Display omitted
•67 Brazilian coffees were analyzed for their δ13C, δ18O, δ2H and δ15N signatures.•Organic coffee presented higher δ15N values.•k-Nearest neighbors was not efficient in classifying ...coffees from different sites.•Support vector machines correctly classified coffees from São Paulo.•Linear discriminant analysis correctly classified conventional coffees.
Authentication of ground coffee has become an important issue because of fraudulent activities in the sector. In the current work, sixty-seven Brazilian coffees produced in different geographical origins using organic (ORG, n = 25) and conventional (CONV, n = 42) systems were analyzed for their stable isotope ratios (δ13C, δ18O, δ2H, and δ15N). Data were analyzed by inferential analysis to compare the factors whereas linear discriminant analysis (LDA), k-nearest neighbors (k-NN), and support vector machines (SVM) were used to classify the coffees based on their origin. ORG and CONV cultivated coffees could not be differentiated according to C stable isotope ratio (δ13C; p = 0.204), but ORG coffees presented higher values of the N stable isotope ratio (δ15N; p = 0.0006). k-NN presented the best classification results for both ORG and CONV coffees (87% and 67%, respectively). SVM correctly classified coffees produced in São Paulo (75% accuracy), while LDA correctly classified 71% of coffees produced in Minas Gerais.
Environmental and plant factors (soil condition, variety, season, and maturity) and exposure risks of aluminum (Al), manganese (Mn), lead (Pb), cadmium (Cd), and copper (Cu) in tea leaves were ...investigated. The concentrations of these metals in tea leaves could not be predicted by their total concentrations in the soil. During any one season, there were differences in Al, Mn, and Cd levels between tea varieties. Seasonally, autumn tea and/or summer tea had far higher levels of Al, Mn, Pb, and Cd than did spring tea. Tea leaf maturity positively correlated with the concentrations of Al, Mn, Pb, and Cd, but negatively with Cu. The calculated average daily intake doses (mg/ kg•d) for these metal elements were 0.14 (Al), 0.11 (Mn), 2.70 × 10−3 (Cu), 2.80 × 10−4 (Pb), and 2.88 × 10−6 (Cd). The hazard quotient values of each metal were all significantly lower than risk level (=1), suggesting that, for the general population, consumption of tea does not result in the intake of excessive amounts of Al, Mn, Pb, Cd, or Cu. This study identified the factors that can be monitored in the field to decrease consumer exposure to Al and Mn through tea consumption.
Practical Application
Environmental and plant factors influence aluminum and heavy metal accumulation in tea leaves. Consumers of tea are not ingesting excessive Al, Mn, Pb, Cd, or Cu. Trackable factors were identified to manage exposure levels.
The aim of this study was to determine the levels of fluoride in commercial teas and to estimate the contribution of tea consumption to the fluoride recommended daily allowance. A total of 558 tea ...products in 6 categories, green tea, black tea, oolong tea, pu'er tea, white tea, and reprocessed tea, were collected in the period from 2010 to 2013. The levels of fluoride in infusions of these teas were determined by a fluoride‐ion selective electrode. The mean fluoride level in all of the tea samples was 85.16 mg/kg. For each category of tea, the mean fluoride levels were 63.04, 99.74, 52.19, 101.67, 159.78, and 110.54 mg/kg for green tea, black tea, white tea, pu'er tea, oolong tea, and reprocessed tea, respectively. The fluoride content of tea from 4 tea zones in descending order were Southern tea zone (111.39 mg/kg) > Southwest tea zone (78.78 mg/kg) > Jiangnan tea zone (71.73 mg/kg) > Jiangbei tea zone (64.63 mg/kg). These areas produced teas with lower fluoride levels than available foreign‐produced tea (161.11 mg/kg). The mean chronic daily intake (CDI) was 0.02 mg/(kg•day) or 1.27 mg/kg. Generally, consuming tea from these 6 categories does not result in the intake of excessive amounts of fluoride for the general population.
Practical Application
A total of 558 tea products in 6 categories were sampled. The mean fluoride level was determined. The daily intake of fluoride through tea consumption was estimated. Tea consumption does not result in the intake of an excessive amount of fluoride for the general population.
