chlorophyll and the decrease of tea polyphenols induced by shading were mainly determined by shading level and tenderness. Meanwhile, shading changed the proportion of main quality components in tea leaves and stems, long-term shading does not promote high quality matcha. All of the results indicated the quality of matcha with grade 1 could be produced by shading rate of 80 % and shading for 12 days. Appropriate shading time and shading rate are beneficial to improve the quality of Matcha.

Chitosan/zein-based sustained-release composite films: Fabrication, physicochemical properties and release kinetics of tea polyphenols from polymer matrix

This study investigated the properties of chitosan/zein/tea polyphenols (C/Z/T) films and analyzed the release kinetics of tea polyphenols (TP) in various food simulants to enhance the sustainability and functionality of food packaging. The results revealed that TP addition enhanced the hydrophilicity, opacity and mechanical properties of film, and improved the compatibility between film matrix. 1.5 % TP film showed the lowest lightness (76.4) and the highest chroma (29.1), while 2 % TP film had the highest hue angle (1.5). However, the excessive TP (above 1 % concentration) led to a decrease in compatibility and mechanical properties of film. The TP concentration (2 %) resulted in the highest swelling degree in aqueous (750.6 %), alcoholic (451.1 %), and fatty (6.4 %) food simulants. The cumulative release of TP decreased to 16.32 %, 47.13 %, and 5.87 % with the increase of TP load in the aqueous, alcoholic, and fatty food simulants, respectively. The Peleg model best described TP release kinetics. The 2 % TP-loaded film showed the highest DPPH (97.13 %) and ABTS (97.86 %) free radical scavenging activity. The results showed TP release influenced by many factors and obeyed Fick's law of diffusion. This study offered valuable insights and theoretical support for the practical application of active films.

Chemical composition and discrimination with volatile profiles of Yongchuan Xiuya green tea with different baking treatments

AbstractThis study aimed to explore the effects of different baking treatments on the quality of Yongchuan Xiuya (YCXY) green tea. It was found that a long time baking at low temperature was beneficial to keep green colour, faint scent, mellow and fresh taste quality, whereas baking under high temperature was adverse to the quality. Baking treatments slightly regulated (−)‐epigallocatechin, (−)‐epicatechin, (−)‐gallocatechin gallate, total chlorophyll and carotenoid. As the baking temperature rose, the content of tea polyphenols, gallic acid, catechins, caffeine, soluble sugar and polyphenols/amino acids ratio obviously decreased. A total of 40 kinds of volatiles were detected in these six tea samples. A model for aroma type discrimination was successfully established based on partial least squares‐discriminant analysis (PLS‐DA). Ten kinds of volatile substances were the key characteristic markers for the faint scent, chestnut aroma and high‐fired aroma types of YCXY green tea. 1‐hexanol, hotrienol and dimethyl sulfide were furtherly used to discriminant aroma type based on Fisher discriminant analysis (FDA).

Effects of the Taste Substances and Metal Cations in Green Tea Infusion on the Turbidity of EGCG-Mucin Mixtures.

Astringency has an important impact on the taste quality of tea infusion, a process which occurs when polyphenols complex with salivary proteins to form an impermeable membrane. (-)-Epigallocatechin gallate (EGCG) is the main astringent compound found in green tea and mucin is the main protein present in saliva. Determining the turbidity of EGCG-mucin mixtures is an effective method to quantify the astringency intensity of EGCG solutions. In this study, the effects of taste-related, substances present during green tea infusion, on the turbidity of EGCG-mucin mixtures was investigated under the reacting conditions of a pH value of 5.0, at 37 °C, and for 30 min. The results showed that epicatechins, caffeic acid, chlorogenic acid, and gallic acid reduced the turbidity of EGCG-mucin mixtures, while rutin increased turbidity. Metal ions increased the turbidity of EGCG-mucin mixtures. These can be arranged by effectiveness as Al3+ > K+ > Mg2+ > Ca2+. Caffeine, theanine, and sodium glutamate all decreased the turbidity values of EGCG-mucin mixtures, but sucrose had a weak effect. Further experiments confirmed that the turbidity of green tea infusion-mucin mixture indicated the astringent intensity of green tea infusion, and that the turbidity was significantly correlated with the contents of tea polyphenols and EGCG.

Assessing the stability of polyphenol content in red rooibos herbal tea using traditional methods and high-resolution mass spectrometry: Implications for studying dietary interventions in preclinical rodent studies

Preclinical rodent models are used to examine the relationship between tea consumption and bone health, where tea is available for rodents and typically replaced weekly. However, the extent to which the tea polyphenols change over time remains uncertain, despite its importance in preparing tea during preclinical rodent trials. Using an untargeted molecular approach, we applied a liquid chromatography quadrupole-time-of-flight mass spectrometry (LC-QTOFMS) system to assess the molecular profile of red rooibos teas throughout a 6-day aging period. We found a significant, 3-fold decrease of polyphenols involved in bone metabolism, including m-coumaric acid, catechin derivatives and courmaroyl tartaric acid over 6 days, likely due to photochemical decomposition and autooxidation within tea extracts. Using a novel untargeted workflow for polyphenol characterization, our findings revealed the complexity of polyphenols in red rooibos teas that can inform the evidence-based decisions of how often to change teas during in vivo rodent trials.

Novel Synthesis Approach for Natural Tea Polyphenol-Integrated Hydroxyapatite.

Hydroxyapatite (HAP) has garnered considerable interest in biomedical engineering for its diverse applications. Yet, the synthesis of HAP integrated with functional natural organic components remains an area ripe for exploration. This study innovatively utilizes the versatile properties of tea polyphenol (TP) to synthesize HAP nanomaterials with superior crystallinity and distinct morphologies, notably rod-like structures, via a chemical deposition process in a nitrogen atmosphere. This method ensures an enhanced integration of TP, as confirmed by thermogravimetric (TGA) analysis and a variety of microscopy techniques, which also reveal the dependence of TP content and crystallinity on the synthesis method employed. The research significantly impacts the field by demonstrating how synthesis conditions can alter material properties. It leads the way in employing TP-modified nano-HAP particles for biomedical applications. The findings of this study are crucial as they open avenues for the future development of tailored HAP nanomaterials, aiming at specific medical applications and advancements in nanotechnology.