Background and Aim: Small amount of Fluoride is one of the most well-known factors being useful in controlling decay. Since high consumption of fluoride may cause fluorosis and osteoarthritis .Considering the high consumption of tea in Iran (as a national drink) and high degree content of fluoride in Iranian commonly-used teas, and considering non-awareness on the effect of brewing time on the degree of fluorine freed from tea, the present research aimed to determine the effect of brewing time on the amount of fluorine released from tea in academic year 2007-08 in Chemistry Laboratory of the Faculty of Pharmacology, Tehran University.Materials and Methods: This survey was done in experimental study. Out of 13 brands of tea in Iranian market two brands named Oghab and Doghazal which, in Iranian market in year 1386 (2007-08), were best seller brands of Iranian and foreign teas respectively were selected and three packs of each brand were purchased from three different places of Tehran City . From each type of the teas six samples were taken and brewed in different periods of time 3, 5, 15, 30, 60, and 120 minutes. In each brewing, one gram dry tea was added to 100 ml of boiling distilled water in a Teflon tea pot. For brewing tea, the tea pots were placed in a incubator at temperature of 80 degrees Celsius. When the pre-determined times passed, 10 ml tea extract was taken from each pot and filtered. Then TISAB II buffer at proportion of 1 to 1 was added to the filtered extract. The concentration of fluoride ion was measured in potentiometer method.The amount of the fluoride of tea for each brewing time and for each tea sample were studied with T-Test statistics in each section and between two teas in following up times through ANOVA Test.Results: The average amount of fluoride in Doghazal tea was 0.77±0.04ppm and in Oghab tea was 2.6±0.11ppm. For all times, this difference was statistically meaningful (p‹0.001). The amount of fluoride freed from both brands (Oghab abd Doghazal) increased meaningfully along with increase in brewing time ((p‹0.001).Conclusion: As the brewing time increases, the amount of fluoride freed from tea increases. The best brewing time for tea is about 5 minutes .Furthermore, comparing Oghab tea with Doghazal tea indicates that fluorine content of Oghab tea is higher than other brand .The brewing time suggested by producing company of Doghazal tea (which has been printed on the packages) is 5 minutes which is suitable time. But the brewing time suggested for Oghab tea is 15 minutes which, as the results of this research indicates, leads to introducing of considerable amount of fluoride in the body and thus it does not seem to be advisable time for brewing tea.

Background & objectives: Tea is a hyperaccumulator of fluoride and chronic fluoride intake is associated with multiple negative health outcomes. In this study, six brands of commercially available black and green tea were selected and the fluoride level in tea infusions tested using an ion-selective electrode method. Methods: In this experimental study, the fluoride contents were determined using ionselective electrode (Mettler Toledo, USA ) in four types of black tea and two types of green tea at different brewing time (3, 5, 15, 30, 60 and 120 min). The amount of tea fluoride at any time was investigated by repeated measure ANOVA and two-way ANOVA. Results: Repeated measure ANOVA analysis showed that fluoride release for green and black tea increased as increased brewing time (p<0. 05). Based on the two-way ANOVA and Bonferroni test results, the mean of fluoride concentrations was high in B black tea in all brewing time. E green tea, D black tea, F green tea, A and C black tea released less fluoride respectively p≤ 0. 05. Conclusion: The results of this study showed that the fluoride content of black and green tea in different companies was different. In regard to the impact of the cultivation site and the plant characteristics which the tea is made, companies should include enough information about their product to inform consumers. The amount of fluoride in the all examined tea increases after 3 and 120 min of brewing.

Introduction: The production process of teas and their brewing conditions play a significant role in the properties and compounds found in various types of tea. In this research, the effect of tea brewing time on the amount of total phenolic compounds, antioxidant activity and caffeine content of extracts from four types of tea was investigated. Materials and Methods: Black, white, green and matcha teas were brewed at a constant temperature of 90°C for 10 and 30 minutes, then the total phenolic compounds were determined by the Folin-Ciocalteu method and antioxidant activity was measured by the DPPH and FRAP methods. Caffeine content was also measured by spectrophotometry. Results: Increasing the brewing time from 10 to 30 minutes increased the antioxidant activity, total phenolic compounds, and caffeine content in the tea extracts. In 10 minutes of brewing the examined teas, the highest amounts of total phenolic compounds (360. 10 g/L of gallic acid), antioxidant properties obtained from the Frap test (1681. 36 µm FeSO4) and caffeine content (25. 59 mmol/L) belonged to matcha tea while the highest IC50 value obtained from the DPPH test (3. 98 mmol/L) belonged to black teas. In 30 minutes of tea brewing, the highest amounts of total phenolic compounds (379. 87 mg/L of gallic acid) and antioxidant activities obtained from the FRAP test (1742. 55 µm FeSO4) belonged to chinese green tea and Iranian green tea, respectively. The highest amounts of IC50 (2. 78 g/L) and caffeine (27. 01 mg/L) belonged to black teas. Conclusion: The results showed that the type of tea and its brewing conditions have a significant effect on the amount of bioactive compounds present in the consumed tea extract.

The final quality and cost of a manufactured product are determined to a large extent ‎by the engineering design of the product and its production process through activities ‎of off-line quality control methods, namely, System Design, Parameter Design and ‎Tolerance Design. However, in the context of most non-industrialized countries, the ‎off-line quality activities of product design and system design of production process ‎design stages are negligible if not absent. Thus, whatever quality control activities ‎there are in these countries should be confined only to conducting parameter (robust) ‎design of manufacturing process design and on-line quality control activities. Out of ‎these two activities, Robust Design is the most economical method as it increases ‎quality and / or reduces costs without imposing any further investment in factors of ‎production. It is in this context that robust design as an optimization method has been ‎used to improve the product quality of cleaning sub-process of beer brewing process ‎of Behnoosh Company in which 358% improvement over the current condition has ‎been achieved‏.‏