Tea Caffeine Research Articles

Variation of catechin and caffeine content in exotic collection of tea [Camellia sinensis (L.) O. Kuntze] in Sri Lanka and potential implication in breeding cultivars with enhanced quality and medicinal properties

Tea leaves are rich in diverse metabolites with medicinal importance. The quality of made tea is largely depended on the qualitative and quantitative attributes of key metabolites. The aim of the present study was to quantify flavan-3-ols and caffeine of exotic tea germplam and explore the medicinal properties. Fresh leaf flavan-3-ols; catechin, epicatechin (EC), epicatechin gallate (ECg), epigallocatechin (EGC) and epigallocatechin gallate (EGCg), caffeine and gallic acid of 131 accessions (87 exotic and 44 improved cultivars) were performed by High Performance Liquid Chromatography. Variations in metabolites among cultivars as well as between seasons were determined. Among the flavan-3-ols, EGCg was the most abundant followed by EGC, ECg and EC. Hierarchical clustering of 131 accessions based on metabolite diversity resulted two major clusters. Indian introductions clustered with well-known high quality cultivars indicating the potential utilization of high quality black tea production. Exotic accessions with low caffeine contents (< 20 mg g−1) were grouped separate cluster indicating the promising genetic resources for the development of low caffeine tea. Present study revealed that selected exotic tea accessions rich in bioactive compounds such as catechins and caffeine content could be utilized in producing speciality teas with enhanced quality and medicinal properties.

Effects and Molecular Mechanism of Mycorrhiza on the Growth, Nutrient Absorption, Quality of Fresh Leaves, and Antioxidant System of Tea Seedlings Suffering from Salt Stress

We studied changes in plant growth, nutrient absorption, quality of fresh leaves, and the antioxidant enzyme systems of leaves treated with AMF (Glomus etunicatum) in tea (tea cultivar “Xinyang 10”) seedlings exposed to 0 and 100 mmol/L sodium chloride (NaCl). The AMF colonization in the tea roots decreased observably by 50.1% after a 5-week soil NaCl (100 mmol/L) treatment. The growth, leaf nutrient levels, and leaf quality parameter contents significantly declined by 18–39% in the 100 mmol/L NaCl treatments. In contrast, these variables exhibited observably higher responses in the mycorrhizal seedlings than in the nonmycorrhizal seedlings. Furthermore, AMF improved the leaves’ total amino acid concentrations dramatically, accompanied by the upregulation of the genes of the amino acid synthetic enzymes, such as glutamate dehydrogenase (CsGDH), glutamate synthase (CsGOGAT), and glutamine synthetase (CsGS), while 100 mmol/L NaCl seedlings represented a negative performance. In addition, the 100 mmol/L NaCl treatments dramatically downregulated the expression level of the tea caffeine synthase 1 gene (CsTCS1), the ascorbate peroxidase gene (CsAPX), and the 3-hydroxy-3-methylglutaryl coenzyme gene (CsHMGR) in the leaves, while the AMF seedlings represented positive performances. These results suggest that AMF may play an active role in fresh leaf quality via the partial upregulation of the relevant genes’ expression. In contrast, salt stress represented the opposite result in tea. The seedlings inoculated with AMF showed significantly increased antioxidant enzyme activities, by 13.3–19.6%, including peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD), over the non-AMF inoculated tea seedlings. Still, they did not affect glutathione reductase (GR), irrespective of the NaCl condition. Further studies indicated that AMF observably upregulated the genes’ expressions (i.e., CsCAT and CsSOD) in both the 0 and 100 mmol/L NaCl seedlings. Meanwhile, the 100 mmol/L NaCl seedlings represented markedly lower antioxidant enzyme activities (i.e., SOD, CAT, and POD) and gene expressions (i.e., CsSOD and CsCAT) than the non-NaCl seedlings, irrespective of AMF inoculation. These results imply that AMF has a positive role in strengthening salt tolerance and on the quality of fresh tea leaves.

