Instant Tea Research Articles

Assessment of fluoride concentration and daily intake by human from tea and herbal infusions

The fluoride content in infusions of commercially available black, green, oolong, pu-erh and white teas was determined by ion-selective electrode. Herbal infusions as well as instant tea and ready-to-drink tea beverages were also examined. It is found that brewing time (5, 10 and 30 min) does increase the fluoride content, which in infusions of black tea (5 min brewing) was higher than that in the other types of tea, with contents ranging between 0.32 and 4.54 mg/l for black tea to 0.37–0.54 mg/l for white tea and with even lower values for herbal tea infusions of 0.02–0.09 mg/l. On the basis of the results obtained, the daily intake of fluoride provided from tea and herbal beverages was estimated for an adult person and for children in comparison with the Polish SAI (Safe and Adequate Daily Intake) of fluoride which is strictly attributable to ADI (Acceptable Daily Intake). The fluoride intake resulted from the regular consumption of black tea infusions was raised as compared to the other types of teas as well as herbal teas. For adult and children tea drinkers consuming five cups of black tea per day the intake of fluoride will be in the range of 8.0–303% and 12–303% of the SAI, respectively. People are often exposed to multiple sources of fluoride, such as in food, water, air and excessive use of toothpaste. The control of tea quality is important to protect human against too high uptake of this element from black tea, which is the most popular beverage. Excessive intake of fluoride with black tea, especially in the regions with its high level in the drinking water, increases the risk of dental fluorosis in children during the years of tooth development. The long-term exposure to large amounts of fluoride can lead to potentially skeletal fluorosis ( WHO, 1984).

Moisture sorption isotherms and heat of sorption of instant (soluble) green tea powder and green tea granules

Moisture adsorption isotherms of green instant tea powder and green tea granules were determined at 20, 30, 40 and 50 °C. A gravimetric static method was used under 0.11–0.90 water activity ranges for the determination of sorption isotherms that were found to be typical type II sigmoid. Experimental data were fitted to various mathematical models and found that Peleg model suits best in describing equilibrium moisture content–equilibrium relative humidity (EMC–ERH) relationships for instant green tea samples as well as green tea granules, over the entire range of temperatures. The net isosteric heat of sorption was determined from the equilibrium data at different temperatures. The isosteric heat of sorption varied between 48.54 and 44.71 kJ/mol at moisture levels varying between 1 and 9 g/g dry matter for instant green tea powder and 47.96 and 44.10 kJ/mol at moisture level varying between 0.2 and 1.4 g/g dry matter for green tea granules.

The Effect of Consuming Instant Black Tea on Postprandial Plasma Glucose and Insulin Concentrations in Healthy Humans

Objective: To determine the effects of black tea on postprandial plasma glucose and insulin concentrations in healthy humans in response to an oral glucose load.Methods: A four-way randomised, crossover trial was designed in which 16 healthy fasted subjects would consume 75g of glucose in either 250ml of water (control), 250ml of water plus 0.052g of caffeine (positive control) or 250 ml of water plus 1.0g or 3.0g of instant black tea. Blood samples were collected at fasting and at 30min intervals for 150min from commencement of drink ingestion. Glucose and insulin concentrations were measured using standard methodology. The tea was chemically characterised using colorimetric and HPLC methods.Results: Chemical analysis showed that the tea was rich in polyphenolic compounds (total, 350mg/g). Results from only 3 treatment arms are reported because the 3.0g tea drink caused gastrointestinal symptoms. Plasma glucose concentrations <60min in response to the drinks were similar, but were significantly reduced at 120min (P<0.01), following ingestion of the 1.0g tea drink, relative to the control and caffeine drinks. Tea consumption resulted in elevated insulin concentrations compared with the control and caffeine drinks at 90min (P<0.01) and compared with caffeine drink alone at 150min (P<0.01).Conclusions: The 1.0g tea drink reduced the late phase plasma glucose response in healthy humans with a corresponding increase in insulin. This may indicate that the attenuation in postprandial glycemia was achieved as a result of an elevated insulin response following stimulation of pancreatic β-cells. This effect may be attributable to the presence of phenolic compounds in the tea

