Instant Tea Research Articles

Production, characterization and applications of tannase

Tannases, tannin acylhydrolases, are an important group of biotechnologically relevant enzymes which were utilized in a number of industrial applications, including the manufacture of instant tea, beer, fruit juices, some wines and gallic acid production. Tannases are by and large produced by microorganisms including Aspergillus, Paecilomyces, Lactobacillus and Bacillus. Tannases are generally produced on tannic carbon such as tannic acid, wheat bran, tea and coffee husk extract. Microbial tannases are mostly induced extracellular enzyme and produced by submerged fermentation and solid-state fermentation. The enzyme is most commonly purified by hydrophobic interaction chromatography in addition to reverse micelle. Most tannases can act in a wide range of temperature and pH, although tannases with acidic pH optima are more common. A sequence-based classification spreads tannases in many families thus reflecting the variety of molecules. Furthermore, tannase from Lactobacillus plantarum had been characterized by three-dimensional architecture. In recent years, a novel approach, metagenomic, was developed to exploring novel tannase from natural communities.

Compositional, Nutritional, and Functional Characteristics of Instant Teas Produced from Low- and High-Quality Black Teas

Two types of instant teas produced from low- and high-quality black teas were examined for their proximate composition, dietary fiber, minerals, water-soluble vitamins, total phenolic content, various antioxidant assays, phenolics (flavanols, condensed phenolics, and phenolic acids), alkaloids, and carotenoids as well as taste-active compounds (sugars, organic acids, and free amino acids). Some variations, albeit to different extents, were observed (p < 0.05) among these parameters between instant teas produced from low- and high-quality black teas. With respect to proximate composition, carbohydrate was the predominant component (56.68-59.84 g/100 g), followed by protein (19.31-19.86 g/100 g). Ash, moisture, and, to a lesser extent, dietary fiber and fat were also present in both instant teas. Thirteen minerals, four water-soluble vitamins, six flavanols, two alkaloids, three condensed phenolics, one phenolic acid, and one carotenoid were identified. Total phenolic content varied between 17.35 and 17.82 g of gallic acid equivalents (GAE)/100 g instant tea. With regard to antioxidant activities, three different assays such as oxygen radical absorbance capacity (ORAC), trolox equivalent antioxidant capacity (TEAC), and cupric ion reducing antioxidant capacity (CUPRAC) were measured. No significant differences (p > 0.05) in total phenolic, ORAC, TEAC, and CUPRAC contents between low- and high-quality instant teas were observed. With regard to taste-active compounds, 3 sugars, 5 organic acids, and 18 free amino acids were positively identified, of which fructose, tannic acid, and theanine predominated, respectively. The present work suggests that despite some differences, instant teas produced from low- and high-quality black teas should not be distinguished on the basis of their compositional, nutritional, and functional characteristics as well as taste-active compounds.

A RAPID HPLC-DAD METHOD FOR ANALYSIS OF THEAFLAVINS USING C12 AS STATIONARY PHASE*

Theaflavins are the major pharmacologically active antioxidant compounds present in the black tea. In this study we have developed a rapid, simple, and sensitive HPLC-DAD method for estimation and analysis of theaflavins using a RP-C12 (4.6 × 250 mm, 4 micron) column. The present study aims at rapid estimation and analysis of theaflavins in black tea and black tea based products (Ready to Drink Teas and Instant Teas) for their qualitative analysis. The use of RP-C12 as stationary phase with a simple gradient method enables the excellent separation of all the four major tea theaflavins: theaflavin (TF-1), theaflavin-3-gallate (TF-2), theaflavin-3, 3′-digallate (TF-3), and theaflavin-3′-gallate (TF-4) within 7 min. A linear calibration curve (r2 = 0.999) was plotted against standard theaflavin. The purification of theaflavins from black tea (CTC) was done by reverse phase solid phase extraction (RP-SPE) technique and quantification of individual theaflavins were carried out as theaflavin equivalent per mg of total purified theaflavins (TFS) from black tea. The results of present study clearly shows that use of C12 as a new stationary phase owes high sensitivity and faster analysis of theaflavins that otherwise are not easy to separate within 10 min.