Effect of the dried limes (Citrus aurantifolia) on the caffeine kinetic extraction in black tea leaves (kinetic and thermodynamic study)

ABSTRACT. The kinetic and thermodynamic parameters were studied for the extraction of caffeine in black tea leaves and tea leaves containing antioxidant dried limes (Citrus aurantifolia). Caffeine is widely used in human consumption and is present in any liquid suitable for drinking except water. However, the health and environmental demerits make it significant to reduce caffeine to much less concentration or decaffeination. Therefore, the effect of the dried antioxidant Citrus aurantifolia on caffeine concentration followed by pseudo-first-order reaction, kinetic parameters (pseudo-first-order rate constant (k), equilibrium absorbance (A∞)), and thermodynamic activation parameters, the activation energy (Ea), change in enthalpy of activation (ΔH#), the change in entropy of activation (ΔS#) and change in activation Gibbs free energy (ΔG#) was calculated at four different temperatures 30, 60, 80, and 100 °C. Using the spectroscopic method the activation energy of the caffeine concentration in free black tea leaves solution (Ea = 13.32 kJmol-1) was higher than the black tea leaves mixed with lime solution (Ea = 9.89 kJmol-1), the higher collision of molecules A-factor (1.96 min-1), and large correlation factor (R2 = 0.95). The thermodynamic activation parameters ΔH#, ΔS#, and ΔG# demonstrate less heat absorption, irreversible, and more spontaneous interaction of lime with caffeine.&#x0D; &#x0D; KEY WORDS: Caffeine, Tea leaves, Citrus aurantifolia, Thermodynamic parameters, Kinetic&#x0D; Bull. Chem. Soc. Ethiop. 2022, 36(3), 697-705. &#x0D; DOI: https://dx.doi.org/10.4314/bcse.v36i3.18

Determination of Caffeine, Total Phenol, and Heavy Metals Content in Green and Black Tea Collected From Gilan Province, Iran by spectroscopic method

Background: Because of its stimulating and valuable effects, tea is the most commonly used beverage in the world after water. These effects are due to caffeine and phenolic compounds in tea. Also, most of the tea in Iran is planted in Gilan Province. However, food pollution from heavy metals is one of the most important problems.&#x0D; Objectives: In this research, we measured the total phenolic content, caffeine, lead, cadmium, and chromium in green and black tea cultivated in Gilan Province.&#x0D; Methods: Ten samples of green and black tea were purchased from different regions of Gilan Province. Methanol and dichloromethane extracts were prepared. Total phenol and caffeine were detected by spectroscopy. Quantification of heavy metals was done by digestion methods and examined by atomic absorption spectrophotometer.&#x0D; Results: The Mesn±SD amounts of total phenolic content, caffeine, lead, cadmium, and chromium in green tea from all regions comprised 27.13±1.54%, 3.20±0.01%, 0.81±0.66 ppm, 1.54±1.39 ppm, and 0.28±0.20 ppm, respectively, and these amounts in black tea were 14.90±1.53%, 3.20±0.05%, 1.00±0.79 ppm, 1.65±0.93 ppm, and 0.24±0.15 ppm, respectively.&#x0D; Conclusion: The content of total phenol and lead in tea was different in various regions of Gilan Province. Green tea contains more phenolic compounds than black tea, but the caffeine in green and black tea is almost equal. The amounts of cadmium and chromium in some Gilan Province areas are higher than the standard level, which needs to be investigated.

CsMYB184 regulates caffeine biosynthesis in tea plants.

CsMYB184 regulates caffeine biosynthesis in tea plants.

Color Shade Nets Affect Plant Growth and Seasonal Leaf Quality of Camellia sinensis Grown in Mississippi, the United States.

Shading modifies the microenvironment and can provide plants with some protection from frequent heat, drought, frost, and hail induced by climate change and has the potential to improve plant growth, yield, and quality. Tea (Camellia sinensis) is an ancient plant originating from tropical and subtropical regions and prefers to grow in partial shade under the forest canopy. The emerging tea industry in the United States (US) requires research support on establishing tea fields in novel environmental conditions as well as on producing high-quality tea products. This study investigated the effects of black, blue, and red shade nets on tea plant growth and seasonal leaf qualities in the southeastern US with a humid subtropical climate. When compared to no-shade control, black, blue, and red shade nets increased plant growth index (PGI), net photosynthetic rate (Pn), and stomatal conductance (gs), decreased air and leaf surface temperatures in summer, and reduced cold damage in winter. No significant difference was found among the black, blue, and red shade nets on tea plant growth. Varying contents of total polyphenols, carbohydrates, free amino acids, L-theanine, gallic acid, caffeine, and catechins in fresh tea leaves were observed among different shade treatments and harvesting seasons. 69.58% of the variations were depicted in a biplot by principal component analysis. Red shade was considered helpful for improving green tea quality by increasing the content of L-theanine and free amino acids in tea leaves collected in spring and fall when compared to no-shade control.

