Acidity and Fluoride Changes in Fruit Juices during 6 months

Fruit juices become favorite healthy beverages in many countries as well as in Thailand. Most of them are naturally acidic and capable to cause erosion. In addition, some fruit juices contain high concentration of fluoride and may induce dental fluorosis in young children, particularly if they frequently intake. Objective: to investigate the changes of acidity and fluoride content in some natural fruit juice beverages available in Thailand during 6 months. Methods: the studied samples were 11 kinds of selected fruit juice beverages manufactured by 2 companies. Each kind was collected from 3 different shops every month until 6 months, so the total samples were 198. The acidity was measured by pH meter (Orion, 710A, U.S.A.) and the fluoride content was determined by fluoride electrode (Orion, EA940 Ion Analyzer, U.S.A.). The data were analyzed by ANOVA at 95% confident limit. Results: at the first month, the range of averaged pH were 3.363 +/- 0.026 to 4.11 +/- 0.065 and fluoride content were 0.033 +/- 0.002 to 0.511 +/- 0.005 ppm . At the sixth month, the range of averaged pH and fluoride content were 3.323 +/- 0.005 to 4.050 +/- 0.041 and 0.033 +/- 0.002 to 0.471 +/- 0.002 ppm respectively. All samples tended to have erosive potential since their pH were lower than critical pH (5.5) while the fluoride contents were lower and within the safe dose of drinking water recommended for Thai people (0.7 ppm). The data analysis showed that, during 6 month, the acidity changed slightly with no significant difference while fluoride contents significantly changed (p<0.05). Conclusions: fluoride contents in fruit juices available in Bangkok changed during 6 months of production but the acidity did not.