Potential Health Risk of Aluminum in Four Camellia sinensis Cultivars and Its Content as a Function of Leaf Position.

Tea plants can accumulate aluminum (Al) in their leaves to a greater extent than most other edible plants. Few studies, however, address the Al concentration in leaves at different positions, which is important information for tea quality control. Leaves from four different cultivars of Camellia sinensis L. grown in Hawaii were analyzed for Al concentrations at 10 different leaf positions. Each cultivar was harvested in the winter and summer to determine seasonal variations of Al concentrations in the leaves. The results showed that Al concentrations in the winter leaves were an average of 1.2-fold higher than those in the summer leaves, although the seasonal variations were not statistically significant. The total Al concentration of successively lower leaves showed an exponential increase (R2 ≥ 0.900) for all four cultivars in the summer season, whereas those of the winter leaves fit a bi-phase linear regression (R2 ≥ 0.968). The regression of the Al concentrations against the top-5 leaf positions in the winter season fit one linear regression, while that against leaf positions 6-11 fit another linear regression. The average Al concentrations between the third leaf and the shoot plus first two leaves increased approximately 2.7-fold and 1.9-fold for all cultivars in the winter and summer months, respectively. The Al concentrations in the rest of the leaves increased approximately 1.5-fold in a sequential order. The target hazard quotient being between 1.69 × 10-2 and 5.06 × 10-1 in the tea leaf samples of the four cultivars in Hawaii were all less than 1, suggesting negligible health risks for consumers. The results of this study may be useful for directing harvest practices and estimating tea quality.

Commercial Food Processing Operations and Mutagen Formation.

Thermally-induced bacterial mutagens are formed when foods are processed by some commercial food preservation techniques. The processes which involve longer times and higher temperatures are most likely to produce mutagens (e.g., canning and evaporative concentration). Pasteurization and spray drying processes possess a low potential for creation of mutagens. The types of food products with the greatest tendency to contain mutagens following heat treatments are muscle foods such as canned meats and fish. Canned beef broth, chili, hash, roast beef, pink and red salmon, and mackerel contain substances which induce mutation rates up to 20 times higher than spontaneous revertant colonies in the Ames Salmonella mutagenicity assay. Using canned pink salmon as a representative product, reprocessing increased mutagen content, whereas addition of Maillard-browning reaction inhibitors led to significant decreases in mutagen formation. Even though thermally-induced mutagens can arise during household cooking (e.g., frying and charcoal grilling), the consumer can choose to minimize their production through use of lower temperature methods such as boiling, steaming or microwave heating. This option is not available to the consumer of commercially canned foods. Hence, further research into the reduction of mutagen formation during thermal processing is needed.