Purine alkaloids in tea plants: component, biosynthetic mechanism and genetic variation

The purine alkaloids, including caffeine, theobromine, and theacrine, are one of the most important quality and functional components of tea plants and commercial teas. In this paper, we review the component, biosynthetic mechanism and genetic variation of purine alkaloids in tea plants. The content of caffeine and theobromine in 403 accessions Chinese tea germplasms core collection preserved in the National Germplasm Hangzhou Tea Repository were analyzed using High Performance Liquid Chromatography (HPLC). The purine alkaloid profiles of different tea varieties, germplasm types, geographical origin, seasons, were highlighted. Some naturally low caffeine or caffeine-free, high theobromine or high theacrine germplasms were identified and the possible biosynthetic mechanism of hypernormal purine alkaloid content in tea plants were partially revealed. Some Cleaved Amplified Polymorphic Sequences (CAPS) DNA markers were developed for the identification of purine alkaloid content. The potential application of genetic engineering and DNA markers developed based on the low caffeine <italic>TCS1</italic> (tea caffeine synthesis gene) alleles for marker assisted selection (MAS), and cocoa tea and kucha in low caffeine/high theacrine tea cultivar breeding programs were also reviewed.

A Quadratic Regression Model to Quantify Plantation Soil Factors That Affect Tea Quality

Tea components (tea polyphenols, catechins, free amino acids, and caffeine) are the key factors affecting the quality of green tea. This study aimed to relate key biochemical substances in tea to soil nutrient composition and the effectiveness of fertilization. Seventy tea samples and their corresponding plantation soil were randomly collected from Xinyang City, China. The catechins, free amino acids, and caffeine in tea were examined, as well as the soil pH, nitrate (NO3--N), ammonium (NH4+-N), available phosphorus (AP), available potassium (AK), and soil organic matter (SOM). The ordinary kriging was employed to visualize the spatial variation characteristic by ArcGIS. A quadratic regression model was used to analyze the effects of the soil environment on the tea. The results showed that the soil pH of the study area was suitable for cultivating tea plants. The relationship between soil pH and tea polyphenols and catechins presented the U-shape curve, whereas the soil pH and NH4+-N and the free amino acids, the soil pH, and caffeine presented the inverted U-shape curve. Soil management measures could be implemented to control the soil environment for improving the tea quality. The combination of the macro metrological model with individual experimentation could help to analyze the detailed influence mechanisms of environmental factors on plant physiological processes.

Capillary electrophoresis-UV analysis using silica-layer coated capillary for separation of seven phenolic acids and caffeine and its application to tea analysis

This work presents an innovative silica-layer coated capillary with comparison study of the silica-layer coated capillary and the fused-silica capillary for the separation of seven phenolic acids viz. p-hydroxyphenylacetic acid (PHPA), p-coumaric acid (PCA), p-hydroxybenzoic acid (PHBA), caffeic acid (CFA), (3,4-dihydroxyphenyl)acetic acid (DHPA), gallic acid (GLA), and 2,3,4-trihydroxybenzoic acid (THBA), together with caffeine (CF), by capillary electro-chromatography (CEC) and micellar electrokinetic chromatography (MEKC), respectively. The running buffer was 25.0 mM borate at pH 9.0, with addition of 50.0 mM sodium dodecyl sulfate for the MEKC mode. The non-coated capillary could not separate all seven phenolic acids by CEC or MEKC. This was achieved using the coated capillary for both CEC and MEKC. The innovative coated capillary with CEC had plate number N ≥ 2.0 × 104 m−1 and resolution Rs ≥ 1.6 for all adjacent pairs of peaks. The capillary was also able to separate GLA and THBA which are structural isomers. Although MEKC mode provided comparable efficiency and selectivity, the reduced EOF of the coated capillary led to longer separation time. The linear calibration range of the seven phenolic acids and caffeine were different but the coefficients of determinations (r2) were all > 0.9965. The precisions of the relative migration times and peak area ratios of analyte to internal standard were 0.1–1.8% and 1.8–6.8%, respectively. There were no statistical differences in the efficiency of separation of the phenolic acids and caffeine for three coated capillaries. It was applied to the analysis of caffeine and phenolic acids in brewed tea using tyramine as the internal standard. The tea samples were diluted prior to analysis by CEC. The separation was less than 15 min. Caffeine, gallic acid and p-coumaric acid were detected and quantified. Caffeine and gallic acid contents were 10.8–15.0 and 2.6–4.8 mg g−1 dry tea leaves, respectively. p-Coumaric acid was detected in only one of the samples with a content of 0.4 mg g−1. Percent recoveries of spiked diluted samples were 90 ± 9 to 106 ± 13%, respectively.Article highlightsSilica-layer coated capillary is first reported for simultaneous separation of seven phenolic acids by non-MEKC analysis.Performance between coated, and non-coated capillaries with analysis by CEC and MEKC were compared.Plate number, resolution, capillary reproducibility, and electroosmotic flow mobility are investigated.Graphical abstract