Preparation of decaffeinated and high caffeine powders from green tea

The aims of this study were to develop optimal conditions for decaffeination and spray drying procedures to produce decaffeinated and high caffeine powders from green tea (Camellia sinensis). Blanching the tea leaves with water at 100 °C for 4 min at a water-to-tea ratio of 20:1 mL/g removed 83% of the caffeine while retaining 94% of the catechins. The optimal spray drying conditions, which gave the highest yield of green tea powder and the highest concentrations of the naturally occurring epistructured catechins were found to be 180 °C for the inlet temperature and 115 °C for the outlet temperature. Using these optimal conditions, a decaffeinated green tea powder (7 mg/g caffeine) and a high caffeine powder (95 mg/g) were produced. These two green tea powders had excellent physical properties and could be used as instant teas by consumers or utilized in the food, cosmetic and nutraceutical industries.

A novel technology for production of instant tea powder from the existing black tea manufacturing process

Instant tea powder is the fully soluble solid of tea that has emerged as a new and fast growing product in every country. The various processes involved in the commercial production of instant tea includeblending of tea leaves, hot water extraction, aroma recovery, soluble solids concentration, aroma restoration and dehydration. An envisaged process has been developed for the production of instant/soluble tea from the expressed juice of fermented tea leaves. Green tea leaves are subjected to withering, maceration, and fermentation process, which are similar to that of existing black tea production process. The fermented leaf is pressed to expel a part of juice containing soluble solids. The juice is then heated, centrifuged and vacuum dried to get soluble/instant tea powder. The pressed leaf residue is subjected to vacuum/hot air drying to obtain low grade conventional tea granules. About 20 ± 2 g of soluble tea and 220 ± 20 g of pressed cake tea are obtained from 1 kg of green tea leaves. The TF:TR ratio for soluble tea is 0.084 and that for pressed cake tea is 0.140. The technology can be easily adopted by existing black tea manufacturers for simultaneous production of instant tea and black tea. The process is economical as both extracted juice and pressed cake are converted into value added products.

ENZYMATIC TREATMENT OF BLACK TEA (CTC AND KANGRA ORTHODOX) USINGPENICILLIUM CHARLESIITANNASE TO IMPROVE THE QUALITY OF TEA

ABSTRACT Tannase mediated biotransformation of black tea (CTC and Kangra orthodox) was investigated. Black tea infusion treated with tannase showed that both epigallocatechin (EGC) gallate and epicatechin (EC) gallate of tea catechins were hydrolyzed by this enzyme into EGC and EC, respectively, accompanied by 11.2-fold (CTC tea) and 10.29-fold (Kangra orthodox tea) increase in gallic acid concentration. The tannase treated tea infusion showed reduction in tea cream formation and an increase in antioxidant activity to 1.73- and 1.61-fold, respectively. However, there was no change in the content and concentration of volatile compounds. Moreover, the results also showed that there was an improvement in the quality of tannase treated black tea infusion in relation to color, brightness, strength and flavor as compared with control. PRACTICAL APPLICATION The tannase mediated biotransformation of tea infusion (CTC and Kangra orthodox) improves the quality of tea in relation to reduction in tea cream formation. The reduction will help to produce a turbidity free, cold water soluble instant tea or tea extract. Furthermore, on tannase treatment, an increase in an antioxidant activity was also observed due to certain flavonoids present in tea that show potential health benefits against cardiovascular diseases and cancer. There was no significant change in the volatile compounds that thereby resulted in an improved color, brightness, strength and flavor of tea.