Preparation of Partially Decaffeinated Instant Green Tea

The caffeine level of instant tea extracted from decaffeinated leaf tea with 4.0 mg g-1 caffeine is commonly above 10.0 mg g-1, the maximum limit of caffeine for decaffeinated instant tea. Further removal of caffeine by active carbon (AC) from the green tea extract was investigated. It showed that the removal of caffeine from the tea extract solutions depended on the treatment time and tea extract concentration while the ethanol concentration and pH had little effect on the removal of caffeine. According to the removal of caffeine and the ratio of total catechins to caffeine in the tested samples, the optimum decaffeination conditions were determined to be as follows: tea extract concentration 15-30 g L-1 for common tea extract but higher for partially decaffeinated tea leaf extract; ratio of tea solution to AC, 100 mL:4 g; treatment time, 4 h; and natural tea extract pH. Instant tea powder extracted from partially decaffeinated leaf tea with a caffeine level of 4.03 mg g-1 and further decaffeinated by AC had a caffeine level of 7.81 mg g-1, which was 31% lower than that without AC treatment.

Process technology for production of soluble tea powder

Instant tea is presently manufactured by spray/freeze drying of the concentrated brew of processed tea leaves/dust and the drawbacks of this method are inferior quality, high cost and energy. A novel technique has been developed for the production of instant/soluble tea powder from the expressed juice of green leaves. After plucking, the leaves are crushed and juice pressed out. The juice is then subjected to fermentation under specified conditions. The fermented juice is steamed, centrifuged and freeze-dried to get instant tea powder. The pressed leaf residue is subjected to fermentation and drying for preparation of tea granules. The instant tea produced is of good liquoring characteristics and various constituents are also in the acceptable range [Theaflavin (TF) to Thearubigin (TR) ratio – 10.71 for instant tea (IT) and 12.12 for tea granules (TG), Caffeine content 40.4 mg/cup of IT and 96 mg per cup of TG]. The tea granules produced is comparable to CTC (crushing, tearing & curling) tea in quality and liquoring characteristics. There is considerable savings in the economy as the juice and residue are converted into value added products in this method.

Optimization of Fermentation Time in Instant Tea Production

Fermentation should be optimum for the production of good quality tea. One of the methods commonly followed today is based on the amount of theaflavin (TF) formed during fermentation. For this, samples (juice for instant tea (IT) and pressed leaf residue for black tea granules (TG» were collected at specific interval of time during fermentation and the optical density values were determined by a spectrophotometer. Optimum period was indicated by the peak of the curve obtained by plotting optical density (00) values of the sample vs. fermentation time. The optimum fermentation time for IT was I h and for TG was 1.5 h. The amount of TF formed, as indicated by the increase in 00 in juice increased with increase in fermentation time up to 60 min and after that it decreased. Similar trend was found for pressed leaf residue also where the 00 increased up to 90 min. The decrease in theaflavin content beyond a certain time may be due to the conversion of theaflavin to the a FU bigins (TR). The result was emphasized by another experiment in which IT and TG were prepared with different fermentation times, and the prepared samples were analyzed for the quality by a sensory evaluation panel

Development of a biosensor for caffeine

We have utilized a microbe, which can degrade caffeine to develop an Amperometric biosensor for determination of caffeine in solutions. Whole cells of Pseudomonas alcaligenes MTCC 5264 having the capability to degrade caffeine were immobilized on a cellophane membrane with a molecular weight cut off (MWCO) of 3000–6000 by covalent crosslinking method using glutaraledhyde as the bifunctional crosslinking agent and gelatin as the protein based stabilizing agent (PBSA). The biosensor system was able to detect caffeine in solution over a concentration range of 0.1 to 1 mg mL −1. With read-times as short as 3 min, this caffeine biosensor acts as a rapid analysis system for caffeine in solutions. Interestingly, successful isolation and immobilization of caffeine degrading bacteria for the analysis of caffeine described here was enabled by a novel selection strategy that incorporated isolation of caffeine degrading bacteria capable of utilizing caffeine as the sole source of carbon and nitrogen from soils and induction of caffeine degrading capacity in bacteria for the development of the biosensor. This biosensor is highly specific for caffeine and response to interfering compounds such as theophylline, theobromine, paraxanthine, other methyl xanthines and sugars was found to be negligible. Although a few biosensing methods for caffeine are reported, they have limitations in application for commercial samples. The development and application of new caffeine detection methods remains an active area of investigation, particularly in food and clinical chemistry. The optimum pH and temperature of measurement were 6.8 and 30 ± 2 °C, respectively. Interference in analysis of caffeine due to different substrates was observed but was not considerable. Caffeine content of commercial samples of instant tea and coffee was analyzed by the biosensor and the results compared well with HPLC analysis.