A surface-modified silicon carbide nanoparticles based electrochemical sensor for free interferences determination of caffeine in tea and coffee

In this work, the surface-modified silicon carbide nanoparticles (SiC-NPs) were used as a sensing material for the determination of caffeine. The [Cu(pydc) (apym)]2 loaded on the surface of functionalized SiC-NPs. The mixture of SiC-NPs/[Cu(pydc)(apym)]2 and graphene nanosheets used as a new electrode material. Cyclic Voltammetry technique used to study the electrochemical behavior of the GC/Gr/SiC-NPs/[Cu(pydc)(apym)]2 modified electrode. The GC/Gr/SiC-NPs/[Cu(pydc)(apym)]2 modified electrode shows excellent electrocatalytic activity toward caffeine oxidation and dramatically reduce the oxidation overpotential. The typical amperometry method is used to evaluate the performance of the sensing material for the determination of caffeine. Under optimum conditions, the detection limit and sensitivity were obtained, 0.313 µM and of 134.1 μA/nM−1, respectively. The performance of the designed sensor was evaluated by the successful determination of caffeine in commercial tea and coffee.

Detection of Changes in Total Antioxidant Capacity, the Content of Polyphenols, Caffeine, and Heavy Metals of Teas in Relation to Their Origin and Fermentation

Tea (Camellia sinensis) is widely sought for beverages worldwide. Heavy metals are often the main aims of the survey of teas, given that the use of agricultural fertilization is very frequent. Some of these may affect the content of bioactive compounds. Therefore, in this study, we analyzed fermented and non-fermented teas of a single plant origin from Japan, Nepal, Korea, and China, and described mutual correlations and changes in the total antioxidant capacity (TAC), and the content of polyphenols (TPC), caffeine, and heavy metals in tea leaves, in relation to the origin and fermentation process. Using UV-VIS spectrophotometry and HPLC-DAD, we determined variations in bioactive compounds’ content in relation to the fermentation process and origin and observed negative correlations between TAC and TPC. Heavy metal content followed this order: Mn > Fe > Cu > Zn > Ni > Cr > Pb > Co > Cd > Hg. Given the homogenous content of these elements in relation to fermentation, this paper also describes the possibility of using heavy metals as determinants of geographical origin. Linear Discriminant Analysis showed an accuracy of 75% for Ni, Co, Cd, Hg, and Pb, explaining 95.19% of the variability between geographical regions.