Abstract
Background
Plant protoplasts constitute unique single-cell systems that can be subjected to genomic, proteomic, and metabolomic analysis. An effective and sustainable method for preparing ...protoplasts from tea plants has yet to be established. The protoplasts were osmotically isolated, and the isolation and purification procedures were optimized. Various potential factors affecting protoplast preparation, including enzymatic composition and type, enzymatic hydrolysis duration, mannitol concentration in the enzyme solution, and iodixanol concentration, were evaluated.
Results
The optimal conditions were 1.5% (w/v) cellulase and 0.4–0.6% (w/v) macerozyme in a solution containing 0.4 M mannitol, enzymatic hydrolysis over 10 h, and an iodixanol concentration of 65%. The highest protoplast yield was 3.27 × 10
6
protoplasts g
−1
fresh weight. As determined through fluorescein diacetate staining, maximal cell viability was 92.94%. The isolated protoplasts were round and regularly shaped without agglomeration, and they were less than 20 μm in diameter. Differences in preparation, with regard to yield and viability in the tissues (roots, branches, and leaves), cultivars, and cultivation method, were also observed.
Conclusions
In summary, we reported on a simple, efficient method for preparing protoplasts of whole-organ tissue from tea plant. The findings are expected to contribute to the rapid development of tea plant biology.
•A low-cost and highly efficient biosorbent was developed by loading Al/Fe oxide onto tea waste.•Al/Fe-loaded tea waste exhibited greater fluoride adsorption capacity than original tea ...waste.•Al/Fe-loaded tea waste displayed high fluoride adsorption and low ion leakage across a useful pH range.•The dissolution of Al and Fe into the treated water was lower than WHO standard concentration.
A low-cost and highly efficient biosorbent was prepared by loading Al/Fe oxides onto tea waste and was tested for the ability to remove fluoride from drinking water. Key factors, including adsorbent dosage, initial fluoride concentration, contact time and initial pH of the biosorbent, were investigated. It was found that the solution pH played an important role in the removal of fluoride. The biosorbent combinations Tea–Al or Tea–Al–Fe could reduce the fluoride concentration to below 1.5mg/L in the drinking water, a level which meets the drinking water standard recommended by the World Health Organization (WHO). In addition, the residual concentrations of Al and Fe in the drinking water after Tea–Al–Fe treatment were below the standards set by WHO when treatment was conducted at pH values ranging from 5.0 to 10.0. The experimental data were analyzed using two-parameter theoretical models. The maximum fluoride adsorption capacities for the original tea, Tea–Fe, Tea–Al and Tea–Al–Fe biosorbents were 3.83, 10.47, 13.79 and 18.52mg/g, respectively. These findings demonstrate the suitability of a prepared biosorbent based on tea waste for the removal of fluoride from drinking water.
Authentication of food geographic origin improves traceability, quality control, and brand protection. In this study, elemental fingerprints of 27 mineral elements from 104 samples of Keemun black ...tea from its core (Qimen) and traditional (Dongzhi and Guichi) production regions were analyzed using inductively coupled plasma - mass spectrometry (ICP-MS) coupled with chemometrics to determine the narrow-geographic origin. Variance analysis revealed that Keemun black teas from different regions had their own elemental fingerprints. Although the orthogonal partial least squares-discriminant analysis (OPLS-DA) presented a satisfactory performance, the discrimination of teas based on linear discriminant analysis (LDA) had 100% accuracy and 99% cross-validation, and thus outperformed OPLS-DA. Similarly, support vector machines was able to differentiate 100% of teas from all geographical origins. The results indicate that elemental fingerprints coupled with chemometrics can be used to authenticate the narrow-geographic origins of Keemun black teas.
•Keemun black teas from narrow-geographic origins were authenticated.•Chemometrics was used for authentication of narrow-geographic origin.•SVM and LDA were able to differentiate 100% of Keemun black teas.•Rb, Ba, Sr, Cu, Zn, Cd, P, Mn, Mo and Ni were important in the classification.