Concentration of sea buckthorn ( Hippophae rhamnoides L.) juice with membrane separation

In our “plastic” world the role of the herbs and the medical products is rising. One of the important herbs is sea buckthorn. The main goal of our work was to examine the possibility of using membrane separation to concentrate sea buckthorn juice and to give the basis of further products (e.g. instant tea) with it. During our experiments the concentration of the juice was examined with the combination of microfiltration (MF) and reverse osmosis (RO1), with nanofiltration (NF) and with reverse osmosis (RO2) without clarification. The operating parameters were determined during the measurements, and the concentrations were carried out on them. The analytical assay of the juice such as the determination of the solid content, Vitamin C content, antioxidant activity, was also done. The modelling of the process was based on the mathematical model which was worked out previously for instant coffee. The modelling was done only for reverse osmosis.

Food Safety: A Tea-Time Mystery

When a 52-year-old Missouri woman approached physicians in 1998 complaining of stiffness and pain in her spine, the symptoms were at first attributed to “disc disease.” But a series of laboratory tests showed that the woman had abnormally thick, dense bones and strikingly high levels of fluoride in her urine—hallmarks of skeletal fluorosis, a disease that has been diagnosed only a handful of times in the United States. The only way to develop skeletal fluorosis is to ingest or inhale too much fluoride. The woman’s drinking water had only about 2.8 parts per million (ppm) fluoride, well below the Environmental Protection Agency (EPA) limit of 4.0 ppm. Other sources of fluoride were also eliminated: She didn’t swallow her toothpaste, she didn’t work with pesticides, and she didn’t live near a mine. So where was she getting all the fluoride? Then the woman revealed she had drunk up to two gallons of extra-strength instant tea every day of her adult life. Physician Michael Whyte of Washington University School of Medicine and his colleagues decided to measure the fluoride levels in her tea preparation. They found that, counting the fluoride in her water, the woman was ingesting 37–74 milligrams of fluoride per day. EPA studies suggest that severe skeletal fluorosis could occur over the course of 20 years from a continuous exposure of 20 milligrams of fluoride per day. Whyte and colleagues then tested 10 instant teas available in grocery stores. They found average fluoride concentrations of 1.0–6.5 ppm in regular-strength tea made with fluoride-free water, with several brands exceeding the Food and Drug Administration limit of 1.4–2.4 ppm for bottled beverages. Their study appears in the January 2005 issue of The American Journal of Medicine. Whyte believes that individuals who drink large volumes of instant tea for a prolonged period may be putting themselves at risk for skeletal fluorosis. But Joe Simrany, president of The Tea Association of the USA, believes that the Missouri incident was highly unusual. “It had less to do with tea than it had to do with excessive behavior,” he says. So should the average tea drinker be concerned? “It may be that certain brands ought to cut down the amount of fluoride in their tea or add a warning label to their product,” says Michael Kleerekoper, director of research for bone and mineral metabolism at Wayne State University, “but it would be a real mistake to throw out the baby with the bathwater.” He adds, “I drink tea—it’s wonderful on a hot summer’s afternoon.” Whyte, who also hasn’t stopped drinking tea, says, “Our research is a call for better understanding of fluoride levels in various teas.” He is now investigating the fluoride levels of bottled tea preparations. Meanwhile, the woman in Missouri has stopped drinking tea, and her pains have abated. She has since switched to lemonade.

Skeletal fluorosis and instant tea

Skeletal fluorosis and instant tea

Determination of ginsenosides Rb1, Rc, and Re in different dosage forms of ginseng by negative ion electrospray liquid chromatography-mass spectrometry.

A method based on high-performance liquid chromatography (HPLC) and negative ion electrospray mass spectrometry (LC-MS) has been used to determine ginsenosides Rb1, Rc, and Re in six different samples of ginseng. These included a liquid extract, capsules, tea bags, and an instant tea. It was found that four of the six samples had detectable levels of at least one of the ginsenosides. The liquid extract, capsules, instant tea, and tea bags labeled ginseng had ginsenosides. The labels on the two samples that did not have ginsenosides indicated that they were a mixture of green tea, licorice, and ginseng. Also, 13C NMR was used to identify the types of complex carbohydrates present in the samples. One of the samples of tea bags had none of the ginsenosides, but did have complex carbohydrates found in most of the other samples. The instant tea had all three ginsenosides, but had no complex carbohydrates, only sucrose. The amounts of ginsenosides found in standard doses from six different sources of ginseng varied considerably. It was found that steeping a tea bag for a longer time than that recommended on the label produced a larger recovery of ginsenosides and that reusing a tea bag produced even higher recoveries.