Analysis of total phenolic compounds and caffeine in teas using variable selection approach with two-dimensional fluorescence and infrared spectroscopy

This paper reports the quantification of total phenolic compounds and caffeine in green and black tea using fluorescence, medium (MIR), and near (NIR) infrared spectroscopy combined with spectral variables selection tools (wavenumber or excitation/emission pairs). Nineteen tea samples were analyzed with a traditional analytical method for phenolic (Folin-Ciocalteu) and the content was expressed as milligrams of Gallic Acid Equivalent per gram of the sample (mgGAE g−1 dry basis). Caffeine quantification was performed by high-performance liquid chromatography. To optimize the variable selection and predict total phenolic and caffeine content, we applied a Pure Spectra chemometric Modeling (PSCM). The predictive quality of the models was assessed using metrics: Root Mean Square Error (RMSE), Mean Absolute Error (MAPE) and Determination Coefficient (R2). The spectroscopic techniques fluorescence, MIR, and NIR presented comparable metrics. Using only 4 variables, RMSE was less than 5.82 mg GAE g−1 for the Test subset to predict total phenolic compounds and 1.79 mg g−1 to predict caffeine. This work demonstrated that fluorescence, MIR, and NIR spectroscopy with the PSCM algorithm could be used to analyze the content of total phenolic compounds and caffeine quickly and non-destructively, using a small number of variables.

Potential of spectroscopic analyses for non-destructive estimation of tea quality-related metabolites in fresh new leaves

Spectroscopic sensing provides physical and chemical information in a non-destructive and rapid manner. To develop non-destructive estimation methods of tea quality-related metabolites in fresh leaves, we estimated the contents of free amino acids, catechins, and caffeine in fresh tea leaves using visible to short-wave infrared hyperspectral reflectance data and machine learning algorithms. We acquired these data from approximately 200 new leaves with various status and then constructed the regression model in the combination of six spectral patterns with pre-processing and five algorithms. In most phenotypes, the combination of de-trending pre-processing and Cubist algorithms was robustly selected as the best combination in each round over 100 repetitions that were evaluated based on the ratio of performance to deviation (RPD) values. The mean RPD values were ranged from 1.1 to 2.7 and most of them were above the acceptable or accurate threshold (RPD = 1.4 or 2.0, respectively). Data-based sensitivity analysis identified the important hyperspectral regions around 1500 and 2000 nm. Present spectroscopic approaches indicate that most tea quality-related metabolites can be estimated non-destructively, and pre-processing techniques help to improve its accuracy.

Comparative Analysis of the Polyphenols, Caffeine, and Antioxidant Activities of Green Tea, White Tea, and Flowers from Azorean Camellia sinensis Varieties Affected by Different Harvested and Processing Conditions.

This study evaluates the polyphenol profiles as well as caffeine (dry weight basis), and antioxidant activities of green tea (GTs), white tea (WTs), and flowers (Fl) samples from Azorean Camellia sinensis varieties affected by different harvested and processing conditions. Epicatechins derivatives, determined by RP-HPLC/PDAD, presented higher values in GTs with respect to WTs, decreasing as follows: epigallocatechin-3-gallate > epicatechin-3-gallate ≫ epicatechin ≫ epigallocatechin, and higher values in summer and early autumn than in spring. This was also accompanied by an in consistent withering time pattern. Esterified catechins were higher in all samples (100.8–312.3 mg/g) with respect to non-esterified catechins (15.1–37.7 mg/g). Caffeine (6.2–27.7 mg/g) decreased as follows: WTs > GTs ≫ Fl, and inconsistent seasonal and withering patterns were observed among the WTs. Total phenolics (125.9–295.4 mg gallic acid equivalents/g dried extract) and total flavonoids (35.2–69.7 mg rutin equivalents/g dried extract), determined by Folin–Ciocalteu and colorimetric methodologies, were higher in GTs than in WTs and Fl. Concerning the antioxidant patterns, the free radical scavenging activity (FRSA) and ferric reducing antioxidant power (FRAP) presented EC50 values ranges from 3.6 to 17.3 µg/mL and 4.8 to 16.5 µg/mL, respectively, and ferrous ion-chelating (FIC) activity ranged from 47.1 to 82.8%, highlighting that FRSA was better than butylated hydroxytoluene (BHT). Tea leaves exhibited, in general, higher activities with respect to tea Fl, and the WT sample plucked in summer and withered for 23 h showed the highest FRAP and FIC activity. In conclusion, this study shows the characteristic variation of GTs, WTs, and Fl of two tea varieties and may support crop quality improvement and promote the valorization of tea Fl.