Recent trends in soft beverages edited by L Jagan Mohan Rao and K Ramalakshmi, Woodhead Publishing India Pvt. Ltd.,New Delhi

Though there are many voluminous books on coffee, tea and soft beverages, this book is unique in providing updated information on tea, coffee and soft fruit drinks in one volume. It is a reader’s delight and has three main parts. Part I deals with coffee, which is the most fascinating beverage throughout the world. This part is in four chapters comprising introduction, health benefits, recent trends in value addition and value added by-products. Coffee is one of the internationally well accepted beverages and is the second largest traded in the world next to crude oil. First section describes a brief historical perspective of beverage, botany, processing of green to roasted coffee, chemical composition and tasting of coffee. Effect of roasting on chemical composition, physical and chemical changes during roasting and their significance in nutritional quality and physiological impact on quality is also discussed in detail. Second section describes the health benefits of coffee and coffee beverage. The positive and negative biological activities of coffee are correlated with central nervous system, reproductive system, bone system and cardiovascular system. Third section deals with recent value-added coffee products. This section details about the variety of speciality coffee beverages, canned coffee, ready mix coffee, coffee jelly, fortified coffees, honeyed coffee, coffee tablets, variety of flavoured coffee, coffee wine, coffee candy, germinated coffee, coffee cookies, pizza with coffee colorant, carbonated coffee, decaffeinated coffee, instant coffee, monsoon coffee and coffee paste. The fourth section describes the utilization of by-products of coffee. Part II describes tea, which is the second most widely consumed beverage in the world next to water. This part is in chapters 5–9, viz., introduction to tea, types of tea and processing, chemical composition, pharmacological and medical properties of tea, high impact value added products of tea and tea by-products. Considerable interest has developed in the past decade in unravelling the beneficial health effects of tea, in particular, polyphenolic components and its antioxidant activity. The origin and history, various types of tea are discussed in the fifth and sixth section respectively. Chemical composition and medicinal and pharmacological properties of tea are explained in the seventh section. Eighth section entitled “High impact value-added products” describes relevant fine points about tea bags, instant tea, iced tea, herbal tea, tea concentrate, carbonated tea, various flavoured teas, decaffeinated tea, different fortified teas, tonic tea, tea cider and vinegar, tea kombucha, toyama kurocha, canned tea and instant tea granules. Detailed description about “Soft drinks” is described Part III, which is presented in chapters 10–17. Introduction to drinks and the beverage consumption pattern is depicted in chapters 10 and 11, respectively. The term ‘soft drinks’ includes all types of non-alcoholic liquid and powder beverages, although it is generally used to signify carbonated beverages. Soft drinks includes ready to drink, concentrated soft drinks and other categories are well explained in 12th chapter. The 13th chapter entitled, “Ingredients of soft drinks” deals the essential components of the soft drinks namely water, sweeteners, acidulants, colors, flavors and clouding agents. Advances in technology have improved all aspects of the soft drink industry. Chapter 14 includes the major processing technologies of soft drinks such as handling raw material, pulping and extraction, clarification, concentration, syrup preparation, blending, pasteurization and carbonation. Clean-in-place system, which is one of the major issues during manufacturing of soft drinks, is also included. Quality control and packaging aspect are well explained in chapters 15 and 16. Future trends presented in chapter 17 includes healthy carbonated drinks, functional drinks, mixed fruit juice beverages and carbonated beverages from waste of fruits. This is a well documented book in a precise manner without missing any of the aspects relevant to the subject. As a very useful ready reckoner, the book gives the latest information on coffee, tea and soft carbonated fruit drinks. The editors have taken utmost care in providing main aspects of chemistry, technology and quality control with respect to raw material as well as finished product. The information on value addition and marketing aspects are dwelt very well. One doesn’t find many books by Indian authors on coffee, tea and soft drinks and the effort by the editors is praiseworthy and the editors need to be complimented for the excellent work. The information provided is highly useful for researchers, teachers, students and industry personnel who are interested in the beverages such as coffee, tea and carbonated beverages.