Recovery of Valuable Tea Aroma Components by Pervaporation

The present work describes the possibility of using pervaporation to recover the tea aroma compounds from tea aroma condensate generated in the manufacturing of tea or instant tea, as well as directly from tea extract. Eight compounds that make a significant contribution to tea aroma, namely, trans-2-hexenal, linalool, cis-3-hexenol, 3-methylbutanal, 2-methylpropanal, benzyl alcohol, phenylacetaldehyde, and β-ionone, were studied in this work. Permeation studies for all of these compounds with poly(octyl methyl siloxane) (POMS) and poly(dimethylsiloxane) (PDMS) membranes in a batch-type vacuum pervaporation system were carried out, first, in their aqueous solutions (binary mixtures); second, in a model solution containing all of the above-mentioned compounds; and last, with an actual tea extract. In this work, mainly the effect of the feed concentration on the organic flux and separation factor was studied. The permeation studies with the mixture revealed that β-ionone, trans-2-hexenal, linalool, cis-3-hexenol, and 3-methylbutanal offered very good selectivity, whereas phenylacetaldehyde, 2-methylpropanal, and benzyl alcohol gave moderate selectivity. The results indicate that pervaporation is an attractive technology for the recovery of tea aroma compounds from tea aroma condensate as it (i) yields good separation and (ii) operates under mild conditions. However, it should be noted that, because the selectivity offered by pervaporation varies considerably from compound to compound, attempts to concentrate a solution of volatiles to a high degree can result in significant alteration in the profile of the aroma. Thus, the commercial utility of this approach will need to be ascertained on a case-by-case basis.

The Use of Catechins and Purine Alkaloids as Descriptors for the Differentiation of Tea Beverages

A high performance liquid chromatography method using a C-18 reversed-phase column, a gradient elution system of acetonitrile-water-formic acid and a photodiode array detector was used to determine catechins and purine alkaloids in tea beverages. (−)-epicatechin, (+)-catechin, (−)-epigallocatechin, (−)-epigallocatechin gallate, (−)-epicatechin gallate, gallic acid, caffeine, theophylline and theobromine were analysed in different tea beverages made of black, green and instant tea. Other products containing tea were also considered. Principal component, cluster, linear discriminant analysis and soft independent modelling class analogy were applied to the data in order to differentiate tea beverages according to the catechin and purine alkaloid profiles of the different samples considered.

A extração de cafeína em bebidas estimulantes: uma nova abordagem para um experimento clássico em química orgânica

Caffeine extraction procedures from water soluble and water insoluble materials for preparing stimulating beverages are described. Water soluble materials used were instant tea and coffee and water insoluble materials were, among others, guarana powder and mate leaves. The extraction of caffeine from water soluble materials, especially instant tea, is more suitable for an organic chemistry teaching laboratory than the classic experiment using tea leaves, due to the economy of time and a larger amount of extracted caffeine. The procedure is time-saving and requires only a four-hour period. The experiments illustrate the extraction process as used in undergraduate organic chemistry laboratories.

GC–MS analysis of essential oil of some commercial Fennel teas

Abstract Fennel teas were prepared by classical infusion or microwave decoction of unbroken and crushed fruits, three pre-packaged teabags and two instant teas. Their volatile constituents were obtained by extraction with n-hexane and analysed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC–MS), using two columns with stationary phases of different polarity. Of the constituents 85–95% were identified on the basis of their GC retention times and their mass spectra in relation to authentic compounds. No volatile constituents were detected in one sample of instant tea. Conventional teas from crushed fruits and teas prepared from the other instant tea showed the highest levels of volatile constituents. Anethole (30–90%) and/or anisaldehyde (0.7–51%) were the main constituents of all the samples. Methychavicol (0.8–4.1%), eugenol (1.5–11.3%) and fenchone (0.5–47%) were detected in most samples. Carvone (2.1–6.1%) was presenting only some teabags and camphor (2.3–2.6%) in others. The volatile constituents of only one instant tea included limonene (1.4%) and α-terpineol (0.4%).