Inoculation with Clariodeoglomus etunicatum improves leaf food quality of tea exposed to P stress

The present study aimed to evaluate the effect of an arbuscular mycorrhizal fungus (AMF), Clariodeoglomus etunicatum, on leaf food quality and relevant gene expression levels of tea (Camellia sinensis cv. ‘Fuding Dabaicha’) seedlings exposed to 0.5 μM P (P0.5) and 50 μM P (P50) levels. Twenty-four weeks later, the seedlings recorded higher root mycorrhizal fungal colonization in P50 than in P0.5. AMF-inoculated tea plants represented significantly higher leaf fructose and glucose contents and lower sucrose content than non-inoculated plants, irrespective of substate P levels. AMF treatment also increased total amino acids content in P0.5 and P50, accompanied with higher expression of glutamate dehydrogenase (CsGDH) and lower expression of glutamine synthetase (CsGS) and glutamine oxoglutarate aminotransferase (CsGOGAT). The total flavonoid content was higher in mycorrhizal versus non-mycorrhizal plants under P0.5 and P50, together with induced expression of phenylalanine ammonia-lyase (CsPAL) and cinnamic acid 4-hydroxylase (CsC4H). Mycorrhizal fungal inoculation improved catechins content, which is due to the up-regulated expression of flavanone 3-hydroxylase (CsF3H), flavonoid 3'-hydroxylase (CsF3'H), dihydroflavonol 4-reductase (CsDFR), leucoanthocyanidin reductase (CsLAR), anthocyanidin reductase (CsANR), and chalcone isomerase (CsCHI) under P0.5. However, under P50, the gene involved in catechins synthesis was not affected or down-regulated by mycorrhization, implying a complex mechanism (e.g. nutrient improvement). AMF also inhibited the tea caffeine synthase 1 (CsTCS1) expression regardless of P levels. Therefore, the results of this study concluded that inoculation with C. etunicatum improves leaf food quality of tea exposed to P stress, but the improved mechanisms were different between P0.5 and P50.

Tea Antioxidants

In thе paper, antioxidant activity (AOA) of tea infusions as a function of infusion time and type or brand of teas as well as a concentration of caffeine were measured. The main components of green tea infusions are identified as epigallocatechin gallate (EGCG), epicatechin gallate (ECG), and caffeine. It has been shown that the antioxidant activity depends on the time of infusion and the degree of tea grinding. while there is a linear dependence between AOA and concentration of caffeine in tea. Thus the only method to reduce content of caffeine in the infusion is a preliminary withdrawal of caffeine from the plant material

Voltammetric Sensing of Caffeine in Food Sample Using Cu‐MOF and Graphene

AbstractCu‐MOF/graphene composite were obtained by solvothermal and electrochemical methods. The interaction and formation of Cu‐MOF/graphene (GE) composite was systematically studied with the support of various characterizations including X‐ray diffraction (XRD), field emission scanning electron microscopy (FE‐SEM) and cyclic voltammogram (CV). The Cu‐MOF/graphene composite coated glassy carbon (GC) electrode exhibited good catalytic performance towards the electro‐oxidation of caffeine in neutral condition. The modified electrode displayed good linear range (5 μM to 450 μM), sensitivity (0.710 μA μM−1 cm−2), detection limit (1.38 μM), selectivity, high stability and reproducibility. Finally, the fabricated electrode extended into successful detection of caffeine in tea and coffee samples with good recoveries.

Management of sleep disturbances in people with dementia living in care homes: The SIESTA qualitative study

AbstractBackgroundSleep disturbances, including difficulty falling asleep, night time awakening, and excessive daytime sleepiness, effect nearly 40% of people with dementia living in care homes. Though hypnotic medications are commonly used, they are not recommended as they have been linked to increased risk of falls and mortality, and have little efficacy. There are currently no evidence‐based treatments. Through the SIESTA qualitative study (Sleep problems In dEmentia: interviews with care home STAff), we aimed to explore the alternative ways that sleep disturbances in residents with dementia are managed by care home staff.MethodWe interviewed 18 nurses and care assistants working both day and night shifts at four care homes in the UK providing residential and nursing care. We used a topic guide to explore staff experience of sleep disturbance in residents with dementia. The interviews were audio‐recorded, transcribed, and analyzed thematically by two researchers independently.ResultAll staff described a range of strategies they used to manage sleep disturbance in residents with dementia. Often this began with preventative techniques in the daytime, with staff ensuring where possible residents stayed active, ate well, and took part in activities to avoid napping. In the evening time staff settled residents into a dark, noise free, comfortable bedroom environment. When residents woke during the night‐time they were often given caffeinated tea or food, particularly if they had not eaten or drank much in the day due to napping. Tea and comfort were often used together, with staff sitting with the resident providing company and reassurance. If someone was agitated staff would think about pain and discomfort, and would use telecare to monitor residents who often left their bed at night and were a safety risk. As the last resort, sleep medications were used, but staff described how they only worked sometimes, as well as the side effects.ConclusionStaff used a range of techniques and described how these often worked in reducing, maintaining or preventing sleep disturbance, however, some of the strategies reported by staff to deal with sleep disturbances such as feeding or providing caffeinated tea at night might be counter‐productive.