FLOW AND FUNCTIONAL CHARACTERIZATION OF CORNSTARCH POWDER IN THE PRESENCE OF WATER AND PREGELATINIZED STARCH

ABSTRACTA model system comprising cornstarch has been agglomerated in the presence of binders like water and pregelatinized starch (PGS). Moisture and PGS contents have been varied between 12.3 and 20.1% and 0 and 6%, respectively. The physical characteristics of powder that have been determined include loose bulk density, wetting time and sinking time. A powder flow analyzer has been employed to determine flow characteristics like maximum force and energy for compression and decompression. An increase in moisture content and/or PGS increases average particle size and loose bulk density of agglomerates. The wet agglomerates show improved wetting and sinking times compared to dried agglomerates. Like wetting time, sinking time also decreases with an increase in moisture content meaning that these two indices behave in a similar manner. The functional properties like wetting and sinking times of powders at 18.5% moisture made with PGS are instant and only take less than 5 s.PRACTICAL APPLICATIONProcessed powdered foods frequently undergo the process of rehydration with a solvent system such as water or milk. Hence, the powder needs to be wetted quickly and thoroughly, sinking into the liquid rather than floating at the liquid surface and disperse/dissolve preferably without any lump formation. The importance of wetting time lies in the development and quality control of several food powders like milk powder, instant tea, coffee and mixes that are claimed to have instant properties. The generated data and findings, although developed on a model system, can be extrapolated to other food systems for developing new products for convenience to consumers.

Determination of biogenic amines in infusions of tea (Camellia sinensis) by HPLC after derivatization with 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl)

The reagent 9-fluorenylmethoxycarbonyl chloride (Fmoc-Cl) was used for the pre-column derivatization of the biogenic amines (BAs) cadaverine (Cad), histamine (Him), octopamine (Ocp), phenylethylamine (Pea), putrescine (Put), spermidine (Spd), spermine (Spm), tyramine (Tym) and the internal standard 1,6-diaminohexane (Dhx). The resulting Fmoc-derivatives were resolved by high-performance liquid chromatography on a Superspher(©) C(18) column using a binary gradient generated from sodium acetate and acetonitrile. For quantification, the fluorescence of derivatives was used at 263 nm excitation and 313 nm emission wavelength. This approach was applied to free BAs extractable with boiling water from 14 black, 5 green, 1 Oolong, and 1 instant tea. Infusions were prepared by adding 35 ml boiling water to one gram of tea and extracted for 20 min. In the Oolong tea and two black teas, no BAs could be detected. Limits of detection were 0.07-1.0 pmol for BAs at signal-to-noise ratio 3:1. Besides most abundant Tym and Spm lower quantities of Pea, Put, and Spd were detected, albeit not in all teas. Quantities of Tym ranged from 16 to 431 μg Tym/L infusion (1.1-25.3 μg Tym/g tea) and 31 to 319 μg Spm/L infusion (1.5-16.9 μg Spm/g tea). In none of the teas, Him was detected. Owing to the low amounts of free BAs in tea infusions, no health risks are to be expected even on consumption of large quantities of tea as beverage.

Skeletal Fluorosis from Brewed Tea

High fluoride ion (F(-)) levels are found in many surface and well waters. Drinking F(-)-contaminated water typically explains endemic skeletal fluorosis (SF). In some regions of Asia, however, poor quality "brick tea" also causes this disorder. The plant source of brick, black, green, orange pekoe, and oolong tea, Camellia sinensis, can contain substantial amounts of F(-). Exposure to 20 mg F(-) per day for 20 yr of adult life is expected to cause symptomatic SF. High F(-) levels stimulate osteoblasts and enhance bone apposition but substitute for OH(-) groups in hydroxyapatite crystals and thereby result in skeletal fragility and perhaps lead to secondary hyperparathyroidism. Beginning in 2005, we showed that daily consumption of 1-2 gallons of instant tea made from this plant can lead to SF. We describe a 48-yr-old American woman who developed SF from brewed tea. Our patient had elevated bone mineral density revealed by dual-energy x-ray absorptiometry (spine Z-score, +9.9), severe chronic bone and joint pain, and kyphosis after consuming 1-2 gallons of brewed orange pekoe tea daily for more than three decades. F(-) levels were high in her serum, urine, and clippings of fingernails and toenails, as well as in our reproduction of her beverage. Renal function was normal. She had vitamin D deficiency. Elevated serum PTH levels were unresponsive to adequate vitamin D supplementation. Pain resolved over several months when she stopped drinking tea and continued ergocalciferol. Our patient shows that SF can result from chronic consumption of large volumes of brewed tea.

