Comparative studies on the qualities of green teas in Karst and non-Karst areas of Yichang, Hubei Province, PR China

United States tea: A synopsis of ongoing tea research and solutions to United States tea production issues

Tea is a steeped beverage made from the leaves of Camellia sinensis. Globally, this healthy, caffeine-containing drink is one of the most widely consumed beverages. At least 50 countries produce tea and most of the production information and tea research is derived from international sources. Here, we discuss information related to tea production, genetics, and chemistry as well as production issues that affect or are likely to affect emerging tea production and research in the United States. With this review, we relay current knowledge on tea production, threats to tea production, and solutions to production problems to inform this emerging market in the United States.

Estimating the catechin concentrations of new shoots in green tea fields using ground-based hyperspectral imagery

Hyperspectral imagery was applied to estimating non-galloyl (EC, EGC) and galloyl (ECG, EGCG) types of catechins in new shoots of green tea. Partial least squares regression models were developed to consider the effects of commercial fertilizer (CF) and organic fertilizer (OF). The models could explain each type of catechin with a precision of more than 0.79, with a few exceptions. When the CF model was applied to the OF hyperspectral reflectance and the OF model was applied to the CF hyperspectral reflectance for mutual prediction, the prediction accuracy was better with the OF models than CF models. The prediction models using both CF and OF data (hyperspectral reflectances, and concentrations of catechins) had a precision of more than 0.76 except for the non-galloyl-type catechins as a group and EGC alone. These results provide useful data for maintaining and improving the quality of green tea.

Environmental Factors Variably Impact Tea Secondary Metabolites in the Context of Climate Change

Climate change is impacting food and beverage crops around the world with implications for environmental and human well-being. While numerous studies have examined climate change effects on crop yields, relatively few studies have examined effects on crop quality (concentrations of nutrients, minerals, and secondary metabolites). This review article employs a culturally relevant beverage crop, tea (Camelia sinensis), as a lens to examine environmental effects linked to climate change on the directionality of crop quality. Our systematic review identified 86 articles as relevant to the review question. Findings provide evidence that shifts in seasonality, water stress, geography, light factors, altitude, herbivory and microbes, temperature, and soil factors that are linked to climate change can result in both increases and decreases up to 50% in secondary metabolites. A gap was found regarding evidence on the direct effects of carbon dioxide on tea quality, highlighting a critical research area for future study. While this systematic review provides evidence that multiple environmental parameters are impacting tea quality, the directionality and magnitude of these impacts is not clear with contradictory evidence between studies likely due to confounding factors including variation in tea variety, cultivar, specific environmental and agricultural management conditions, and differences in research methods. The environmental factors with the most consistent evidence in this systematic review were seasonality and water stress with 14 out of 18 studies (78%) demonstrating a decrease in concentrations of phenolic compounds or their bioactivity with a seasonal shift from the spring and /or first tea harvest to other seasons and seven out of 10 studies (70%) showing an increase in levels of phenolic compounds or their bioactivity with drought stress. Herbivory and soil fertility were two of the variables that showed the greatest contradictory evidence on tea quality. Both herbivory and soil fertility are variables which farmers have the greatest control over, pointing to the importance of agricultural management for climate mitigation and adaptation. The development of evidence-based management strategies and crop breeding programs for resilient cultivars are called for to mitigate climate impacts on crop quality and overall risk in agricultural and food systems.

Monitoring of essential and heavy metals in green tea from different geographical origins

The present study measured the concentrations of toxic metals (Cd, Pb) and other elements (Ca, K, Mg, Na, P, Mn, Fe, Zn, Cu, Co, Cr, Ni) in tea leaves and their infusions. The total metal contents were determined by atomic absorption spectrometry. Phosphorus concentration was determined using an ultraviolet-visible spectrophotometer. Assessment of the mineral composition enabled determination of the leaching percentage and the risk of exceeding provisional tolerable weekly intake for Cd through daily tea consumption. The concentrations of bioelements were analyzed based on the recommended daily intake values for each. According to recently established standards, green tea was found to be a rich source of Mn. The average Pb and Cd levels in a 200-mL beverage were 0.002 and 0.003 mg, respectively. Indian teas had the highest percentage of Cd leaching (43.8%) and Chinese tea had the lowest (9.41%). Multivariate analysis techniques such as factor analysis and cluster analysis were used to differentiate samples according to geographical origin (China, India, or Japan). Potassium, P, Mn, Fe, Cu, Co, and Cd were effective descriptors for the identification of tea samples from China, India, and Japan.

Fluoride content and distribution pattern in groundwater of eastern Yunnan and western Guizhou, China

For study, the fluoride (F) content and distribution pattern in groundwater of eastern Yunnan and western Guizhou fluorosis area in southwestern China, the F content of 93 water samples [groundwater (fissure water, cool spring, and hot springs), rivers water] and 60 rock samples were measured. The result shows the F content of the fissure water and cold spring water is 0.027-0.47 mg/L, and river water is 0.048-0.224 mg/L. The F content of hot spring water is 1.02-6.907 mg/L. The drinking water supplied for local resident is mainly from fissure water, cool spring, and river water. And the F content in all of them is much lower than the Chinese National Standard (1.0 mg/L), which is the safe intake of F in drinking water. The infected people in eastern Yunnan and western Guizhou fluorosis area have very little F intake from the drinking water. The hot spring water in fluorosis area of eastern Yunnan and western Guizhou, southwest China has high F content, which is not suitable for drinking.

Lead and other elemental content of normal and Erwinia carotovora infected Amorphallus konjac corms

Amorphallus konjac corms are important agriculture products in Yichang, Hubei Province, China. The Erwinia carotovora infected Amorphallus konjac corms are processed to food as normal corms. The contents of elements and L: -Proline in the normal and infected Amorphallus konjac corms are analyzed for food safety. Even growing in the almost same soil condition, the contents of Pb, Cd, Mn and L: -Proline in infected corms are significantly higher than those of normal corms (show data as suggestion by peers). Our study suggested that the infected corms are not suitable for food purpose.

A comparison of aluminum levels in tea products from Hong Kong markets and in varieties of tea plants from Hong Kong and India

This study project aimed to investigate the concentrations of aluminum (Al) in tea products available in Hong Kong markets. Tea samples consisting of 47 different tea bags and 28 samples of tea leaves were analysed for concentrations of Al. All tea samples released Al (0.70-5.93 mg L(-1)) during a standard infusion period. In comparison to the Joint FAO/WHO Provisional Tolerable Weekly Intake guideline of 7 mg Al kg(-1) body weight, it was concluded that tea made with these tea leaves will not impose adverse human health impacts. The relative effects of age, soil available Al, and genetic differences on the levels of Al accumulated by tea bushes were investigated. It was found that there was no definite trend between the amount of Al accumulated and the age of tea bushes. The soil available Al influenced the levels of Al in Camellia sinensis to a certain extent, but it was evident that the ability of different varieties of C. sinensis to accumulate Al was variable. C. sinensis accumulated Al in all stages of growth. Young seedlings had lower contents of Al while the mobility of Al within the tea bushes was high. In a manner typical of hyperaccumulators, Al was not retained in the roots, but was consistently transported to the shoots. Aluminum in the tea bush was distributed between the different parts in the following order: mature leaves>roots>branches>young leaves.