Patel Shilpa, Omid Narges, Zohoori Fatemeh V, Maguire Anne, Waldron Kevin J, Valentine Ruth A
1 Centre for Oral Health Research, Newcastle University, UK.
2 School of Health and Social Care, Teesside University, UK.
Nutr Health. 2018 Jun;24(2):111-119. doi: 10.1177/0260106018758781. Epub 2018 Apr 4.
Tea is the second most consumed drink in the UK and a primary source of hydration; it is an important source of dietary fluoride (F) for consumers and also abundant in aluminium (Al). Varying ranges of F concentrations in teas have been reported worldwide which may be, in part, due to differences in analytical techniques used to measure this ion.
The effect of using total ionic adjustment buffers (TISAB) III or IV when measuring F concentration of black teas available in the UK was investigated and compared. Based on this evaluation, the effects of three different infusion times, 1 min, 10 min and 1 h, caffeine content and tea form on the F contents of the tea samples were investigated.
The F concentrations of 47 tea samples were measured directly using a fluoride ion-selective electrode (F-ISE), TISAB III and IV and infusion times of 1 min, 10 min and 1 h.
Mean (SD) F concentration of tea samples for all infusion times was statistically significantly higher ( p < 0.001) measured by TISAB IV (4.37 (2.16) mg/l) compared with TISAB III (3.54 (1.65) mg/l). A statistically significant positive correlation ( p < 0.001) was found between Al concentration (mg/l) and differences in F concentration (mg/l) measured using the two TISABs; the difference in F concentration measured by the two TISABs increased with the magnitude of Al concentration.
Due to higher concentrations of F and Al in teas and their complexing potential, use of TISAB IV facilitates more accurate measurement of F concentration when using an F-ISE and a direct method.
茶是英国第二大消费饮品，也是补水的主要来源；它是消费者膳食氟（F）的重要来源，并且铝（Al）含量也很丰富。全球范围内报道的茶中氟浓度范围各不相同，这可能部分归因于用于测量该离子的分析技术的差异。
研究并比较在测量英国市售红茶的氟浓度时使用总离子强度调节缓冲液（TISAB）III或IV的效果。基于此评估，研究了三种不同冲泡时间（1分钟、10分钟和1小时）、咖啡因含量和茶的形态对茶样品中氟含量的影响。
使用氟离子选择性电极（F-ISE）、TISAB III和IV直接测量47个茶样品的氟浓度，冲泡时间分别为1分钟、10分钟和1小时。
与TISAB III（3.54（1.65）mg/l）相比，使用TISAB IV测量的所有冲泡时间的茶样品平均（标准差）氟浓度在统计学上显著更高（p < 0.001）（4.37（2.16）mg/l）。在铝浓度（mg/l）与使用两种TISAB测量的氟浓度差异（mg/l）之间发现了统计学上显著的正相关（p < 0.001）；两种TISAB测量的氟浓度差异随着铝浓度的增加而增加。
由于茶中氟和铝的浓度较高及其络合潜力，当使用F-ISE和直接法时，使用TISAB IV有助于更准确地测量氟浓度。