Quantification of estragole in fennel herbal teas: Implications on the assessment of dietary exposure to estragole

Quantification of estragole content in commercial fennel herbal teas was carried out in order to allow for a more accurate estimate of the dietary exposure to estragole. A simple and rapid analytical method, based on Stir Bar Sorptive Extraction and GC–MS, was developed for this purpose. Fennel teas obtained from different types of commercial products were analysed. Concentration levels ranged from 241 to 2058μgL−1 in teas from teabags, from 9 to 912μgL−1 in diluted instant teas, from 251 to 1718μgL−1 in teas from not packaged seeds. Based on these data and considering the daily consumption of three portions of herbal tea, a maximum exposure to estragole for adults of 10μg/kgbw/day was calculated. The relatively high level observed in diluted instant teas of some brands deserves attention since these products are designed for infant consumption. Estimated exposure in infants was up to 51μg/kgbw/day for teas from teabags, and up to 23μg/kgbw/day for instant teas. A generalization of the use of suitable technologies in production processes of instant teas could substantially reduce the exposure to estragole in the vulnerable population groups (infants, young children, pregnant and breastfeeding women) who consume these products.

Fluoride content of beverages intended for infants and young children in Poland

Results of the studies indicate that fluoride content in beverages may be highly variable and children can consume substantial amounts of fluoride with these products. Ingestion of excessive fluoride during infancy and early childhood may cause dental fluorosis of permanent maxillary central incisors – the most aesthetically important teeth.The aim of this study was to determine the fluoride content in Polish beverages designed for infants and young children nutrition.Forty-three brands of juices and juice-flavored drinks and 23 instant teas were evaluated. Analyses were performed with the use of ion-selective fluoride electrode (09-37 type) and a RAE 111 chloride-silver reference electrode (MARAT). Fluoride concentrations in most beverages did not exceed 0.3ppm. However, in three beverages containing tea extract levels of fluoride were higher (0.35–1.14ppm). Consumption of these beverages could significantly increase child’s fluoride exposure. Therefore, the need exists for continuous monitoring of fluoride levels in products intended for children. Listing fluoride content on beverages would be desirable. Knowledge about possible fluoride ingestion from dietary sources permits the clinician to recommend the safest schedule of fluoride treatment so as the optimal caries preventive effect can be obtained and the risk of dental fluorosis reduced.

What Is Your Guess? A Case of Thick but Brittle Bones and Instant Tea

A 45-year-old white male was found to have radiographic findings of a diffusely dense appendicular skeleton, mild trabecular thickening, and multiple thoracic compression fractures indicating structural weakness. Bone mineral density was above the expected range for his age on the lumbar spine and femoral neck. Social history was significant for well-water consumption and daily instant-tea ingestion …