Two-phase anaerobic digestion of spent tea leaves for biogas and manure generation

Anaerobic digestion of spent tea leaves from an instant tea manufacturing factory was studied in a two-phase digester. The hydrolysis and acidification phase resulted in the formation of high organic strength liquid called leachate, with a chemical oxygen demand (COD) of 12,880 mg/l, within the retention time of 10 days. The leachate was tested in a batch methanaogensis reactor for biogas production. An average biogas yield of 0.48 m 3/ kg of COD destroyed was obtained with an average COD reduction of 93%. The biogas was analyzed for 73% methane content.

Effect of pH on cream particle formation and solids extraction yield of black tea

Effect of pH on tea solids extraction yield was significant in increasing instant tea yield. Solids extraction yield was doubled when tea was extracted at pH 1.2 compared with that extracted in boiling distilled water with pH 6.8. H+ encouraged black tea cream particle formation by either releasing more solids into the infusion or stimulating polyphenols to interact with polysaccharides and nucleophilic groups on protein in tea infusions. HPLC results revealed that theaflavins and tea catechins were leading substances affecting the formation of cream particles and infusion colour. Theaflavins and some tea catechins, such as EGCG, ECG and EGC, were dissociated or degraded under alkaline conditions and thus tea cream particles tended to dissolve and tea infusion became dark in colour. Feasibility of stepwise extraction of instant teas used for iced tea and normal drinking tea, by controlling temperature and pH, is also considered in the present paper.

Preparation, composition and consumption patterns of tea-based beverages in Arizona

Flavonoids in black and green tea have been implicated in cancer chemoprevention. The concentration of flavonoids in tea is likely to vary by preparation techniques. Inconsistencies between epidemiological studies may arise from the lack of information on methods of preparation. The purpose of this study was to assess the pattern of tea consumption among an older Arizonan population and to determine tea polyphenol and flavonoid levels in the most commonly used tea preparation techniques for a Southwestern US population. A specific tea questionnaire was developed using focus groups and semi-structured interviews. The reliability of the tea questionnaire was very high even after 6 months (r= 0.93 for average tea intake/day). Forty samples, representing the most typical preparation techniques of hot, iced, and sun tea, were analyzed by HPLC for total flavonoids, catechins, theaflavins, thearubigins, caffeine and gallic acid. In black tea, the highest concentrations of flavonoids (μg/ml) were found in brewed hot tea (range: 541–692) while the lowest concentrations were for instant tea preparations (range: 90–100). Results show that tea concentration, brewing time, and beverage temperature also have major influences on flavonoid concentrations. Use of specific questions focusing on tea preparation and availability of quantitative estimates of tea flavonoids should enhance epidemiological studies of the relationship between tea consumption and disease risk.

Sonoelectroanalysis--an overview.

The coupling of power-ultrasound with well established but under-exploited electrochemical stripping voltammetry has led to the emergence of a powerful new analytical technique--sonoelectroanalysis. Where classical electroanalytical techniques were plagued with electrode-fouling and/or sensitivity limitations, the introduction of ultrasound into the system has given great increases in analytical efficiency and substrate applicability, predominantly through enhanced mass transport and electrode surface activation. This revitalised analytical technology has been applied to a range of modern analytical problems, allowing sensitive determination of a wide number of analytes from a variety of otherwise hostile matrices, including copper in beer and blood, lead in wine, petrol and river bed sediment, vanadium in aqueous media, nitrite in egg and manganese in instant tea granules. This paper gives an overview of these recent advances.

HPLC determination of catechins and caffeine in tea. Differentiation of green, black and instant teas.

A simple and fast high performance liquid chromatographic method for five catechins and caffeine using an ODS column and a water-acetonitrile-formic acid mobile phase system was developed. The catechins (epicatechin, catechin, epigallocatechin, epigallocatechin gallate, epicatechin gallate) and caffeine were separated by an acetonitrile gradient within 20 min. The detection limit of the method was approximately 10 ng for all the compounds (by injecting 10 microL). Several green, black and instant teas were analysed using this method. By using the studied compounds as chemical descriptors, linear discriminant analysis was performed and complete differentiation of the green, black and instant teas was achieved.