Exogenous melatonin improves tea quality under moderate high temperatures by increasing epigallocatechin-3-gallate and theanine biosynthesis in Camellia sinensis L.

Global warming has multifarious effects on crop growth and productivity. Nonetheless, the effects of moderate-high temperatures and melatonin on tea yield and quality remain unclear. In this study, we found that melatonin, a universal growth stimulatory molecule, not only promotes photosynthesis and biomass accumulation in tea plants (Camellia sinensis L.) but also improves tea quality under sub high temperature (SHT). SHT increased the dry biomass and photosynthesis by 40.8% and 28.1%, respectively, and exogenous melatonin caused a further improvement. Moreover, SHT increased the total polyphenol concentrations and decreased the free amino acid concentrations, leading to a significant increase (68.2%) in polyphenol to free amino acid ratio. However, melatonin decreased the polyphenol to free amino acid ratio by delicately improving the concentrations of polyphenols and amino acids. Consistent with the total polyphenol, melatonin increased the concentrations of (-)-catechin, (-)-gallocatechin (GC), and (-)-epigallocatechin-3-gallate (EGCG) in tea leaves. The qRT-PCR analysis revealed that melatonin increased the transcript levels of catechins biosynthesis genes, such as CsCHS, CsCH1, CsF3H, CsDFR, CsANS, CsLAR, and CsANR under SHT. Meanwhile, the theanine concentration was decreased by SHT, which was attributed to the attenuated expression of CsGS, CsGOGAT, CsGDH, and CsTS1. Nonetheless, melatonin significantly increased those transcripts and the content of theanine under SHT. Melatonin also increased the caffeine content by inducing the expression of CsTIDH, CssAMS, and CsTCS1. These results suggest that melatonin could positively alter tea growth and quality by modulating the photosynthesis and biosynthesis of polyphenols, amino acids, and caffeine in tea leaves under SHT.

Rapid prediction of caffeine in tea based on surface-enhanced Raman spectroscopy coupled multivariate calibration

This study was focused on the quantitation of caffeine in black tea by surface-enhanced Raman spectroscopy coupled with gold nanoparticles. Caffeine has its own importance in tea due to its significant role against cardiovascular diseases and many other benefits. Caffeine was predicted for the first time as low cost and rapid by surface-enhanced Raman spectroscopy (SERS) coupled chemometrics in black tea. Gold nanoparticles (AuNPs) were synthesized successfully with high enhancement factors as SERS substrate used for SERS detection coupled partial least squares (PLS) algorithms. Caffeine exhibited several SERS characteristic peaks after adsorption on AuNPs owing to electromagnetic enhancement while excited by laser excitation. Quantification of caffeine in black tea was predicted using four build models, PLS, synergy interval-PLS (Si-PLS), genetic algorithm-PLS (GA-PLS), and Si-GA-PLS on preprocessed spectral data by standard normal variate (SNV). The better results were noted by using Si-GA-PLS while latent variables, (LVs) was 5, the correlation coefficient of calibration (RC) = 0.9705 where root mean square error of cross validation (RMSECV) = 0.114% and correlation coefficient of prediction (RP) = 0.9233 where root mean square error of prediction (RMSEP) = 0.165% and residual predicted deviation (RPD) was noted 2.43 and relative standard deviation (RSD) for precision was recorded as ≤3.42%. Based on the predicted results it is obvious that the purposed AuNPs nanosensor coupled Si-GA-PLS model could be successfully employed for caffeine prediction in tea with high sensitivity and rapidity.