Formation of trihalomethanes in foods and beverages

Trihalomethanes (THMs) are suspected carcinogens and reproductive toxicants commonly found in chlorinated drinking water. This study investigates THM formation during the preparation of beverages and foods using chlorinated drinking water. A total of 11 foods and 17 beverages were tested. Under the experimental conditions, each food and beverage formed THMs, primarily chloroform, although low or trace levels of brominated THMs were also detected. Tea formed the highest THM levels (e.g., chloroform levels from 3 to 67 µg l−1), followed by coffee (from 3 to 13 µg l−1), rice (9 µg l−1), soups (from 0.4 to 3.0 µg l−1), vegetables (<1 µg l−1), and baby food (<0.7 µg l−1). Chloroform formation with instant tea, used as a highly reproducible model system, increased with free chlorine concentration, decreased with higher food (tea) concentration, and was unaffected by reaction (steeping) time and bromide ion concentration. These findings indicate that chlorine-food reactions are fast, but that formation decreases as the chlorine demand of the food system increases. THMs are formed in the preparation and cooking of a wide variety of foods if free chlorine is present, and our results suggest that tea can be a significant source of exposure to THMs.

Absolute determination of soluble potassium in tea infusion by gamma-ray spectroscopy

Abstract Potassium content in tea brew was determined by gamma-ray spectroscopy, using the 1461 keV gamma-ray from 40K, the naturally occurring radioactive isotope of potassium. We measured radiation with a shielded HPGe detector from individual test samples of tea leaves, before and after infusion preparation, and from commercial instant tea powder. The correction factor for the gamma-ray self-absorption in the extended source was determined with the help of Monte-Carlo simulations. This gamma-ray spectroscopy technique enabled the absolute determination of potassium content with a relative uncertainty smaller than 4%, at the one standard deviation confidence level, showing the feasibility of this method. An experiment to evaluate a possible systematic uncertainty due to K distribution heterogeneity in the sample was performed, with the result that the corresponding relative standard deviation is smaller than 2% at 95% confidence level.

Fuzzy Analysis of Sensory Data for Quality Evaluation and Ranking of Instant Green Tea Powder and Granules

Two brands of green tea samples available in the market were used for the sensory evaluation along with the instant tea powder and green tea granules prepared from fresh tea leaves (Camellia sinensis). The main objective of this study was to evaluate the sensory scores of different tea samples using fuzzy logic and grade the samples as per their sensory qualities. Brew was prepared as per the standard procedure, and sensory evaluation was carried out by a trained panel of 16 judges. Fuzzy logic was used for ranking the samples and also to find out the preference of quality attributes of green tea drink in general. Green tea granules obtained from pressed leaf residue was ranked first followed by instant tea drink. Both the market samples were rated low in quality compared to the prepared tea samples. It was also concluded that in general, taste and flavor of green tea drink is considered to be the highly important quality attributes. The color and strength were reported under the category important. The strength and weakness of individual samples were also determined.

Authenticity evaluation of tea-based products

This study proposes a method for estimating the content of tea in tea-based products. Broadly, this methodology is based on selecting chemical markers of the quality and authenticity of tea (and, therefore, of tea-based products), optimising the relevant analytical methods, and determining variations (type, origin, quality) among samples of green and black leaf teas. The contents of the selected markers (theobromine, caffeine, theanine, and total polyphenols) in tea-based products (iced teas, instant teas) were determined. Then, the dry tea content in these products, expressed as the equivalent amount of dry tea leaves, was calculated on the basis of two sets of mean data for these analytes: average literature data, and the mean experimental data obtained with our samples of leaf tea. With regards to the latter, we propose to use of the following averages for caffeine, theobromine, theanine, and polyphenols: for 100 g of black tea-based products 1.9 g, 0.13 g, 1.3 g, and 9.1 g, respectively; for 100 g of green tea-based products 1.9 g, 0.16, 1.7 g, and 14.7 g, respectively. Using this method, we found that approximately one third of the analysed samples failed to meet the tea extract levels required by German and Austrian legislations, while about 10% did not comply with the less demanding Czech legislative requirements.

Development of a potentiometric sensor for the determination of saccharin in instant tea powders, diet soft drinks and strawberry dietetic jam

The construction and the analytical evaluation of a potentiometric sensor, namely, Pt∣Hg∣Hg 2(Sac) 2∣Graphite, where Sac stands for saccharinate ion, are described. This electrode has a wide linear dynamic range between 5.0 × 10 − 7 and 1.0 × 10 − 2 mol L − 1 with a near-Nernstian slope of − 58.1 ± 1.1 mV decade − 1 and a detection limit of 3.9 × 10 − 7 mol L − 1 . The potentiometric response is independent of the pH of the solution in the pH range 3.0–9.0. The electrode is easily constructed at a relatively low-cost with fast response time (within 10–30 s) and can be used for a period of 10 months without significant change in its performance characteristics. The proposed sensor displayed good selectivities over a variety of other anions (carboxylates and inorganic anions). The potentiometric sensor was successfully applied to the determination of saccharin in real food samples, that is, in instant tea powders, diet soft drinks and strawberry dietetic jam.

Skeletal Fluorosis From Instant Tea

Skeletal fluorosis (SF) can result from prolonged consumption of well water with >4 ppm fluoride ion (F(-); i.e., >4 mg/liter). Black and green teas can contain significant amounts of F(-). In 2005, SF caused by drinking 1-2 gallons of double-strength instant tea daily throughout adult life was reported in a 52-yr-old woman. A 49-yr-old woman developed widespread musculoskeletal pains, considered fibromyalgia, in her mid-30s. Additionally, she had unexplained, increasing, axial osteosclerosis. She reported drinking 2 gallons of instant tea each day since 12 yr of age. Fluoxetine had been taken intermittently for 5 yr. Ion-selective electrode methodology quantitated F(-) in her blood, urine, fingernail and toenail clippings, tap water, and beverage. Radiographs showed marked uniform osteosclerosis involving the axial skeleton without calcification of the paraspinal, intraspinal, sacrotuberous, or iliolumbar ligaments. Minimal bone excrescences affected ligamentous attachments in her forearms and tibias. DXA Z-scores were +10.3 in the lumbar spine and +2.8 in the total hip. Her serum F(-) level was 120 microg/liter (reference range, 20-80 microg/liter), and a 24-h urine collection contained 18 mg F(-)/g creatinine (reference value, <3). Fingernail and toenail clippings showed 3.50 and 5.58 mg F(-)/kg (control means, 1.61 and 2.02, respectively; p(s) < 0.001). The instant tea beverage, prepared as usual extra strength using tap water with approximately 1.2 ppm F(-), contained 5.8 ppm F(-). Therefore, the tea powder contributed approximately 35 mg of the 44 mg daily F(-) exposure from her beverage. Fluoxetine provided at most 3.3 mg of F(-) daily. SF from habitual consumption of large volumes of extra strength instant tea calls for recognition and better understanding of a skeletal safety limit for this modern preparation of the world's most popular beverage.

An exposure and risk assessment for fluoride and trace metals in black tea

Exposure and associated health risks for fluoride and trace metals in black tea were estimated. Fifty participants were randomly recruited to supply samples from the tea that they drink, and self-administer a questionnaire that inquired about personal characteristics and daily tea intake. Analyzed trace metals included aluminum, arsenic, barium, cadmium, cobalt, chromium, copper, manganese, nickel, strontium, and zinc. Fluoride and four metals (Al, Cr, Mn, Ni) were detected in all samples while barium was detected only in one sample. The remaining metals were detected in >60% of the samples. Fluoride and aluminum levels in instant tea bag samples were greater than in loose tea samples ( p < 0.05) while the differences in elemental concentrations of loose and pot bag tea samples were not significant. Median and 90th percentile daily tea intake rates were estimated as 0.35 and 1.1 l/day, respectively. Neither fluoride nor aluminum levels in black tea were found to associate with considerable risks of fluorosis and Alzheimer's disease, respectively. However, carcinogenic risk levels for arsenic were high; R > 1.0 × 10 −6 even at the median level. According to sensitivity analysis, daily tea intake was the most influencing variable to the risk except for arsenic for which the concentration distribution was of more importance.